Insect cells as factories for biomanufacturing.

PubMed

Drugmand, Jean-Christophe; Schneider, Yves-Jacques; Agathos, Spiros N

2012-01-01

Insect cells (IC) and particularly lepidopteran cells are an attractive alternative to mammalian cells for biomanufacturing. Insect cell culture, coupled with the lytic expression capacity of baculovirus expression vector systems (BEVS), constitutes a powerful platform, IC-BEVS, for the abundant and versatile formation of heterologous gene products, including proteins, vaccines and vectors for gene therapy. Such products can be manufactured on a large scale thanks to the development of efficient and scaleable production processes involving the integration of a cell growth stage and a stage of cell infection with the recombinant baculovirus vector. Insect cells can produce multimeric proteins functionally equivalent to the natural ones and engineered vectors can be used for efficient expression. Insect cells can be cultivated easily in serum- and protein-free media. A growing number of companies are currently developing an interest in producing therapeutics using IC-BEVS, and many products are today in clinical trials and on the market for veterinary and human applications. This review summarizes current knowledge on insect cell metabolism, culture conditions and applications. Copyright © 2011 Elsevier Inc. All rights reserved.

Predators indirectly reduce the prevalence of an insect-vectored plant pathogen independent of predator diversity.

PubMed

Long, Elizabeth Y; Finke, Deborah L

2015-04-01

A widely cited benefit of predator diversity is greater suppression of insect herbivores, with corresponding increases in plant biomass. In the context of a vector-borne pathogen system, predator species richness may also influence plant disease risk via the direct effects of predators on the abundance and behavior of herbivores that also act as pathogen vectors. Using an assemblage of generalist insect predators, we examined the relationship between predator species richness and the prevalence of the aphid-vectored cereal yellow dwarf virus in wheat. We found that increasing predator richness enhanced suppression of the vector population and that pathogen prevalence was reduced when predators were present, but the reduction in prevalence was independent of predator species richness. To determine the mechanism(s) by which predator species richness contributes to vector suppression, but not pathogen prevalence, we evaluated vector movement and host plant occupancy in response to predator treatments. We found that pathogen prevalence was unrelated to vector suppression because host plant occupancy by vectors did not vary as a function of vector abundance. However, the presence of predators reduced pathogen prevalence because predators stimulated greater plant-to-plant movement by vectors, which likely diminished vector feeding time and reduced the transmission efficiency of this persistent pathogen. We conclude that community structure (i.e., the presence of predators), but not predator diversity, is a potential factor influencing local plant infection by this insect-vectored pathogen.

Insects as alternative hosts for phytopathogenic bacteria.

PubMed

Nadarasah, Geetanchaly; Stavrinides, John

2011-05-01

Phytopathogens have evolved specialized pathogenicity determinants that enable them to colonize their specific plant hosts and cause disease, but their intimate associations with plants also predispose them to frequent encounters with herbivorous insects, providing these phytopathogens with ample opportunity to colonize and eventually evolve alternative associations with insects. Decades of research have revealed that these associations have resulted in the formation of bacterial-vector relationships, in which the insect mediates dissemination of the plant pathogen. Emerging research, however, has highlighted the ability of plant pathogenic bacteria to use insects as alternative hosts, exploiting them as they would their primary plant host. The identification of specific bacterial genetic determinants that mediate the interaction between bacterium and insect suggests that these interactions are not incidental, but have likely arisen following the repeated association of microorganisms with particular insects over evolutionary time. This review will address the biology and ecology of phytopathogenic bacteria that interact with insects, including the traditional role of insects as vectors, as well as the newly emerging paradigm of insects serving as alternative primary hosts. Also discussed is one case where an insect serves as both host and vector, which may represent a transitionary stage in the evolution of insect-phytopathogen associations. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Sterile-Insect Methods for Control of Mosquito-Borne Diseases: An Analysis

PubMed Central

Benedict, Mark; Bellini, Romeo; Clark, Gary G.; Dame, David A.; Service, Mike W.; Dobson, Stephen L.

2010-01-01

Abstract Effective vector control, and more specifically mosquito control, is a complex and difficult problem, as illustrated by the continuing prevalence (and spread) of mosquito-transmitted diseases. The sterile insect technique and similar methods control certain agricultural insect pest populations in a species-specific, environmentally sound, and effective manner; there is increased interest in applying this approach to vector control. Such an approach, like all others in use and development, is not a one-size-fits-all solution, and will be more appropriate in some situations than others. In addition, the proposed release of pest insects, and more so genetically modified pest insects, is bound to raise questions in the general public and the scientific community as to such a method's efficacy, safety, and sustainability. This article attempts to address these concerns and indicate where sterile-insect methods are likely to be useful for vector control. PMID:19725763

Prevention of vector transmitted diseases with clove oil insect repellent.

PubMed

Shapiro, Rochel

2012-08-01

Vector repellent is one element in the prevention of vector-borne diseases. Families that neglect protecting their children against vectors risk their children contracting illnesses such as West Nile virus, eastern equine encephalitis, Lyme disease, malaria, dengue hemorrhagic fever, yellow fever, babesiosis, Crimean-Congo hemorrhagic fever, Rocky Mountain spotted fever, Southern tick-associated rash illness, ehrlichiosis, tick-borne relapsing fever, tularemia, and other insect and arthropod related diseases (CDC, 2011). Identification of families at risk includes screening of the underlying basis for reluctance to apply insect repellent. Nurses and physicians can participate in a positive role by assisting families to determine the proper prophylaxis by recommending insect repellent choices that are economical, safe, and easy to use. A holistic alternative might include the suggestion of clove oil in cases where families might have trepidations regarding the use of DEET on children. This article will explore the safety and effectiveness of clove oil and its use as an insect repellent. Copyright © 2012 Elsevier Inc. All rights reserved.

Cell-cell signaling controls Xylella fastidiosa interactions with both insects and plants

PubMed Central

Newman, Karyn L.; Almeida, Rodrigo P. P.; Purcell, Alexander H.; Lindow, Steven E.

2004-01-01

Xylella fastidiosa, which causes Pierce's disease of grapevine and other important plant diseases, is a xylem-limited bacterium that depends on insect vectors for transmission. Although many studies have addressed disease symptom development and transmission of the pathogen by vectors, little is known about the bacterial mechanisms driving these processes. Recently available X. fastidiosa genomic sequences and molecular tools have provided new routes for investigation. Here, we show that a diffusible signal molecule is required for biofilm formation in the vector and for vector transmission to plants. We constructed strains of X. fastidiosa mutated in the rpfF gene and determined that they are unable to produce the signal activity. In addition, rpfF mutants are more virulent than the wild type when mechanically inoculated into plants. This signal therefore directs interaction of X. fastidiosa with both its insect vector and plant host. Interestingly, rpfF mutants can still form in planta biofilms, which differ architecturally from biofilms in insects, suggesting that biofilm architecture, rather than a passive response to the environment, is actively determined by X. fastidiosa gene expression. This article reports a cell-cell signaling requirement for vector transmission. Identification of the genes regulated by rpfF should elucidate bacterial factors involved in transmission and biofilm formation in the insect. PMID:14755059

CRISPR-Cas9 vectors for genome editing and host engineering in the baculovirus-insect cell system.

PubMed

Mabashi-Asazuma, Hideaki; Jarvis, Donald L

2017-08-22

The baculovirus-insect cell system (BICS) has been widely used to produce many different recombinant proteins for basic research and is being used to produce several biologics approved for use in human or veterinary medicine. Early BICS were technically complex and constrained by the relatively primordial nature of insect cell protein glycosylation pathways. Since then, recombination has been used to modify baculovirus vectors-which has simplified the system-and transform insect cells, which has enhanced its protein glycosylation capabilities. Now, CRISPR-Cas9 tools for site-specific genome editing are needed to facilitate further improvements in the BICS. Thus, in this study, we used various insect U6 promoters to construct CRISPR-Cas9 vectors and assessed their utility for site-specific genome editing in two insect cell lines commonly used as hosts in the BICS. We demonstrate the use of CRISPR-Cas9 to edit an endogenous insect cell gene and alter protein glycosylation in the BICS.

In vivo production of recombinant proteins using occluded recombinant AcMNPV-derived baculovirus vectors.

PubMed

Guijarro-Pardo, Eva; Gómez-Sebastián, Silvia; Escribano, José M

2017-12-01

Trichoplusia ni insect larvae infected with vectors derived from the Autographa californica multiple nucleopolyhedrovirus (AcMNPV), are an excellent alternative to insect cells cultured in conventional bioreactors to produce recombinant proteins because productivity and cost-efficiency reasons. However, there is still a lot of work to do to reduce the manual procedures commonly required in this production platform that limit its scalability. To increase the scalability of this platform technology, a current bottleneck to be circumvented in the future is the need of injection for the inoculation of larvae with polyhedrin negative baculovirus vectors (Polh-) because of the lack of oral infectivity of these viruses, which are commonly used for production in insect cell cultures. In this work we have developed a straightforward alternative to obtain orally infective vectors derived from AcMNPV and expressing recombinant proteins that can be administered to the insect larvae (Trichoplusia ni) by feeding, formulated in the insect diet. The approach developed was based on the use of a recombinant polyhedrin protein expressed by a recombinant vector (Polh+), able to co-occlude any recombinant Polh- baculovirus vector expressing a recombinant protein. A second alternative was developed by the generation of a dual vector co-expressing the recombinant polyhedrin protein and the foreign gene of interest to obtain the occluded viruses. Additionally, by the incorporation of a reporter gene into the helper Polh+ vector, it was possible the follow-up visualization of the co-occluded viruses infection in insect larvae and will help to homogenize infection conditions. By using these methodologies, the production of recombinant proteins in per os infected larvae, without manual infection procedures, was very similar in yield to that obtained by manual injection of recombinant Polh- AcMNPV-based vectors expressing the same proteins. However, further analyses will be required for a detailed comparison of production yields reached by injection vs oral infections for different recombinant proteins. In conclusion, these results open the possibility of future industrial scaling-up production of recombinant proteins in insect larvae by reducing manual operations. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of mycoflora and infestation of insects, vector of Aspergillus section Flavi, in stored peanut from Argentina.

PubMed

Nesci, Andrea; Montemarani, Analía; Etcheverry, Miriam

2011-02-01

The occurrence of spoilage fungi and Aspergillus section Flavi populations, the aflatoxins incidence, the role of insects as vectors of mycotoxin-producing fungi and the AFs-producing ability of the isolated species throughout the peanut (Arachis hypogaea L.) storage period were evaluated. Analyses of fungal populations from 95 peanut seed samples did not demonstrate significant differences between the incidences in each sampling period. Aspergillus section Flavi were isolated during all incubation periods. Cryptolestes spp. (Coleoptera: Cucujidae) were collected in August, September and October with 18, 16 and 28% of peanut samples contaminated, respectively. Insects isolated during August showed 69% of Aspergillus section Flavi contamination. A. flavus was the most frequently isolated (79%) from peanut seeds and from insect (59%). The greater levels of AFB1 were detected in September and October with a mean of 68.86 μg/kg and 69.12 μg/kg respectively. The highest proportion of A. flavus toxigenic strains (87.5%) was obtained in June. The presence of Aspergillus section Flavi and insect vectors of aflatoxigenic fungi presented a potential risk for aflatoxin production during the peanut storage period. Integrated management of fungi and insect vectors is in progress.

Insects as vectors: systematics and biology.

PubMed

Rodhain, F

2015-04-01

Among the many complex relationships between insects and microorganisms such as viruses, bacteria and parasites, some have resulted in the establishment of biological systems within which the insects act as a biological vector for infectious agents. It is therefore advisable to understand the identity and biology of these vectors in depth, in order to define procedures for epidemiological surveillance and anti-vector control. The following are successively reviewed in this article: Anoplura (lice), Siphonaptera (fleas), Heteroptera (bugs: Cimicidae, Triatoma, Belostomatidae), Psychodidae (sandflies), Simuliidae (black flies), Ceratopogonidae (biting midges), Culicidae (mosquitoes), Tabanidae (horseflies) and Muscidae (tsetse flies, stable flies and pupipara). The authors provide a rapid overview of the morphology, systematics, development cycle and bio-ecology of each of these groups of vectors. Finally, their medical and veterinary importance is briefly reviewed.

Development of a novel set of Gateway-compatible vectors for live imaging in insect cells.

PubMed

Maroniche, G A; Mongelli, V C; Alfonso, V; Llauger, G; Taboga, O; del Vas, Mariana

2011-10-01

Insect genomics is a growing area of research. To exploit fully the genomic data that are being generated, high-throughput systems for the functional characterization of insect proteins and their interactomes are required. In this work, a Gateway-compatible vector set for expression of fluorescent fusion proteins in insect cells was developed. The vector set was designed to express a protein of interest fused to any of four different fluorescent proteins [green fluorescent protein (GFP), cyan fluorescent protein (CFP), yellow fluorescent protein (YFP) and mCherry] by either the C-terminal or the N-terminal ends. Additionally, a collection of organelle-specific fluorescent markers was assembled for colocalization with fluorescent recombinant proteins of interest. Moreover, the vector set was proven to be suitable for simultaneously detecting up to three proteins by multiple labelling. The use of the vector set was exemplified by defining the subcellular distribution of Mal de Río Cuarto virus (MRCV) outer coat protein P10 and by analysing the in vivo self-interaction of the MRCV viroplasm matrix protein P9-1 in Förster resonance energy transfer (FRET) experiments. In conclusion, we have developed a valuable tool for high-throughput studies of protein subcellular localization that will aid in the elucidation of the function of newly described insect and virus proteins. © 2011 The Authors. Insect Molecular Biology © 2011 The Royal Entomological Society.

The Role of Bacterial Chaperones in the Circulative Transmission of Plant Viruses by Insect Vectors

PubMed Central

Kliot, Adi; Ghanim, Murad

2013-01-01

Persistent circulative transmission of plant viruses involves complex interactions between the transmitted virus and its insect vector. Several studies have shown that insect vector proteins are involved in the passage and the transmission of the virus. Interestingly, proteins expressed by bacterial endosymbionts that reside in the insect vector, were also shown to influence the transmission of these viruses. Thus far, the transmission of two plant viruses that belong to different virus genera was shown to be facilitated by a bacterial chaperone protein called GroEL. This protein was shown to be implicated in the transmission of Potato leafroll virus (PLRV) by the green peach aphid Myzus persicae, and the transmission of Tomato yellow leaf curl virus (TYLCV) by the sweetpotato whitefly Bemisia tabaci. These tri-trophic levels of interactions and their possible evolutionary implications are reviewed. PMID:23783810

Evidence on Possible Mycoplasma Etiology of Aster Yellows Disease II. Suppression of Aster Yellows in Insect Vectors

PubMed Central

Whitcomb, R. F.; Davis, R. E.

1970-01-01

Chlortetracycline or chloramphenicol (but not kanamycin, penicillin, or erythromycin), when administered in hydroponic solution to diseased aster, reduced the availability of the aster yellows (AY) agent to nymphs of Macrosteles fascifrons (Stål). Insects exposed to healthy plants whose roots were immersed in chlortetracycline were able to acquire AY agent from diseased plants the day after removal from the antibiotic-treated plants, but the latent period of the ensuing disease in the insects was prolonged. Chlortetracycline or tylosin tartrate blocked AY infection in nymphs injected with a mixture of antibiotic and the AY agent, but polymyxin, neomycin, vancomycin, penicillin, carbomycin, or chloramphenicol did not. All tetracyclines tested, methacycline, oxytetracycline, and chlortetracycline, produced a dramatic reduction in the ability of infected vectors to transmit AY agent. Tylosin tartrate also reduced transmission when injected into AY-transmitting vectors, but carbomycin, spectinomycin, cycloserine, penicillin, erythromycin, or kanamycin had no such effect. During the first 10 days after injection of tylosin tartrate or oxytetracycline into transmitting vectors, ability of the insects to transmit AY decayed rapidly. Transmission by insects injected with buffer alone, after decreasing the first day after injection, gradually returned to its normal level in less than 1 week. By 2 to 3 weeks after injection with tylosin or oxytetracycline, ability to transmit AY was regained by vectors. The results suggest that tetracycline antibiotics and tylosin tartrate inhibit multiplication of AY agent in the insect. The spectrum of antibiotic activity in the insect is consistent with the hypothesis that AY and other plant yellows diseases are caused by mycoplasma-like organisms. PMID:16557821

Learning and memory in disease vector insects

PubMed Central

Vinauger, Clément; Lahondère, Chloé; Cohuet, Anna; Lazzari, Claudio R.; Riffell, Jeffrey A.

2016-01-01

Learning and memory plays an important role in host preference and parasite transmission by disease vector insects. Historically there has been a dearth of standardized protocols that permit testing their learning abilities, thus limiting discussion on the potential epidemiological consequences of learning and memory to a largely speculative extent. However, with increasing evidence that individual experience and associative learning can affect processes such as oviposition site selection and host preference, it is timely to review the recently acquired knowledge, identify research gaps and discuss the implication of learning in disease vector insects in perspective with control strategies. PMID:27450224

Identification of Migratory Insects from their Physical Features using a Decision-Tree Support Vector Machine and its Application to Radar Entomology.

PubMed

Hu, Cheng; Kong, Shaoyang; Wang, Rui; Long, Teng; Fu, Xiaowei

2018-04-03

Migration is a key process in the population dynamics of numerous insect species, including many that are pests or vectors of disease. Identification of insect migrants is critically important to studies of insect migration. Radar is an effective means of monitoring nocturnal insect migrants. However, species identification of migrating insects is often unachievable with current radar technology. Special-purpose entomological radar can measure radar cross-sections (RCSs) from which the insect mass, wingbeat frequency and body length-to-width ratio (a measure of morphological form) can be estimated. These features may be valuable for species identification. This paper explores the identification of insect migrants based on the mass, wingbeat frequency and length-to-width ratio, and body length is also introduced to assess the benefit of adding another variable. A total of 23 species of migratory insects captured by a searchlight trap are used to develop a classification model based on decision-tree support vector machine method. The results reveal that the identification accuracy exceeds 80% for all species if the mass, wingbeat frequency and length-to-width ratio are utilized, and the addition of body length is shown to further increase accuracy. It is also shown that improving the precision of the measurements leads to increased identification accuracy.

Immune tolerance of vector beetle to its partner plant parasitic nematode modulated by its insect parasitic nematode.

PubMed

Zhou, Jiao; Zhao, Li-Lin; Yu, Hai-Ying; Wang, Yan-Hong; Zhang, Wei; Hu, Song-Nian; Zou, Zhen; Sun, Jiang-Hua

2018-04-02

Immune response of insect vectors to transmitted pathogens or insect hosts against parasites are well studied, whereas the mechanism of tripartite interactions remains elusive. In this study, we investigated the immune interactions of the vector beetle Monochamus alternatus ( Ma) to the devastating plant parasitic nematode Bursaphelenchus xylophilus ( Bx) and the insect parasitic nematode Howardula phyllotretae ( Hp). We report the unique immune mechanism by which the vector beetle tolerates many devastating Bx in its trachea, yet that immune tolerance is compromised by the parasitic nematode Hp. Contact with either nematode species triggers epithelial reactive oxygen species (ROS) production in Ma. Only the entry of Bx, not Hp, infection, induces increased expression of antioxidative genes, through which the ROS levels are balanced in the trachea of beetles. Furthermore, we found that up-regulation of antioxidative genes was induced by the interaction of Toll receptors. In contrast, beetles infected by Hp retain high levels of oxidative stress and melanization in trachea, and as a result, decrease Bx loading. This study highlights the role of Toll receptors in mediating the activation of antioxidative genes in immune tolerance to plant parasitic nematodes, and suggests the use of insect parasites as a biologic control.-Zhou, J., Zhao, L.-L., Yu, H.-Y., Wang, Y.-H., Zhang, W., Hu, S.-N., Zou, Z., Sun, J.-H. Immune tolerance of vector beetle to its partner plant parasitic nematode modulated by its insect parasitic nematode.

Insect Repellents: Modulators of mosquito odorant receptor activity

USDA-ARS?s Scientific Manuscript database

Mosquitoes vector numerous pathogens that cause diseases including malaria, yellow fever, dengue fever and chikungunya. DEET, IR3535, Picaridin and 2-undecanone are insect repellents that are used to prevent interactions between humans and a broad array of disease vectors including mosquitoes. While...

Olfactory disruption: towards controlling important insect vectors of disease

USDA-ARS?s Scientific Manuscript database

Chemical repellents are used to decrease contacts between insect disease vectors and their hosts, thus reducing the probability of disease transmission. The molecular mechanisms by which repellents have their effects are poorly understood and remain a controversial topic. Here we present recent re...

Cellular and molecular aspects of rhabdovirus interactions with insect and plant hosts.

PubMed

Ammar, El-Desouky; Tsai, Chi-Wei; Whitfield, Anna E; Redinbaugh, Margaret G; Hogenhout, Saskia A

2009-01-01

The rhabdoviruses form a large family (Rhabdoviridae) whose host ranges include humans, other vertebrates, invertebrates, and plants. There are at least 90 plant-infecting rhabdoviruses, several of which are economically important pathogens of various crops. All definitive plant-infecting and many vertebrate-infecting rhabdoviruses are persistently transmitted by insect vectors, and a few putative plant rhabdoviruses are transmitted by mites. Plant rhabdoviruses replicate in their plant and arthropod hosts, and transmission by vectors is highly specific, with each virus species transmitted by one or a few related insect species, mainly aphids, leafhoppers, or planthoppers. Here, we provide an overview of plant rhabdovirus interactions with their insect hosts and of how these interactions compare with those of vertebrate-infecting viruses and with the Sigma rhabdovirus that infects Drosophila flies. We focus on cellular and molecular aspects of vector/host specificity, transmission barriers, and virus receptors in the vectors. In addition, we briefly discuss recent advances in understanding rhabdovirus-plant interactions.

Seasonal Abundance and Natural Inoculativity of Insect Vectors of Xylella fastidiosa in Oklahoma Tree Nurseries and Vineyards.

PubMed

Overall, Lisa M; Rebek, Eric J

2015-12-01

Xylella fastidiosa is the causative agent of diseases of perennial plants including peach, plum, elm, oak, pecan, and grape. This bacterial pathogen is transmitted by xylem-feeding insects. In recent years, Pierce's disease of grape has been detected in 10 counties in central and northeastern Oklahoma, prompting further investigation of the disease epidemiology in this state. We surveyed vineyards and tree nurseries in Oklahoma for potential insect vectors to determine species composition, infectivity, and natural inoculativity of commonly captured insect vectors. Yellow sticky cards were used to sample insect fauna at each location. Insects were removed from sticky cards and screened for X. fastidiosa using immunocapture-PCR to determine their infectivity. A second objective was to test the natural inoculativity of insect vectors that are found in vineyards. Graphocephala versuta (Say), Graphocephala coccinea (Forster), Paraulacizes irrorata (F.), Oncometopia orbona (F.), Cuerna costalis (F.), and Entylia carinata Germar were collected from vineyards and taken back to the lab to determine their natural inoculativity. Immunocapture-PCR was used to test plant and insect samples for presence of X. fastidiosa. The three most frequently captured species from vineyards and tree nurseries were G. versuta, Clastoptera xanthocephala Germar, and O. orbona. Of those insects screened for X. fastidiosa, 2.4% tested positive for the bacterium. Field-collected G. versuta were inoculative to both ragweed and alfalfa. Following a 7-d inoculation access period, a higher percentage of alfalfa became infected than ragweed. Results from this study provide insight into the epidemiology of X. fastidiosa in Oklahoma. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Model Framework to Estimate Impact and Cost of Genetics-Based Sterile Insect Methods for Dengue Vector Control

PubMed Central

Alphey, Nina; Alphey, Luke; Bonsall, Michael B.

2011-01-01

Vector-borne diseases impose enormous health and economic burdens and additional methods to control vector populations are clearly needed. The Sterile Insect Technique (SIT) has been successful against agricultural pests, but is not in large-scale use for suppressing or eliminating mosquito populations. Genetic RIDL technology (Release of Insects carrying a Dominant Lethal) is a proposed modification that involves releasing insects that are homozygous for a repressible dominant lethal genetic construct rather than being sterilized by irradiation, and could potentially overcome some technical difficulties with the conventional SIT technology. Using the arboviral disease dengue as an example, we combine vector population dynamics and epidemiological models to explore the effect of a program of RIDL releases on disease transmission. We use these to derive a preliminary estimate of the potential cost-effectiveness of vector control by applying estimates of the costs of SIT. We predict that this genetic control strategy could eliminate dengue rapidly from a human community, and at lower expense (approximately US$ 2∼30 per case averted) than the direct and indirect costs of disease (mean US$ 86–190 per case of dengue). The theoretical framework has wider potential use; by appropriately adapting or replacing each component of the framework (entomological, epidemiological, vector control bio-economics and health economics), it could be applied to other vector-borne diseases or vector control strategies and extended to include other health interventions. PMID:21998654

Harnessing Host-Vector Microbiome for Sustainable Plant Disease Management of Phloem-Limited Bacteria.

PubMed

Trivedi, Pankaj; Trivedi, Chanda; Grinyer, Jasmine; Anderson, Ian C; Singh, Brajesh K

2016-01-01

Plant health and productivity is strongly influenced by their intimate interaction with deleterious and beneficial organisms, including microbes, and insects. Of the various plant diseases, insect-vectored diseases are of particular interest, including those caused by obligate parasites affecting plant phloem such as Candidatus ( Ca .) Phytoplasma species and several species of Ca. Liberibacter. Recent studies on plant-microbe and plant-insect interactions of these pathogens have demonstrated that plant-microbe-insect interactions have far reaching consequences for the functioning and evolution of the organisms involved. These interactions take place within complex pathosystems and are shaped by a myriad of biotic and abiotic factors. However, our current understanding of these processes and their implications for the establishment and spread of insect-borne diseases remains limited. This article highlights the molecular, ecological, and evolutionary aspects of interactions among insects, plants, and their associated microbial communities with a focus on insect vectored and phloem-limited pathogens belonging to Ca. Phytoplasma and Ca. Liberibacter species. We propose that innovative and interdisciplinary research aimed at linking scales from the cellular to the community level will be vital for increasing our understanding of the mechanisms underpinning plant-insect-microbe interactions. Examination of such interactions could lead us to applied solutions for sustainable disease and pest management.

Flufenoxuron, an insect growth regulator, promotes peroral infection by nucleopolyhedrovirus (BmNPV) budded particles in the silkworm, Bombyx mori L.

PubMed

Arakawa, Toru; Furuta, Yoji; Miyazawa, Mitsuhiro; Kato, Masao

2002-02-01

A novel method was developed to infect perorally the silkworm Bombyx mori L. with budded particles of nucleopolyhedrovirus (BmNPV) using flufenoxuron, an insect growth regulator. NPV vectors are used to obtain proteins that occur naturally in minute amounts. NPV vectors are constructed conventionally by replacing the polyhedrin gene with the foreign gene of interest. These vectors thus do not produce polyhedra. The budded virus particle suspension of these vectors is produced in a cell culture and used as the stock inoculum. Budded NPV particles do not infect their host perorally. The inoculum is injected manually into the individual host using a syringe. It was found that B. mori L. fed on the insect growth regulator flufenoxuron were sensitive to BmNPV budded particles given perorally. Over 90% of B. mori L. ingesting BmNPV budded particles (1.3 x 10(6) TCID(50) units per larva) after consuming an artificial diet for 24 h, containing 0.1% (w/w) flufenoxuron died of the viral infection. The peroral inoculation of BmNPV budded particles by flufenoxuron may thus lead to industrial pharmaceutical production using a baculovirus vector for large numbers of insect hosts.

Egg maturation by the glassy-winged sharpshooter (Hemiptera: Cicadellidae); a vector of Xylella fastidiosa

USDA-ARS?s Scientific Manuscript database

Rates of spread of insect-transmitted plant pathogens are a function of vector abundance. Despite this, factors affecting population growth rates of insects that transmit plant pathogens have received limited attention. The glassy-winged sharpshooter (Homalodisca vitripennis) feeds on xylem-sap and ...

From Fossil Parasitoids to Vectors: Insects as Parasites and Hosts.

PubMed

Nagler, Christina; Haug, Joachim T

2015-01-01

Within Metazoa, it has been proposed that as many as two-thirds of all species are parasitic. This propensity towards parasitism is also reflected within insects, where several lineages independently evolved a parasitic lifestyle. Parasitic behaviour ranges from parasitic habits in the strict sense, but also includes parasitoid, phoretic or kleptoparasitic behaviour. Numerous insects are also the host for other parasitic insects or metazoans. Insects can also serve as vectors for numerous metazoan, protistan, bacterial and viral diseases. The fossil record can report this behaviour with direct (parasite associated with its host) or indirect evidence (insect with parasitic larva, isolated parasitic insect, pathological changes of host). The high abundance of parasitism in the fossil record of insects can reveal important aspects of parasitic lifestyles in various evolutionary lineages. For a comprehensive view on fossil parasitic insects, we discuss here different aspects, including phylogenetic systematics, functional morphology and a direct comparison of fossil and extant species. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Plant Bacterial Pathogen Manipulates Its Insect Vector's Energy Metabolism

PubMed Central

Hijaz, Faraj; Ebert, Timothy A.; Rogers, Michael E.

2016-01-01

ABSTRACT Insect-transmitted plant-pathogenic bacteria may alter their vectors' fitness, survival, behavior, and metabolism. Because these pathogens interact with their vectors on the cellular and organismal levels, potential changes at the biochemical level might occur. “Candidatus Liberibacter asiaticus” (CLas) is transmitted in a persistent, circulative, and propagative manner. The genome of CLas revealed the presence of an ATP translocase that mediates the uptake of ATP and other nucleotides from medium to achieve its biological processes, such as growth and multiplication. Here, we showed that the levels of ATP and many other nucleotides were significantly higher in CLas-infected than healthy psyllids. Gene expression analysis showed upregulation for ATP synthase subunits, while ATPase enzyme activity showed a decrease in ATPase activity. These results indicated that CLas stimulated Diaphorina citri to produce more ATP and many other energetic nucleotides, while it may inhibit their consumption by the insect. As a result of ATP accumulation, the adenylated energy charge (AEC) increased and the AMP/ATP and ADP/ATP ratios decreased in CLas-infected D. citri psyllids. Survival analysis confirmed a shorter life span for CLas-infected D. citri psyllids. In addition, electropenetrography showed a significant reduction in total nonprobing time, salivation time, and time from the last E2 (phloem ingestion) to the end of recording, indicating that CLas-infected psyllids were at a higher hunger level and they tended to forage more often. This increased feeding activity reflects the CLas-induced energetic stress. In conclusion, CLas alters the energy metabolism of its psyllid vector, D. citri, in order to secure its need for energetic nucleotides. IMPORTANCE Insect transmission of plant-pathogenic bacteria involves propagation and circulation of the bacteria within their vectors. The transmission process is complex and requires specific interactions at the molecular and biochemical levels. The growth of the plant-pathogenic bacteria in the hemolymph of their vectors indicated that the hemolymph contains all the necessary nutrients for their growth. In addition to nutrients, “Candidatus Liberibacter asiaticus” (CLas) can take up energetic nucleotides, such as ATP, from its vector, Diaphorina citri, using ATP translocase. In this study, we found that the CLas pathogen manipulates the energy metabolism of its insect vector. The accumulation of ATP in CLas-infected D. citri psyllids indicated that CLas induces ATP production to fulfill its need for this energetic compound. As a result of ATP accumulation, a shorter life span and altered feeding behavior were observed. These findings increase our knowledge of insect transmission of the persistent-circulative-propagative type of plant pathogens vectored by insects. PMID:28039132

Effects of Cucumber mosaic virus infection on vector and non-vector herbivores of squash.

PubMed

Mauck, Kerry E; De Moraes, Consuelo M; Mescher, Mark C

2010-11-01

Plant chemicals mediating interactions with insect herbivores seem a likely target for manipulation by insectvectored plant pathogens. Yet, little is currently known about the chemical ecology of insect-vectored diseases or their effects on the ecology of vector and nonvector insects. We recently reported that a widespread plant pathogen, Cucumber mosaic virus (CMV), greatly reduces the quality of host-plants (squash) for aphid vectors, but that aphids are nevertheless attracted to the odors of infected plants-which exhibit elevated emissions of a volatile blend otherwise similar to the odor of healthy plants. This finding suggests that exaggerating existing host-location cues can be a viable vector attraction strategy for pathogens that otherwise reduce host quality for vectors. Here we report additional data regarding the effects of CMV infection on plant interactions with a common nonvector herbivore, the squash bug, Anasa tristis, which is a pest in this system. We found that adult A. tristis females preferred to oviposit on healthy plants in the field, and that healthy plants supported higher populations of nymphs. Collectively, our recent findings suggest that CMV-induced changes in host plant chemistry influence the behavior of both vector and non-vector herbivores, with significant implications both for disease spread and for broader community-level interactions.

Vector-Borne Bacterial Plant Pathogens: Interactions with Hemipteran Insects and Plants

PubMed Central

Perilla-Henao, Laura M.; Casteel, Clare L.

2016-01-01

Hemipteran insects are devastating pests of crops due to their wide host range, rapid reproduction, and ability to transmit numerous plant-infecting pathogens as vectors. While the field of plant–virus–vector interactions has flourished in recent years, plant–bacteria–vector interactions remain poorly understood. Leafhoppers and psyllids are by far the most important vectors of bacterial pathogens, yet there are still significant gaps in our understanding of their feeding behavior, salivary secretions, and plant responses as compared to important viral vectors, such as whiteflies and aphids. Even with an incomplete understanding of plant–bacteria–vector interactions, some common themes have emerged: (1) all known vector-borne bacteria share the ability to propagate in the plant and insect host; (2) particular hemipteran families appear to be incapable of transmitting vector-borne bacteria; (3) all known vector-borne bacteria have highly reduced genomes and coding capacity, resulting in host-dependence; and (4) vector-borne bacteria encode proteins that are essential for colonization of specific hosts, though only a few types of proteins have been investigated. Here, we review the current knowledge on important vector-borne bacterial pathogens, including Xylella fastidiosa, Spiroplasma spp., Liberibacter spp., and ‘Candidatus Phytoplasma spp.’. We then highlight recent approaches used in the study of vector-borne bacteria. Finally, we discuss the application of this knowledge for control and future directions that will need to be addressed in the field of vector–plant–bacteria interactions. PMID:27555855

Harnessing Host-Vector Microbiome for Sustainable Plant Disease Management of Phloem-Limited Bacteria

PubMed Central

Trivedi, Pankaj; Trivedi, Chanda; Grinyer, Jasmine; Anderson, Ian C.; Singh, Brajesh K.

2016-01-01

Plant health and productivity is strongly influenced by their intimate interaction with deleterious and beneficial organisms, including microbes, and insects. Of the various plant diseases, insect-vectored diseases are of particular interest, including those caused by obligate parasites affecting plant phloem such as Candidatus (Ca.) Phytoplasma species and several species of Ca. Liberibacter. Recent studies on plant–microbe and plant–insect interactions of these pathogens have demonstrated that plant–microbe–insect interactions have far reaching consequences for the functioning and evolution of the organisms involved. These interactions take place within complex pathosystems and are shaped by a myriad of biotic and abiotic factors. However, our current understanding of these processes and their implications for the establishment and spread of insect-borne diseases remains limited. This article highlights the molecular, ecological, and evolutionary aspects of interactions among insects, plants, and their associated microbial communities with a focus on insect vectored and phloem-limited pathogens belonging to Ca. Phytoplasma and Ca. Liberibacter species. We propose that innovative and interdisciplinary research aimed at linking scales from the cellular to the community level will be vital for increasing our understanding of the mechanisms underpinning plant–insect–microbe interactions. Examination of such interactions could lead us to applied solutions for sustainable disease and pest management. PMID:27746788

Transmission of Xylella fastidiosa to Grapevine by the Meadow Spittlebug.

PubMed

Cornara, D; Sicard, A; Zeilinger, A R; Porcelli, F; Purcell, A H; Almeida, R P P

2016-11-01

There is little information available on Xylella fastidiosa transmission by spittlebugs (Hemiptera, Cercopoidea). This group of insect vectors may be of epidemiological relevance in certain diseases, so it is important to better understand the basic parameters of X. fastidiosa transmission by spittlebugs. We used grapevines as a host plant and the aphrophorid Philaenus spumarius as a vector to estimate the effect of plant access time on X. fastidiosa transmission to plants; in addition, bacterial population estimates in the heads of vectors were determined and correlated with plant infection status. Results show that transmission efficiency of X. fastidiosa by P. spumarius increased with plant access time, similarly to insect vectors in another family (Hemiptera, Cicadellidae). Furthermore, a positive correlation between pathogen populations in P. spumarius and transmission to plants was observed. Bacterial populations in insects were one to two orders of magnitude lower than those observed in leafhopper vectors, and population size peaked within 3 days of plant access period. These results suggest that P. spumarius has either a limited number of sites in the foregut that may be colonized, or that fluid dynamics in the mouthparts of these insects is different from that in leafhoppers. Altogether our results indicate that X. fastidiosa transmission by spittlebugs is similar to that by leafhoppers. In addition, the relationship between cell numbers in vectors and plant infection may have under-appreciated consequences to pathogen spread.

Protein interaction networks at the host-microbe interface in Diaphorina citri, the insect vector of the citrus greening pathogen.

PubMed

Ramsey, J S; Chavez, J D; Johnson, R; Hosseinzadeh, S; Mahoney, J E; Mohr, J P; Robison, F; Zhong, X; Hall, D G; MacCoss, M; Bruce, J; Cilia, M

2017-02-01

The Asian citrus psyllid ( Diaphorina citri) is the insect vector responsible for the worldwide spread of ' Candidatus Liberibacter asiaticus' (CLas), the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission, such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs when compared with adults. We hypothesize that expression changes in the D. citri immune system and commensal microbiota occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults when compared with nymphs, including insect proteins involved in bacterial adhesion and immunity. Compared with nymphs, adult insects had a higher titre of CLas and the bacterial endosymbionts Wolbachia, Profftella and Carsonella. All Wolbachia and Profftella proteins differentially expressed between nymphs and adults are upregulated in adults, while most differentially expressed Carsonella proteins are upregulated in nymphs. Discovery of protein interaction networks has broad applicability to the study of host-microbe relationships. Using protein interaction reporter technology, a D. citri haemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A (CoA) biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. CLas pantothenate kinase, which catalyses the rate-limiting step of CoA biosynthesis, was found to interact with a D. citri myosin protein. Two Carsonella enzymes involved in histidine and tryptophan biosynthesis were found to physically interact with D. citri proteins. These co-evolved protein interaction networks at the host-microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening.

Protein interaction networks at the host–microbe interface in Diaphorina citri, the insect vector of the citrus greening pathogen

PubMed Central

Chavez, J. D.; Johnson, R.; Hosseinzadeh, S.; Mahoney, J. E.; Mohr, J. P.; Robison, F.; Zhong, X.; Hall, D. G.; MacCoss, M.; Bruce, J.; Cilia, M.

2017-01-01

The Asian citrus psyllid (Diaphorina citri) is the insect vector responsible for the worldwide spread of ‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission, such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs when compared with adults. We hypothesize that expression changes in the D. citri immune system and commensal microbiota occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults when compared with nymphs, including insect proteins involved in bacterial adhesion and immunity. Compared with nymphs, adult insects had a higher titre of CLas and the bacterial endosymbionts Wolbachia, Profftella and Carsonella. All Wolbachia and Profftella proteins differentially expressed between nymphs and adults are upregulated in adults, while most differentially expressed Carsonella proteins are upregulated in nymphs. Discovery of protein interaction networks has broad applicability to the study of host–microbe relationships. Using protein interaction reporter technology, a D. citri haemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A (CoA) biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. CLas pantothenate kinase, which catalyses the rate-limiting step of CoA biosynthesis, was found to interact with a D. citri myosin protein. Two Carsonella enzymes involved in histidine and tryptophan biosynthesis were found to physically interact with D. citri proteins. These co-evolved protein interaction networks at the host–microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening. PMID:28386418

Discovery of a novel mastrevirus and alphasatellite-like circular DNA in dragonflies (Epiprocta) from Puerto Rico.

PubMed

Rosario, Karyna; Padilla-Rodriguez, Marco; Kraberger, Simona; Stainton, Daisy; Martin, Darren P; Breitbart, Mya; Varsani, Arvind

2013-01-01

Geminiviruses have emerged as serious agricultural pathogens. Despite all the species that have been already catalogued, new molecular techniques continue to expand the diversity and geographical ranges of these single-stranded DNA viruses and their associated satellite molecules. Since all geminiviruses are insect-transmitted, examination of insect vector populations through vector-enabled metagenomics (VEM) has been recently used to investigate the diversity of geminiviruses transmitted by a specific vector in a given region. Here we used a more comprehensive adaptation of the VEM approach by surveying small circular DNA viruses found within top insect predators, specifically dragonflies (Epiprocta). This 'predator-enabled' approach is not limited to viral groups transmitted by specific vectors since dragonflies can accumulate the wide range of viruses transmitted by their diverse insect prey. Analysis of six dragonflies collected from an agricultural field in Puerto Rico culminated in the discovery of the first mastrevirus (Dragonfly-associated mastrevirus; DfasMV) and alphasatellite molecule (Dragonfly-associated alphasatellite; Dfas-alphasatellite) from the Caribbean. Since DfasMV and Dfas-alphasatellite are divergent from the limited number of sequences that have been reported from the Americas, this study unequivocally demonstrates that there have been at least two independent past introductions of both mastreviruses and alphasatellites to the New World. Overall, the use of predacious insects as sampling tools can profoundly alter our views of natural plant virus diversity and biogeography by allowing the discovery of novel geminiviruses and associated satellite molecules without a priori knowledge of the types of viruses or insect vectors in a given area. Copyright © 2012 Elsevier B.V. All rights reserved.

Acoustic communication in insect disease vectors

PubMed Central

Vigoder, Felipe de Mello; Ritchie, Michael Gordon; Gibson, Gabriella; Peixoto, Alexandre Afranio

2013-01-01

Acoustic signalling has been extensively studied in insect species, which has led to a better understanding of sexual communication, sexual selection and modes of speciation. The significance of acoustic signals for a blood-sucking insect was first reported in the XIX century by Christopher Johnston, studying the hearing organs of mosquitoes, but has received relatively little attention in other disease vectors until recently. Acoustic signals are often associated with mating behaviour and sexual selection and changes in signalling can lead to rapid evolutionary divergence and may ultimately contribute to the process of speciation. Songs can also have implications for the success of novel methods of disease control such as determining the mating competitiveness of modified insects used for mass-release control programs. Species-specific sound “signatures” may help identify incipient species within species complexes that may be of epidemiological significance, e.g. of higher vectorial capacity, thereby enabling the application of more focussed control measures to optimise the reduction of pathogen transmission. Although the study of acoustic communication in insect vectors has been relatively limited, this review of research demonstrates their value as models for understanding both the functional and evolutionary significance of acoustic communication in insects. PMID:24473800

Small Interfering RNA Pathway Modulates Initial Viral Infection in Midgut Epithelium of Insect after Ingestion of Virus.

PubMed

Lan, Hanhong; Chen, Hongyan; Liu, Yuyan; Jiang, Chaoyang; Mao, Qianzhuo; Jia, Dongsheng; Chen, Qian; Wei, Taiyun

2016-01-15

Numerous viruses are transmitted in a persistent manner by insect vectors. Persistent viruses establish their initial infection in the midgut epithelium, from where they disseminate to the midgut visceral muscles. Although propagation of viruses in insect vectors can be controlled by the small interfering RNA (siRNA) antiviral pathway, whether the siRNA pathway can control viral dissemination from the midgut epithelium is unknown. Infection by a rice virus (Southern rice black streaked dwarf virus [SRBSDV]) of its incompetent vector (the small brown planthopper [SBPH]) is restricted to the midgut epithelium. Here, we show that the siRNA pathway is triggered by SRBSDV infection in continuously cultured cells derived from the SBPH and in the midgut of the intact insect. Knockdown of the expression of the core component Dicer-2 of the siRNA pathway by RNA interference strongly increased the ability of SRBSDV to propagate in continuously cultured SBPH cells and in the midgut epithelium, allowing viral titers in the midgut epithelium to reach the threshold (1.99 × 10(9) copies of the SRBSDV P10 gene/μg of midgut RNA) needed for viral dissemination into the SBPH midgut muscles. Our results thus represent the first elucidation of the threshold for viral dissemination from the insect midgut epithelium. Silencing of Dicer-2 further facilitated the transmission of SRBSDV into rice plants by SBPHs. Taken together, our results reveal the new finding that the siRNA pathway can control the initial infection of the insect midgut epithelium by a virus, which finally affects the competence of the virus's vector. Many viral pathogens that cause significant global health and agricultural problems are transmitted via insect vectors. The first bottleneck in viral infection, the midgut epithelium, is a principal determinant of the ability of an insect species to transmit a virus. Southern rice black streaked dwarf virus (SRBSDV) is restricted exclusively to the midgut epithelium of an incompetent vector, the small brown planthopper (SBPH). Here, we show that silencing of the core component Dicer-2 of the small interfering RNA (siRNA) pathway increases viral titers in the midgut epithelium past the threshold (1.99 × 10(9) copies of the SRBSDV P10 gene/μg of midgut RNA) for viral dissemination into the midgut muscles and then into the salivary glands, allowing the SBPH to become a competent vector of SRBSDV. This result is the first evidence that the siRNA antiviral pathway has a direct role in the control of viral dissemination from the midgut epithelium and that it affects the competence of the virus's vector. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Small Interfering RNA Pathway Modulates Initial Viral Infection in Midgut Epithelium of Insect after Ingestion of Virus

PubMed Central

Lan, Hanhong; Chen, Hongyan; Liu, Yuyan; Jiang, Chaoyang; Mao, Qianzhuo; Jia, Dongsheng; Chen, Qian

2015-01-01

ABSTRACT Numerous viruses are transmitted in a persistent manner by insect vectors. Persistent viruses establish their initial infection in the midgut epithelium, from where they disseminate to the midgut visceral muscles. Although propagation of viruses in insect vectors can be controlled by the small interfering RNA (siRNA) antiviral pathway, whether the siRNA pathway can control viral dissemination from the midgut epithelium is unknown. Infection by a rice virus (Southern rice black streaked dwarf virus [SRBSDV]) of its incompetent vector (the small brown planthopper [SBPH]) is restricted to the midgut epithelium. Here, we show that the siRNA pathway is triggered by SRBSDV infection in continuously cultured cells derived from the SBPH and in the midgut of the intact insect. Knockdown of the expression of the core component Dicer-2 of the siRNA pathway by RNA interference strongly increased the ability of SRBSDV to propagate in continuously cultured SBPH cells and in the midgut epithelium, allowing viral titers in the midgut epithelium to reach the threshold (1.99 × 109 copies of the SRBSDV P10 gene/μg of midgut RNA) needed for viral dissemination into the SBPH midgut muscles. Our results thus represent the first elucidation of the threshold for viral dissemination from the insect midgut epithelium. Silencing of Dicer-2 further facilitated the transmission of SRBSDV into rice plants by SBPHs. Taken together, our results reveal the new finding that the siRNA pathway can control the initial infection of the insect midgut epithelium by a virus, which finally affects the competence of the virus's vector. IMPORTANCE Many viral pathogens that cause significant global health and agricultural problems are transmitted via insect vectors. The first bottleneck in viral infection, the midgut epithelium, is a principal determinant of the ability of an insect species to transmit a virus. Southern rice black streaked dwarf virus (SRBSDV) is restricted exclusively to the midgut epithelium of an incompetent vector, the small brown planthopper (SBPH). Here, we show that silencing of the core component Dicer-2 of the small interfering RNA (siRNA) pathway increases viral titers in the midgut epithelium past the threshold (1.99 × 109 copies of the SRBSDV P10 gene/μg of midgut RNA) for viral dissemination into the midgut muscles and then into the salivary glands, allowing the SBPH to become a competent vector of SRBSDV. This result is the first evidence that the siRNA antiviral pathway has a direct role in the control of viral dissemination from the midgut epithelium and that it affects the competence of the virus's vector. PMID:26537672

Analysis of Acquisition and Titer of Maize Mosaic Rhabdovirus in Its Vector, Peregrinus maidis (Hemiptera: Delphacidae)

PubMed Central

Barandoc-Alviar, Karen; Ramirez, Girly M.; Rotenberg, Dorith; Whitfield, Anna E.

2016-01-01

The corn planthopper, Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae), transmits Maize mosaic rhabdovirus (MMV), an important pathogen of maize and sorghum, in a persistent propagative manner. To better understand the vectorial capacity of P. maidis, we determined the efficiency of MMV acquisition by nymphal and adult stages, and characterized MMV titer through development. Acquisition efficiency, i.e., proportion of insects that acquired the virus, was determined by reverse transcriptase polymerase chain reaction (RT-PCR) and virus titer of individual insects was estimated by quantitative RT-PCR. Acquisition efficiency of MMV differed significantly between nymphs and adults. MMV titer increased significantly over time and throughout insect development from nymphal to adult stage, indication of virus replication in the vector during development. There was a positive association between the vector developmental stage and virus titer. Also, the average titer in male insects was threefold higher than female titers, and this difference persisted up to 30 d post adult eclosion. Overall, our findings indicate that nymphs are more efficient than adults at acquiring MMV and virus accumulated in the vector over the course of nymphal development. Furthermore, sustained infection over the lifespan of P. maidis indicates a potentially high capacity of this vector to transmit MMV. PMID:28076276

Insulated piggyBac vectors for insect transgenesis

PubMed Central

Sarkar, Abhimanyu; Atapattu, Asela; Belikoff, Esther J; Heinrich, Jörg C; Li, Xuelei; Horn, Carsten; Wimmer, Ernst A; Scott, Maxwell J

2006-01-01

Background Germ-line transformation of insects is now a widely used method for analyzing gene function and for the development of genetically modified strains suitable for pest control programs. The most widely used transposable element for the germ-line transformation of insects is piggyBac. The site of integration of the transgene can influence gene expression due to the effects of nearby transcription enhancers or silent heterochromatic regions. Position effects can be minimized by flanking a transgene with insulator elements. The scs/scs' and gypsy insulators from Drosophila melanogaster as well as the chicken β-globin HS4 insulator function in both Drosophila and mammalian cells. Results To minimize position effects we have created a set of piggyBac transformation vectors that contain either the scs/scs', gypsy or chicken β-globin HS4 insulators. The vectors contain either fluorescent protein or eye color marker genes and have been successfully used for germ-line transformation of Drosophila melanogaster. A set of the scs/scs' vectors contains the coral reef fluorescent protein marker genes AmCyan, ZsGreen and DsRed that have not been optimized for translation in human cells. These marker genes are controlled by a combined GMR-3xP3 enhancer/promoter that gives particularly strong expression in the eyes. This is also the first report of the use of the ZsGreen and AmCyan reef fluorescent proteins as transformation markers in insects. Conclusion The insulated piggyBac vectors should protect transgenes against position effects and thus facilitate fine control of gene expression in a wide spectrum of insect species. These vectors may also be used for transgenesis in other invertebrate species. PMID:16776846

[Use of a novel baculovirus vector to express nucleoprotein gene of Crimean-Congo hemorrhagic fever virus in both insect and mammalian cells].

PubMed

Ma, Benjiang; Hang, Changshou; Zhao, Yun; Wang, Shiwen; Xie, Yanxiang

2002-09-01

To construct a novel baculovirus vector which is capable of promoting the high-yield expression of foreign gene in mammalian cells and to express by this vector the nucleoprotein (NP) gene of Crimean-Congo hemorrhagic fever virus (CCHFV) Chinese isolate (Xinjiang hemorrhagic fever virus, XHFV) BA88166 in insect and Vero cells. Human cytomegalovirus (CMV) immediate early (IE) promoter was ligated to the baculovirus vector pFastBac1 downstream of the polyhedrin promoter to give rise to the novel vector pCB1. XHFV NP gene was cloned to this vector and was well expressed in COS-7 cells and Vero cells by means of recombinant plasmid transfection and baculovirus infection. The XHFV NP gene in vector pCB1 could be well expressed in mammalian cells. Vero cells infected with recombinant baculovirus harboring NP gene could be employed as antigens to detect XHF serum specimens whose results were in good correlation with those of ELISA and in parallel with clinical diagnoses. This novel baculovirus vector is able to express the foreign gene efficiently in both insect and mammalian cells, which provides not only the convenient diagnostic antigens but also the potential for developing recombinant virus vaccines and gene therapies.

Transcriptomic response of the insect vector, Peregrinus maidis, to Maize mosaic rhabdovirus and identification of conserved responses to propagative viruses in hopper vectors.

PubMed

Martin, Kathleen M; Barandoc-Alviar, Karen; Schneweis, Derek J; Stewart, Catherine L; Rotenberg, Dorith; Whitfield, Anna E

2017-09-01

Maize mosaic virus (MMV) is a plant-pathogenic rhabdovirus that is transmitted by the corn planthopper, Peregrinus maidis, in a propagative manner. P. maidis supports long-term MMV infections with no negative effects on insect performance. To elucidate whole-body transcriptome responses to virus infection, RNA-Seq was used to examine differential gene expression of virus-infected adult insects, and libraries were prepared from replicated groups of virus-exposed insects and non-exposed insects. From the 68,003 de novo-assembled transcripts, 144 were differentially-expressed (DE) during viral infection with comparable numbers up- and down-regulated. DE transcripts with similarity to genes associated with transposable elements (i.e., RNA-directed DNA polymerases) were enriched and may represent a mechanisim for modulating virus infection. Comparison of the P. maidis DE transcripts to published propagative virus-responsive transcript databases for two other hopper vectors revealed that 16% of the DE transcripts were shared across the three systems and may represent conserved responses to propagative viruses. Copyright © 2017 Elsevier Inc. All rights reserved.

Insecticide Control of Vector-Borne Diseases: When Is Insecticide Resistance a Problem?

PubMed Central

Rivero, Ana; Vézilier, Julien; Weill, Mylène; Read, Andrew F.; Gandon, Sylvain

2010-01-01

Many of the most dangerous human diseases are transmitted by insect vectors. After decades of repeated insecticide use, all of these vector species have demonstrated the capacity to evolve resistance to insecticides. Insecticide resistance is generally considered to undermine control of vector-transmitted diseases because it increases the number of vectors that survive the insecticide treatment. Disease control failure, however, need not follow from vector control failure. Here, we review evidence that insecticide resistance may have an impact on the quality of vectors and, specifically, on three key determinants of parasite transmission: vector longevity, competence, and behaviour. We argue that, in some instances, insecticide resistance is likely to result in a decrease in vector longevity, a decrease in infectiousness, or in a change in behaviour, all of which will reduce the vectorial capacity of the insect. If this effect is sufficiently large, the impact of insecticide resistance on disease management may not be as detrimental as previously thought. In other instances, however, insecticide resistance may have the opposite effect, increasing the insect's vectorial capacity, which may lead to a dramatic increase in the transmission of the disease and even to a higher prevalence than in the absence of insecticides. Either way—and there may be no simple generality—the consequence of the evolution of insecticide resistance for disease ecology deserves additional attention. PMID:20700451

[Culicidae insect fauna from rural zone in Amazonas State with incidence of sylvatic yellow fever].

PubMed

Fé, Nelson Ferreira; Barbosa Md, Maria das Graças Vale; Fé, Flávio Augusto Andrade; Guerra, Marcus Vinitius de Farias; Alecrim, Wilson Duarte

2003-01-01

After the occurrence of 14 sylvatic yellow fever cases in 10 cities in the State of Amazonas during 1996, an investigation into the presence of sylvatic yellow fever vectors was carried out. The material of larvae and adult insects was collected around residences and canopy trees within forests, using a light trap (CDC) and human bait. A total of 424 insects was collected. Thirty seven species were identified, some of which were sylvatic yellow fever vectors: Haemagogus janthinomys, Ha. leucocelaenus, Aedes fulvus.

Molecular interactions and immune responses between maize fine streak virus and the leafhopper vector G. nigrifrons through differential expression and RNA interference

USDA-ARS?s Scientific Manuscript database

Maize fine streak virus (MFSV) is an emerging virus of maize that is transmitted by an insect vector, the leafhopper called Graminella nigrifrons. Virus transmission by the leafhopper requires that the virus enter into and multiply in insect cells, tissues and organs before being transmitted to a ne...

Harnessing insect-microbe chemical communications to control insect pest of agricultural systems

USDA-ARS?s Scientific Manuscript database

Insect pests have long been known to impose serious yield, economic, and food safety problems to managed crops worldwide, and are known to vector microbes, many of which are pathogenic or toxigenic. At the heart of many of these studies has been the vital understanding of the plant-insect interactio...

Chemosterilants for Control of Insects and Insect Vectors of Disease.

PubMed

Baxter, Richard H G

2016-10-01

Both historically and at present, vector control is the most generally effective means of controlling malaria transmission. Insecticides are the predominant method of vector control, but the sterile insect technique (SIT) is a complementary strategy with a successful track record in both agricultural and public health sectors. Strategies of genetic and radiation-induced sterilization of Anopheles have to date been limited by logistical and/or regulatory hurdles. A safe and effective mosquito chemosterilant would therefore be of major utility to future deployment of SIT for malaria control. Here we review the prior and current use of chemosterilants in SIT, and assess the potential for future research. Recent genomic and proteomic studies reveal opportunities for specific targeting of seminal fluid proteins, and the capacity to interfere with sperm motility and storage in the female.

Baculovirus: an Insect-derived Vector for Diverse Gene Transfer Applications

PubMed Central

Airenne, Kari J; Hu, Yu-Chen; Kost, Thomas A; Smith, Richard H; Kotin, Robert M; Ono, Chikako; Matsuura, Yoshiharu; Wang, Shu; Ylä-Herttuala, Seppo

2013-01-01

Insect-derived baculoviruses have emerged as versatile and safe workhorses of biotechnology. Baculovirus expression vectors (BEVs) have been applied widely for crop and forest protection, as well as safe tools for recombinant protein production in insect cells. However, BEVs ability to efficiently transduce noninsect cells is still relatively poorly recognized despite the fact that efficient baculovirus-mediated in vitro and ex vivo gene delivery into dormant and dividing vertebrate cells of diverse origin has been described convincingly by many authors. Preliminary proof of therapeutic potential has also been established in preclinical studies. This review summarizes the advantages and current status of baculovirus-mediated gene delivery. Stem cell transduction, preclinical animal studies, tissue engineering, vaccination, cancer gene therapy, viral vector production, and drug discovery are covered. PMID:23439502

Machine learning for characterization of insect vector feeding

USDA-ARS?s Scientific Manuscript database

Insects that feed by ingesting plant and animal fluids cause devastating damage to humans, livestock, and agriculture worldwide, primarily by transmitting phytopathogenic and zoonotic pathogens. The feeding processes required for successful disease transmission by sucking insects can be recorded by ...

Toxicological effects of pyrethroids on non-target aquatic insects.

PubMed

Antwi, Frank B; Reddy, Gadi V P

2015-11-01

The toxicological effects of pyrethroids on non-target aquatic insects are mediated by several modes of entry of pyrethroids into aquatic ecosystems, as well as the toxicological characteristics of particular pyrethroids under field conditions. Toxicokinetics, movement across the integument of aquatic insects, and the toxicodynamics of pyrethroids are discussed, and their physiological, symptomatic and ecological effects evaluated. The relationship between pyrethroid toxicity and insecticide uptake is not fully defined. Based on laboratory and field data, it is likely that the susceptibility of aquatic insects (vector and non-vector) is related to biochemical and physiological constraints associated with life in aquatic ecosystems. Understanding factors that influence aquatic insects susceptibility to pyrethroids is critical for the effective and safe use of these compounds in areas adjacent to aquatic environments. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Analysis of Acquisition and Titer of Maize Mosaic Rhabdovirus in Its Vector, Peregrinus maidis (Hemiptera: Delphacidae).

PubMed

Barandoc-Alviar, Karen; Ramirez, Girly M; Rotenberg, Dorith; Whitfield, Anna E

2016-01-01

The corn planthopper, Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae), transmits Maize mosaic rhabdovirus (MMV), an important pathogen of maize and sorghum, in a persistent propagative manner. To better understand the vectorial capacity of P. maidis, we determined the efficiency of MMV acquisition by nymphal and adult stages, and characterized MMV titer through development. Acquisition efficiency, i.e., proportion of insects that acquired the virus, was determined by reverse transcriptase polymerase chain reaction (RT-PCR) and virus titer of individual insects was estimated by quantitative RT-PCR. Acquisition efficiency of MMV differed significantly between nymphs and adults. MMV titer increased significantly over time and throughout insect development from nymphal to adult stage, indication of virus replication in the vector during development. There was a positive association between the vector developmental stage and virus titer. Also, the average titer in male insects was threefold higher than female titers, and this difference persisted up to 30 d post adult eclosion. Overall, our findings indicate that nymphs are more efficient than adults at acquiring MMV and virus accumulated in the vector over the course of nymphal development. Furthermore, sustained infection over the lifespan of P. maidis indicates a potentially high capacity of this vector to transmit MMV. © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

Machine learning for characterization of insect vector feeding

USDA-ARS?s Scientific Manuscript database

Insects that feed by ingesting plant and animal fluids cause devastating damage to humans, livestock, and agriculture worldwide, primarily by transmitting pathogens of plants and animals. The feeding processes required for successful pathogen transmission by sucking insects can be recorded by monito...

Single inverted terminal repeats of the Junonia coenia Densovirus promotes somatic chromosomal integration of vector plasmids in insect cells and supports high efficiency expression

USDA-ARS?s Scientific Manuscript database

Plasmids that contain a disrupted genome of the Junonia coenia densovirus (JcDNV) integrate into the chromosomes of the somatic cells of insects. When subcloned individually, both the P9 inverted terminal repeat (P9-ITR) and the P93-ITR promote the chromosomal integration of vector plasmids in insec...

Circadian rhythms in insect disease vectors

PubMed Central

Meireles-Filho, Antonio Carlos Alves; Kyriacou, Charalambos Panayiotis

2013-01-01

Organisms from bacteria to humans have evolved under predictable daily environmental cycles owing to the Earth’s rotation. This strong selection pressure has generated endogenous circadian clocks that regulate many aspects of behaviour, physiology and metabolism, anticipating and synchronising internal time-keeping to changes in the cyclical environment. In haematophagous insect vectors the circadian clock coordinates feeding activity, which is important for the dynamics of pathogen transmission. We have recently witnessed a substantial advance in molecular studies of circadian clocks in insect vector species that has consolidated behavioural data collected over many years, which provided insights into the regulation of the clock in the wild. Next generation sequencing technologies will facilitate the study of vector genomes/transcriptomes both among and within species and illuminate some of the species-specific patterns of adaptive circadian phenotypes that are observed in the field and in the laboratory. In this review we will explore these recent findings and attempt to identify potential areas for further investigation. PMID:24473802

O Antigen Modulates Insect Vector Acquisition of the Bacterial Plant Pathogen Xylella fastidiosa

PubMed Central

Rapicavoli, Jeannette N.; Kinsinger, Nichola; Perring, Thomas M.; Backus, Elaine A.; Shugart, Holly J.; Walker, Sharon

2015-01-01

Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen. PMID:26386068

O antigen modulates insect vector acquisition of the bacterial plant pathogen Xylella fastidiosa.

PubMed

Rapicavoli, Jeannette N; Kinsinger, Nichola; Perring, Thomas M; Backus, Elaine A; Shugart, Holly J; Walker, Sharon; Roper, M Caroline

2015-12-01

Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Trypanosoma cruzi, Etiological Agent of Chagas Disease, Is Virulent to Its Triatomine Vector Rhodnius prolixus in a Temperature-Dependent Manner

PubMed Central

Elliot, Simon L.; Rodrigues, Juliana de O.; Lorenzo, Marcelo G.; Martins-Filho, Olindo A.; Guarneri, Alessandra A.

2015-01-01

It is often assumed that parasites are not virulent to their vectors. Nevertheless, parasites commonly exploit their vectors (nutritionally for example) so these can be considered a form of host. Trypanosoma cruzi, a protozoan found in mammals and triatomine bugs in the Americas, is the etiological agent of Chagas disease that affects man and domestic animals. While it has long been considered avirulent to its vectors, a few reports have indicated that it can affect triatomine fecundity. We tested whether infection imposed a temperature-dependent cost on triatomine fitness. We held infected insects at four temperatures between 21 and 30°C and measured T. cruzi growth in vitro at the same temperatures in parallel. Trypanosoma cruzi infection caused a considerable delay in the time the insects took to moult (against a background effect of temperature accelerating moult irrespective of infection status). Trypanosoma cruzi also reduced the insects’ survival, but only at the intermediate temperatures of 24 and 27°C (against a background of increased mortality with increasing temperatures). Meanwhile, in vitro growth of T. cruzi increased with temperature. Our results demonstrate virulence of a protozoan agent of human disease to its insect vector under these conditions. It is of particular note that parasite-induced mortality was greatest over the range of temperatures normally preferred by these insects, probably implying adaptation of the parasite to perform well at these temperatures. Therefore we propose that triggering this delay in moulting is adaptive for the parasites, as it will delay the next bloodmeal taken by the bug, thus allowing the parasites time to develop and reach the insect rectum in order to make transmission to a new vertebrate host possible. PMID:25793495

Potentialities of Mermithid Nematodes for the Biocontrol of Blackflies (Diptera: Simuliidae)--A Review,

DTIC Science & Technology

biocontrol agents of agricultural insect pests and medically important insect vectors. More specifically, mermithid nematodes appear to regulate natural...Mermithids comprise a family of nematodes which invariably kill/sterilize their insect host(s). These nematodes have considerable potential as

Morphology and physiology of the olfactory system of blood-feeding insects.

PubMed

Guidobaldi, F; May-Concha, I J; Guerenstein, P G

2014-01-01

Several blood-feeding (hematophagous) insects are vectors of a number of diseases including dengue, Chagas disease and leishmaniasis which persistently affect public health throughout Latin America. The vectors of those diseases include mosquitoes, triatomine bugs and sandflies. As vector control is an efficient way to prevent these illnesses it is important to understand the sensory biology of those harmful insects. We study the physiology of the olfactory system of those insects and apply that knowledge on the development of methods to manipulate their behavior. Here we review some of the latest information on insect olfaction with emphasis on hematophagous insects. The insect olfactory sensory neurons are housed inside hair-like organs called sensilla which are mainly distributed on the antenna and mouthparts. The identity of many of the odor compounds that those neurons detect are already known in hematophagous insects. They include several constituents of host (vertebrate) odor, sex, aggregation and alarm pheromones, and compounds related to egg-deposition behavior. Recent work has contributed significant knowledge on how odor information is processed in the insect first odor-processing center in the brain, the antennal lobe. The quality, quantity, and temporal features of the odor stimuli are encoded by the neural networks of the antennal lobe. Information regarding odor mixtures is also encoded. While natural mixtures evoke strong responses, synthetic mixtures that deviate from their natural counterparts in terms of key constituents or proportions of those constituents evoke weaker responses. The processing of olfactory information is largely unexplored in hematophagous insects. However, many aspects of their olfactory behavior are known. As in other insects, responses to relevant single odor compounds are weak while natural mixtures evoke strong responses. Future challenges include studying how information about odor mixtures is processed in their brain. This could help develop highly attractive synthetic odor blends to lure them into traps. Copyright © 2014 Elsevier Ltd. All rights reserved.

Exploring New Thermal Fog and Ultra-Low Volume Technologies to Improve Indoor Control of the Dengue Vector, Aedes aegypti (Diptera: Culicidae)

DTIC Science & Technology

2014-07-01

urban structures. An insect growth regulator was also applied to determine howwell each sprayer delivered lethal doses of active ingredient to indoor...vector suppressionwhencombinedwith aneffective insect growth regulator. However, during a dengue outbreak, either delivery system should provide an...sion(Morrisonetal. 2008,Eisenetal. 2009). Successful control programs rely on a combination of intradomi- ciliary adulticide application, larvicidal

Maplike representation of celestial E-vector orientations in the brain of an insect.

PubMed

Heinze, Stanley; Homberg, Uwe

2007-02-16

For many insects, the polarization pattern of the blue sky serves as a compass cue for spatial navigation. E-vector orientations are detected by photoreceptors in a dorsal rim area of the eye. Polarized-light signals from both eyes are finally integrated in the central complex, a brain area consisting of two subunits, the protocerebral bridge and the central body. Here we show that a topographic representation of zenithal E-vector orientations underlies the columnar organization of the protocerebral bridge in a locust. The maplike arrangement is highly suited to signal head orientation under the open sky.

Conditions for success of engineered underdominance gene drive systems.

PubMed

Edgington, Matthew P; Alphey, Luke S

2017-10-07

Engineered underdominance is one of a number of different gene drive strategies that have been proposed for the genetic control of insect vectors of disease. Here we model a two-locus engineered underdominance based gene drive system that is based on the concept of mutually suppressing lethals. In such a system two genetic constructs are introduced, each possessing a lethal element and a suppressor of the lethal at the other locus. Specifically, we formulate and analyse a population genetics model of this system to assess when different combinations of release strategies (i.e. single or multiple releases of both sexes or males only) and genetic systems (i.e. bisex lethal or female-specific lethal elements and different strengths of suppressors) will give population replacement or fail to do so. We anticipate that results presented here will inform the future design of engineered underdominance gene drive systems as well as providing a point of reference regarding release strategies for those looking to test such a system. Our discussion is framed in the context of genetic control of insect vectors of disease. One of several serious threats in this context are Aedes aegypti mosquitoes as they are the primary vectors of dengue viruses. However, results are also applicable to Ae. aegypti as vectors of Zika, yellow fever and chikungunya viruses and also to the control of a number of other insect species and thereby of insect-vectored pathogens. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

The Repellent DEET Potentiates Carbamate Effects via Insect Muscarinic Receptor Interactions: An Alternative Strategy to Control Insect Vector-Borne Diseases.

PubMed

Abd-Ella, Aly; Stankiewicz, Maria; Mikulska, Karolina; Nowak, Wieslaw; Pennetier, Cédric; Goulu, Mathilde; Fruchart-Gaillard, Carole; Licznar, Patricia; Apaire-Marchais, Véronique; List, Olivier; Corbel, Vincent; Servent, Denis; Lapied, Bruno

2015-01-01

Insect vector-borne diseases remain one of the principal causes of human mortality. In addition to conventional measures of insect control, repellents continue to be the mainstay for personal protection. Because of the increasing pyrethroid-resistant mosquito populations, alternative strategies to reconstitute pyrethroid repellency and knock-down effects have been proposed by mixing the repellent DEET (N,N-Diethyl-3-methylbenzamide) with non-pyrethroid insecticide to better control resistant insect vector-borne diseases. By using electrophysiological, biochemichal, in vivo toxicological techniques together with calcium imaging, binding studies and in silico docking, we have shown that DEET, at low concentrations, interacts with high affinity with insect M1/M3 mAChR allosteric site potentiating agonist effects on mAChRs coupled to phospholipase C second messenger pathway. This increases the anticholinesterase activity of the carbamate propoxur through calcium-dependent regulation of acetylcholinesterase. At high concentrations, DEET interacts with low affinity on distinct M1/M3 mAChR site, counteracting the potentiation. Similar dose-dependent dual effects of DEET have also been observed at synaptic mAChR level. Additionally, binding and in silico docking studies performed on human M1 and M3 mAChR subtypes indicate that DEET only displays a low affinity antagonist profile on these M1/M3 mAChRs. These results reveal a selective high affinity positive allosteric site for DEET in insect mAChRs. Finally, bioassays conducted on Aedes aegypti confirm the synergistic interaction between DEET and propoxur observed in vitro, resulting in a higher mortality of mosquitoes. Our findings reveal an unusual allosterically potentiating action of the repellent DEET, which involves a selective site in insect. These results open exciting research areas in public health particularly in the control of the pyrethroid-resistant insect-vector borne diseases. Mixing low doses of DEET and a non-pyrethroid insecticide will lead to improvement in the efficiency treatments thus reducing both the concentration of active ingredients and side effects for non-target organisms. The discovery of this insect specific site may pave the way for the development of new strategies essential in the management of chemical use against resistant mosquitoes.

The Repellent DEET Potentiates Carbamate Effects via Insect Muscarinic Receptor Interactions: An Alternative Strategy to Control Insect Vector-Borne Diseases

PubMed Central

Abd-Ella, Aly; Stankiewicz, Maria; Mikulska, Karolina; Nowak, Wieslaw; Pennetier, Cédric; Goulu, Mathilde; Fruchart-Gaillard, Carole; Licznar, Patricia; Apaire-Marchais, Véronique; List, Olivier; Corbel, Vincent; Servent, Denis; Lapied, Bruno

2015-01-01

Insect vector-borne diseases remain one of the principal causes of human mortality. In addition to conventional measures of insect control, repellents continue to be the mainstay for personal protection. Because of the increasing pyrethroid-resistant mosquito populations, alternative strategies to reconstitute pyrethroid repellency and knock-down effects have been proposed by mixing the repellent DEET (N,N-Diethyl-3-methylbenzamide) with non-pyrethroid insecticide to better control resistant insect vector-borne diseases. By using electrophysiological, biochemichal, in vivo toxicological techniques together with calcium imaging, binding studies and in silico docking, we have shown that DEET, at low concentrations, interacts with high affinity with insect M1/M3 mAChR allosteric site potentiating agonist effects on mAChRs coupled to phospholipase C second messenger pathway. This increases the anticholinesterase activity of the carbamate propoxur through calcium-dependent regulation of acetylcholinesterase. At high concentrations, DEET interacts with low affinity on distinct M1/M3 mAChR site, counteracting the potentiation. Similar dose-dependent dual effects of DEET have also been observed at synaptic mAChR level. Additionally, binding and in silico docking studies performed on human M1 and M3 mAChR subtypes indicate that DEET only displays a low affinity antagonist profile on these M1/M3 mAChRs. These results reveal a selective high affinity positive allosteric site for DEET in insect mAChRs. Finally, bioassays conducted on Aedes aegypti confirm the synergistic interaction between DEET and propoxur observed in vitro, resulting in a higher mortality of mosquitoes. Our findings reveal an unusual allosterically potentiating action of the repellent DEET, which involves a selective site in insect. These results open exciting research areas in public health particularly in the control of the pyrethroid-resistant insect-vector borne diseases. Mixing low doses of DEET and a non-pyrethroid insecticide will lead to improvement in the efficiency treatments thus reducing both the concentration of active ingredients and side effects for non-target organisms. The discovery of this insect specific site may pave the way for the development of new strategies essential in the management of chemical use against resistant mosquitoes. PMID:25961834

Infrared absorption characteristics of Culicoides sonorensis in relation to insect age

USDA-ARS?s Scientific Manuscript database

Biting midges can transmit diseases that significantly impact livestock in many parts of the world. The age structure of an insect vector population determines its likelihood of transmitting pathogens because the older insects are more likely to be infected than younger ones. Understanding the insec...

Military Infectious Diseases Update on Vaccine Development

DTIC Science & Technology

2011-01-24

Research Program (MIDRP) Insect Vector ControlDiagnostics Prevention Treatment Infectious diseases adversely impact military operations. Vaccines...appropriate treatment and aids commanders in the field. Most militarily relevant infectious diseases are transmitted by biting insects and other...based Insect Repellent (1946) Vaccines Protectants Antiparasitic Drugs Research Effort Advanced Development Fielded Products Malaria Rapid

Evaluation of Spatially Targeted Strategies to Control Non-Domiciliated Triatoma dimidiata Vector of Chagas Disease

PubMed Central

Barbu, Corentin; Dumonteil, Eric; Gourbière, Sébastien

2011-01-01

Background Chagas disease is a major neglected tropical disease with deep socio-economical effects throughout Central and South America. Vector control programs have consistently reduced domestic populations of triatomine vectors, but non-domiciliated vectors still have to be controlled efficiently. Designing control strategies targeting these vectors is challenging, as it requires a quantitative description of the spatio-temporal dynamics of village infestation, which can only be gained from combinations of extensive field studies and spatial population dynamic modelling. Methodology/Principal Findings A spatially explicit population dynamic model was combined with a two-year field study of T. dimidiata infestation dynamics in the village of Teya, Mexico. The parameterized model fitted and predicted accurately both intra-annual variation and the spatial gradient in vector abundance. Five different control strategies were then applied in concentric rings to mimic spatial design targeting the periphery of the village, where vectors were most abundant. Indoor insecticide spraying and insect screens reduced vector abundance by up to 80% (when applied to the whole village), and half of this effect was obtained when control was applied only to the 33% of households closest to the village periphery. Peri-domicile cleaning was able to eliminate up to 60% of the vectors, but at the periphery of the village it has a low effect, as it is ineffective against sylvatic insects. The use of lethal traps and the management of house attractiveness provided similar levels of control. However this required either house attractiveness to be null, or ≥5 lethal traps, at least as attractive as houses, to be installed in each household. Conclusion/Significance Insecticide and insect screens used in houses at the periphery of the village can contribute to reduce house infestation in more central untreated zones. However, this beneficial effect remains insufficient to allow for a unique spatially targeted strategy to offer protection to all households. Most efficiently, control should combine the use of insect screens in outer zones to reduce infestation by both sylvatic and peri-domiciliated vectors, and cleaning of peri-domicile in the centre of the village where sylvatic vectors are absent. The design of such spatially mixed strategies of control offers a promising avenue to reduce the economic cost associated with the control of non-domiciliated vectors. PMID:21610862

Influence of a propagative plant virus on the fitness and wing dimorphism of infected and exposed insect vectors.

PubMed

Higashi, Clesson H V; Bressan, Alberto

2013-07-01

To maximize fitness, plant pathogenic viruses may manipulate their arthropod vectors through direct and indirect (via the host plant) interactions. For many virus-vector-plant associations, insect feeding does not always lead to virus acquisition. In fact, many plant viruses, especially those that propagate into their vectors, are acquired at low rates. Although the majority of insects colonizing an infected plant escape from viral infection, they are still exposed to the indirect effects (i.e. the effect of plant metabolism modification following virus infection). Little information has been reported on the effects of plant viruses on insects that become infected versus those that do not (here referred to as "exposed"). The effect that the Maize mosaic virus (MMV) (Rhabdoviridae) exerts on the fitness and wing dimorphism of the planthopper vector, Peregrinus maidis (Hemiptera, Delphacidae), that developed on leaves from either young or old corn plants was examined. MMV exerted non-consistent to minimal direct effects on developmental time, longevity, nymphal mortality and fecundity. In addition, some small yet significant fitness costs were encountered by exposed planthoppers to escape MMV infection. Furthermore, a significantly higher proportion of macropters over brachypters were produced on MMV-infected old leaves compared with healthy leaves of a similar age. We conclude that the virus influences the dispersal of the vector, promoting a larger production of macropters at the costs of brachypters at a late stage of the plant infection. Because MMV infection in planthoppers did not segregate by wing morphotype, our results indicate that the dispersal of both infected and exposed planthoppers was a likely consequence of the indirect effects of MMV.

A Neurocomputational Model of Goal-Directed Navigation in Insect-Inspired Artificial Agents

PubMed Central

Goldschmidt, Dennis; Manoonpong, Poramate; Dasgupta, Sakyasingha

2017-01-01

Despite their small size, insect brains are able to produce robust and efficient navigation in complex environments. Specifically in social insects, such as ants and bees, these navigational capabilities are guided by orientation directing vectors generated by a process called path integration. During this process, they integrate compass and odometric cues to estimate their current location as a vector, called the home vector for guiding them back home on a straight path. They further acquire and retrieve path integration-based vector memories globally to the nest or based on visual landmarks. Although existing computational models reproduced similar behaviors, a neurocomputational model of vector navigation including the acquisition of vector representations has not been described before. Here we present a model of neural mechanisms in a modular closed-loop control—enabling vector navigation in artificial agents. The model consists of a path integration mechanism, reward-modulated global learning, random search, and action selection. The path integration mechanism integrates compass and odometric cues to compute a vectorial representation of the agent's current location as neural activity patterns in circular arrays. A reward-modulated learning rule enables the acquisition of vector memories by associating the local food reward with the path integration state. A motor output is computed based on the combination of vector memories and random exploration. In simulation, we show that the neural mechanisms enable robust homing and localization, even in the presence of external sensory noise. The proposed learning rules lead to goal-directed navigation and route formation performed under realistic conditions. Consequently, we provide a novel approach for vector learning and navigation in a simulated, situated agent linking behavioral observations to their possible underlying neural substrates. PMID:28446872

A Neurocomputational Model of Goal-Directed Navigation in Insect-Inspired Artificial Agents.

PubMed

Goldschmidt, Dennis; Manoonpong, Poramate; Dasgupta, Sakyasingha

2017-01-01

Despite their small size, insect brains are able to produce robust and efficient navigation in complex environments. Specifically in social insects, such as ants and bees, these navigational capabilities are guided by orientation directing vectors generated by a process called path integration. During this process, they integrate compass and odometric cues to estimate their current location as a vector, called the home vector for guiding them back home on a straight path. They further acquire and retrieve path integration-based vector memories globally to the nest or based on visual landmarks. Although existing computational models reproduced similar behaviors, a neurocomputational model of vector navigation including the acquisition of vector representations has not been described before. Here we present a model of neural mechanisms in a modular closed-loop control-enabling vector navigation in artificial agents. The model consists of a path integration mechanism, reward-modulated global learning, random search, and action selection. The path integration mechanism integrates compass and odometric cues to compute a vectorial representation of the agent's current location as neural activity patterns in circular arrays. A reward-modulated learning rule enables the acquisition of vector memories by associating the local food reward with the path integration state. A motor output is computed based on the combination of vector memories and random exploration. In simulation, we show that the neural mechanisms enable robust homing and localization, even in the presence of external sensory noise. The proposed learning rules lead to goal-directed navigation and route formation performed under realistic conditions. Consequently, we provide a novel approach for vector learning and navigation in a simulated, situated agent linking behavioral observations to their possible underlying neural substrates.

Mosquitoes meet microfluidics: High-throughput microfluidic tools for insect-parasite ecology in field conditions

NASA Astrophysics Data System (ADS)

Prakash, Manu; Mukundarajan, Haripriya

2013-11-01

A simple bite from an insect is the transmission mechanism for many deadly diseases worldwide--including malaria, yellow fever, west nile and dengue. Very little is known about how populations of numerous insect species and disease-causing parasites interact in their natural habitats due to a lack of measurement techniques. At present, vector surveillance techniques involve manual capture by using humans as live bait, which is hard to justify on ethical grounds. Individual mosquitoes are manually dissected to isolate salivary glands to detect sporozites. With typical vector infection rates being very low even in endemic areas, it is almost impossible to get an accurate picture of disease distribution, in both space and time. Here we present novel high-throughput microfluidic tools for vector surveillance, specifically mosquitoes. A two-dimensional high density array with baits provide an integrated platform for multiplex PCR for detection of both vector and parasite species. Combining techniques from engineering and field ecology, methods and tools developed here will enable high-throughput measurement of infection rates for a number of diseases in mosquito populations in field conditions. Pew Foundation.

Carryover effects of larval exposure to different environmental bacteria drive adult trait variation in a mosquito vector

PubMed Central

Dickson, Laura B.; Jiolle, Davy; Minard, Guillaume; Moltini-Conclois, Isabelle; Volant, Stevenn; Ghozlane, Amine; Bouchier, Christiane; Ayala, Diego; Paupy, Christophe; Moro, Claire Valiente; Lambrechts, Louis

2017-01-01

Conditions experienced during larval development of holometabolous insects can affect adult traits, but whether differences in the bacterial communities of larval development sites contribute to variation in the ability of insect vectors to transmit human pathogens is unknown. We addressed this question in the mosquito Aedes aegypti, a major arbovirus vector breeding in both sylvatic and domestic habitats in Sub-Saharan Africa. Targeted metagenomics revealed differing bacterial communities in the water of natural breeding sites in Gabon. Experimental exposure to different native bacterial isolates during larval development resulted in significant differences in pupation rate and adult body size but not life span. Larval exposure to an Enterobacteriaceae isolate resulted in decreased antibacterial activity in adult hemolymph and reduced dengue virus dissemination titer. Together, these data provide the proof of concept that larval exposure to different bacteria can drive variation in adult traits underlying vectorial capacity. Our study establishes a functional link between larval ecology, environmental microbes, and adult phenotypic variation in a holometabolous insect vector. PMID:28835919

The quest for a non-vector psyllid: Natural variation in acquisition and transmission of the huanglongbing pathogen 'Candidatus Liberibacter asiaticus' by Asian citrus psyllid isofemale lines

USDA-ARS?s Scientific Manuscript database

Genetic variability in insect vectors is valuable to study vector competence determinants and to select non-vector populations that may help reduce the spread of vector-borne pathogens. We collected and tested vector competency of 15 isofemale lines of Asian citrus psyllid (ACP) Diaphorina citri, v...

A new method for forensic DNA analysis of the blood meal in chagas disease vectors demonstrated using Triatoma infestans from Chuquisaca, Bolivia.

PubMed

Pizarro, Juan Carlos; Stevens, Lori

2008-01-01

Feeding patterns of the vector are important in the epidemiology of Chagas disease, the leading cause of heart disease in Latin America. Chagas disease is caused by the parasite, Trypanasoma cruzi, which is transmitted by blood feeding insects. Historically, feeding behaviours of haematophagous insects have been investigated using serological reactions, which have detection limits in terms of both taxonomic resolution, and quantity and quality of the blood meal. They are labor intensive, require technical expertise, need fresh or frozen samples and antibodies often are either not available commercially or the resources for synthesis and purification are not available. We describe an assay to identify vertebrate blood meal sources, and the parasite T. cruzi using species-specific PCR assays from insect vectors and use the method to provide information regarding three questions: (1) Do domestic and peri-domestic (chicken coop and animal corral) habitats vary in the blood meals detected in the vectors? (2) What is the pattern of multiple blood meals? (3) Does the rate of T. cruzi infection vary among habitats and is it associated with specific blood meal types? Assays based on the polymerase chain reaction were evaluated for identification of the blood meal source in the heamatophagous Chagas disease vector Triatoma infestans. We evaluate a technique to identify 11 potential vertebrate food sources from the complex mixture extracted from the vector's abdomen. We tested the assay on 81 T. infestans specimens collected from the Andean highlands in the department of Chuquisaca, located in central Bolivia, one of the regions in South America where sylvatic T. infestans have been reported. This area is suggested to be the geographic origin of T. infestans and has very high human infection rates that may be related to sylvatic vector populations. The results of the assays revealed that a high percentage of insects collected in human dwellings had fed on peri-domestic animals. In contrast, one insect from a chicken coop but no bugs from corrals tested positive for human blood. Forty-eight percent of insects tested positive for more than one vertebrate species. T. cruzi infection was detected in 42% of the specimens. From the epidemiological point of view, the results reveal an overall pattern of movement from peri-domestic structures to human habitations for T. infestans in this region of Bolivia as well as the important role of pigs, dogs, chickens and guinea pigs in the dynamics of T. cruzi infection.

A New Method for Forensic DNA Analysis of the Blood Meal in Chagas Disease Vectors Demonstrated Using Triatoma infestans from Chuquisaca, Bolivia

PubMed Central

Pizarro, Juan Carlos; Stevens, Lori

2008-01-01

Background Feeding patterns of the vector are important in the epidemiology of Chagas disease, the leading cause of heart disease in Latin America. Chagas disease is caused by the parasite, Trypanasoma cruzi, which is transmitted by blood feeding insects. Historically, feeding behaviours of haematophagous insects have been investigated using serological reactions, which have detection limits in terms of both taxonomic resolution, and quantity and quality of the blood meal. They are labor intensive, require technical expertise, need fresh or frozen samples and antibodies often are either not available commercially or the resources for synthesis and purification are not available. We describe an assay to identify vertebrate blood meal sources, and the parasite T. cruzi using species-specific PCR assays from insect vectors and use the method to provide information regarding three questions: (1) Do domestic and peri-domestic (chicken coop and animal corral) habitats vary in the blood meals detected in the vectors? (2) What is the pattern of multiple blood meals? (3) Does the rate of T. cruzi infection vary among habitats and is it associated with specific blood meal types? Methodology/Principal Findings Assays based on the polymerase chain reaction were evaluated for identification of the blood meal source in the heamatophagous Chagas disease vector Triatoma infestans. We evaluate a technique to identify 11 potential vertebrate food sources from the complex mixture extracted from the vector's abdomen. We tested the assay on 81 T. infestans specimens collected from the Andean highlands in the department of Chuquisaca, located in central Bolivia, one of the regions in South America where sylvatic T. infestans have been reported. This area is suggested to be the geographic origin of T. infestans and has very high human infection rates that may be related to sylvatic vector populations. Conclusion/Significance The results of the assays revealed that a high percentage of insects collected in human dwellings had fed on peri-domestic animals. In contrast, one insect from a chicken coop but no bugs from corrals tested positive for human blood. Forty-eight percent of insects tested positive for more than one vertebrate species. T. cruzi infection was detected in 42% of the specimens. From the epidemiological point of view, the results reveal an overall pattern of movement from peri-domestic structures to human habitations for T. infestans in this region of Bolivia as well as the important role of pigs, dogs, chickens and guinea pigs in the dynamics of T. cruzi infection. PMID:18974787

The Molecular Characterization of the Kinin Transcript and the Physiological Effects of Kinins in the Blood-Gorging Insect Rhodnius prolixus

USDA-ARS?s Scientific Manuscript database

The dramatic feeding-related activities of the Chagas' disease vector, Rhodnius prolixus are under neurohormonal regulation of serotonin and various neuropeptides. One such family of neuropeptides, the insect kinins, possess diuretic, digestive and myotropic activities in many insects. In this study...

Mutualism and Antagonism: Ecological Interactions Among Bark Beetles, Mite and Fungi

Treesearch

K.D. Klepzig; J.C. Moser; M.J. Lombardero; M.P. Ayres; R.W. Hofstetter; C.J. Walkinshaw

2001-01-01

Insect-fungal complexes provide challenging and fascinating systems for the study of biotic interactions between plants. plant pathogens, insect vectors and other associated organisms. The types of interactions among these organisms (mutualism. antagonism. parasitism. phoresy. etc.) are as variable as the range of organisms involved (plants, fungi, insects. mites. etc...

Seed treatments for the control of insects and diseases in sugarbeet

USDA-ARS?s Scientific Manuscript database

Insect feeding and vectoring of viruses cause serious problems in sugarbeet production worldwide. In order to ameliorate insect and disease problems on sugarbeet, two seed treatments, Poncho Beta (60 g a.i. clothianidin + 8 g a.i. beta-cyfluthrin/100,000 seed) and Cruiser Tef (60 g a.i. thiamethoxa...

Diaphorina citri Induces Huanglongbing-Infected Citrus Plant Volatiles to Repel and Reduce the Performance of Propylaea japonica.

PubMed

Lin, Yongwen; Lin, Sheng; Akutse, Komivi S; Hussain, Mubasher; Wang, Liande

2016-01-01

Transmission of plant pathogens through insect vectors is a complex biological process involving interactions between the host plants, insects, and pathogens. Simultaneous impact of the insect damage and pathogenic bacteria in infected host plants induce volatiles that modify not only the behavior of its insect vector but also of their natural enemies, such as parasitoid wasps. Therefore, it is essential to understand how insects such as the predator ladybird beetle responds to volatiles emitted from a host plant and how the disease transmission alters the interactions between predators, vector, pathogens, and plants. In this study, we investigated the response of Propylaea japonica to volatiles from citrus plants damaged by Diaphorina citri and Candidatus Liberibacter asiaticus through olfactometer bioassays. Synthetic chemical blends were also used to determine the active compounds in the plant volatile. The results showed that volatiles emitted by healthy plants attracted more P. japonica than other treatments, due to the presence of high quantities of D-limonene and beta-ocimene, and the lack of methyl salicylate. When using synthetic chemicals in the olfactory tests, we found that D-limonene attracted P. japonica while methyl salicylate repelled the predator. However, beta-ocimene attracted the insects at lower concentrations but repelled them at higher concentrations. These results indicate that P. japonica could not efficiently search for its host by using volatile cues emitted from psyllids- and Las bacteria-infected citrus plants.

Not all GMOs are crop plants: non-plant GMO applications in agriculture.

PubMed

Hokanson, K E; Dawson, W O; Handler, A M; Schetelig, M F; St Leger, R J

2014-12-01

Since tools of modern biotechnology have become available, the most commonly applied and often discussed genetically modified organisms are genetically modified crop plants, although genetic engineering is also being used successfully in organisms other than plants, including bacteria, fungi, insects, and viruses. Many of these organisms, as with crop plants, are being engineered for applications in agriculture, to control plant insect pests or diseases. This paper reviews the genetically modified non-plant organisms that have been the subject of permit approvals for environmental release by the United States Department of Agriculture/Animal and Plant Health Inspection Service since the US began regulating genetically modified organisms. This is an indication of the breadth and progress of research in the area of non-plant genetically modified organisms. This review includes three examples of promising research on non-plant genetically modified organisms for application in agriculture: (1) insects for insect pest control using improved vector systems; (2) fungal pathogens of insects to control insect pests; and (3) virus for use as transient-expression vectors for disease control in plants.

Artificial Lighting as a Vector Attractant and Cause of Disease Diffusion

PubMed Central

Barghini, Alessandro; de Medeiros, Bruno A. S.

2010-01-01

Background Traditionally, epidemiologists have considered electrification to be a positive factor. In fact, electrification and plumbing are typical initiatives that represent the integration of an isolated population into modern society, ensuring the control of pathogens and promoting public health. Nonetheless, electrification is always accompanied by night lighting that attracts insect vectors and changes people’s behavior. Although this may lead to new modes of infection and increased transmission of insect-borne diseases, epidemiologists rarely consider the role of night lighting in their surveys. Objective We reviewed the epidemiological evidence concerning the role of lighting in the spread of vector-borne diseases to encourage other researchers to consider it in future studies. Discussion We present three infectious vector-borne diseases—Chagas, leishmaniasis, and malaria—and discuss evidence that suggests that the use of artificial lighting results in behavioral changes among human populations and changes in the prevalence of vector species and in the modes of transmission. Conclusion Despite a surprising lack of studies, existing evidence supports our hypothesis that artificial lighting leads to a higher risk of infection from vector-borne diseases. We believe that this is related not only to the simple attraction of traditional vectors to light sources but also to changes in the behavior of both humans and insects that result in new modes of disease transmission. Considering the ongoing expansion of night lighting in developing countries, additional research on this subject is urgently needed. PMID:20675268

LIGHT-EMITTING DIODE TECHNOLOGY IMPROVES INSECT TRAPPING

PubMed Central

GILLEN, JONATHON I.; MUNSTERMANN, LEONARD E.

2008-01-01

In a climate of increased funding for vaccines, chemotherapy, and prevention of vector-borne diseases, fewer resources have been directed toward improving disease and vector surveillance. Recently developed light-emitting diode (LED) technology was applied to standard insect-vector traps to produce a more effective lighting system. This approach improved phlebotomine sand fly capture rates by 50%, and simultaneously reduced the energy consumption by 50–60%. The LEDs were incorporated into 2 lighting designs, 1) a LED combination bulb for current light traps and 2) a chip-based LED design for a modified Centers for Disease Control and Prevention light trap. Detailed descriptions of the 2 designs are presented. PMID:18666546

[Analysis on the results of etiology and serology of plague in Qinghai province from 2001 to 2010].

PubMed

Yang, Yonghai; Wang, Mei; Zhao, Xiaolong; Zhao, Zhongzhi; Zhang, Aiping; Wei, Rongjie; Wei, Baiqing; Wang, Zuyun

2014-02-01

To analyze the results of etiology and serology of plague among human and infected animals in Qinghai province from 2001 to 2010. Thirty-seven cases of human infected with plague, 53 541 different animal samples, 5 685 sets of vector insects flea and 49 039 different animal serum samples were obtained between 2001 and 2010. A total of 7 811 samples of serum from healthy farmers and herdsmen in 14 counties in Qinghai from 2005 to 2007 were collected. Yersinia pestis (Y. pestis) were detected in visceral and secretions from human, infected animals and vector insects, respectively. Plague antigen was detected by reverse indirect hemagglutination assay (RIHA) in those samples. Indirect hemagglutination assay (IHA) was used to test plague FI antibody in serum of human and infected animals. 37 human plague cases were confirmed, 21 strains of plague Y. pestis were isolated from human cases and 14 positive were detected out. 133 of 7 811 samples of human serum were IHA positive, with the positive rate at 1.7%. A total of 146 strains of plague were isolated from infected animals and vector insects, 99 out of which were from infected animals, with a ratio of Marmota himalayan at 72.7% (72/99) and the other 47 were from vector insects, with a ratio of callopsylla solaris at 68.1% (32/47). The number of IHA and PIHA positive were 300 and 10, respectively. A total of 3 animals and 3 insects species were identified as new epidemic hosts for plague. The natural plague focus of Microtus fuscus was discovered and confirmed and coexisted with natural focus of Marmota himalayan in Chengduo county, Yushu prefecture. The epidemic situation of plague is distributed mainly in Haixi, Yushu and Hainan prefectures. From 2001 to 2010, animal infected with plague was detected in successive years and human plague was very common in Qinghai. New infected animals and vector insects species and new epidemic areas were confirmed, hence the trend of plague prevalence for humans and animals is very active in Qinghai province.

Diversity and role of cave-dwelling hematophagous insects in pathogen transmission in the Afrotropical region.

PubMed

Obame-Nkoghe, Judicaël; Leroy, Eric-Maurice; Paupy, Christophe

2017-04-12

The progressive anthropization of caves for food resources or economic purposes increases human exposure to pathogens that naturally infect cave-dwelling animals. The presence of wild or domestic animals in the immediate surroundings of caves also may contribute to increasing the risk of emergence of such pathogens. Some zoonotic pathogens are transmitted through direct contact, but many others require arthropod vectors, such as blood-feeding insects. In Africa, hematophagous insects often play a key role in the epidemiology of many pathogens; however, their ecology in cave habitats remains poorly known. During the last decades, several investigations carried out in Afrotropical caves suggested the medical and veterinary importance particularly of insect taxa of the Diptera order. Therefore, the role of some of these insects as vectors of pathogens that infect cave-dwelling vertebrates has been studied. The present review summarizes these findings, brings insights into the diversity of cave-dwelling hematophagous Diptera and their involvement in pathogen transmission, and finally discusses new challenges and future research directions.

Deceptive chemical signals induced by a plant virus attract insect vectors to inferior hosts.

PubMed

Mauck, Kerry E; De Moraes, Consuelo M; Mescher, Mark C

2010-02-23

Previous studies have shown that vector-borne pathogens can alter the phenotypes of their hosts and vectors in ways that influence the frequency and nature of interactions between them, with significant implications for the transmission and spread of disease. For insect-borne pathogens, host odors are particularly likely targets for manipulation, because both plant- and animal-feeding insects use volatile compounds derived from their hosts as key foraging cues. Here, we document the effects of a widespread plant pathogen, Cucumber mosaic virus (CMV), on the quality and attractiveness of one of its host plants (Cucurbita pepo cv. Dixie) for two aphid vectors, Myzus persicae and Aphis gossypii. Our results indicate that CMV greatly reduces host-plant quality-aphids performed poorly on infected plants and rapidly emigrated from them-but increases the attractiveness of infected plants to aphids by inducing elevated emissions of a plant volatile blend otherwise similar to that emitted by healthy plants. Thus, CMV appears to attract vectors deceptively to infected plants from which they then disperse rapidly, a pattern highly conducive to the nonpersistent transmission mechanism employed by CMV and very different from the pattern previously reported for persistently transmitted viruses that require sustained aphid feeding for transmission. In addition to providing a documented example of a pathogen inducing a deceptive signal of host-plant quality to vectors, our results suggest that the transmission mechanism is a major factor shaping pathogen-induced changes in host-plant phenotypes. Furthermore, our findings yield a general hypothesis that, when vector-borne plant or animal pathogens reduce host quality for vectors, pathogen-induced changes in host phenotypes that enhance vector attraction frequently will involve the exaggeration of existing host-location cues.

Deceptive chemical signals induced by a plant virus attract insect vectors to inferior hosts

PubMed Central

Mauck, Kerry E.; De Moraes, Consuelo M.; Mescher, Mark C.

2010-01-01

Previous studies have shown that vector-borne pathogens can alter the phenotypes of their hosts and vectors in ways that influence the frequency and nature of interactions between them, with significant implications for the transmission and spread of disease. For insect-borne pathogens, host odors are particularly likely targets for manipulation, because both plant- and animal-feeding insects use volatile compounds derived from their hosts as key foraging cues. Here, we document the effects of a widespread plant pathogen, Cucumber mosaic virus (CMV), on the quality and attractiveness of one of its host plants (Cucurbita pepo cv. Dixie) for two aphid vectors, Myzus persicae and Aphis gossypii. Our results indicate that CMV greatly reduces host-plant quality—aphids performed poorly on infected plants and rapidly emigrated from them—but increases the attractiveness of infected plants to aphids by inducing elevated emissions of a plant volatile blend otherwise similar to that emitted by healthy plants. Thus, CMV appears to attract vectors deceptively to infected plants from which they then disperse rapidly, a pattern highly conducive to the nonpersistent transmission mechanism employed by CMV and very different from the pattern previously reported for persistently transmitted viruses that require sustained aphid feeding for transmission. In addition to providing a documented example of a pathogen inducing a deceptive signal of host-plant quality to vectors, our results suggest that the transmission mechanism is a major factor shaping pathogen-induced changes in host-plant phenotypes. Furthermore, our findings yield a general hypothesis that, when vector-borne plant or animal pathogens reduce host quality for vectors, pathogen-induced changes in host phenotypes that enhance vector attraction frequently will involve the exaggeration of existing host-location cues. PMID:20133719

Floral traits influence pollen vectors' choices in higher elevation communities in the Himalaya-Hengduan Mountains.

PubMed

Zhao, Yan-Hui; Ren, Zong-Xin; Lázaro, Amparo; Wang, Hong; Bernhardt, Peter; Li, Hai-Dong; Li, De-Zhu

2016-05-24

How floral traits and community composition influence plant specialization is poorly understood and the existing evidence is restricted to regions where plant diversity is low. Here, we assessed whether plant specialization varied among four species-rich subalpine/alpine communities on the Yulong Mountain, SW China (elevation from 2725 to 3910 m). We analyzed two factors (floral traits and pollen vector community composition: richness and density) to determine the degree of plant specialization across 101 plant species in all four communities. Floral visitors were collected and pollen load analyses were conducted to identify and define pollen vectors. Plant specialization of each species was described by using both pollen vector diversity (Shannon's diversity index) and plant selectiveness (d' index), which reflected how selective a given species was relative to available pollen vectors. Pollen vector diversity tended to be higher in communities at lower elevations, while plant selectiveness was significantly lower in a community with the highest proportion of unspecialized flowers (open flowers and clusters of flowers in open inflorescences). In particular, we found that plant species with large and unspecialized flowers attracted a greater diversity of pollen vectors and showed higher selectiveness in their use of pollen vectors. Plant species with large floral displays and high flower abundance were more selective in their exploitation of pollen vectors. Moreover, there was a negative relationship between plant selectiveness and pollen vector density. These findings suggest that flower shape and flower size can increase pollen vector diversity but they also increased plant selectiveness. This indicated that those floral traits that were more attractive to insects increased the diversity of pollen vectors to plants while decreasing overlap among co-blooming plant species for the same pollen vectors. Furthermore, floral traits had a more important impact on the diversity of pollen vectors than the composition of anthophilous insect communities. Plant selectiveness of pollen vectors was strongly influenced by both floral traits and insect community composition. These findings provide a basis for a better understanding of how floral traits and community context shape interactions between flowers and their pollen vectors in species-rich communities.

Differential profiles of direct and indirect modification of vector feeding behaviour by a plant virus.

PubMed

He, Wen-Bo; Li, Jie; Liu, Shu-Sheng

2015-01-08

Plant viruses interact with their insect vectors directly and indirectly via host plants, and this tripartite interaction may produce fitness benefits to both the vectors and the viruses. Our previous studies show that the Middle East-Asia Minor 1 (MEAM1) species of the whitefly Bemisia tabaci complex improved its performance on tobacco plants infected by the Tomato yellow leaf curl China virus (TYLCCNV), which it transmits, although virus infection of the whitefly per se reduced its performance. Here, we use electrical penetration graph recording to investigate the direct and indirect effects of TYLCCNV on the feeding behaviour of MEAM1. When feeding on either cotton, a non-host of TYLCCNV, or uninfected tobacco, a host of TYLCCNV, virus-infection of the whiteflies impeded their feeding. Interestingly, when viruliferous whiteflies fed on virus-infected tobacco, their feeding activities were no longer negatively affected; instead, the virus promoted whitefly behaviour related to rapid and effective sap ingestion. Our findings show differential profiles of direct and indirect modification of vector feeding behaviour by a plant virus, and help to unravel the behavioural mechanisms underlying a mutualistic relationship between an insect vector and a plant virus that also has features reminiscent of an insect pathogen.

Differential profiles of direct and indirect modification of vector feeding behaviour by a plant virus

PubMed Central

He, Wen-Bo; Li, Jie; Liu, Shu-Sheng

2015-01-01

Plant viruses interact with their insect vectors directly and indirectly via host plants, and this tripartite interaction may produce fitness benefits to both the vectors and the viruses. Our previous studies show that the Middle East-Asia Minor 1 (MEAM1) species of the whitefly Bemisia tabaci complex improved its performance on tobacco plants infected by the Tomato yellow leaf curl China virus (TYLCCNV), which it transmits, although virus infection of the whitefly per se reduced its performance. Here, we use electrical penetration graph recording to investigate the direct and indirect effects of TYLCCNV on the feeding behaviour of MEAM1. When feeding on either cotton, a non-host of TYLCCNV, or uninfected tobacco, a host of TYLCCNV, virus-infection of the whiteflies impeded their feeding. Interestingly, when viruliferous whiteflies fed on virus-infected tobacco, their feeding activities were no longer negatively affected; instead, the virus promoted whitefly behaviour related to rapid and effective sap ingestion. Our findings show differential profiles of direct and indirect modification of vector feeding behaviour by a plant virus, and help to unravel the behavioural mechanisms underlying a mutualistic relationship between an insect vector and a plant virus that also has features reminiscent of an insect pathogen. PMID:25567524

Newer insecticides for plant virus disease management

USDA-ARS?s Scientific Manuscript database

Effective management of insect and mite vectors of plant pathogens is of crucial importance to minimizing vector-borne diseases in crops. Insecticides play an important role in managing vector populations by reducing the number of individuals that can acquire and transmit a virus, thereby potentiall...

A Multi-species Bait for Chagas Disease Vectors

PubMed Central

Mota, Theo; Vitta, Ana C. R.; Lorenzo-Figueiras, Alicia N.; Barezani, Carla P.; Zani, Carlos L.; Lazzari, Claudio R.; Diotaiuti, Liléia; Jeffares, Lynne; Bohman, Björn; Lorenzo, Marcelo G.

2014-01-01

Background Triatomine bugs are the insect vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. These insects are known to aggregate inside shelters during daylight hours and it has been demonstrated that within shelters, the aggregation is induced by volatiles emitted from bug feces. These signals promote inter-species aggregation among most species studied, but the chemical composition is unknown. Methodology/Principal Findings In the present work, feces from larvae of the three species were obtained and volatile compounds were identified by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). We identified five compounds, all present in feces of all of the three species: Triatoma infestans, Panstrongylus megistus and Triatoma brasiliensis. These substances were tested for attractivity and ability to recruit insects into shelters. Behaviorally active doses of the five substances were obtained for all three triatomine species. The bugs were significantly attracted to shelters baited with blends of 160 ng or 1.6 µg of each substance. Conclusions/Significance Common compounds were found in the feces of vectors of Chagas disease that actively recruited insects into shelters, which suggests that this blend of compounds could be used for the development of baits for early detection of reinfestation with triatomine bugs. PMID:24587457

A simple, rapid and inexpensive method for localization of Tomato yellow leaf curl virus and Potato leafroll virus in plant and insect vectors.

PubMed

Ghanim, Murad; Brumin, Marina; Popovski, Smadar

2009-08-01

A simple, rapid, inexpensive method for the localization of virus transcripts in plant and insect vector tissues is reported here. The method based on fluorescent in situ hybridization using short DNA oligonucleotides complementary to an RNA segment representing a virus transcript in the infected plant or insect vector. The DNA probe harbors a fluorescent molecule at its 5' or 3' ends. The protocol: simple fixation, hybridization, minimal washing and confocal microscopy, provides a highly specific signal. The reliability of the protocol was tested by localizing two phloem-limited plant virus transcripts in infected plants and insect tissues: Tomato yellow leaf curl virus (TYLCV) (Begomovirus: Geminiviridae), exclusively transmitted by the whitefly Bemisia tabaci (Gennadius) in a circulative non-propagative manner, and Potato leafroll virus (Polerovirus: Luteoviridae), similarly transmitted by the aphid Myzus persicae (Sulzer). Transcripts for both viruses were localized specifically to the phloem sieve elements of infected plants, while negative controls showed no signal. TYLCV transcripts were also localized to the digestive tract of B. tabaci, confirming TYLCV route of transmission. Compared to previous methods for localizing virus transcripts in plant and insect tissues that include complex steps for in-vitro probe preparation or antibody raising, tissue fixation, block preparation, sectioning and hybridization, the method described below provides very reliable, convincing, background-free results with much less time, effort and cost.

Characterization of constitutive and putative differentially expressed mRNAs by means of expressed sequence tags, differential display reverse transcriptase-PCR and randomly amplified polymorphic DNA-PCR from the sand fly vector Lutzomyia longipalpis.

PubMed

Ramalho-Ortigão, J M; Temporal, P; de Oliveira , S M; Barbosa, A F; Vilela, M L; Rangel, E F; Brazil, R P; Traub-Cseko, Y M

2001-01-01

Molecular studies of insect disease vectors are of paramount importance for understanding parasite-vector relationship. Advances in this area have led to important findings regarding changes in vectors' physiology upon blood feeding and parasite infection. Mechanisms for interfering with the vectorial capacity of insects responsible for the transmission of diseases such as malaria, Chagas disease and dengue fever are being devised with the ultimate goal of developing transgenic insects. A primary necessity for this goal is information on gene expression and control in the target insect. Our group is investigating molecular aspects of the interaction between Leishmania parasites and Lutzomyia sand flies. As an initial step in our studies we have used random sequencing of cDNA clones from two expression libraries made from head/thorax and abdomen of sugar fed L. longipalpis for the identification of expressed sequence tags (EST). We applied differential display reverse transcriptase-PCR and randomly amplified polymorphic DNA-PCR to characterize differentially expressed mRNA from sugar and blood fed insects, and, in one case, from a L. (V.) braziliensis-infected L. longipalpis. We identified 37 cDNAs that have shown homology to known sequences from GeneBank. Of these, 32 cDNAs code for constitutive proteins such as zinc finger protein, glutamine synthetase, G binding protein, ubiquitin conjugating enzyme. Three are putative differentially expressed cDNAs from blood fed and Leishmania-infected midgut, a chitinase, a V-ATPase and a MAP kinase. Finally, two sequences are homologous to Drosophila melanogaster gene products recently discovered through the Drosophila genome initiative.

Harnessing mosquito-Wolbachia symbiosis for vector and disease control.

PubMed

Bourtzis, Kostas; Dobson, Stephen L; Xi, Zhiyong; Rasgon, Jason L; Calvitti, Maurizio; Moreira, Luciano A; Bossin, Hervé C; Moretti, Riccardo; Baton, Luke Anthony; Hughes, Grant L; Mavingui, Patrick; Gilles, Jeremie R L

2014-04-01

Mosquito species, members of the genera Aedes, Anopheles and Culex, are the major vectors of human pathogens including protozoa (Plasmodium sp.), filariae and of a variety of viruses (causing dengue, chikungunya, yellow fever, West Nile). There is lack of efficient methods and tools to treat many of the diseases caused by these major human pathogens, since no efficient vaccines or drugs are available; even in malaria where insecticide use and drug therapies have reduced incidence, 219 million cases still occurred in 2010. Therefore efforts are currently focused on the control of vector populations. Insecticides alone are insufficient to control mosquito populations since reduced susceptibility and even resistance is being observed more and more frequently. There is also increased concern about the toxic effects of insecticides on non-target (even beneficial) insect populations, on humans and the environment. During recent years, the role of symbionts in the biology, ecology and evolution of insect species has been well-documented and has led to suggestions that they could potentially be used as tools to control pests and therefore diseases. Wolbachia is perhaps the most renowned insect symbiont, mainly due to its ability to manipulate insect reproduction and to interfere with major human pathogens thus providing new avenues for pest control. We herein present recent achievements in the field of mosquito-Wolbachia symbiosis with an emphasis on Aedes albopictus. We also discuss how Wolbachia symbiosis can be harnessed for vector control as well as the potential to combine the sterile insect technique and Wolbachia-based approaches for the enhancement of population suppression programs. Copyright © 2013 International Atomic Energy Agency 2013. Published by Elsevier B.V. All rights reserved.

Plant based insect repellent and insecticide treated bed nets to protect against malaria in areas of early evening biting vectors: double blind randomised placebo controlled clinical trial in the Bolivian Amazon.

PubMed

Hill, N; Lenglet, A; Arnéz, A M; Carneiro, I

2007-11-17

To determine the effectiveness in reducing malaria of combining an insect repellent with insecticide treated bed nets compared with the nets alone in an area where vector mosquitoes feed in the early evening. A double blind, placebo controlled cluster-randomised clinical study. Rural villages and peri-urban districts in the Bolivian Amazon. 4008 individuals in 860 households. All individuals slept under treated nets; one group also used a plant based insect repellent each evening, a second group used placebo. Episodes of Plasmodium falciparum or P vivax malaria confirmed by rapid diagnostic test or blood slide, respectively. We analysed 15,174 person months at risk and found a highly significant 80% reduction in episodes of P vivax in the group that used treated nets and repellent (incidence rate ratio 0.20, 95% confidence interval 0.11 to 0.38, P<0.001). Numbers of P falciparum cases during the study were small and, after adjustment for age, an 82% protective effect was observed, although this was not significant (0.18, 0.02 to 1.40, P=0.10). Reported episodes of fever with any cause were reduced by 58% in the group that used repellent (0.42, 0.31 to 0.56, P<0.001). Insect repellents can provide protection against malaria. In areas where vectors feed in the early evening, effectiveness of treated nets can be significantly increased by using repellent between dusk and bedtime. This has important implications in malaria vector control programmes outside Africa and shows that the combined use of treated nets and insect repellents, as advocated for most tourists travelling to high risk areas, is fully justified. NCT 00144716.

What is the 'true' effect of Trypanosoma rangeli on its triatomine bug vector?

PubMed

Peterson, Jennifer K; Graham, Andrea L

2016-06-01

The phrase, "T. rangeli is pathogenic to its insect vector," is commonly found in peer-reviewed publications on the matter, such that it has become the orthodox view of this interaction. In a literature survey, we identified over 20 papers with almost the exact phrase and several others alluding to it. The idea is of particular importance in triatomine population dynamics and the study of vector-borne T. cruzi transmission, as it could mean that triatomines infected with T. rangeli have lower fitness than uninfected insects. Trypanosoma rangeli pathogenicity was first observed in a series of studies carried out over fifty years ago using the triatomine species Rhodnius prolixus. However, there are few studies of the effect of T. rangeli on its other vector species, and several of the studies were carried out with R. prolixus under non-physiological conditions. Here, we re-evaluate the published studies that led to the conclusion that T. rangeli is pathogenic to its vector, to determine whether or not this indeed is the "true" effect of T. rangeli on its triatomine vector. © 2016 The Society for Vector Ecology.

Polarized skylight navigation in insects: model and electrophysiology of e-vector coding by neurons in the central complex.

PubMed

Sakura, Midori; Lambrinos, Dimitrios; Labhart, Thomas

2008-02-01

Many insects exploit skylight polarization for visual compass orientation or course control. As found in crickets, the peripheral visual system (optic lobe) contains three types of polarization-sensitive neurons (POL neurons), which are tuned to different ( approximately 60 degrees diverging) e-vector orientations. Thus each e-vector orientation elicits a specific combination of activities among the POL neurons coding any e-vector orientation by just three neural signals. In this study, we hypothesize that in the presumed orientation center of the brain (central complex) e-vector orientation is population-coded by a set of "compass neurons." Using computer modeling, we present a neural network model transforming the signal triplet provided by the POL neurons to compass neuron activities coding e-vector orientation by a population code. Using intracellular electrophysiology and cell marking, we present evidence that neurons with the response profile of the presumed compass neurons do indeed exist in the insect brain: each of these compass neuron-like (CNL) cells is activated by a specific e-vector orientation only and otherwise remains silent. Morphologically, CNL cells are tangential neurons extending from the lateral accessory lobe to the lower division of the central body. Surpassing the modeled compass neurons in performance, CNL cells are insensitive to the degree of polarization of the stimulus between 99% and at least down to 18% polarization and thus largely disregard variations of skylight polarization due to changing solar elevations or atmospheric conditions. This suggests that the polarization vision system includes a gain control circuit keeping the output activity at a constant level.

Better Together: Association With 'Candidatus Liberibacter Asiaticus' Increases the Reproductive Fitness of Its Insect Vector, Diaphorina citri (Hemiptera: Liviidae).

PubMed

Pelz-Stelinski, K S; Killiny, N

2016-05-01

The duration of the evolutionary association between a pathogen and vector can be inferred based on the strength of their mutualistic interactions. A well-adapted pathogen is likely to confer some benefit or, at a minimum, exhibit low pathogenicity toward its host vector. Coevolution of the two toward a mutually beneficial association appears to have occurred between the citrus greening disease pathogen, Candidatus Liberibacter asiaticus (Las), and its insect vector, the Asian citrus psyllid, Diaphorina citri (Kuwayama). To better understand the dynamics facilitating transmission, we evaluated the effects of Las infection on the fitness of its vector. Diaphorina citri harboring Las were more fecund than their uninfected counterparts; however, their nymphal development rate and adult survival were comparatively reduced. The finite rate of population increase and net reproductive rate were both greater among Las-infected D. citri as compared with uninfected counterparts, indicating that overall population fitness of infected psyllids was improved given the greater number of offspring produced. Previous reports of transovarial transmission, in conjunction with increased fecundity and population growth rates of Las-positive D. citri found in the current investigation, suggest a long evolutionary relationship between pathogen and vector. The survival of Las-infected adult D. citri was lower compared with uninfected D. citri , which suggests that there may be a fitness trade-off in response to Las infection. A beneficial effect of a plant pathogen on vector fitness may indicate that the pathogen developed a relationship with the insect before secondarily moving to plants.

Better Together: Association With ‘Candidatus Liberibacter Asiaticus’ Increases the Reproductive Fitness of Its Insect Vector, Diaphorina citri (Hemiptera: Liviidae)

PubMed Central

Pelz-Stelinski, K. S.; Killiny, N.

2016-01-01

The duration of the evolutionary association between a pathogen and vector can be inferred based on the strength of their mutualistic interactions. A well-adapted pathogen is likely to confer some benefit or, at a minimum, exhibit low pathogenicity toward its host vector. Coevolution of the two toward a mutually beneficial association appears to have occurred between the citrus greening disease pathogen, Candidatus Liberibacter asiaticus (Las), and its insect vector, the Asian citrus psyllid, Diaphorina citri (Kuwayama). To better understand the dynamics facilitating transmission, we evaluated the effects of Las infection on the fitness of its vector. Diaphorina citri harboring Las were more fecund than their uninfected counterparts; however, their nymphal development rate and adult survival were comparatively reduced. The finite rate of population increase and net reproductive rate were both greater among Las-infected D. citri as compared with uninfected counterparts, indicating that overall population fitness of infected psyllids was improved given the greater number of offspring produced. Previous reports of transovarial transmission, in conjunction with increased fecundity and population growth rates of Las-positive D. citri found in the current investigation, suggest a long evolutionary relationship between pathogen and vector. The survival of Las-infected adult D. citri was lower compared with uninfected D. citri, which suggests that there may be a fitness trade-off in response to Las infection. A beneficial effect of a plant pathogen on vector fitness may indicate that the pathogen developed a relationship with the insect before secondarily moving to plants. PMID:27418697

Transmission dynamics of an insect-specific flavivirus in a naturally infected Culex pipiens laboratory colony and effects of co-infection on vector competence for West Nile virus

PubMed Central

Bolling, Bethany G.; Olea-Popelka, Francisco J.; Eisen, Lars; Moore, Chester G.; Blair, Carol D.

2012-01-01

We established a laboratory colony of Culex pipiens mosquitoes from eggs collected in Colorado and discovered that mosquitoes in the colony are naturally infected with Culex flavivirus (CxFV), an insect-specific flavivirus. In this study we examined transmission dynamics of CxFV and effects of persistent CxFV infection on vector competence for West Nile virus (WNV). We found that vertical transmission is the primary mechanism for persistence of CxFV in Cx. pipiens, with venereal transmission potentially playing a minor role. Vector competence experiments indicated possible early suppression of WNV replication by persistent CxFV infection in Cx. pipiens. This is the first description of insect-specific flavivirus transmission dynamics in a naturally infected mosquito colony and the observation of delayed dissemination of superinfecting WNV suggests that the presence of CxFV may impact the intensity of enzootic transmission of WNV and the risk of human exposure to this important pathogen. PMID:22425062

Optimization of Control Strategies for Non-Domiciliated Triatoma dimidiata, Chagas Disease Vector in the Yucatán Peninsula, Mexico

PubMed Central

Barbu, Corentin; Dumonteil, Eric; Gourbière, Sébastien

2009-01-01

Background Chagas disease is the most important vector-borne disease in Latin America. Regional initiatives based on residual insecticide spraying have successfully controlled domiciliated vectors in many regions. Non-domiciliated vectors remain responsible for a significant transmission risk, and their control is now a key challenge for disease control. Methodology/Principal Findings A mathematical model was developed to predict the temporal variations in abundance of non-domiciliated vectors inside houses. Demographic parameters were estimated by fitting the model to two years of field data from the Yucatan peninsula, Mexico. The predictive value of the model was tested on an independent data set before simulations examined the efficacy of control strategies based on residual insecticide spraying, insect screens, and bednets. The model accurately fitted and predicted field data in the absence and presence of insecticide spraying. Pyrethroid spraying was found effective when 50 mg/m2 were applied yearly within a two-month period matching the immigration season. The >80% reduction in bug abundance was not improved by larger doses or more frequent interventions, and it decreased drastically for different timing and lower frequencies of intervention. Alternatively, the use of insect screens consistently reduced bug abundance proportionally to the reduction of the vector immigration rate. Conclusion/Significance Control of non-domiciliated vectors can hardly be achieved by insecticide spraying, because it would require yearly application and an accurate understanding of the temporal pattern of immigration. Insect screens appear to offer an effective and sustainable alternative, which may be part of multi-disease interventions for the integrated control of neglected vector-borne diseases. PMID:19365542

Development of a baculovirus vector carrying a small hairpin RNA for suppression of sf-caspase-1 expression and improvement of recombinant protein production.

PubMed

Zhang, Xiaoyue; Xu, Keyan; Ou, Yanmei; Xu, Xiaodong; Chen, Hongying

2018-05-02

The Baculovirus expression vector system (BEVS) is a transient expression platform for recombinant protein production in insect cells. Baculovirus infection of insect cells will shutoff host translation and induce apoptosis and lead to the termination of protein expression. Previous reports have demonstrated the enhancement of protein yield in BEVS using stable insect cell lines expressing interference RNA to suppress the expression of caspase-1. In this study, short-hairpin RNA (shRNA) expression cassettes targeting Spodoptera frugiperda caspase-1 (Sf-caspase-1) were constructed and inserted into an Autographa californica multiple nucleopolyhedrovirus (AcMNPV) vector. Using the recombinant baculovirus vectors, we detected the suppression of Sf-caspase-1 expression and cell apoptosis. Green fluorescent protein (GFP), Discosoma sp. Red (DsRed) and firefly luciferase were then expressed as reporter proteins. The results showed that suppression of apoptosis enhanced the accumulation of exogenous proteins at 2 and 3 days post infection. After 4 days post infection, the activity of the reporter proteins remained higher in BEVS using the baculovirus carrying shRNA in comparison with the control without shRNA, but the accumulated protein levels showed no obvious difference between them, suggesting that apoptosis suppression resulted in improved protein folding rather than translation efficiency at the very late stage of baculovirus infection. The baculovirus vector developed in this study would be a useful tool for the production of active proteins suitable for structural and functional studies or pharmaceutical applications in Sf9 cells, and it also has the potential to be adapted for the improvement of protein expression in different insect cell lines that can be infected by AcMNPV.

Floral Scent Mimicry and Vector-Pathogen Associations in a Pseudoflower-Inducing Plant Pathogen System

PubMed Central

McArt, Scott H.; Miles, Timothy D.; Rodriguez-Saona, Cesar; Schilder, Annemiek; Adler, Lynn S.; Grieshop, Matthew J.

2016-01-01

Several fungal plant pathogens induce ‘pseudoflowers’ on their hosts to facilitate insect-mediated transmission of gametes and spores. When spores must be transmitted to host flowers to complete the fungal life cycle, we predict that pseudoflowers should evolve traits that mimic flowers and attract the most effective vectors in the flower-visiting community. We quantified insect visitation to flowers, healthy leaves and leaves infected with Monilinia vaccinii-corymbosi (Mvc), the causative agent of mummy berry disease of blueberry. We developed a nested PCR assay for detecting Mvc spores on bees, flies and other potential insect vectors. We also collected volatiles from blueberry flowers, healthy leaves and leaves infected with Mvc, and experimentally manipulated specific pathogen-induced volatiles to assess attractiveness to potential vectors. Bees and flies accounted for the majority of contacts with flowers, leaves infected with Mvc and healthy leaves. Flowers were contacted most often, while there was no difference between bee or fly contacts with healthy and infected leaves. While bees contacted flowers more often than flies, flies contacted infected leaves more often than bees. Bees were more likely to have Mvc spores on their bodies than flies, suggesting that bees may be more effective vectors than flies for transmitting Mvc spores to flowers. Leaves infected with Mvc had volatile profiles distinct from healthy leaves but similar to flowers. Two volatiles produced by flowers and infected leaves, cinnamyl alcohol and cinnamic aldehyde, were attractive to bees, while no volatiles manipulated were attractive to flies or any other insects. These results suggest that Mvc infection of leaves induces mimicry of floral volatiles, and that transmission occurs primarily via bees, which had the highest likelihood of carrying Mvc spores and visited flowers most frequently. PMID:27851747

Floral Scent Mimicry and Vector-Pathogen Associations in a Pseudoflower-Inducing Plant Pathogen System.

PubMed

McArt, Scott H; Miles, Timothy D; Rodriguez-Saona, Cesar; Schilder, Annemiek; Adler, Lynn S; Grieshop, Matthew J

2016-01-01

Several fungal plant pathogens induce 'pseudoflowers' on their hosts to facilitate insect-mediated transmission of gametes and spores. When spores must be transmitted to host flowers to complete the fungal life cycle, we predict that pseudoflowers should evolve traits that mimic flowers and attract the most effective vectors in the flower-visiting community. We quantified insect visitation to flowers, healthy leaves and leaves infected with Monilinia vaccinii-corymbosi (Mvc), the causative agent of mummy berry disease of blueberry. We developed a nested PCR assay for detecting Mvc spores on bees, flies and other potential insect vectors. We also collected volatiles from blueberry flowers, healthy leaves and leaves infected with Mvc, and experimentally manipulated specific pathogen-induced volatiles to assess attractiveness to potential vectors. Bees and flies accounted for the majority of contacts with flowers, leaves infected with Mvc and healthy leaves. Flowers were contacted most often, while there was no difference between bee or fly contacts with healthy and infected leaves. While bees contacted flowers more often than flies, flies contacted infected leaves more often than bees. Bees were more likely to have Mvc spores on their bodies than flies, suggesting that bees may be more effective vectors than flies for transmitting Mvc spores to flowers. Leaves infected with Mvc had volatile profiles distinct from healthy leaves but similar to flowers. Two volatiles produced by flowers and infected leaves, cinnamyl alcohol and cinnamic aldehyde, were attractive to bees, while no volatiles manipulated were attractive to flies or any other insects. These results suggest that Mvc infection of leaves induces mimicry of floral volatiles, and that transmission occurs primarily via bees, which had the highest likelihood of carrying Mvc spores and visited flowers most frequently.

Microbial ecology-based methods to characterize the bacterial communities of non-model insects.

PubMed

Prosdocimi, Erica M; Mapelli, Francesca; Gonella, Elena; Borin, Sara; Crotti, Elena

2015-12-01

Among the animals of the Kingdom Animalia, insects are unparalleled for their widespread diffusion, diversity and number of occupied ecological niches. In recent years they have raised researcher interest not only because of their importance as human and agricultural pests, disease vectors and as useful breeding species (e.g. honeybee and silkworm), but also because of their suitability as animal models. It is now fully recognized that microorganisms form symbiotic relationships with insects, influencing their survival, fitness, development, mating habits and the immune system and other aspects of the biology and ecology of the insect host. Thus, any research aimed at deepening the knowledge of any given insect species (perhaps species of applied interest or species emerging as novel pests or vectors) must consider the characterization of the associated microbiome. The present review critically examines the microbiology and molecular ecology techniques that can be applied to the taxonomical and functional analysis of the microbiome of non-model insects. Our goal is to provide an overview of current approaches and methods addressing the ecology and functions of microorganisms and microbiomes associated with insects. Our focus is on operational details, aiming to provide a concise guide to currently available advanced techniques, in an effort to extend insect microbiome research beyond simple descriptions of microbial communities. Copyright © 2015 Elsevier B.V. All rights reserved.

Red blotch in Oregon

USDA-ARS?s Scientific Manuscript database

During 2016 we found three potential virus vector insects in Oregon vineyards. Spissistilus festinus was found in Southern Oregon and was recorded in all production regions throughout Oregon during the last 100 years (data from OSU insect collection). We additionally found the treehopper species (Me...

Optimal multiguidance integration in insect navigation.

PubMed

Hoinville, Thierry; Wehner, Rüdiger

2018-03-13

In the last decades, desert ants have become model organisms for the study of insect navigation. In finding their way, they use two major navigational routines: path integration using a celestial compass and landmark guidance based on sets of panoramic views of the terrestrial environment. It has been claimed that this information would enable the insect to acquire and use a centralized cognitive map of its foraging terrain. Here, we present a decentralized architecture, in which the concurrently operating path integration and landmark guidance routines contribute optimally to the directions to be steered, with "optimal" meaning maximizing the certainty (reliability) of the combined information. At any one time during its journey, the animal computes a path integration (global) vector and landmark guidance (local) vector, in which the length of each vector is proportional to the certainty of the individual estimates. Hence, these vectors represent the limited knowledge that the navigator has at any one place about the direction of the goal. The sum of the global and local vectors indicates the navigator's optimal directional estimate. Wherever applied, this decentralized model architecture is sufficient to simulate the results of quite a number of diverse cue-conflict experiments, which have recently been performed in various behavioral contexts by different authors in both desert ants and honeybees. They include even those experiments that have deliberately been designed by former authors to strengthen the evidence for a metric cognitive map in bees.

Neuroethology of Olfactory-Guided Behavior and Its Potential Application in the Control of Harmful Insects.

PubMed

Reisenman, Carolina E; Lei, Hong; Guerenstein, Pablo G

2016-01-01

Harmful insects include pests of crops and storage goods, and vectors of human and animal diseases. Throughout their history, humans have been fighting them using diverse methods. The fairly recent development of synthetic chemical insecticides promised efficient crop and health protection at a relatively low cost. However, the negative effects of those insecticides on human health and the environment, as well as the development of insect resistance, have been fueling the search for alternative control tools. New and promising alternative methods to fight harmful insects include the manipulation of their behavior using synthetic versions of "semiochemicals", which are natural volatile and non-volatile substances involved in the intra- and/or inter-specific communication between organisms. Synthetic semiochemicals can be used as trap baits to monitor the presence of insects, so that insecticide spraying can be planned rationally (i.e., only when and where insects are actually present). Other methods that use semiochemicals include insect annihilation by mass trapping, attract-and- kill techniques, behavioral disruption, and the use of repellents. In the last decades many investigations focused on the neural bases of insect's responses to semiochemicals. Those studies help understand how the olfactory system detects and processes information about odors, which could lead to the design of efficient control tools, including odor baits, repellents or ways to confound insects. Here we review our current knowledge about the neural mechanisms controlling olfactory responses to semiochemicals in harmful insects. We also discuss how this neuroethology approach can be used to design or improve pest/vector management strategies.

Neuroethology of Olfactory-Guided Behavior and Its Potential Application in the Control of Harmful Insects

PubMed Central

Reisenman, Carolina E.; Lei, Hong; Guerenstein, Pablo G.

2016-01-01

Harmful insects include pests of crops and storage goods, and vectors of human and animal diseases. Throughout their history, humans have been fighting them using diverse methods. The fairly recent development of synthetic chemical insecticides promised efficient crop and health protection at a relatively low cost. However, the negative effects of those insecticides on human health and the environment, as well as the development of insect resistance, have been fueling the search for alternative control tools. New and promising alternative methods to fight harmful insects include the manipulation of their behavior using synthetic versions of “semiochemicals”, which are natural volatile and non-volatile substances involved in the intra- and/or inter-specific communication between organisms. Synthetic semiochemicals can be used as trap baits to monitor the presence of insects, so that insecticide spraying can be planned rationally (i.e., only when and where insects are actually present). Other methods that use semiochemicals include insect annihilation by mass trapping, attract-and- kill techniques, behavioral disruption, and the use of repellents. In the last decades many investigations focused on the neural bases of insect's responses to semiochemicals. Those studies help understand how the olfactory system detects and processes information about odors, which could lead to the design of efficient control tools, including odor baits, repellents or ways to confound insects. Here we review our current knowledge about the neural mechanisms controlling olfactory responses to semiochemicals in harmful insects. We also discuss how this neuroethology approach can be used to design or improve pest/vector management strategies. PMID:27445858

On the study of the transmission networks of blood parasites from SW Spain: diversity of avian haemosporidians in the biting midge Culicoides circumscriptus and wild birds.

PubMed

Ferraguti, Martina; Martínez-de la Puente, Josué; Ruiz, Santiago; Soriguer, Ramón; Figuerola, Jordi

2013-07-15

Blood-sucking flying insects play a key role in the transmission of pathogens of vector-borne diseases. However, at least for the case of avian malaria parasites, the vast majority of studies focus on the interaction between parasites and vertebrate hosts, but there is a lack of information regarding the interaction between the parasites and the insect vectors. Here, we identified the presence of malaria and malaria-like parasite lineages harbored by the potential vector Culicoides circumscriptus (Kieffer). Also, we identified some nodes of the transmission network connecting parasite lineages, potential insect vectors and avian hosts by comparing Haemoproteus and Plasmodium lineages isolated from insects with those infecting wild birds in this and previous studies. Using a molecular approach, we analysed the presence of blood parasites in a total of 97 biting midges trapped in the Doñana National Park (SW Spain) and surrounding areas. Also, 123 blood samples from 11 bird species were analyzed for the presence of blood parasite infections. Blood parasites Haemoproteus and Plasmodium were identified by amplification of a 478 bp fragment of the mitochondrial cytochrome b gen. Thirteen biting midges harboured blood parasites including six Haemoproteus and two Plasmodium lineages, supporting the potential role of these insects on parasite transmission. Moreover, ten (8.1%) birds carried blood parasites. Seven Plasmodium and one Haemoproteus lineages were isolated from birds. Overall, six new Haemoproteus lineages were described in this study. Also, we identified the transmission networks of some blood parasites. Two Haemoproteus lineages, hCIRCUM03 and GAGLA03, were identical to those isolated from Corvus monedula in southern Spain and Garrulus glandarius in Bulgaria, respectively. Furthermore, the new Haemoproteus lineage hCIRCUM05 showed a 99% similarity with a lineage found infecting captive penguins in Japan. The comparison of the parasite lineages isolated in this study with those previously found infecting birds allowed us to identify some potential nodes in the transmission network of avian blood parasite lineages. These results highlight the complexity of the transmission networks of blood parasites in the wild that may involve a high diversity of susceptible birds and insect vectors.

The NSs protein of tomato spotted wilt virus is required for persistent infection and transmission by Frankliniella occidentalis.

PubMed

Margaria, P; Bosco, L; Vallino, M; Ciuffo, M; Mautino, G C; Tavella, L; Turina, M

2014-05-01

Tomato spotted wilt virus (TSWV) is the type member of tospoviruses (genus Tospovirus), plant-infecting viruses that cause severe damage to ornamental and vegetable crops. Tospoviruses are transmitted by thrips in the circulative propagative mode. We generated a collection of NSs-defective TSWV isolates and showed that TSWV coding for truncated NSs protein could not be transmitted by Frankliniella occidentalis. Quantitative reverse transcription (RT)-PCR and immunostaining of individual insects detected the mutant virus in second-instar larvae and adult insects, demonstrating that insects could acquire and accumulate the NSs-defective virus. Nevertheless, adults carried a significantly lower viral load, resulting in the absence of transmission. Genome sequencing and analyses of reassortant isolates showed genetic evidence of the association between the loss of competence in transmission and the mutation in the NSs coding sequence. Our findings offer new insight into the TSWV-thrips interaction and Tospovirus pathogenesis and highlight, for the first time in the Bunyaviridae family, a major role for the S segment, and specifically for the NSs protein, in virulence and efficient infection in insect vector individuals. Our work is the first to show a role for the NSs protein in virus accumulation in the insect vector in the Bunyaviridae family: demonstration was obtained for the system TSWV-F. occidentalis, arguably one of the most damaging combination for vegetable crops. Genetic evidence of the involvement of the NSs protein in vector transmission was provided with multiple approaches.

The NSs Protein of Tomato spotted wilt virus Is Required for Persistent Infection and Transmission by Frankliniella occidentalis

PubMed Central

Margaria, P.; Bosco, L.; Vallino, M.; Ciuffo, M.; Mautino, G. C.; Tavella, L.

2014-01-01

ABSTRACT Tomato spotted wilt virus (TSWV) is the type member of tospoviruses (genus Tospovirus), plant-infecting viruses that cause severe damage to ornamental and vegetable crops. Tospoviruses are transmitted by thrips in the circulative propagative mode. We generated a collection of NSs-defective TSWV isolates and showed that TSWV coding for truncated NSs protein could not be transmitted by Frankliniella occidentalis. Quantitative reverse transcription (RT)-PCR and immunostaining of individual insects detected the mutant virus in second-instar larvae and adult insects, demonstrating that insects could acquire and accumulate the NSs-defective virus. Nevertheless, adults carried a significantly lower viral load, resulting in the absence of transmission. Genome sequencing and analyses of reassortant isolates showed genetic evidence of the association between the loss of competence in transmission and the mutation in the NSs coding sequence. Our findings offer new insight into the TSWV-thrips interaction and Tospovirus pathogenesis and highlight, for the first time in the Bunyaviridae family, a major role for the S segment, and specifically for the NSs protein, in virulence and efficient infection in insect vector individuals. IMPORTANCE Our work is the first to show a role for the NSs protein in virus accumulation in the insect vector in the Bunyaviridae family: demonstration was obtained for the system TSWV-F. occidentalis, arguably one of the most damaging combination for vegetable crops. Genetic evidence of the involvement of the NSs protein in vector transmission was provided with multiple approaches. PMID:24623427

Approaches to control diseases vectored by ambrosia beetles in avocado and other American Lauraceae

USDA-ARS?s Scientific Manuscript database

Invasive ambrosia beetles and the plant pathogenic fungi they vector represent a significant challenge to North American agriculture, native and landscape trees. Ambrosia beetles encompass a range of insect species and they vector a diverse set of plant pathogenic fungi. Our lab has taken several bi...

Genetics and evolution of triatomines: from phylogeny to vector control

PubMed Central

Gourbière, S; Dorn, P; Tripet, F; Dumonteil, E

2012-01-01

Triatomines are hemipteran bugs acting as vectors of the protozoan parasite Trypanosoma cruzi. This parasite causes Chagas disease, one of the major parasitic diseases in the Americas. Studies of triatomine genetics and evolution have been particularly useful in the design of rational vector control strategies, and are reviewed here. The phylogeography of several triatomine species is now slowly emerging, and the struggle to reconcile the phenotypic, phylogenetic, ecological and epidemiological species concepts makes for a very dynamic field. Population genetic studies using different markers indicate a wide range of population structures, depending on the triatomine species, ranging from highly fragmented to mobile, interbreeding populations. Triatomines transmit T. cruzi in the context of complex interactions between the insect vectors, their bacterial symbionts and the parasites; however, an integrated view of the significance of these interactions in triatomine biology, evolution and in disease transmission is still lacking. The development of novel genetic markers, together with the ongoing sequencing of the Rhodnius prolixus genome and more integrative studies, will provide key tools to expanding our understanding of these important insect vectors and allow the design of improved vector control strategies. PMID:21897436

Improved annotation of the insect vector of citrus greening disease: biocuration by a diverse genomics community

PubMed Central

Hosmani, Prashant S.; Villalobos-Ayala, Krystal; Miller, Sherry; Shippy, Teresa; Flores, Mirella; Rosendale, Andrew; Cordola, Chris; Bell, Tracey; Mann, Hannah; DeAvila, Gabe; DeAvila, Daniel; Moore, Zachary; Buller, Kyle; Ciolkevich, Kathryn; Nandyal, Samantha; Mahoney, Robert; Van Voorhis, Joshua; Dunlevy, Megan; Farrow, David; Hunter, David; Morgan, Taylar; Shore, Kayla; Guzman, Victoria; Izsak, Allison; Dixon, Danielle E.; Cridge, Andrew; Cano, Liliana; Cao, Xiaolong; Jiang, Haobo; Leng, Nan; Johnson, Shannon; Cantarel, Brandi L.; Richards, Stephen; English, Adam; Shatters, Robert G.; Childers, Chris; Chen, Mei-Ju; Hunter, Wayne; Cilia, Michelle; Mueller, Lukas A.; Munoz-Torres, Monica; Nelson, David; Poelchau, Monica F.; Benoit, Joshua B.; Wiersma-Koch, Helen; D’Elia, Tom; Brown, Susan J.

2017-01-01

Abstract The Asian citrus psyllid (Diaphorina citri Kuwayama) is the insect vector of the bacterium Candidatus Liberibacter asiaticus (CLas), the pathogen associated with citrus Huanglongbing (HLB, citrus greening). HLB threatens citrus production worldwide. Suppression or reduction of the insect vector using chemical insecticides has been the primary method to inhibit the spread of citrus greening disease. Accurate structural and functional annotation of the Asian citrus psyllid genome, as well as a clear understanding of the interactions between the insect and CLas, are required for development of new molecular-based HLB control methods. A draft assembly of the D. citri genome has been generated and annotated with automated pipelines. However, knowledge transfer from well-curated reference genomes such as that of Drosophila melanogaster to newly sequenced ones is challenging due to the complexity and diversity of insect genomes. To identify and improve gene models as potential targets for pest control, we manually curated several gene families with a focus on genes that have key functional roles in D. citri biology and CLas interactions. This community effort produced 530 manually curated gene models across developmental, physiological, RNAi regulatory and immunity-related pathways. As previously shown in the pea aphid, RNAi machinery genes putatively involved in the microRNA pathway have been specifically duplicated. A comprehensive transcriptome enabled us to identify a number of gene families that are either missing or misassembled in the draft genome. In order to develop biocuration as a training experience, we included undergraduate and graduate students from multiple institutions, as well as experienced annotators from the insect genomics research community. The resulting gene set (OGS v1.0) combines both automatically predicted and manually curated gene models. Database URL: https://citrusgreening.org/ PMID:29220441

Infection Density Dynamics of the Citrus Greening Bacterium “Candidatus Liberibacter asiaticus” in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants

PubMed Central

Ukuda-Hosokawa, Rie; Sadoyama, Yasutsune; Kishaba, Misaki; Kuriwada, Takashi; Anbutsu, Hisashi

2015-01-01

Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, “Candidatus Liberibacter asiaticus,” and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of “Ca. Liberibacter asiaticus” in field populations of D. citri with experiments using field-collected insects to address how “Ca. Liberibacter asiaticus” infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from “Ca. Liberibacter asiaticus”-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were “Ca. Liberibacter asiaticus” positive. The infections were systemic across head-thorax and abdomen, ranging from 103 to 107 bacteria per insect. In spring, the infection densities were low in March, at ∼103 bacteria per insect, increasing up to 106 to 107 bacteria per insect in April and May, and decreasing to 105 to 106 bacteria per insect in late May, whereas the infection densities were constantly ∼106 to 107 bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with “Ca. Liberibacter asiaticus” infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected “Ca. Liberibacter asiaticus”-infected insects suggested that (i) “Ca. Liberibacter asiaticus”-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (∼106 bacteria per insect) of “Ca. Liberibacter asiaticus” density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits “Ca. Liberibacter asiaticus” to citrus plants in a stochastic manner. These findings provide valuable insights into understanding, predicting, and controlling this notorious citrus pathogen. PMID:25819961

Optimal control of malaria: combining vector interventions and drug therapies.

PubMed

Khamis, Doran; El Mouden, Claire; Kura, Klodeta; Bonsall, Michael B

2018-04-24

The sterile insect technique and transgenic equivalents are considered promising tools for controlling vector-borne disease in an age of increasing insecticide and drug-resistance. Combining vector interventions with artemisinin-based therapies may achieve the twin goals of suppressing malaria endemicity while managing artemisinin resistance. While the cost-effectiveness of these controls has been investigated independently, their combined usage has not been dynamically optimized in response to ecological and epidemiological processes. An optimal control framework based on coupled models of mosquito population dynamics and malaria epidemiology is used to investigate the cost-effectiveness of combining vector control with drug therapies in homogeneous environments with and without vector migration. The costs of endemic malaria are weighed against the costs of administering artemisinin therapies and releasing modified mosquitoes using various cost structures. Larval density dependence is shown to reduce the cost-effectiveness of conventional sterile insect releases compared with transgenic mosquitoes with a late-acting lethal gene. Using drug treatments can reduce the critical vector control release ratio necessary to cause disease fadeout. Combining vector control and drug therapies is the most effective and efficient use of resources, and using optimized implementation strategies can substantially reduce costs.

Transforming Lepidopteran Insect Cells for Improved Protein Processing and Expression

USDA-ARS?s Scientific Manuscript database

The lepidopteran insect cells used with the baculovirus expression vector system (BEVS) are capable of synthesizing and accurately processing foreign proteins. However, proteins expressed in baculovirus-infected cells often fail to be completely processed, or are not processed in a manner that meet...

The dark side of suibsidies: quantifying contaminant exposure to riparian predators via stream insects

EPA Science Inventory

Aquatic insects provide a critical nutrient subsidy to riparian food webs, yet their role as vectors of contaminants to terrestrial ecosystems is poorly understood. We investigated relationships between aquatic (resource utilization) and contaminant exposure for a riparian invert...

Molecular Biology of Insect Sodium Channels and Pyrethroid Resistance

PubMed Central

Dong, Ke; Du, Yuzhe; Rinkevich, Frank; Nomura, Yoshiko; Xu, Peng; Wang, Lingxin; Silver, Kristopher; Zhorov, Boris S.

2015-01-01

Voltage-gated sodium channels are essential for the initiation and propagation of the action potential in neurons and other excitable cells. Because of their critical roles in electrical signaling, sodium channels are targets of a variety of naturally occurring and synthetic neurotoxins, including several classes of insecticides. This review is intended to provide an update on the molecular biology of insect sodium channels and the molecular mechanism of pyrethroid resistance. Although mammalian and insect sodium channels share fundamental topological and functional properties, most insect species carry only one sodium channel gene, compared to multiple sodium channel genes found in each mammalian species. Recent studies showed that two posttranscriptional mechanisms, alternative splicing and RNA editing, are involved in generating functional diversity of sodium channels in insects. More than 50 sodium channel mutations have been identified to be responsible for or associated with knockdown resistance (kdr) to pyrethroids in various arthropod pests and disease vectors. Elucidation of molecular mechanism of kdr led to the identification of dual receptor sites of pyrethroids on insect sodium channels. Most of the kdr mutations appear to be located within or close to the two receptor sites. The accumulating knowledge of insect sodium channels and their interactions with insecticides provides a foundation for understanding the neurophysiology of sodium channels in vivo and the development of new and safer insecticides for effective control of arthropod pests and human disease vectors. PMID:24704279

Insights from agriculture for the management of insecticide resistance in disease vectors.

PubMed

Sternberg, Eleanore D; Thomas, Matthew B

2018-04-01

Key to contemporary management of diseases such as malaria, dengue, and filariasis is control of the insect vectors responsible for transmission. Insecticide-based interventions have contributed to declines in disease burdens in many areas, but this progress could be threatened by the emergence of insecticide resistance in vector populations. Insecticide resistance is likewise a major concern in agriculture, where insect pests can cause substantial yield losses. Here, we explore overlaps between understanding and managing insecticide resistance in agriculture and in public health. We have used the Global Plan for Insecticide Resistance Management in malaria vectors, developed under the auspices of the World Health Organization Global Malaria Program, as a framework for this exploration because it serves as one of the few cohesive documents for managing a global insecticide resistance crisis. Generally, this comparison highlights some fundamental differences between insect control in agriculture and in public health. Moreover, we emphasize that the success of insecticide resistance management strategies is strongly dependent on the biological specifics of each system. We suggest that the biological, operational, and regulatory differences between agriculture and public health limit the wholesale transfer of knowledge and practices from one system to the other. Nonetheless, there are some valuable insights from agriculture that could assist in advancing the existing Global Plan for Insecticide Resistance Management framework.

Trap Type, Chirality of a-Pinene, and Geographic Region Affect Sampling Efficiency of Root and Lower Stem Insects in Pine

Treesearch

Nadir Erbilgin; Alex Szele; Kier Dean Klepzig; Kenneth Francis Raffa

2001-01-01

Root and lower stem insects cause significant damage to conifers, vector phytopathogenic fungi, and can predispose trees to bark beetle attacks. The development of effective sampling techniques is an important component in managing these cryptic insects. We tested the effects of trap type and stereochemistry of a-pinene, in combination with ethanol, on catches of the...

Insect E-probe Diagnostic Nucleic acid Analysis (EDNA): the application of a novel bioinformatic tool to detection of vectors and pathogens in individual insect and simulated insect trap metagenomes

USDA-ARS?s Scientific Manuscript database

Plant pathogen detection takes many forms. In simple cases, researchers are attempting to detect a known pathogen from a known host utilizing targeted nucleic acid or antigenic assays. However, in more complex scenarios researchers may not know the identity of a pathogen, or they may need to screen ...

Release of genetically engineered insects: a framework to identify potential ecological effects

PubMed Central

David, Aaron S; Kaser, Joe M; Morey, Amy C; Roth, Alexander M; Andow, David A

2013-01-01

Genetically engineered (GE) insects have the potential to radically change pest management worldwide. With recent approvals of GE insect releases, there is a need for a synthesized framework to evaluate their potential ecological and evolutionary effects. The effects may occur in two phases: a transitory phase when the focal population changes in density, and a steady state phase when it reaches a new, constant density. We review potential effects of a rapid change in insect density related to population outbreaks, biological control, invasive species, and other GE organisms to identify a comprehensive list of potential ecological and evolutionary effects of GE insect releases. We apply this framework to the Anopheles gambiae mosquito – a malaria vector being engineered to suppress the wild mosquito population – to identify effects that may occur during the transitory and steady state phases after release. Our methodology reveals many potential effects in each phase, perhaps most notably those dealing with immunity in the transitory phase, and with pathogen and vector evolution in the steady state phase. Importantly, this framework identifies knowledge gaps in mosquito ecology. Identifying effects in the transitory and steady state phases allows more rigorous identification of the potential ecological effects of GE insect release. PMID:24198955

Transmission dynamics of an insect-specific flavivirus in a naturally infected Culex pipiens laboratory colony and effects of co-infection on vector competence for West Nile virus.

PubMed

Bolling, Bethany G; Olea-Popelka, Francisco J; Eisen, Lars; Moore, Chester G; Blair, Carol D

2012-06-05

We established a laboratory colony of Culex pipiens mosquitoes from eggs collected in Colorado and discovered that mosquitoes in the colony are naturally infected with Culex flavivirus (CxFV), an insect-specific flavivirus. In this study we examined transmission dynamics of CxFV and effects of persistent CxFV infection on vector competence for West Nile virus (WNV). We found that vertical transmission is the primary mechanism for persistence of CxFV in Cx. pipiens, with venereal transmission potentially playing a minor role. Vector competence experiments indicated possible early suppression of WNV replication by persistent CxFV infection in Cx. pipiens. This is the first description of insect-specific flavivirus transmission dynamics in a naturally infected mosquito colony and the observation of delayed dissemination of superinfecting WNV suggests that the presence of CxFV may impact the intensity of enzootic transmission of WNV and the risk of human exposure to this important pathogen. Copyright © 2012 Elsevier Inc. All rights reserved.

Propagation of Homalodisca Coagulata Virus-01 via Homalodisca Vitripennis cell culture

USDA-ARS?s Scientific Manuscript database

The glassy-winged sharpshooter (Homalodisca vitripennis) is a highly vagile and polyphagous insect found throughout the southwestern United States. These insects are the predominant vectors of Xylella fastidiosa, a xylem-limited bacterium that is the causal agent of Pierce's disease (PD) of grapevin...

Development of leafhopper cell culture to trace the early infection process of a nucleorhabdovirus, rice yellow stunt virus, in insect vector cells.

PubMed

Wang, Haitao; Wang, Juan; Xie, Yunjie; Fu, Zhijun; Wei, Taiyun; Zhang, Xiao-Feng

2018-04-20

In China, the rice pathogen Rice yellow stunt virus (RYSV), a member of the genus Nucleorhabdovirus in the family Rhabdoviridae, was a severe threat to rice production during the1960s and1970s. Fundamental aspects of the biology of this virus such as protein localization and formation of the RYSV viroplasm during infection of insect vector cells are largely unexplored. The specific role(s) of the structural proteins nucleoprotein (N) and phosphoprotein (P) in the assembly of the viroplasm during RYSV infection in insect vector is also unclear. In present study, we used continuous leafhopper cell culture, immunocytochemical techniques, and transmission electron microscopy to investigate the subcellular distributions of N and P during RYSV infection. Both GST pull-down assay and yeast two-hybrid assay were used to assess the in vitro interaction of N and P. The dsRNA interference assay was performed to study the functional roles of N and P in the assembly of RYSV viroplasm. Here we demonstrated that N and P colocalized in the nucleus of RYSV-infected Nephotettix cincticeps cell and formed viroplasm-like structures (VpLSs). The transiently expressed N and P are sufficient to form VpLSs in the Sf9 cells. In addition, the interactions of N/P, N/N and P/P were confirmed in vitro. More interestingly, the accumulation of RYSV was significantly reduced when the transcription of N gene or P gene was knocked down by dsRNA treatment. In summary, our results suggest that N and P are the main viral factors responsible for the formation of viroplasm in RYSV-infected insect cells. Early during RYSV infection in the insect vector, N and P interacted with each other in the nucleus to form viroplasm-like structures, which are essential for the infection of RYSV.

Insect vector interations and transmission of cereal infecting Cereal rhabdoviruses

USDA-ARS?s Scientific Manuscript database

The cereal infecting cytorhabdoviruses and nucelorhabdoviruses are transmitted to new plant hosts in a persistent, propagative manner by their leafhopper (Cicadellidae) and planthopper (Fulgoroidea) vectors. We discuss our current knowledge of virus acquisition by, replication and movement in, and ...

Plant and animal rhabdovirus host range: a bug's view.

PubMed

Hogenhout, Saskia A; Redinbaugh, Margaret G; Ammar, El-Desouky

2003-06-01

Rhabdoviruses affect human health, terrestrial and aquatic livestock and crops. Most rhabdoviruses are transmitted by insects to their vertebrate or plant hosts. For insect transmission to occur, rhabdoviruses must negotiate barriers to acquisition, replication, movement, escape and inoculation. A better understanding of the molecular interactions of rhabdoviruses with insects will clarify the complexities of rhabdovirus infection processes and epidemiology. A unique opportunity for studying how insects become hosts and vectors of rhabdoviruses is provided by five maize-infecting rhabdoviruses that are differentially transmitted by one or more related species of two divergent homopteran families.

Disruption of Vector Host Preference with Plant Volatiles May Reduce Spread of Insect-Transmitted Plant Pathogens.

PubMed

Martini, Xavier; Willett, Denis S; Kuhns, Emily H; Stelinski, Lukasz L

2016-05-01

Plant pathogens can manipulate the odor of their host; the odor of an infected plant is often attractive to the plant pathogen vector. It has been suggested that this odor-mediated manipulation attracts vectors and may contribute to spread of disease; however, this requires further broad demonstration among vector-pathogen systems. In addition, disruption of this indirect chemical communication between the pathogen and the vector has not been attempted. We present a model that demonstrates how a phytophathogen (Candidatus Liberibacter asiaticus) can increase its spread by indirectly manipulating the behavior of its vector (Asian citrus psyllid, Diaphorina citri Kuwayama). The model indicates that when vectors are attracted to pathogen-infected hosts, the proportion of infected vectors increases, as well as, the proportion of infected hosts. Additionally, the peak of infected host populations occurs earlier as compared with controls. These changes in disease dynamics were more important during scenarios with higher vector mortality. Subsequently, we conducted a series of experiments to disrupt the behavior of the Asian citrus psyllid. To do so, we exposed the vector to methyl salicylate, the major compound released following host infection with the pathogen. We observed that during exposure or after pre-exposure to methyl salicylate, the host preference can be altered; indeed, the Asian citrus psyllids were unable to select infected hosts over uninfected counterparts. We suggest mechanisms to explain these interactions and potential applications of disrupting herbivore host preference with plant volatiles for sustainable management of insect vectors.

Spread of plant pathogens and insect vectors at the northern range margin of cypress in Italy

NASA Astrophysics Data System (ADS)

Zocca, Alessia; Zanini, Corrado; Aimi, Andrea; Frigimelica, Gabriella; La Porta, Nicola; Battisti, Andrea

2008-05-01

The Mediterranean cypress ( Cupressus sempervirens) is a multi-purpose tree widely used in the Mediterranean region. An anthropogenic range expansion of cypress has taken place at the northern margin of the range in Italy in recent decades, driven by ornamental planting in spite of climatic constraints imposed by low winter temperature. The expansion has created new habitats for pathogens and pests, which strongly limit tree survival in the historical (core) part of the range. Based on the enemy release hypothesis, we predicted that damage should be lower in the expansion area. By comparing tree and seed cone damage by pathogens and pests in core and expansion areas of Trentino, a district in the southern Alps, we showed that tree damage was significantly higher in the core area. Seed cones of C. sempervirens are intensively colonized by an aggressive and specific pathogen (the canker fungus Seiridium cardinale, Coelomycetes), associated with seed insect vectors Megastigmus wachtli (Hymenoptera Torymidae) and Orsillus maculatus (Heteroptera Lygaeidae). In contrast, we observed lower tree damage in the expansion area, where a non-aggressive fungus ( Pestalotiopsis funerea, Coelomycetes) was more frequently associated with the same insect vectors. Our results indicate that both insect species have a great potential to reach the range margin, representing a continuous threat of the arrival of fungal pathogens to trees planted at extreme sites. Global warming may accelerate this process since both insects and fungi profit from increased temperature. In the future, cypress planted at the range margin may then face similar pest and pathogen threats as in the historical range.

Genome of Rhodnius prolixus, an insect vector of Chagas disease, reveals unique adaptations to hematophagy and parasite infection

PubMed Central

Mesquita, Rafael D.; Vionette-Amaral, Raquel J.; Lowenberger, Carl; Rivera-Pomar, Rolando; Monteiro, Fernando A.; Minx, Patrick; Spieth, John; Carvalho, A. Bernardo; Panzera, Francisco; Lawson, Daniel; Torres, André Q.; Ribeiro, Jose M. C.; Sorgine, Marcos H. F.; Waterhouse, Robert M.; Abad-Franch, Fernando; Alves-Bezerra, Michele; Amaral, Laurence R.; Araujo, Helena M.; Aravind, L.; Atella, Georgia C.; Azambuja, Patricia; Berni, Mateus; Bittencourt-Cunha, Paula R.; Braz, Gloria R. C.; Calderón-Fernández, Gustavo; Carareto, Claudia M. A.; Christensen, Mikkel B.; Costa, Igor R.; Costa, Samara G.; Dansa, Marilvia; Daumas-Filho, Carlos R. O.; De-Paula, Iron F.; Dias, Felipe A.; Dimopoulos, George; Emrich, Scott J.; Esponda-Behrens, Natalia; Fampa, Patricia; Fernandez-Medina, Rita D.; da Fonseca, Rodrigo N.; Fontenele, Marcio; Fronick, Catrina; Fulton, Lucinda A.; Gandara, Ana Caroline; Garcia, Eloi S.; Genta, Fernando A.; Giraldo-Calderón, Gloria I.; Gomes, Bruno; Gondim, Katia C.; Granzotto, Adriana; Guarneri, Alessandra A.; Guigó, Roderic; Harry, Myriam; Hughes, Daniel S. T.; Jablonka, Willy; Jacquin-Joly, Emmanuelle; Juárez, M. Patricia; Koerich, Leonardo B.; Lange, Angela B.; Latorre-Estivalis, José Manuel; Lavore, Andrés; Lawrence, Gena G.; Lazoski, Cristiano; Lazzari, Claudio R.; Lopes, Raphael R.; Lorenzo, Marcelo G.; Lugon, Magda D.; Marcet, Paula L.; Mariotti, Marco; Masuda, Hatisaburo; Megy, Karine; Missirlis, Fanis; Mota, Theo; Noriega, Fernando G.; Nouzova, Marcela; Nunes, Rodrigo D.; Oliveira, Raquel L. L.; Oliveira-Silveira, Gilbert; Ons, Sheila; Orchard, Ian; Pagola, Lucia; Paiva-Silva, Gabriela O.; Pascual, Agustina; Pavan, Marcio G.; Pedrini, Nicolás; Peixoto, Alexandre A.; Pereira, Marcos H.; Pike, Andrew; Polycarpo, Carla; Prosdocimi, Francisco; Ribeiro-Rodrigues, Rodrigo; Robertson, Hugh M.; Salerno, Ana Paula; Salmon, Didier; Santesmasses, Didac; Schama, Renata; Seabra-Junior, Eloy S.; Silva-Cardoso, Livia; Silva-Neto, Mario A. C.; Souza-Gomes, Matheus; Sterkel, Marcos; Taracena, Mabel L.; Tojo, Marta; Tu, Zhijian Jake; Tubio, Jose M. C.; Ursic-Bedoya, Raul; Venancio, Thiago M.; Walter-Nuno, Ana Beatriz; Wilson, Derek; Warren, Wesley C.; Wilson, Richard K.; Huebner, Erwin; Dotson, Ellen M.; Oliveira, Pedro L.

2015-01-01

Rhodnius prolixus not only has served as a model organism for the study of insect physiology, but also is a major vector of Chagas disease, an illness that affects approximately seven million people worldwide. We sequenced the genome of R. prolixus, generated assembled sequences covering 95% of the genome (∼702 Mb), including 15,456 putative protein-coding genes, and completed comprehensive genomic analyses of this obligate blood-feeding insect. Although immune-deficiency (IMD)-mediated immune responses were observed, R. prolixus putatively lacks key components of the IMD pathway, suggesting a reorganization of the canonical immune signaling network. Although both Toll and IMD effectors controlled intestinal microbiota, neither affected Trypanosoma cruzi, the causal agent of Chagas disease, implying the existence of evasion or tolerance mechanisms. R. prolixus has experienced an extensive loss of selenoprotein genes, with its repertoire reduced to only two proteins, one of which is a selenocysteine-based glutathione peroxidase, the first found in insects. The genome contained actively transcribed, horizontally transferred genes from Wolbachia sp., which showed evidence of codon use evolution toward the insect use pattern. Comparative protein analyses revealed many lineage-specific expansions and putative gene absences in R. prolixus, including tandem expansions of genes related to chemoreception, feeding, and digestion that possibly contributed to the evolution of a blood-feeding lifestyle. The genome assembly and these associated analyses provide critical information on the physiology and evolution of this important vector species and should be instrumental for the development of innovative disease control methods. PMID:26627243

Genome sequences of the human body louse and its primary endosymbiont provide insights into the permanent parasitic lifestyle.

PubMed

Kirkness, Ewen F; Haas, Brian J; Sun, Weilin; Braig, Henk R; Perotti, M Alejandra; Clark, John M; Lee, Si Hyeock; Robertson, Hugh M; Kennedy, Ryan C; Elhaik, Eran; Gerlach, Daniel; Kriventseva, Evgenia V; Elsik, Christine G; Graur, Dan; Hill, Catherine A; Veenstra, Jan A; Walenz, Brian; Tubío, José Manuel C; Ribeiro, José M C; Rozas, Julio; Johnston, J Spencer; Reese, Justin T; Popadic, Aleksandar; Tojo, Marta; Raoult, Didier; Reed, David L; Tomoyasu, Yoshinori; Kraus, Emily; Krause, Emily; Mittapalli, Omprakash; Margam, Venu M; Li, Hong-Mei; Meyer, Jason M; Johnson, Reed M; Romero-Severson, Jeanne; Vanzee, Janice Pagel; Alvarez-Ponce, David; Vieira, Filipe G; Aguadé, Montserrat; Guirao-Rico, Sara; Anzola, Juan M; Yoon, Kyong S; Strycharz, Joseph P; Unger, Maria F; Christley, Scott; Lobo, Neil F; Seufferheld, Manfredo J; Wang, Naikuan; Dasch, Gregory A; Struchiner, Claudio J; Madey, Greg; Hannick, Linda I; Bidwell, Shelby; Joardar, Vinita; Caler, Elisabet; Shao, Renfu; Barker, Stephen C; Cameron, Stephen; Bruggner, Robert V; Regier, Allison; Johnson, Justin; Viswanathan, Lakshmi; Utterback, Terry R; Sutton, Granger G; Lawson, Daniel; Waterhouse, Robert M; Venter, J Craig; Strausberg, Robert L; Berenbaum, May R; Collins, Frank H; Zdobnov, Evgeny M; Pittendrigh, Barry R

2010-07-06

As an obligatory parasite of humans, the body louse (Pediculus humanus humanus) is an important vector for human diseases, including epidemic typhus, relapsing fever, and trench fever. Here, we present genome sequences of the body louse and its primary bacterial endosymbiont Candidatus Riesia pediculicola. The body louse has the smallest known insect genome, spanning 108 Mb. Despite its status as an obligate parasite, it retains a remarkably complete basal insect repertoire of 10,773 protein-coding genes and 57 microRNAs. Representing hemimetabolous insects, the genome of the body louse thus provides a reference for studies of holometabolous insects. Compared with other insect genomes, the body louse genome contains significantly fewer genes associated with environmental sensing and response, including odorant and gustatory receptors and detoxifying enzymes. The unique architecture of the 18 minicircular mitochondrial chromosomes of the body louse may be linked to the loss of the gene encoding the mitochondrial single-stranded DNA binding protein. The genome of the obligatory louse endosymbiont Candidatus Riesia pediculicola encodes less than 600 genes on a short, linear chromosome and a circular plasmid. The plasmid harbors a unique arrangement of genes required for the synthesis of pantothenate, an essential vitamin deficient in the louse diet. The human body louse, its primary endosymbiont, and the bacterial pathogens that it vectors all possess genomes reduced in size compared with their free-living close relatives. Thus, the body louse genome project offers unique information and tools to use in advancing understanding of coevolution among vectors, symbionts, and pathogens.

Migration and Gene Flow Among Domestic Populations of the Chagas Insect Vector Triatoma dimidiata (Hemiptera: Reduviidae) Detected by Microsatellite Loci

PubMed Central

Stevens, Lori; Monroy, M. Carlota; Rodas, Antonieta Guadalupe; Hicks, Robin M.; Lucero, David E.; Lyons, Leslie A.; Dorn, Patricia L.

2015-01-01

Triatoma dimidiata (Latreille, 1811) is the most abundant and significant insect vector of the parasite Trypanosoma cruzi in Central America, and particularly in Guatemala. Tr. cruzi is the causative agent of Chagas disease, and successful disease control requires understanding the geographic distribution and degree of migration of vectors such as T. dimidiata that frequently re-infest houses within months following insecticide application. The population genetic structure of T. dimidiata collected from six villages in southern Guatemala was studied to gain insight into the migration patterns of the insects in this region where populations are largely domestic. This study provided insight into the likelihood of eliminating T. dimidiata by pesticide application as has been observed in some areas for other domestic triatomines such as Triatoma infestans. Genotypes of microsatellite loci for 178 insects from six villages were found to represent five genetic clusters using a Bayesian Markov Chain Monte Carlo method. Individual clusters were found in multiple villages, with multiple clusters in the same house. Although migration occurred, there was statistically significant genetic differentiation among villages (FRT = 0.05) and high genetic differentiation among houses within villages (FSR = 0.11). Relatedness of insects within houses varied from 0 to 0.25, i.e., from unrelated to half-sibs. The results suggest that T. dimidiata in southern Guatemala moves between houses and villages often enough that recolonization is likely, implying the use of insecticides alone is not sufficient for effective control of Chagas disease in this region and more sustainable solutions are required. PMID:26334816

Genome sequences of the human body louse and its primary endosymbiont provide insights into the permanent parasitic lifestyle

PubMed Central

Kirkness, Ewen F.; Haas, Brian J.; Sun, Weilin; Braig, Henk R.; Perotti, M. Alejandra; Clark, John M.; Lee, Si Hyeock; Robertson, Hugh M.; Kennedy, Ryan C.; Elhaik, Eran; Gerlach, Daniel; Kriventseva, Evgenia V.; Elsik, Christine G.; Graur, Dan; Hill, Catherine A.; Veenstra, Jan A.; Walenz, Brian; Tubío, José Manuel C.; Ribeiro, José M. C.; Rozas, Julio; Johnston, J. Spencer; Reese, Justin T.; Popadic, Aleksandar; Tojo, Marta; Raoult, Didier; Reed, David L.; Tomoyasu, Yoshinori; Kraus, Emily; Mittapalli, Omprakash; Margam, Venu M.; Li, Hong-Mei; Meyer, Jason M.; Johnson, Reed M.; Romero-Severson, Jeanne; VanZee, Janice Pagel; Alvarez-Ponce, David; Vieira, Filipe G.; Aguadé, Montserrat; Guirao-Rico, Sara; Anzola, Juan M.; Yoon, Kyong S.; Strycharz, Joseph P.; Unger, Maria F.; Christley, Scott; Lobo, Neil F.; Seufferheld, Manfredo J.; Wang, NaiKuan; Dasch, Gregory A.; Struchiner, Claudio J.; Madey, Greg; Hannick, Linda I.; Bidwell, Shelby; Joardar, Vinita; Caler, Elisabet; Shao, Renfu; Barker, Stephen C.; Cameron, Stephen; Bruggner, Robert V.; Regier, Allison; Johnson, Justin; Viswanathan, Lakshmi; Utterback, Terry R.; Sutton, Granger G.; Lawson, Daniel; Waterhouse, Robert M.; Venter, J. Craig; Strausberg, Robert L.; Collins, Frank H.; Zdobnov, Evgeny M.; Pittendrigh, Barry R.

2010-01-01

As an obligatory parasite of humans, the body louse (Pediculus humanus humanus) is an important vector for human diseases, including epidemic typhus, relapsing fever, and trench fever. Here, we present genome sequences of the body louse and its primary bacterial endosymbiont Candidatus Riesia pediculicola. The body louse has the smallest known insect genome, spanning 108 Mb. Despite its status as an obligate parasite, it retains a remarkably complete basal insect repertoire of 10,773 protein-coding genes and 57 microRNAs. Representing hemimetabolous insects, the genome of the body louse thus provides a reference for studies of holometabolous insects. Compared with other insect genomes, the body louse genome contains significantly fewer genes associated with environmental sensing and response, including odorant and gustatory receptors and detoxifying enzymes. The unique architecture of the 18 minicircular mitochondrial chromosomes of the body louse may be linked to the loss of the gene encoding the mitochondrial single-stranded DNA binding protein. The genome of the obligatory louse endosymbiont Candidatus Riesia pediculicola encodes less than 600 genes on a short, linear chromosome and a circular plasmid. The plasmid harbors a unique arrangement of genes required for the synthesis of pantothenate, an essential vitamin deficient in the louse diet. The human body louse, its primary endosymbiont, and the bacterial pathogens that it vectors all possess genomes reduced in size compared with their free-living close relatives. Thus, the body louse genome project offers unique information and tools to use in advancing understanding of coevolution among vectors, symbionts, and pathogens. PMID:20566863

Genome of Rhodnius prolixus, an insect vector of Chagas disease, reveals unique adaptations to hematophagy and parasite infection.

PubMed

Mesquita, Rafael D; Vionette-Amaral, Raquel J; Lowenberger, Carl; Rivera-Pomar, Rolando; Monteiro, Fernando A; Minx, Patrick; Spieth, John; Carvalho, A Bernardo; Panzera, Francisco; Lawson, Daniel; Torres, André Q; Ribeiro, Jose M C; Sorgine, Marcos H F; Waterhouse, Robert M; Montague, Michael J; Abad-Franch, Fernando; Alves-Bezerra, Michele; Amaral, Laurence R; Araujo, Helena M; Araujo, Ricardo N; Aravind, L; Atella, Georgia C; Azambuja, Patricia; Berni, Mateus; Bittencourt-Cunha, Paula R; Braz, Gloria R C; Calderón-Fernández, Gustavo; Carareto, Claudia M A; Christensen, Mikkel B; Costa, Igor R; Costa, Samara G; Dansa, Marilvia; Daumas-Filho, Carlos R O; De-Paula, Iron F; Dias, Felipe A; Dimopoulos, George; Emrich, Scott J; Esponda-Behrens, Natalia; Fampa, Patricia; Fernandez-Medina, Rita D; da Fonseca, Rodrigo N; Fontenele, Marcio; Fronick, Catrina; Fulton, Lucinda A; Gandara, Ana Caroline; Garcia, Eloi S; Genta, Fernando A; Giraldo-Calderón, Gloria I; Gomes, Bruno; Gondim, Katia C; Granzotto, Adriana; Guarneri, Alessandra A; Guigó, Roderic; Harry, Myriam; Hughes, Daniel S T; Jablonka, Willy; Jacquin-Joly, Emmanuelle; Juárez, M Patricia; Koerich, Leonardo B; Lange, Angela B; Latorre-Estivalis, José Manuel; Lavore, Andrés; Lawrence, Gena G; Lazoski, Cristiano; Lazzari, Claudio R; Lopes, Raphael R; Lorenzo, Marcelo G; Lugon, Magda D; Majerowicz, David; Marcet, Paula L; Mariotti, Marco; Masuda, Hatisaburo; Megy, Karine; Melo, Ana C A; Missirlis, Fanis; Mota, Theo; Noriega, Fernando G; Nouzova, Marcela; Nunes, Rodrigo D; Oliveira, Raquel L L; Oliveira-Silveira, Gilbert; Ons, Sheila; Orchard, Ian; Pagola, Lucia; Paiva-Silva, Gabriela O; Pascual, Agustina; Pavan, Marcio G; Pedrini, Nicolás; Peixoto, Alexandre A; Pereira, Marcos H; Pike, Andrew; Polycarpo, Carla; Prosdocimi, Francisco; Ribeiro-Rodrigues, Rodrigo; Robertson, Hugh M; Salerno, Ana Paula; Salmon, Didier; Santesmasses, Didac; Schama, Renata; Seabra-Junior, Eloy S; Silva-Cardoso, Livia; Silva-Neto, Mario A C; Souza-Gomes, Matheus; Sterkel, Marcos; Taracena, Mabel L; Tojo, Marta; Tu, Zhijian Jake; Tubio, Jose M C; Ursic-Bedoya, Raul; Venancio, Thiago M; Walter-Nuno, Ana Beatriz; Wilson, Derek; Warren, Wesley C; Wilson, Richard K; Huebner, Erwin; Dotson, Ellen M; Oliveira, Pedro L

2015-12-01

Rhodnius prolixus not only has served as a model organism for the study of insect physiology, but also is a major vector of Chagas disease, an illness that affects approximately seven million people worldwide. We sequenced the genome of R. prolixus, generated assembled sequences covering 95% of the genome (∼ 702 Mb), including 15,456 putative protein-coding genes, and completed comprehensive genomic analyses of this obligate blood-feeding insect. Although immune-deficiency (IMD)-mediated immune responses were observed, R. prolixus putatively lacks key components of the IMD pathway, suggesting a reorganization of the canonical immune signaling network. Although both Toll and IMD effectors controlled intestinal microbiota, neither affected Trypanosoma cruzi, the causal agent of Chagas disease, implying the existence of evasion or tolerance mechanisms. R. prolixus has experienced an extensive loss of selenoprotein genes, with its repertoire reduced to only two proteins, one of which is a selenocysteine-based glutathione peroxidase, the first found in insects. The genome contained actively transcribed, horizontally transferred genes from Wolbachia sp., which showed evidence of codon use evolution toward the insect use pattern. Comparative protein analyses revealed many lineage-specific expansions and putative gene absences in R. prolixus, including tandem expansions of genes related to chemoreception, feeding, and digestion that possibly contributed to the evolution of a blood-feeding lifestyle. The genome assembly and these associated analyses provide critical information on the physiology and evolution of this important vector species and should be instrumental for the development of innovative disease control methods.

Metabolic Interplay between the Asian Citrus Psyllid and Its Profftella Symbiont: An Achilles’ Heel of the Citrus Greening Insect Vector

PubMed Central

Ramsey, John S.; Johnson, Richard S.; Hoki, Jason S.; Kruse, Angela; Mahoney, Jaclyn; Hilf, Mark E.; Hunter, Wayne B.; Hall, David G.; Schroeder, Frank C.; MacCoss, Michael J.; Cilia, Michelle

2015-01-01

‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including ‘Candidatus Profftella armatura’, are likely to impact transmission of CLas. We used quantitative mass spectrometry to compare the proteomes of CLas(+) and CLas(-) populations of D. citri, and found that proteins involved in polyketide biosynthesis by the endosymbiont Profftella were up-regulated in CLas(+) insects. Mass spectrometry analysis of the Profftella polyketide diaphorin in D. citri metabolite extracts revealed the presence of a novel diaphorin-related polyketide and the ratio of these two polyketides was changed in CLas(+) insects. Insect proteins differentially expressed between CLas(+) and CLas(-) D. citri included defense and immunity proteins, proteins involved in energy storage and utilization, and proteins involved in endocytosis, cellular adhesion, and cytoskeletal remodeling which are associated with microbial invasion of host cells. Insight into the metabolic interdependence between the insect vector, its endosymbionts, and the citrus greening pathogen reveals novel opportunities for control of this disease, which is currently having a devastating impact on citrus production worldwide. PMID:26580079

Insect symbiotic bacteria harbour viral pathogens for transovarial transmission.

PubMed

Jia, Dongsheng; Mao, Qianzhuo; Chen, Yong; Liu, Yuyan; Chen, Qian; Wu, Wei; Zhang, Xiaofeng; Chen, Hongyan; Li, Yi; Wei, Taiyun

2017-03-06

Many insects, including mosquitoes, planthoppers, aphids and leafhoppers, are the hosts of bacterial symbionts and the vectors for transmitting viral pathogens 1-3 . In general, symbiotic bacteria can indirectly affect viral transmission by enhancing immunity and resistance to viruses in insects 3-5 . Whether symbiotic bacteria can directly interact with the virus and mediate its transmission has been unknown. Here, we show that an insect symbiotic bacterium directly harbours a viral pathogen and mediates its transovarial transmission to offspring. We observe rice dwarf virus (a plant reovirus) binding to the envelopes of the bacterium Sulcia, a common obligate symbiont of leafhoppers 6-8 , allowing the virus to exploit the ancient oocyte entry path of Sulcia in rice leafhopper vectors. Such virus-bacterium binding is mediated by the specific interaction of the viral capsid protein and the Sulcia outer membrane protein. Treatment with antibiotics or antibodies against Sulcia outer membrane protein interferes with this interaction and strongly prevents viral transmission to insect offspring. This newly discovered virus-bacterium interaction represents the first evidence that a viral pathogen can directly exploit a symbiotic bacterium for its transmission. We believe that such a model of virus-bacterium communication is a common phenomenon in nature.

A multiplex TaqMan qPCR assay for sensitive and rapid detection of phytoplasmas infecting Rubus species.

PubMed

Linck, Holger; Krüger, Erika; Reineke, Annette

2017-01-01

Rubus stunt is an economically important disease in the production of raspberries, blackberries, and loganberries. A fast, sensitive, and reliable diagnosis of phytoplasmas, the causal agent of the disease, is of prime importance to stop its spread by vegetative propagation and by insect vectors. Therefore, multiplex qPCR assays using TaqMan probes with different kinds of fluorophores in one reaction were developed, allowing the detection of phytoplasmas in general as well as a more specific detection of phytoplasmas belonging to group 16SrV and host DNA (either plant or insect). This assay now provides a practical tool for the screening of motherplants and monitoring the presence and distribution of phytoplasmas in Rubus plants of different geographic origins, cultivars, and cultivation systems, as well as in putative insect vectors like leafhoppers.

A multiplex TaqMan qPCR assay for sensitive and rapid detection of phytoplasmas infecting Rubus species

PubMed Central

Krüger, Erika; Reineke, Annette

2017-01-01

Rubus stunt is an economically important disease in the production of raspberries, blackberries, and loganberries. A fast, sensitive, and reliable diagnosis of phytoplasmas, the causal agent of the disease, is of prime importance to stop its spread by vegetative propagation and by insect vectors. Therefore, multiplex qPCR assays using TaqMan probes with different kinds of fluorophores in one reaction were developed, allowing the detection of phytoplasmas in general as well as a more specific detection of phytoplasmas belonging to group 16SrV and host DNA (either plant or insect). This assay now provides a practical tool for the screening of motherplants and monitoring the presence and distribution of phytoplasmas in Rubus plants of different geographic origins, cultivars, and cultivation systems, as well as in putative insect vectors like leafhoppers. PMID:28545043

Effects of azadirachtin on the biology of Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) adult female, the main vector of American visceral leishmaniasis.

PubMed

De Andrade-Coelho, Cláudia Alves; De Souza, Nataly Araujo; Silva, Vanderlei Campos; Souza, Adelson A; Gonzalez, Marcelo Salabert; Rangel, Elizabeth Ferreira

2014-07-01

The effects of azadirachtin A added to the sucrose diet of the adult females on the mortality, oviposition, and hatching of the sand fly vector of American visceral leishmaniasis Lutzomyia longipalpis (Lutz & Neiva, 1912) were investigated. Concentrations of 0.1, 1.0, and 10.0 microg/mg of azadirachtin significantly increased insect mortality in comparison with control insects. The same dose also significantly reduced oviposition but not hatching. After a long development period, significantly fewer adult insects were obtained from eggs hatching by azadirachtin-treated females in a dose-response manner. These results indicate that azadirachtin is a potent sterilizer that could be used against the development of Lu. longipalpis populations and as a tool for studying physiological and biochemical processes in phlebotomine species.

Proteomic analysis of interaction between P7-1 of Southern rice black-streaked dwarf virus and the insect vector reveals diverse insect proteins involved in successful transmission.

PubMed

Mar, ThiThi; Liu, Wenwen; Wang, Xifeng

2014-05-06

Southern rice black-streaked dwarf virus (SRBSDV), transmitted by the white-backed planthopper (Sogatella furcifera) in a persistent-propagative manner, has caused serious yield losses in Asia. Here in a yeast two-hybrid system, protein interactions between SRBSDV P7-1 as a bait protein and a cDNA library of S. furcifera as prey protein were assessed. Of 153 proteins identified as putative interactors, 24 were selected for further analysis. Of the 24 proteins, 18 were further confirmed in a chemiluminescent coimmunoprecipitation (Co-IP) assay as true positive interactors with different strengths of interactions. Six potential candidate proteins (neuroglian, myosin light chain 2 [MLC2], polyubiquitin, E3 ubiquitin ligase, ribophorin ii, and profilin) were analyzed for gene expression in five organs by qRT-PCR; mRNA levels were highest in the gut for neuroglian, MLC2, polyubiquitin and profilin, in the salivary glands for ribophorin ii, and in the haemolymph for E3 ubiquitin ligase. A virus-host protein interaction network was constructed using SRBSDV P7-1 and 18 prey positive protein homologs of Drosophila melanogaster. Our findings suggest that these proteins are involved in the complex host reaction to infection by SRBSDV and provide new insights into the molecular basis of transmission. Southern rice black-streaked dwarf virus (SRBSDV), transmitted by S. furcifera in a persistent-propagative manner, is a new found virus and a tentative member of the genus Fijivirus in the family Reoviridae. It was widely noted by plant virologist, government officials and the farmers in Asia in recent years because of its epidemic outbreak and causing serious yield losses after 2009. However, the molecular mechanism by which SRBSDV successfully infects and replicates in both plant and insect hosts remains unclear, and much less is known about how the virus spreads from initially infected cells to adjacent cells in the insect vector. In the present study, we examined protein interactions between SRBSDV P7-1 as the bait and cDNA library of WBPH as the prey by using yeast two-hybrid system, 153 proteins were identified as putative interactors and 24 putative proteins were selected for chemiluminescent coimmunoprecipitation (Co-IP) assay, and then constructed a viral protein-host protein interaction network with homologs of D. melanogaster. Six WBPH proteins were confirmed as potential P7-1 partners that take part in a pivotal role for viral movement in insect vector. These findings will greatly facilitate the understanding of the transmission mechanisms of SRBSDV by its insect vector. This is the first to study the molecular interaction between SRBSDV and its insect vector. Copyright © 2014 Elsevier B.V. All rights reserved.

Laser system for identification, tracking, and control of flying insects

USDA-ARS?s Scientific Manuscript database

Flying insects are common vectors for transmission of pathogens and inflict significant harm on humans in large parts of the developing world. Besides the direct impact to humans, these pathogens also cause harm to crops and result in agricultural losses. Here, we present a laser-based system that c...

Trypanosoma cruzi TcSMUG L-surface mucins promote development and infectivity in the triatomine vector Rhodnius prolixus.

PubMed

Gonzalez, Marcelo S; Souza, Marcela S; Garcia, Eloi S; Nogueira, Nadir F S; Mello, Cícero B; Cánepa, Gaspar E; Bertotti, Santiago; Durante, Ignacio M; Azambuja, Patrícia; Buscaglia, Carlos A

2013-11-01

TcSMUG L products were recently identified as novel mucin-type glycoconjugates restricted to the surface of insect-dwelling epimastigote forms of Trypanosoma cruzi, the etiological agent of Chagas disease. The remarkable conservation of their predicted mature N-terminal region, which is exposed to the extracellular milieu, suggests that TcSMUG L products may be involved in structural and/or functional aspects of the interaction with the insect vector. Here, we investigated the putative roles of TcSMUG L mucins in both in vivo development and ex vivo attachment of epimastigotes to the luminal surface of the digestive tract of Rhodnius prolixus. Our results indicate that the exogenous addition of TcSMUG L N-terminal peptide, but not control T. cruzi mucin peptides, to the infected bloodmeal inhibited the development of parasites in R. prolixus in a dose-dependent manner. Pre-incubation of insect midguts with the TcSMUG L peptide impaired the ex vivo attachment of epimastigotes to the luminal surface epithelium, likely by competing out TcSMUG L binding sites on the luminal surface of the posterior midgut, as revealed by fluorescence microscopy. Together, these observations indicate that TcSMUG L mucins are a determinant of both adhesion of T. cruzi epimastigotes to the posterior midgut epithelial cells of the triatomine, and the infection of the insect vector, R. prolixus.

Genome-Wide RNAi Screen Identifies Broadly-Acting Host Factors That Inhibit Arbovirus Infection

PubMed Central

Yasunaga, Ari; Hanna, Sheri L.; Li, Jianqing; Cho, Hyelim; Rose, Patrick P.; Spiridigliozzi, Anna; Gold, Beth; Diamond, Michael S.; Cherry, Sara

2014-01-01

Vector-borne viruses are an important class of emerging and re-emerging pathogens; thus, an improved understanding of the cellular factors that modulate infection in their respective vertebrate and insect hosts may aid control efforts. In particular, cell-intrinsic antiviral pathways restrict vector-borne viruses including the type I interferon response in vertebrates and the RNA interference (RNAi) pathway in insects. However, it is likely that additional cell-intrinsic mechanisms exist to limit these viruses. Since insects rely on innate immune mechanisms to inhibit virus infections, we used Drosophila as a model insect to identify cellular factors that restrict West Nile virus (WNV), a flavivirus with a broad and expanding geographical host range. Our genome-wide RNAi screen identified 50 genes that inhibited WNV infection. Further screening revealed that 17 of these genes were antiviral against additional flaviviruses, and seven of these were antiviral against other vector-borne viruses, expanding our knowledge of invertebrate cell-intrinsic immunity. Investigation of two newly identified factors that restrict diverse viruses, dXPO1 and dRUVBL1, in the Tip60 complex, demonstrated they contributed to antiviral defense at the organismal level in adult flies, in mosquito cells, and in mammalian cells. These data suggest the existence of broadly acting and functionally conserved antiviral genes and pathways that restrict virus infections in evolutionarily divergent hosts. PMID:24550726

Insect-specific irreversible inhibitors of acetylcholinesterase in pests including the bed bug, the eastern yellowjacket, German and American cockroaches, and the confused flour beetle.

PubMed

Polsinelli, Gregory A; Singh, Sanjay K; Mishra, Rajesh K; Suranyi, Robert; Ragsdale, David W; Pang, Yuan-Ping; Brimijoin, Stephen

2010-09-06

Insecticides directed against acetylcholinesterase (AChE) are facing increased resistance among target species as well as increasing concerns for human toxicity. The result has been a resurgence of disease vectors, insects destructive to agriculture, and residential pests. We previously reported a free cysteine (Cys) residue at the entrance to the AChE active site in some insects but not higher vertebrates. We also reported Cys-targeting methanethiosulfonate molecules (AMTSn), which, under conditions that spared human AChE, caused total irreversible inhibition of aphid AChE, 95% inhibition of AChE from the malaria vector mosquito (Anopheles gambia), and >80% inhibition of activity from the yellow fever mosquito (Aedes aegypti) and northern house mosquito (Culex pipiens). We now find the same compounds inhibit AChE from cockroaches (Blattella germanica and Periplaneta americana), the flour beetle (Tribolium confusum), the multi-colored Asian ladybird beetle (Harmonia axyridis), the bed bug (Cimex lectularius), and a wasp (Vespula maculifrons), with IC(50) values of approximately 1-11muM. Our results support further study of Cys-targeting inhibitors as conceptually novel insecticides that may be free of resistance in a range of insect pests and disease vectors and, compared with current compounds, should demonstrate much lower toxicity to mammals, birds, and fish. Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.

Devising novel strategies against vector mosquitoes and house flies

USDA-ARS?s Scientific Manuscript database

In 1932, the United States Department of Agriculture established an entomological research laboratory in Orlando, Florida. The initial focus of the program was on investigations of mosquitoes (including malaria vectors under conditions “simulating those of South Pacific jungles”) and other insects ...

Germ line transformation of the yellow fever mosquito, Aedes aegypti, mediated by transpositional insertion of a piggyBac vector.

PubMed

Lobo, N F; Hua-Van, A; Li, X; Nolen, B M; Fraser, M J

2002-04-01

Mosquito-vectored diseases such as yellow fever and dengue fever continue to have a substantial impact on human populations world-wide. Novel strategies for control of these mosquito vectored diseases can arise through the development of reliable systems for genetic manipulation of the insect vector. A piggyBac vector marked with the Drosophila melanogaster cinnabar (cn) gene was used to transform the white-eyed khw strain of Aedes aegypti. Microinjection of preblastoderm embryos resulted in four families of cinnabar transformed insects. An overall transformation frequency of 4%, with a range of 0% to as high as 13% for individual experiments, was achieved when using a heat-shock induced transposase providing helper plasmid. Southern hybridizations indicated multiple insertion events in three of four transgenic lines, while the presence of duplicated target TTAA sites at either ends of individual insertions confirmed characteristic piggyBac transposition events in these three transgenic lines. The transgenic phenotype has remained stable for more than twenty generations. The transformations effected using the piggyBac element establish the potential of this element as a germ-line transformation vector for Aedine mosquitoes.

Chagas disease vector blood meal sources identified by protein mass spectrometry

PubMed Central

Keller, Judith I.; Ballif, Bryan A.; St. Clair, Riley M.; Vincent, James J.; Monroy, M. Carlota

2017-01-01

Chagas disease is a complex vector borne parasitic disease involving blood feeding Triatominae (Hemiptera: Reduviidae) insects, also known as kissing bugs, and the vertebrates they feed on. This disease has tremendous impacts on millions of people and is a global health problem. The etiological agent of Chagas disease, Trypanosoma cruzi (Kinetoplastea: Trypanosomatida: Trypanosomatidae), is deposited on the mammalian host in the insect’s feces during a blood meal, and enters the host’s blood stream through mucous membranes or a break in the skin. Identifying the blood meal sources of triatomine vectors is critical in understanding Chagas disease transmission dynamics, can lead to identification of other vertebrates important in the transmission cycle, and aids management decisions. The latter is particularly important as there is little in the way of effective therapeutics for Chagas disease. Several techniques, mostly DNA-based, are available for blood meal identification. However, further methods are needed, particularly when sample conditions lead to low-quality DNA or to assess the risk of human cross-contamination. We demonstrate a proteomics-based approach, using liquid chromatography tandem mass spectrometry (LC-MS/MS) to identify host-specific hemoglobin peptides for blood meal identification in mouse blood control samples and apply LC-MS/MS for the first time to Triatoma dimidiata insect vectors, tracing blood sources to species. In contrast to most proteins, hemoglobin, stabilized by iron, is incredibly stable even being preserved through geologic time. We compared blood stored with and without an anticoagulant and examined field-collected insect specimens stored in suboptimal conditions such as at room temperature for long periods of time. To our knowledge, this is the first study using LC-MS/MS on field-collected arthropod disease vectors to identify blood meal composition, and where blood meal identification was confirmed with more traditional DNA-based methods. We also demonstrate the potential of synthetic peptide standards to estimate relative amounts of hemoglobin acquired when insects feed on multiple blood sources. These LC-MS/MS methods can contribute to developing Ecohealth control strategies for Chagas disease transmission and can be applied to other arthropod disease vectors. PMID:29232402

Biological Control of the Chagas Disease Vector Triatoma infestans with the Entomopathogenic Fungus Beauveria bassiana Combined with an Aggregation Cue: Field, Laboratory and Mathematical Modeling Assessment

PubMed Central

Forlani, Lucas; Pedrini, Nicolás; Girotti, Juan R.; Mijailovsky, Sergio J.; Cardozo, Rubén M.; Gentile, Alberto G.; Hernández-Suárez, Carlos M.; Rabinovich, Jorge E.; Juárez, M. Patricia

2015-01-01

Background Current Chagas disease vector control strategies, based on chemical insecticide spraying, are growingly threatened by the emergence of pyrethroid-resistant Triatoma infestans populations in the Gran Chaco region of South America. Methodology and findings We have already shown that the entomopathogenic fungus Beauveria bassiana has the ability to breach the insect cuticle and is effective both against pyrethroid-susceptible and pyrethroid-resistant T. infestans, in laboratory as well as field assays. It is also known that T. infestans cuticle lipids play a major role as contact aggregation pheromones. We estimated the effectiveness of pheromone-based infection boxes containing B. bassiana spores to kill indoor bugs, and its effect on the vector population dynamics. Laboratory assays were performed to estimate the effect of fungal infection on female reproductive parameters. The effect of insect exuviae as an aggregation signal in the performance of the infection boxes was estimated both in the laboratory and in the field. We developed a stage-specific matrix model of T. infestans to describe the fungal infection effects on insect population dynamics, and to analyze the performance of the biopesticide device in vector biological control. Conclusions The pheromone-containing infective box is a promising new tool against indoor populations of this Chagas disease vector, with the number of boxes per house being the main driver of the reduction of the total domestic bug population. This ecologically safe approach is the first proven alternative to chemical insecticides in the control of T. infestans. The advantageous reduction in vector population by delayed-action fungal biopesticides in a contained environment is here shown supported by mathematical modeling. PMID:25969989

Weather, host and vector — their interplay in the spread of insect-borne animal virus diseases

PubMed Central

Sellers, R. F.

1980-01-01

The spread of insect-borne animal virus diseases is influenced by a number of factors. Hosts migrate, move or are conveyed over long distances: vectors are carried on the wind for varying distances in search of hosts and breeding sites; weather and climate affect hosts and vectors through temperature, moisture and wind. As parasites of host and vector, viruses are carried by animals, birds and insects, and their spread can be correlated with the migration of hosts and the carriage of vectors on winds associated with the movements of the Intertropical Convergence Zone (ITCZ) and warm winds to the north and south of the limits of the ITCZ. The virus is often transmitted from a local cycle to a migratory cycle and back again. Examples of insect-borne virus diseases and their spread are analysed. Japanese, Murray Valley, Western equine, Eastern equine and St Louis encephalitis represent viruses transmitted by mosquito—bird or pig cycles. The areas experiencing infection with these viruses can be divided into a number of zones: A, B, C, D, E and F. In zone A there is a continuous cycle of virus in host and vector throughout the year; in zone B, there is an upsurge in the cycle during the wet season, but the cycle continues during the dry season; there is movement of infected vectors between and within zones A and B on the ITCZ and the virus is introduced to zone C by infected vectors on warm winds; persistence may occur in zone C if conditions are right. In zone D, virus is introduced each year by infected vectors on warm winds and the arrival of the virus coincides with the presence of susceptible nestling birds and susceptible piglets. The disappearance of virus occurs at the time when migrating mosquitoes and birds are returning to warmer climates. The virus is introduced to zone E only on occasions every 5-10 years when conditions are suitable. Infected hosts introduced to zone F do not lead to circulation of virus, since the climate is unsuitable for vectors. Zones A, B and C correspond to endemic and zones D and E to epidemic conditions. Similar zones can be recognized for African horse sickness, bluetongue, Ibaraki disease and bovine ephemeral fever — examples of diseases transmitted in a midge-mammal cycle. In zones A and B viruses are transported by infected midges carried on the wind in association with the movement of ITCZ and undergo cycles in young animals. In these zones and in zone C there is a continual movement of midges on the warm wind between one area and another, colonizing new sites or reinforcing populations of midges already present. Virus is introduced at times into fringe areas (zones D and E) and, as there is little resistance in the host, gives rise to clinical signs of disease. In some areas there is persistence during adverse conditions; in others, the virus is carried back to the endemic zones by infected midges or vectors. Examples of viruses maintained in a mosquito/biting fly—mammal cycle are Venezuelan equine encephalitis and vesicular stomatitis. These viruses enter a migratory cycle from a local cycle and the vectors in the migratory cycle are carried over long distances on the wind. Further examples of virus spread by movement of vectors include West Nile, Rift Valley fever, yellow fever, epizootic haemorrhagic disease of deer and Akabane viruses. In devising means of control it is essential to decide the relationship of host, vector and virus and the nature of the zone in which the area to be controlled lies. Because of the continual risk of reintroduction of infected vectors, it is preferable to protect the host by dipping, spraying or by vaccination rather than attempting to eliminate the local population of insects. PMID:6131919

Water deficit enhances the transmission of plant viruses by insect vectors

PubMed Central

Yvon, Michel; Vile, Denis; Dader, Beatriz; Fereres, Alberto

2017-01-01

Drought is a major threat to crop production worldwide and is accentuated by global warming. Plant responses to this abiotic stress involve physiological changes overlapping, at least partially, the defense pathways elicited both by viruses and their herbivore vectors. Recently, a number of theoretical and empirical studies anticipated the influence of climate changes on vector-borne viruses of plants and animals, mainly addressing the effects on the virus itself or on the vector population dynamics, and inferring possible consequences on virus transmission. Here, we directly assess the effect of a severe water deficit on the efficiency of aphid-transmission of the Cauliflower mosaic virus (CaMV) or the Turnip mosaic virus (TuMV). For both viruses, our results demonstrate that the rate of vector-transmission is significantly increased from water-deprived source plants: CaMV transmission reproducibly increased by 34% and that of TuMV by 100%. In both cases, the enhanced transmission rate could not be explained by a higher virus accumulation, suggesting a more complex drought-induced process that remains to be elucidated. The evidence that infected plants subjected to drought are much better virus sources for insect vectors may have extensive consequences for viral epidemiology, and should be investigated in a wide range of plant-virus-vector systems. PMID:28467423

Water deficit enhances the transmission of plant viruses by insect vectors.

PubMed

van Munster, Manuella; Yvon, Michel; Vile, Denis; Dader, Beatriz; Fereres, Alberto; Blanc, Stéphane

2017-01-01

Drought is a major threat to crop production worldwide and is accentuated by global warming. Plant responses to this abiotic stress involve physiological changes overlapping, at least partially, the defense pathways elicited both by viruses and their herbivore vectors. Recently, a number of theoretical and empirical studies anticipated the influence of climate changes on vector-borne viruses of plants and animals, mainly addressing the effects on the virus itself or on the vector population dynamics, and inferring possible consequences on virus transmission. Here, we directly assess the effect of a severe water deficit on the efficiency of aphid-transmission of the Cauliflower mosaic virus (CaMV) or the Turnip mosaic virus (TuMV). For both viruses, our results demonstrate that the rate of vector-transmission is significantly increased from water-deprived source plants: CaMV transmission reproducibly increased by 34% and that of TuMV by 100%. In both cases, the enhanced transmission rate could not be explained by a higher virus accumulation, suggesting a more complex drought-induced process that remains to be elucidated. The evidence that infected plants subjected to drought are much better virus sources for insect vectors may have extensive consequences for viral epidemiology, and should be investigated in a wide range of plant-virus-vector systems.

Invasive mutualisms between a plant pathogen and insect vectors in the Middle East and Brazil

PubMed Central

Queiroz, Renan Batista; Silva, Fábio Nascimento; Al-Mahmmoli, Issa Hashil; Al-Sadi, Abdullah Mohammed; Carvalho, Claudine Márcia; Elliot, Simon L.

2016-01-01

Complex multi-trophic interactions in vectorborne diseases limit our understanding and ability to predict outbreaks. Arthropod-vectored pathogens are especially problematic, with the potential for novel interspecific interactions during invasions. Variations and novelties in plant–arthropod–pathogen triumvirates present significant threats to global food security. We examined aspects of a phytoplasma pathogen of citrus across two continents. ‘Candidatus Phytoplasma aurantifolia’ causes Witches' Broom Disease of Lime (WBDL) and has devastated citrus production in the Middle East. A variant of this phytoplasma currently displays asymptomatic or ‘silent’ infections in Brazil. We first studied vector capacity and fitness impacts of the pathogen on its vectors. The potential for co-occurring weed species to act as pathogen reservoirs was analysed and key transmission periods in the year were also studied. We demonstrate that two invasive hemipteran insects—Diaphorina citri and Hishimonus phycitis—can vector the phytoplasma. Feeding on phytoplasma-infected hosts greatly increased reproduction of its invasive vector D. citri both in Oman and Brazil; suggesting that increased fitness of invasive insect vectors thereby further increases the pathogen's capacity to spread. Based on our findings, this is a robust system for studying the effects of invasions on vectorborne diseases and highlights concerns about its spread to warmer, drier regions of Brazil. PMID:28083099

Impact of Terminalia chebula Retz. against Aedes aegypti L. and non-target aquatic predatory insects.

PubMed

Thanigaivel, Annamalai; Vasantha-Srinivasan, Prabhakaran; Senthil-Nathan, Sengottayan; Edwin, Edward-Sam; Ponsankar, Athirstam; Chellappandian, Muthiah; Selin-Rani, Selvaraj; Lija-Escaline, Jalasteen; Kalaivani, Kandaswamy

2017-03-01

Aedes aegypti Linn is one of the most important mosquito species. The vectors are responsible for causing deadly diseases like dengue and dengue hemorrhagic fever. Several chemical pesticides used to control these dengue vectors caused severe toxic significances on human health and other non-target beneficial insects. Therefore the current investigation has been made to access the bio-efficacy of the crude seed extracts of T. chebula against the dengue vector Ae. aegypti. The GC-MS analysis of crude seed extracts of T. chebula identified nine chemical compounds with major peak area in the 1,2,3-Benzenetriol (61.96%), followed by Tridecanoic acid (09.55%). Ae. aegypti larvae showed dose dependent mortality rate was observed between the treatments. Prominent protection rate at greater concentrations of 100ppm and moderate protection at 75 and 50ppm was observed in the repellent assay. Lethal concentration (LC 50 and LC 90 ) of fourth instar larvae of Ae. aegypti was observed in 138 and 220ppm concentration respectively. Similarly, the seed extracts showed 100% adulticidal activity at the concentration of 400ppm at 30min of exposure time. Phytochemicals present in the seed extracts of T. chebula significantly affects the major portions of the midgut tissues of Ae. aegypti at the concentration of 100ppm. The toxicological evaluation of seed extracts also proved non-toxic towards the A. bouvieri and Tx. splendens aquatic predatory insects. Hence, the present result suggest that bio-rational plant derived T. chebula could be incorporated in the dengue vector control and have no adverse effects on non-target beneficial insects. Copyright © 2016 Elsevier Inc. All rights reserved.

Cultivation-independent methods reveal differences among bacterial gut microbiota in triatomine vectors of Chagas disease.

PubMed

da Mota, Fabio Faria; Marinho, Lourena Pinheiro; Moreira, Carlos José de Carvalho; Lima, Marli Maria; Mello, Cícero Brasileiro; Garcia, Eloi Souza; Carels, Nicolas; Azambuja, Patricia

2012-01-01

Chagas disease is a trypanosomiasis whose agent is the protozoan parasite Trypanosoma cruzi, which is transmitted to humans by hematophagous bugs known as triatomines. Even though insecticide treatments allow effective control of these bugs in most Latin American countries where Chagas disease is endemic, the disease still affects a large proportion of the population of South America. The features of the disease in humans have been extensively studied, and the genome of the parasite has been sequenced, but no effective drug is yet available to treat Chagas disease. The digestive tract of the insect vectors in which T. cruzi develops has been much less well investigated than blood from its human hosts and constitutes a dynamic environment with very different conditions. Thus, we investigated the composition of the predominant bacterial species of the microbiota in insect vectors from Rhodnius, Triatoma, Panstrongylus and Dipetalogaster genera. Microbiota of triatomine guts were investigated using cultivation-independent methods, i.e., phylogenetic analysis of 16s rDNA using denaturing gradient gel electrophoresis (DGGE) and cloned-based sequencing. The Chao index showed that the diversity of bacterial species in triatomine guts is low, comprising fewer than 20 predominant species, and that these species vary between insect species. The analyses showed that Serratia predominates in Rhodnius, Arsenophonus predominates in Triatoma and Panstrongylus, while Candidatus Rohrkolberia predominates in Dipetalogaster. The microbiota of triatomine guts represents one of the factors that may interfere with T. cruzi transmission and virulence in humans. The knowledge of its composition according to insect species is important for designing measures of biological control for T. cruzi. We found that the predominant species of the bacterial microbiota in triatomines form a group of low complexity whose structure differs according to the vector genus.

Molecular biology of insect sodium channels and pyrethroid resistance.

PubMed

Dong, Ke; Du, Yuzhe; Rinkevich, Frank; Nomura, Yoshiko; Xu, Peng; Wang, Lingxin; Silver, Kristopher; Zhorov, Boris S

2014-07-01

Voltage-gated sodium channels are essential for the initiation and propagation of the action potential in neurons and other excitable cells. Because of their critical roles in electrical signaling, sodium channels are targets of a variety of naturally occurring and synthetic neurotoxins, including several classes of insecticides. This review is intended to provide an update on the molecular biology of insect sodium channels and the molecular mechanism of pyrethroid resistance. Although mammalian and insect sodium channels share fundamental topological and functional properties, most insect species carry only one sodium channel gene, compared to multiple sodium channel genes found in each mammalian species. Recent studies showed that two posttranscriptional mechanisms, alternative splicing and RNA editing, are involved in generating functional diversity of sodium channels in insects. More than 50 sodium channel mutations have been identified to be responsible for or associated with knockdown resistance (kdr) to pyrethroids in various arthropod pests and disease vectors. Elucidation of molecular mechanism of kdr led to the identification of dual receptor sites of pyrethroids on insect sodium channels. Many of the kdr mutations appear to be located within or close to the two receptor sites. The accumulating knowledge of insect sodium channels and their interactions with insecticides provides a foundation for understanding the neurophysiology of sodium channels in vivo and the development of new and safer insecticides for effective control of arthropod pests and human disease vectors. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reverse chemical ecology approach for the identification of a mosquito oviposition attractant

USDA-ARS?s Scientific Manuscript database

Pheromones and other semiochemicals play a crucial role in today’s integrated pest and vector management strategies for controlling populations of insects causing loses to agriculture and vectoring diseases to humans. These semiochemicals are typically discovered by bioassay-guided approaches. Here,...

Parasite-Vector Interaction of Chagas Disease: A Mini-Review.

PubMed

de Oliveira, Ana Beatriz Bortolozo; Alevi, Kaio Cesar Chaboli; Imperador, Carlos Henrique Lima; Madeira, Fernanda Fernandez; Azeredo-Oliveira, Maria Tercília Vilela de

2018-03-01

Trypanosoma cruzi is a protozoan of great importance to public health: it has infected millions of people in the world and is the etiologic agent of Chagas disease, which can cause cardiac and gastrointestinal disorders in patients and may even lead to death. The main vector of transmission of this parasite is triatomine bugs, which have a habit of defecating while feeding on blood and passing the parasite to their own hosts through their feces. Although it has been argued that T. cruzi is not pathogenic for this vector, other studies indicate that the success of the infection depends on several molecules and factors, including the insect's intestinal microbiota, which may experience changes as a result of infection that include decreased fitness. Moreover, the effects of infection depend on the insect species, the parasite strain, and environmental conditions involved. However, the parasite-vector interaction is still underexplored. A deeper understanding of this relationship is an important tool for discovering new approaches to T. cruzi transmission and Chagas disease.

Lice outbreak in buffaloes: evidence of Anaplasma marginale transmission by sucking lice Haematopinus tuberculatus.

PubMed

Da Silva, Aleksandro Schafer; Lopes, Leandro Sâmia; Diaz, Jorge Damian Stumpfs; Tonin, Alexandre Alberto; Stefani, Lenita Moura; Araújo, Denise Nunes

2013-06-01

Lice infestations are commonly seen in buffaloes, causing damage directly to the animal, i.e., itching, skin lesions, and anemia. In addition, these insects can also be vectors for infectious diseases. The present study describes an outbreak of lice in buffaloes as well as evidence for Haematopinus tuberculatus acting as a vector of anaplasmosis. Lice and blood were collected from 4 young buffaloes (2- to 4-mo-old) and a molecular analysis for the presence of Anaplasma marginale was conducted. DNA of A. marginale was detected in the blood of all 4 animals. Twelve lice were collected and separated in 4 groups, with 3 insects each, to comprise a pool of samples. After DNA extraction and molecular analysis, a positive PCR for A. marginale was found in all pooled samples. These results identify sucking lice as potential vectors of anaplasmosis. However, additional studies are necessary to fully evaluate the vector potential of H. tuberculatus for A. maginale transmission.

A gravity model for the spread of a pollinator-borne plant pathogen.

PubMed

Ferrari, Matthew J; Bjørnstad, Ottar N; Partain, Jessica L; Antonovics, Janis

2006-09-01

Many pathogens of plants are transmitted by arthropod vectors whose movement between individual hosts is influenced by foraging behavior. Insect foraging has been shown to depend on both the quality of hosts and the distances between hosts. Given the spatial distribution of host plants and individual variation in quality, vector foraging patterns may therefore produce predictable variation in exposure to pathogens. We develop a "gravity" model to describe the spatial spread of a vector-borne plant pathogen from underlying models of insect foraging in response to host quality using the pollinator-borne smut fungus Microbotryum violaceum as a case study. We fit the model to spatially explicit time series of M. violaceum transmission in replicate experimental plots of the white campion Silene latifolia. The gravity model provides a better fit than a mean field model or a model with only distance-dependent transmission. The results highlight the importance of active vector foraging in generating spatial patterns of disease incidence and for pathogen-mediated selection for floral traits.

Gold nanoparticles - against parasites and insect vectors.

PubMed

Benelli, Giovanni

2018-02-01

Nanomaterials are currently considered for many biological, biomedical and environmental purposes, due to their outstanding physical and chemical properties. The synthesis of gold nanoparticles (Au NPs) is of high interest for research in parasitology and entomology, since these nanomaterials showed promising applications, ranging from detection techniques to drug development, against a rather wide range of parasites of public health relevance, as well as on insect vectors. Here, I reviewed current knowledge about the bioactivity of Au NPs on selected insect species of public health relevance, including major mosquito vectors, such as Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. The toxicity of Au NPs against helminths was reviewed, covering Schistosoma mansoni trematodes as well as Raillietina cestodes. Furthermore, I summarized the information available on the antiparasitic role of Au NPs in the fight against malaria, leishmaniosis, toxoplasmosis, trypanosomiasis, cryptosporidiosis, and microsporidian parasites affecting human and animals health. Besides, I examined the employ of Au NPs as biomarkers, tools for diagnostics and adjuvants for the induction of transmission blocking immunity in malaria vaccine research. In the final section, major challenges and future outlooks for further research are discussed, with special reference to the pressing need of further knowledge about the effect of Au NPs on other arthropod vectors, such as ticks, tsetse flies, tabanids, sandflies and blackflies, and related ecotoxicology assays. Copyright © 2017 Elsevier B.V. All rights reserved.

Infection Density Dynamics of the Citrus Greening Bacterium "Candidatus Liberibacter asiaticus" in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants.

PubMed

Ukuda-Hosokawa, Rie; Sadoyama, Yasutsune; Kishaba, Misaki; Kuriwada, Takashi; Anbutsu, Hisashi; Fukatsu, Takema

2015-06-01

Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, "Candidatus Liberibacter asiaticus," and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of "Ca. Liberibacter asiaticus" in field populations of D. citri with experiments using field-collected insects to address how "Ca. Liberibacter asiaticus" infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from "Ca. Liberibacter asiaticus"-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were "Ca. Liberibacter asiaticus" positive. The infections were systemic across head-thorax and abdomen, ranging from 10(3) to 10(7) bacteria per insect. In spring, the infection densities were low in March, at ∼ 10(3) bacteria per insect, increasing up to 10(6) to 10(7) bacteria per insect in April and May, and decreasing to 10(5) to 10(6) bacteria per insect in late May, whereas the infection densities were constantly ∼ 10(6) to 10(7) bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with "Ca. Liberibacter asiaticus" infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected "Ca. Liberibacter asiaticus"-infected insects suggested that (i) "Ca. Liberibacter asiaticus"-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (∼ 10(6) bacteria per insect) of "Ca. Liberibacter asiaticus" density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits "Ca. Liberibacter asiaticus" to citrus plants in a stochastic manner. These findings provide valuable insights into understanding, predicting, and controlling this notorious citrus pathogen. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Efficiency of an air curtain as an anti-insect barrier: the honey bee as a model insect.

PubMed

Kairo, Guillaume; Pioz, Maryline; Tchamitchian, Sylvie; Pelissier, Michel; Brunet, Jean-Luc; Belzunces, Luc P

2018-05-28

Vector-borne diseases are of high concern for human, animal and plant health. In humans, such diseases are often transmitted by flying insects. Flying insects stop their flight when their kinetic energy cannot compensate for the wind speed. Here, the efficiency of an air curtain in preventing insects from entering a building was studied using the honey bee as a model. Bees were trained to visit a food source placed in a building. The air curtain was tested with strongly motivated bees, when the visiting activity was very high. Airflow velocity was modulated by setting an air curtain device at different voltages. At the nominal voltage, the anti-insect efficiency was 99.9 ± 0.2% compared with both the number of bees at a given time in the absence of the air curtain and the number of bees before the activation of the air curtain. The efficiency decreased as the airflow velocity decreased. The results show that an air curtain operating at an airflow velocity of 7.5 m/sec may prevent a strong flyer with high kinetic energy, such as the honey bee, from entering a building. Thus, air curtains offer an alternative approach for combating vector-borne diseases. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Salivary enzymes are injected into xylem by the glassy-winged sharpshooter, a vector of Xylella fastidiosa

USDA-ARS?s Scientific Manuscript database

Certain hemipteran insects such as the glassy-winged sharpshooter, Homalodisca vitripennis, subsist entirely on xylem fluid, notwithstanding the poor nutrition of such food. Among many adaptations enabling xylem-feeding are aspects of the insect’s salivation that may also allow these insects to tra...

Seasonal fluctuations of sap-feeding insect species infected by Xylella fastidiosa in apulian olive groves of southern Italy

USDA-ARS?s Scientific Manuscript database

A study on seasonal abundance and infectivity by Xylella fastidiosa of Auchenorrhyncha species in the Apulia region of Italy was conducted to identify ideal periods for monitoring and adoption of potential control measures against insect vectors. Adult populations of Auchenorrhyncha species were mon...

Invasive Bark Beetles, Forest Insect& Disease Leaflet 176

Treesearch

J.C. Lee; R.A. Haack; J.F. Negron; J.J. Witcosky; S.J. Seybold

2007-01-01

Bark beetles (Scolytidae) are among the most damaging insects in Northern Hemisphere forests, killing trees by direct feeding and by vectoring fungal pathogens. In addition to an already formidable native bark beetle complex, the number of exotic scolytids in U.S. forests has increased rapidly, with 53 known species established as of June 2007.

Evaluation of the House Fly Musca domestica as a Mechanical Vector for an Anthrax

PubMed Central

Fasanella, Antonio; Scasciamacchia, Silvia; Garofolo, Giuliano; Giangaspero, Annunziata; Tarsitano, Elvira; Adone, Rosanna

2010-01-01

Anthrax is a disease of human beings and animals caused by the encapsulated, spore-forming, Bacillus anthracis. The potential role of insects in the spread of B. anthracis to humans and domestic animals during an anthrax outbreak has been confirmed by many studies. Among insect vectors, the house fly Musca domestica is considered a potential agent for disease transmission. In this study, laboratory-bred specimens of Musca domestica were infected by feeding on anthrax-infected rabbit carcass or anthrax contaminated blood, and the presence of anthrax spores in their spots (faeces and vomitus) was microbiologically monitored. It was also evaluated if the anthrax spores were able to germinate and replicate in the gut content of insects. These results confirmed the role of insects in spreading anthrax infection. This role, although not major, given the huge size of fly populations often associated with anthrax epidemics in domestic animals, cannot be neglected from an epidemiological point of view and suggest that fly control should be considered as part of anthrax control programs. PMID:20808920

Dressed for success: the surface coats of insect-borne protozoan parasites.

PubMed

Roditi, Isabel; Liniger, Matthias

2002-03-01

Three major human diseases, malaria, sleeping sickness and leishmaniasis, are caused by protozoan parasites that are transmitted by blood-sucking insects. These insects are not mere 'flying syringes' that mechanically transfer parasites from one mammal to the next. Instead, they provide a specific environment--albeit not a particularly hospitable one--in which the parasites differentiate, proliferate and migrate to the correct tissues to ensure transmission to the next mammalian host. Recent studies on the role of parasite surface molecules in insect vectors have delivered some surprises and could provide insights on ways to interrupt transmission.

Viral Paratransgenesis in the Malaria Vector Anopheles gambiae

PubMed Central

Ren, Xiaoxia; Hoiczyk, Egbert; Rasgon, Jason L.

2008-01-01

Paratransgenesis, the genetic manipulation of insect symbiotic microorganisms, is being considered as a potential method to control vector-borne diseases such as malaria. The feasibility of paratransgenic malaria control has been hampered by the lack of candidate symbiotic microorganisms for the major vector Anopheles gambiae. In other systems, densonucleosis viruses (DNVs) are attractive agents for viral paratransgenesis because they infect important vector insects, can be genetically manipulated and are transmitted to subsequent generations. However, An. gambiae has been shown to be refractory to DNV dissemination. We discovered, cloned and characterized the first known DNV (AgDNV) capable of infection and dissemination in An. gambiae. We developed a flexible AgDNV-based expression vector to express any gene of interest in An. gambiae using a two-plasmid helper-transducer system. To demonstrate proof-of-concept of the viral paratransgenesis strategy, we used this system to transduce expression of an exogenous gene (enhanced green fluorescent protein; EGFP) in An. gambiae mosquitoes. Wild-type and EGFP-transducing AgDNV virions were highly infectious to An. gambiae larvae, disseminated to and expressed EGFP in epidemiologically relevant adult tissues such as midgut, fat body and ovaries and were transmitted to subsequent mosquito generations. These proof-of-principle data suggest that AgDNV could be used as part of a paratransgenic malaria control strategy by transduction of anti-Plasmodium peptides or insect-specific toxins in Anopheles mosquitoes. AgDNV will also be extremely valuable as an effective and easy-to-use laboratory tool for transient gene expression or RNAi in An. gambiae. PMID:18725926

Broader prevalence of Wolbachia in insects including potential human disease vectors.

PubMed

de Oliveira, C D; Gonçalves, D S; Baton, L A; Shimabukuro, P H F; Carvalho, F D; Moreira, L A

2015-06-01

Wolbachia are intracellular, maternally transmitted bacteria considered the most abundant endosymbionts found in arthropods. They reproductively manipulate their host in order to increase their chances of being transmitted to the offspring, and currently are being used as a tool to control vector-borne diseases. Studies on distribution of Wolbachia among its arthropod hosts are important both for better understanding why this bacterium is so common, as well as for its potential use as a biological control agent. Here, we studied the incidence of Wolbachia in a broad range of insect species, collected from different regions of Brazil, using three genetic markers (16S rRNA, wsp and ftsZ), which varied in terms of their sensitivity to detect this bacterium. The overall incidence of Wolbachia among species belonging to 58 families and 14 orders was 61.9%. The most common positive insect orders were Coleoptera, Diptera, Hemiptera and Hymenoptera, with Diptera and Hemiptera having the highest numbers of Wolbachia-positive families. They included potential human disease vectors whose infection status has never been reported before. Our study further shows the importance of using quantitative polymerase chain reaction for high-throughput and sensitive Wolbachia screening.

Olfactory Mechanisms for Discovery of Odorants to Reduce Insect-Host Contact

PubMed Central

Clark, Jonathan T.; Ray, Anandasankar

2016-01-01

Insects have developed highly sophisticated and sensitive olfactory systems to find animal or plant hosts for feeding. Some insects vector pathogens that cause diseases in hundreds of millions of people and destroy billions of dollars of food products every year. There is great interest, therefore, in understanding how the insect olfactory system can be manipulated to reduce their contact with hosts. Here, we review recent advances in our understanding of insect olfactory detection mechanisms, which may serve as a foundation for designing insect control programs based on manipulation of their behaviors by using odorants. Because every insect species has a unique set of olfactory receptors and olfactory-mediated behaviors, we focus primarily on general principles of odor detection that potentially apply to most insects. While these mechanisms have emerged from studies on model systems for study of insect olfaction, such as Drosophila melanogaster, they provide a foundation for discovery of odorants to repel insects or reduce host-seeking behavior. PMID:27628342

Recilia banda Kramer (Hemiptera: Cicadellidae), a vector of Napier stunt phytoplasma in Kenya

NASA Astrophysics Data System (ADS)

Obura, Evans; Midega, Charles A. O.; Masiga, Daniel; Pickett, John A.; Hassan, Mohamed; Koji, Shinsaku; Khan, Zeyaur R.

2009-10-01

Napier grass ( Pennisetum purpureum) is the most important fodder crop in smallholder dairy production systems in East Africa, characterized by small zero-grazing units. It is also an important trap crop used in the management of cereal stemborers in maize in the region. However, production of Napier grass in the region is severely constrained by Napier stunt disease. The etiology of the disease is known to be a phytoplasma, 16SrXI strain. However, the putative insect vector was yet unknown. We sampled and identified five leafhopper and three planthopper species associated with Napier grass and used them as candidates in pathogen transmission experiments. Polymerase chain reaction (PCR), based on the highly conserved 16S gene, primed by P1/P6-R16F2n/R16R2 nested primer sets was used to diagnose phytoplasma on test plants and insects, before and after transmission experiments. Healthy plants were exposed for 60 days to insects that had fed on diseased plants and acquired phytoplasma. The plants were then incubated for another 30 days. Nested PCR analyses showed that 58.3% of plants exposed to Recilia banda Kramer (Hemiptera: Cicadellidae) were positive for phytoplasma and developed characteristic stunt disease symptoms while 60% of R. banda insect samples were similarly phytoplasma positive. We compared the nucleotide sequences of the phytoplasma isolated from R. banda, Napier grass on which these insects were fed, and Napier grass infected by R. banda, and found them to be virtually identical. The results confirm that R. banda transmits Napier stunt phytoplasma in western Kenya, and may be the key vector of Napier stunt disease in this region.

Laboratory evaluation of traditionally used plant-based insect repellent against the malaria vector Anopheles arabiensis Patton (Diptera: Culicidae).

PubMed

Karunamoorthi, Kaliyaperumal; Ilango, Kandan; Murugan, Kadarkarai

2010-04-01

A laboratory study was carried out to evaluate the repellent efficacy of a methanol-leaf extract of Ethiopian traditionally used insect repellent plant viz., Lomi sar [vernacular name (local native language, Amharic); Cymbopogon citratus (DC) Stapf. (Poaceae)] against Anopheles arabiensis at four different concentrations viz., 1.0, 1.5, 2.0, and 2.5 mg/cm(2). The percentage protection in relation to the dose method was performed. C. citratus extract has shown various degrees of repellency impact against A. arabiensis. It provided the maximum total percentage protection of 78.83% at 2.5 mg/cm(2) and followed 68.06% at 2.0 mg/cm(2) for 12 h. All four tested concentrations of C. citratus extract offered significant protection and Student's t test results shows statistically significant (p value = 0.001) [1.0 mg/cm(2) (t = 22.89; df = 4); 1.5 mg/cm(2) (t = 24.03; df = 4); 2.0 mg/cm(2) (t = 36.92; df = 4); 2.5 mg/cm(2) (t = 22.31; df = 4)] difference between treated and control groups. The result suggests that it could serve as a potent insect repellent against vectors of disease. Globally, C. citratus is renowned for its therapeutic values. Above and beyond, due to its user- as well as environmental-friendly nature, it should be promoted among the marginalized populations in order to reduce man-vector contact. In addition, this appropriate strategy affords the opportunity to minimize chemical repellent usage and the risks associated with adverse side effects. At the end of the day, traditionally used plant-based insect repellents could be viable safer alternative sources for chemical insect repellents.

Determination of Airborne Concentrations of Dichlorvos Over a Range of Temperatures When Using Commercially Available Pesticide Strips In a Simulated Military Guard Post

DTIC Science & Technology

2013-03-22

insects, such as mosquitoes and sand flies. Currently, in the Afghanistan area of operations (AO), there is an intermediate to high risk for vector...Agency (EPA) to kill flies, mosquitoes , gnats, bedbugs, and other arthropod pests. Available in two sizes, the strips are hung in an enclosed room with...toluamide (DEET) to repel biting insects, further assists in protecting exposed personnel. Buildings and areas are also protected from insects by

Trypanosoma cruzi TcSMUG L-surface Mucins Promote Development and Infectivity in the Triatomine Vector Rhodnius prolixus

PubMed Central

Gonzalez, Marcelo S.; Souza, Marcela S.; Garcia, Eloi S.; Nogueira, Nadir F. S.; Mello, Cícero B.; Cánepa, Gaspar E.; Bertotti, Santiago; Durante, Ignacio M.; Azambuja, Patrícia; Buscaglia, Carlos A.

2013-01-01

Background TcSMUG L products were recently identified as novel mucin-type glycoconjugates restricted to the surface of insect-dwelling epimastigote forms of Trypanosoma cruzi, the etiological agent of Chagas disease. The remarkable conservation of their predicted mature N-terminal region, which is exposed to the extracellular milieu, suggests that TcSMUG L products may be involved in structural and/or functional aspects of the interaction with the insect vector. Methodology and Principal Findings Here, we investigated the putative roles of TcSMUG L mucins in both in vivo development and ex vivo attachment of epimastigotes to the luminal surface of the digestive tract of Rhodnius prolixus. Our results indicate that the exogenous addition of TcSMUG L N-terminal peptide, but not control T. cruzi mucin peptides, to the infected bloodmeal inhibited the development of parasites in R. prolixus in a dose-dependent manner. Pre-incubation of insect midguts with the TcSMUG L peptide impaired the ex vivo attachment of epimastigotes to the luminal surface epithelium, likely by competing out TcSMUG L binding sites on the luminal surface of the posterior midgut, as revealed by fluorescence microscopy. Conclusion and Significance Together, these observations indicate that TcSMUG L mucins are a determinant of both adhesion of T. cruzi epimastigotes to the posterior midgut epithelial cells of the triatomine, and the infection of the insect vector, R. prolixus. PMID:24244781

Sequencing of a new target genome: the Pediculus humanus humanus (Phthiraptera: Pediculidae) genome project.

PubMed

Pittendrigh, B R; Clark, J M; Johnston, J S; Lee, S H; Romero-Severson, J; Dasch, G A

2006-11-01

The human body louse, Pediculus humanus humanus (L.), and the human head louse, Pediculus humanus capitis, belong to the hemimetabolous order Phthiraptera. The body louse is the primary vector that transmits the bacterial agents of louse-borne relapsing fever, trench fever, and epidemic typhus. The genomes of the bacterial causative agents of several of these aforementioned diseases have been sequenced. Thus, determining the body louse genome will enhance studies of host-vector-pathogen interactions. Although not important as a major disease vector, head lice are of major social concern. Resistance to traditional pesticides used to control head and body lice have developed. It is imperative that new molecular targets be discovered for the development of novel compounds to control these insects. No complete genome sequence exists for a hemimetabolous insect species primarily because hemimetabolous insects often have large (2000 Mb) to very large (up to 16,300 Mb) genomes. Fortuitously, we determined that the human body louse has one of the smallest genome sizes known in insects, suggesting it may be a suitable choice as a minimal hemimetabolous genome in which many genes have been eliminated during its adaptation to human parasitism. Because many louse species infest birds and mammals, the body louse genome-sequencing project will facilitate studies of their comparative genomics. A 6-8X coverage of the body louse genome, plus sequenced expressed sequence tags, should provide the entomological, evolutionary biology, medical, and public health communities with useful genetic information.

The Immune Responses of the Animal Hosts of West Nile Virus: A Comparison of Insects, Birds, and Mammals.

PubMed

Ahlers, Laura R H; Goodman, Alan G

2018-01-01

Vector-borne diseases, including arboviruses, pose a serious threat to public health worldwide. Arboviruses of the flavivirus genus, such as Zika virus (ZIKV), dengue virus, yellow fever virus (YFV), and West Nile virus (WNV), are transmitted to humans from insect vectors and can cause serious disease. In 2017, over 2,000 reported cases of WNV virus infection occurred in the United States, with two-thirds of cases classified as neuroinvasive. WNV transmission cycles through two different animal populations: birds and mosquitoes. Mammals, particularly humans and horses, can become infected through mosquito bites and represent dead-end hosts of WNV infection. Because WNV can infect diverse species, research on this arbovirus has investigated the host response in mosquitoes, birds, humans, and horses. With the growing geographical range of the WNV mosquito vector and increased human exposure, improved surveillance and treatment of the infection will enhance public health in areas where WNV is endemic. In this review, we survey the bionomics of mosquito species involved in Nearctic WNV transmission. Subsequently, we describe the known immune response pathways that counter WNV infection in insects, birds, and mammals, as well as the mechanisms known to curb viral infection. Moreover, we discuss the bacterium Wolbachia and its involvement in reducing flavivirus titer in insects. Finally, we highlight the similarities of the known immune pathways and identify potential targets for future studies aimed at improving antiviral therapeutic and vaccination design.

Efficient production of antibody Fab fragment by transient gene expression in insect cells.

PubMed

Mori, Keita; Hamada, Hirotsugu; Ogawa, Takafumi; Ohmuro-Matsuyama, Yuki; Katsuda, Tomohisa; Yamaji, Hideki

2017-08-01

Transient gene expression allows a rapid production of diverse recombinant proteins in early-stage preclinical and clinical developments of biologics. Insect cells have proven to be an excellent platform for the production of functional recombinant proteins. In the present study, the production of an antibody Fab fragment by transient gene expression in lepidopteran insect cells was investigated. The DNA fragments encoding heavy-chain (Hc; Fd fragment) and light-chain (Lc) genes of an Fab fragment were individually cloned into the plasmid vector pIHAneo, which contained the Bombyx mori actin promoter downstream of the B. mori nucleopolyhedrovirus (BmNPV) IE-1 transactivator and the BmNPV HR3 enhancer for high-level expression. Trichoplusia ni BTI-TN-5B1-4 (High Five) cells were co-transfected with the resultant plasmid vectors using linear polyethyleneimine. When the transfection efficiency was evaluated, a plasmid vector encoding an enhanced green fluorescent protein (EGFP) gene was also co-transfected. Transfection and culture conditions were optimized based on both the flow cytometry of the EGFP expression in transfected cells and the yield of the secreted Fab fragments determined by enzyme-linked immunosorbent assay (ELISA). Under optimal conditions, a yield of approximately 120 mg/L of Fab fragments was achieved in 5 days in a shake-flask culture. Transient gene expression in insect cells may offer a promising approach to the high-throughput production of recombinant proteins. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Elucidating the Potential of Plant Rhabdoviruses as Vector Expressions Systems

USDA-ARS?s Scientific Manuscript database

Maize fine streak virus (MFSV) is a member of the genus Nucleorhabdovirus that is transmitted by the leafhopper Graminella nigrifons. The virus replicates in both its maize host and its insect vector. To determine whether Drosophila S2 cells support the production of full-length MFSV proteins, we ...

Reduction in fecundity and shifts in cellular processes by a native virus on an invasive insect

USDA-ARS?s Scientific Manuscript database

Pathogens and their vectors have co-evolutionary histories that are intricately intertwined with their ecologies, environments and genetic interactions. The majority of non-persistently transmitted plant viruses are transmitted by aphid species. One important aphid vector in soybean-growing regions ...

Complete genome sequence of a Klebsiella pneumoniae strain isolated from a known cotton insect boll vector

USDA-ARS?s Scientific Manuscript database

Klebsiella pneumoniae (associated with bacterial pneumonia) was previously isolated from Nezara viridula, a significant vector of cotton boll-rot pathogens. We provide the first annotated genome sequence of the cotton opportunistic strain K. pneumoniae 5-1. This data provides guidance to study the...

Sand fly control in Kenya with residual pesticide application on HESCO barriers

USDA-ARS?s Scientific Manuscript database

US military operations in hot-arid regions still face significant impacts from mosquito and sand fly vectors of diseases. Personal protective measures (PPM) such as DEET or treated bed nets and clothing can reduce contact with disease vectors and nuisance insects; however, irregular use of PPM coupl...

Repellency and other biological effects of natural substances against the sand fly, Phlebotomus papatasi

USDA-ARS?s Scientific Manuscript database

Leishmaniasis is an insect-borne disease caused by several protozoan species in the genus Leishmania, vectored by sand fly species in the genera Phlebotomus, Lutzomyia or others, with different species affecting different geographic ranges. Phlebotomus papatasi (Scopoli) is a major vector of Leishma...

Sugarcane White Leaf Disease Incidences and Population Dynamic of Leafhopper Insect Vectors in Sugarcane Plantations in Northeast Thailand.

PubMed

Rattanabunta, Chiranan; Hanboonsong, Yupa

2015-04-01

The work consisted of two experiments, i.e. Experiment 1 was conducted under controlled environments where sugarcane plants were used as hosts. This investigation aimed to monitor the occurrence of the Sugarcane White Leaf disease and the abundance of Leafhopper insect vectors and also the work aimed to provide useful information in understanding some aspects on epidemiology of the Sugarcane White Leaf disease. A Completely Randomized Design with three replications was used to justify growth and development of Leafhopper insects as affected by different temperatures: 20 (T1), 25 (T2), 30 (T3) and 35 degrees C (T4). Experiment 2 was carried out to determine the numbers of Leafhopper insects with the use of light traps in the sugarcane Field 1 (ratoon plants), Field 2 (newly planted), Field 3 (newly planted) and Field 4 (ratoon plants). The results of Experiment 1 showed that growth and development of Leafhopper insects were highly affected by temperatures i.e. the higher the environmental temperature the faster the growth and development of the insects to reach its full adulthood. At 20 degrees C, Leafhopper insects took 12 days to lay eggs whereas at 25 degrees C the insects took only 6 days. Male reached its adulthood approximately 9 days earlier than female when cultured at 25 degrees C and became approximately one week at 30 degrees C or higher. The results of Experiment 2 showed that the majority of Leafhopper insects were found within the months of June and July for both newly planted and ratoon crops. A small amount was found in May and August with an exceptional case of Field 4 where the highest number of Leafhopper insects was found in April followed by June and July. For Sugarcane White Leaf disease, the disease was found in all months of the year except February for Fields 2 and 3. Newly planted sugarcane plants attained much smaller percentages of disease than those of the ratoon plants.

Development of Serologic Assays for the Diagnosis of New World Leishmaniasis

DTIC Science & Technology

1986-02-20

the skin by the bite of the phlebotomine sandfly vector , and is maintained by subsequent parasite invasion of and multiplication within cells of the...distribution within the lipid bilayer may play a significant role in the behavior of the parasite within the insect vector and the mammalian host...by the phlebotomine sandfly vector . Promastigotes are then phagocytized by dermal macrophages, where they differentiate into the intracellular, or

Plant water stress effects on the net dispersal rate of the insect vector Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) and movement of its egg parasitoid, Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae)

USDA-ARS?s Scientific Manuscript database

Homalodisca vitripennis, one of the main vectors of Xylella fastidiosa, is associated with citrus plantings in California, USA. Infested citrus orchards act as a source of vectors to adjacent vineyards where X. fastidiosa causes Pierce’s disease (PD). An analysis of the pattern and rate of movement ...

The role of gut bacteria in Schmallenberg virus transmission by Culicoides biting midges

USDA-ARS?s Scientific Manuscript database

When an arbo-virus enters a vector it will first enter the gut system of this insect before entering cells of the insect body. Once in the gut-system, arbo-viruses and gut microbiota can interact with each other. We wondered if different gut bacterial communities could influence virus infection of b...

Dispersal of Invasive Forest Insects via Recreational Firewood: A Quantitative Analysis

Treesearch

Frank H. Koch; Denys Yemshanov; Roger D. Magarey; William D. Smith

2012-01-01

Recreational travel is a recognized vector for the spread of invasive species in North America. However, there has been little quantitative analysis of the risks posed by such travel and the associated transport of firewood. In this study, we analyzed the risk of forest insect spread with firewood and estimated related dispersal parameters for application in...

Combining 'omics and microscopy to visualize interactions between the Asian citrus psyllid vector and the Huanglongbing pathogen Candidatus Liberibacter asiaticus in the insect gut

USDA-ARS?s Scientific Manuscript database

Huanglongbing, or citrus greening disease, is an economically devastating bacterial disease of citrus. It is associated with infection by the gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). CLas is transmitted by Diaphorina citri, the Asian citrus psyllid (ACP). For insect transmis...

Potential applications of insect symbionts in biotechnology.

PubMed

Berasategui, Aileen; Shukla, Shantanu; Salem, Hassan; Kaltenpoth, Martin

2016-02-01

Symbiotic interactions between insects and microorganisms are widespread in nature and are often the source of ecological innovations. In addition to supplementing their host with essential nutrients, microbial symbionts can produce enzymes that help degrade their food source as well as small molecules that defend against pathogens, parasites, and predators. As such, the study of insect ecology and symbiosis represents an important source of chemical compounds and enzymes with potential biotechnological value. In addition, the knowledge on insect symbiosis can provide novel avenues for the control of agricultural pest insects and vectors of human diseases, through targeted manipulation of the symbionts or the host-symbiont associations. Here, we discuss different insect-microbe interactions that can be exploited for insect pest and human disease control, as well as in human medicine and industrial processes. Our aim is to raise awareness that insect symbionts can be interesting sources of biotechnological applications and that knowledge on insect ecology can guide targeted efforts to discover microorganisms of applied value.

Time-specific ecological niche modeling predicts spatial dynamics of vector insects and human dengue cases.

PubMed

Peterson, A Townsend; Martínez-Campos, Carmen; Nakazawa, Yoshinori; Martínez-Meyer, Enrique

2005-09-01

Numerous human diseases-malaria, dengue, yellow fever and leishmaniasis, to name a few-are transmitted by insect vectors with brief life cycles and biting activity that varies in both space and time. Although the general geographic distributions of these epidemiologically important species are known, the spatiotemporal variation in their emergence and activity remains poorly understood. We used ecological niche modeling via a genetic algorithm to produce time-specific predictive models of monthly distributions of Aedes aegypti in Mexico in 1995. Significant predictions of monthly mosquito activity and distributions indicate that predicting spatiotemporal dynamics of disease vector species is feasible; significant coincidence with human cases of dengue indicate that these dynamics probably translate directly into transmission of dengue virus to humans. This approach provides new potential for optimizing use of resources for disease prevention and remediation via automated forecasting of disease transmission risk.

Diaphorina citri (Hemiptera: Liviidae) Vector Competence for the Citrus Greening Pathogen 'Candidatus Liberibacter Asiaticus'.

PubMed

Tabachnick, Walter J

2015-06-01

Characterizing the vector competence of Diaphorina citri Kuwayama for 'Candidatus Liberibacter asiaticus,' the pathogen causing citrus greening, is essential for understanding the epidemiology of this disease that is threatening the U.S. citrus industry. Vector competence studies have been difficult because of the biology of D. citri, the inability to culture the pathogen, and the available diagnostic methods used to detect the bacteria in plant and insect tissues. The methods employed in many studies of D. citri vector competence may have overestimated amounts of live 'Ca. L. asiaticus' in both plant and insect tissues, and it is possible that the amounts of phloem ingested by psyllids may not contain sufficient detectable pathogen using current diagnostic methods. As a result of the difficulty in characterizing D. citri vector competence, the several daunting challenges for providing D. citri that are unable to inoculate 'Ca. L. asiaticus', as a novel method to control greening are discussed. Suggestions to overcome some of these challenges are provided. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Harnessing Insect-Microbe Chemical Communications To Control Insect Pests of Agricultural Systems.

PubMed

Beck, John J; Vannette, Rachel L

2017-01-11

Insect pests cause serious economic, yield, and food safety problems to managed crops worldwide. Compounding these problems, insect pests often vector pathogenic or toxigenic microbes to plants. Previous work has considered plant-insect and plant-microbe interactions separately. Although insects are well-understood to use plant volatiles to locate hosts, microorganisms can produce distinct and abundant volatile compounds that in some cases strongly attract insects. In this paper, we focus on the microbial contribution to plant volatile blends, highlighting the compounds emitted and the potential for variation in microbial emission. We suggest that these aspects of microbial volatile emission may make these compounds ideal for use in agricultural applications, as they may be more specific or enhance methods currently used in insect control or monitoring. Our survey of microbial volatiles in insect-plant interactions suggests that these emissions not only signal host suitability but may indicate a distinctive time frame for optimal conditions for both insect and microbe. Exploitation of these host-specific microbe semiochemicals may provide important microbe- and host-based attractants and a basis for future plant-insect-microbe chemical ecology investigations.

A mathematical model of Chagas disease transmission

NASA Astrophysics Data System (ADS)

Hidayat, Dayat; Nugraha, Edwin Setiawan; Nuraini, Nuning

2018-03-01

Chagas disease is a parasitic infection caused by protozoan Trypanosoma cruzi which is transmitted to human by insects of the subfamily Triatominae, including Rhodnius prolixus. This disease is a major problem in several countries of Latin America. A mathematical model of Chagas disease with separate vector reservoir and a neighboring human resident is constructed. The basic reproductive ratio is obtained and stability analysis of the equilibria is shown. We also performed sensitivity populations dynamics of infected humans and infected insects based on migration rate, carrying capacity, and infection rate parameters. Our findings showed that the dynamics of the infected human and insect is mostly affected by carrying capacity insect in the settlement.

A chitinase is required for Xylella fastidiosa colonization of its insect and plant hosts.

PubMed

Labroussaa, Fabien; Ionescu, Michael; Zeilinger, Adam R; Lindow, Steven E; Almeida, Rodrigo P P

2017-04-01

Xylella fastidiosa colonizes the xylem network of host plant species as well as the foregut of its required insect vectors to ensure efficient propagation. Disease management strategies remain inefficient due to a limited comprehension of the mechanisms governing both insect and plant colonization. It was previously shown that X. fastidiosa has a functional chitinase (ChiA), and that chitin likely serves as a carbon source for this bacterium. We expand on that research, showing that a chiA mutant strain is unable to grow on chitin as the sole carbon source. Quantitative PCR assays allowed us to detect bacterial cells in the foregut of vectors after pathogen acquisition; populations of the wild-type and complemented mutant strain were both significantly larger than the chiA mutant strain 10 days, but not 3 days, post acquisition. These results indicate that adhesion of the chiA mutant strain to vectors may not be impaired, but that cell multiplication is limited. The mutant was also affected in its transmission by vectors to plants. In addition, the chiA mutant strain was unable to colonize host plants, suggesting that the enzyme has other substrates associated with plant colonization. Lastly, ChiA requires other X. fastidiosa protein(s) for its in vitro chitinolytic activity. The observation that the chiA mutant strain is not able to colonize plants warrants future attention to be paid to the substrates for this enzyme.

Formic and acetic acids in degradation products of plant volatiles elicit olfactory and behavorial responses from an insect vector

USDA-ARS?s Scientific Manuscript database

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) vectors the bacterial pathogen presumed to be the etiological agent of citrus greening disease, Huanglongbing (HLB), a major threat to citrus industry worldwide. We studied antennal and behavioral responses of Diaphorina citri...

Biocuration and improvement of the Diaphorina citri draft genome assembly with long reads, optical maps and long-range scaffolding

USDA-ARS?s Scientific Manuscript database

The Asian citrus psyllid (Diaphorina citri Kuwayama) is the insect vector of the bacterium Candidatus Liberibacter asiaticus (CLas), the causal agent for the citrus greening or Huanglongbing disease which threatens citrus industry worldwide. This vector is the primary target of approaches to stop th...

Evaluation of pyriproxyfen dissemination via Aedes albopictus from a point source larvicide application in northeast Florida

USDA-ARS?s Scientific Manuscript database

The Asian tiger mosquito, Aedes albopictus, ranks among the most important vectors of dengue fever, Zika virus, and chikungunya virus. With no specific medications or vaccines available, vector control is the only way to combat these diseases. Autodissemination of the insect growth regulator pyripro...

The influence of learning on host plant preference in a significant phytopathogen vector, Diaphorina citri

USDA-ARS?s Scientific Manuscript database

Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri, vector ...

Hosts of stolbur phytoplasmas in maize redness affected fields

USDA-ARS?s Scientific Manuscript database

The plant host range of a phytoplasma is strongly dependent on the host range of its insect vector. Maize redness in Serbia is caused by stolbur phytoplasma (subgroup 16SrXII-A) and is transmitted by the cixiid planthoper, Reptalus panzeri (Löw). R. panzeri was the only potential vector found to be ...

Virulence of a malaria parasite, Plasmodium mexicanum, for its sand fly vectors, Lutzomyia vexator and Lutzomyia stewarti (Diptera: Psychodidae).

PubMed

Schall, Jos J

2011-11-01

Evolutionary theory predicts that virulence of parasites for mobile vector insects will be low for natural parasite-host associations that have coevolved. I determined virulence of the malaria parasite of lizards, Plasmodium mexicanum, for its vectors, two species of sand fly (Diptera: Psychodidae), Lutzomyia vexator (Coquillett 1907) and Lutzomyia stewarti (Mangabeira Fo & Galindo 1944), by measuring several life history traits. Developmental rate from egg to eclosion differed for the two species when noninfected. For both sand fly species, developmental rate for each stage (egg to larval hatching, larval period, pupal period) and life span were not altered by infection. Infected sand flies, however, produced fewer eggs. This reduction in fecundity may be a result of lower quality of the blood meal taken from infected lizards (lower concentration of hemoglobin). This report is the first measure of virulence of Plasmodium for an insect vector other than a mosquito and concords with both expectations of theory and previous studies on natural parasite-host associations that revealed low virulence.

Studies of the Biology of Phleboviruses in Sandflies.

DTIC Science & Technology

1983-02-01

8217Ahiebotomus fever, sand fly fever, arbovirus, medical entomology, Phiebotomus, Lutzomyia, vector-borne diseases, insect cell cultures, _)_Laboratory...parenteral administration. Most of the viruses replicated in sand flies after intrathorazic inoculation; however, the insects were quite refractory to oral...cells was also established and tested for its ability to support the growth of a number of different arbaviruses. Most of the rhabdoviruses

Odorant receptor-based discovery of natural repellents of human lice.

PubMed

Pelletier, Julien; Xu, Pingxi; Yoon, Kyong S; Clark, John M; Leal, Walter S

2015-11-01

The body louse, Pediculus humanus humanus, is an obligate blood-feeding ectoparasite and an important insect vector that mediates the transmission of diseases to humans. The analysis of the body louse genome revealed a drastic reduction of the chemosensory gene repertoires when compared to other insects, suggesting specific olfactory adaptations to host specialization and permanent parasitic lifestyle. Here, we present for the first time functional evidence for the role of odorant receptors (ORs) in this insect, with the objective to gain insight into the chemical ecology of this vector. We identified seven putative full-length ORs, in addition to the odorant receptor co-receptor (Orco), and expressed four of them in the Xenopus laevis oocytes system. When screened with a panel of ecologically-relevant odorants, PhumOR2 responded to a narrow set of compounds. At the behavior level, both head and body lice were repelled by the physiologically-active chemicals. This study presents the first evidence of the OR pathway being functional in lice and identifies PhumOR2 as a sensitive receptor of natural repellents that could be used to develop novel efficient molecules to control these insects. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Gene silencing in non-model insects: Overcoming hurdles using symbiotic bacteria for trauma-free sustainable delivery of RNA interference: Sustained RNA interference in insects mediated by symbiotic bacteria: Applications as a genetic tool and as a biocide.

PubMed

Whitten, Miranda; Dyson, Paul

2017-03-01

Insight into animal biology and development provided by classical genetic analysis of the model organism Drosophila melanogaster was an incentive to develop advanced genetic tools for this insect. But genetic systems for the over one million other known insect species are largely undeveloped. With increasing information about insect genomes resulting from next generation sequencing, RNA interference is now the method of choice for reverse genetics, although it is constrained by the means of delivery of interfering RNA. A recent advance to ensure sustained delivery with minimal experimental intervention or trauma to the insect is to exploit commensal bacteria for symbiont-mediated RNA interference. This technology not only offers an efficient means for RNA interference in insects in laboratory conditions, but also has potential for use in the control of human disease vectors, agricultural pests and pathogens of beneficial insects. © 2017 WILEY Periodicals, Inc.

Transposon mutagenesis of Xylella fastidiosa by electroporation of Tn5 synaptic complexes.

PubMed

Guilhabert, M R; Hoffman, L M; Mills, D A; Kirkpatrick, B C

2001-06-01

Pierce's disease, a lethal disease of grapevine, is caused by Xylella fastidiosa, a gram-negative, xylem-limited bacterium that is transmitted from plant to plant by xylem-feeding insects. Strains of X. fastidiosa also have been associated with diseases that cause tremendous losses in many other economically important plants, including citrus. Although the complete genome sequence of X. fastidiosa has recently been determined, the inability to transform or produce transposon mutants of X. fastidiosa has been a major impediment to understanding pathogen-, plant-, and insect-vector interactions. We evaluated the ability of four different suicide vectors carrying either Tn5 or Tn10 transposons as well as a preformed Tn5 transposase-transposon synaptic complex (transposome) to transpose X. fastidiosa. The four suicide vectors failed to produce any detectable transposition events. Electroporation of transposomes, however, yielded 6 x 10(3) and 4 x 10(3) Tn5 mutants per microg of DNA in two different grapevine strains of X. fastidiosa. Molecular analysis showed that the transposition insertions were single, independent, stable events. Sequence analysis of the Tn5 insertion sites indicated that the transpositions occur randomly in the X. fastidiosa genome. Transposome-mediated mutagenesis should facilitate the identification of X. fastidiosa genes that mediate plant pathogenicity and insect transmission.

First comparative transcriptomic analysis of wild adult male and female Lutzomyia longipalpis, vector of visceral leishmaniasis.

PubMed

McCarthy, Christina B; Santini, María Soledad; Pimenta, Paulo F P; Diambra, Luis A

2013-01-01

Leishmaniasis is a vector-borne disease with a complex epidemiology and ecology. Visceral leishmaniasis (VL) is its most severe clinical form as it results in death if not treated. In Latin America VL is caused by the protist parasite Leishmania infantum (syn. chagasi) and transmitted by Lutzomyia longipalpis. This phlebotomine sand fly is only found in the New World, from Mexico to Argentina. However, due to deforestation, migration and urbanisation, among others, VL in Latin America is undergoing an evident geographic expansion as well as dramatic changes in its transmission patterns. In this context, the first VL outbreak was recently reported in Argentina, which has already caused 7 deaths and 83 reported cases. Insect vector transcriptomic analyses enable the identification of molecules involved in the insect's biology and vector-parasite interaction. Previous studies on laboratory reared Lu. longipalpis have provided a descriptive repertoire of gene expression in the whole insect, midgut, salivary gland and male reproductive organs. Nevertheless, the study of wild specimens would contribute a unique insight into the development of novel bioinsecticides. Given the recent VL outbreak in Argentina and the compelling need to develop appropriate control strategies, this study focused on wild male and female Lu. longipalpis from an Argentine endemic (Posadas, Misiones) and a Brazilian non-endemic (Lapinha Cave, Minas Gerais) VL location. In this study, total RNA was extracted from the sand flies, submitted to sequence independent amplification and high-throughput pyrosequencing. This is the first time an unbiased and comprehensive transcriptomic approach has been used to analyse an infectious disease vector in its natural environment. Transcripts identified in the sand flies showed characteristic profiles which correlated with the environment of origin and with taxa previously identified in these same specimens. Among these, various genes represented putative targets for vector control via RNA interference (RNAi).

First Comparative Transcriptomic Analysis of Wild Adult Male and Female Lutzomyia longipalpis, Vector of Visceral Leishmaniasis

PubMed Central

McCarthy, Christina B.; Santini, María Soledad; Pimenta, Paulo F. P.; Diambra, Luis A.

2013-01-01

Leishmaniasis is a vector-borne disease with a complex epidemiology and ecology. Visceral leishmaniasis (VL) is its most severe clinical form as it results in death if not treated. In Latin America VL is caused by the protist parasite Leishmania infantum (syn. chagasi) and transmitted by Lutzomyia longipalpis. This phlebotomine sand fly is only found in the New World, from Mexico to Argentina. However, due to deforestation, migration and urbanisation, among others, VL in Latin America is undergoing an evident geographic expansion as well as dramatic changes in its transmission patterns. In this context, the first VL outbreak was recently reported in Argentina, which has already caused 7 deaths and 83 reported cases. Insect vector transcriptomic analyses enable the identification of molecules involved in the insect's biology and vector-parasite interaction. Previous studies on laboratory reared Lu. longipalpis have provided a descriptive repertoire of gene expression in the whole insect, midgut, salivary gland and male reproductive organs. Nevertheless, the study of wild specimens would contribute a unique insight into the development of novel bioinsecticides. Given the recent VL outbreak in Argentina and the compelling need to develop appropriate control strategies, this study focused on wild male and female Lu. longipalpis from an Argentine endemic (Posadas, Misiones) and a Brazilian non-endemic (Lapinha Cave, Minas Gerais) VL location. In this study, total RNA was extracted from the sand flies, submitted to sequence independent amplification and high-throughput pyrosequencing. This is the first time an unbiased and comprehensive transcriptomic approach has been used to analyse an infectious disease vector in its natural environment. Transcripts identified in the sand flies showed characteristic profiles which correlated with the environment of origin and with taxa previously identified in these same specimens. Among these, various genes represented putative targets for vector control via RNA interference (RNAi). PMID:23554910

Microsatellites Reveal a High Population Structure in Triatoma infestans from Chuquisaca, Bolivia

PubMed Central

Pizarro, Juan Carlos; Gilligan, Lauren M.; Stevens, Lori

2008-01-01

Background For Chagas disease, the most serious infectious disease in the Americas, effective disease control depends on elimination of vectors through spraying with insecticides. Molecular genetic research can help vector control programs by identifying and characterizing vector populations and then developing effective intervention strategies. Methods and Findings The population genetic structure of Triatoma infestans (Hemiptera: Reduviidae), the main vector of Chagas disease in Bolivia, was investigated using a hierarchical sampling strategy. A total of 230 adults and nymphs from 23 localities throughout the department of Chuquisaca in Southern Bolivia were analyzed at ten microsatellite loci. Population structure, estimated using analysis of molecular variance (AMOVA) to estimate FST (infinite alleles model) and RST (stepwise mutation model), was significant between western and eastern regions within Chuquisaca and between insects collected in domestic and peri-domestic habitats. Genetic differentiation at three different hierarchical geographic levels was significant, even in the case of adjacent households within a single locality (R ST = 0.14, F ST = 0.07). On the largest geographic scale, among five communities up to 100 km apart, R ST = 0.12 and F ST = 0.06. Cluster analysis combined with assignment tests identified five clusters within the five communities. Conclusions Some houses are colonized by insects from several genetic clusters after spraying, whereas other households are colonized predominately by insects from a single cluster. Significant population structure, measured by both R ST and F ST, supports the hypothesis of poor dispersal ability and/or reduced migration of T. infestans. The high degree of genetic structure at small geographic scales, inferences from cluster analysis and assignment tests, and demographic data suggest reinfesting vectors are coming from nearby and from recrudescence (hatching of eggs that were laid before insecticide spraying). Suggestions for using these results in vector control strategies are made. PMID:18365033

Aster leafhopper survival and reproduction, and Aster yellows transmission under static and fluctuating temperatures, using ddPCR for phytoplasma quantification.

PubMed

Bahar, Md H; Wist, Tyler J; Bekkaoui, Diana R; Hegedus, Dwayne D; Olivier, Chrystel Y

2018-01-10

Aster yellows (AY) is an important disease of Brassica crops and is caused by Candidatus Phytoplasma asteris and transmitted by the insect vector, Aster leafhopper (Macrosteles quadrilineatus). Phytoplasma-infected Aster leafhoppers were incubated at various constant and fluctuating temperatures ranging from 0 to 35 °C with the reproductive host plant barley (Hordium vulgare). At 0 °C, leafhopper adults survived for 18 days, but failed to reproduce, whereas at 35 °C insects died within 18 days, but successfully reproduced before dying. Temperature fluctuation increased thermal tolerance in leafhoppers at 25 °C and increased fecundity of leafhoppers at 5 and 20 °C. Leafhopper adults successfully infected and produced AY-symptoms in canola plants after incubating for 18 days at 0-20 °C on barley, indicating that AY-phytoplasma maintains its virulence in this temperature range. The presence and number of AY-phytoplasma in insects and plants were confirmed by droplet digital PCR (ddPCR) quantification. The number of phytoplasma in leafhoppers increased over time, but did not differ among temperatures. The temperatures associated with a typical crop growing season on the Canadian Prairies will not limit the spread of AY disease by their predominant insect vector. Also, ddPCR quantification is a useful tool for early detection and accurate quantification of phytoplasma in plants and insects.

Feeding and defecation behavior of Triatoma rubida (Uhler, 1894) (Hemiptera: Reduviidae) under laboratory conditions, and its potential role as a vector of Chagas disease in Arizona, USA.

PubMed

Reisenman, Carolina E; Gregory, Teresa; Guerenstein, Pablo G; Hildebrand, John G

2011-10-01

Chagas disease is caused by the parasite Trypanosoma cruzi, which is transmitted to humans by blood-sucking triatomine insects. This disease is endemic throughout Mexico and Central and South America, but only a few autochthonous cases have been reported in the United States, despite the fact that infected insects readily invade houses and feed on humans. Competent vectors defecate during or shortly after feeding so that infective feces contact the host. We thus studied the feeding and defecation behaviors of the prevalent species in southern Arizona, Triatoma rubida. We found that whereas defecation during feeding was frequent in females (93%), it was very rare in immature stages (3%), and absent in males. Furthermore, more than half of the immature insects that exhibited multiple feeding bouts (62%) defecated during interruptions of feeding, i.e., while likely on or near the host. These results indicate that T. rubida potentially could transmit T. cruzi to humans.

Living in two worlds: the plant and insect lifestyles of Xylella fastidiosa.

PubMed

Chatterjee, Subhadeep; Almeida, Rodrigo P P; Lindow, Steven

2008-01-01

Diseases caused by Xylella fastidiosa have attained great importance worldwide as the pathogen and its insect vectors have been disseminated. Since this is the first plant pathogenic bacterium for which a complete genome sequence was determined, much progress has been made in understanding the process by which it spreads within the xylem vessels of susceptible plants as well as the traits that contribute to its acquisition and transmission by sharpshooter vectors. Although this pathogen shares many similarities with Xanthomonas species, such as its use of a small fatty acid signal molecule to coordinate virulence gene expression, the traits that it utilizes to cause disease and the manner in which they are regulated differ substantially from those of related plant pathogens. Its complex lifestyle as both a plant and insect colonist involves traits that are in conflict with these stages, thus apparently necessitating the use of a gene regulatory scheme that allows cells expressing different traits to co-occur in the plant.

Paratransgenic Control of Vector Borne Diseases

PubMed Central

Hurwitz, Ivy; Fieck, Annabeth; Read, Amber; Hillesland, Heidi; Klein, Nichole; Kang, Angray; Durvasula, Ravi

2011-01-01

Conventional methodologies to control vector borne diseases with chemical pesticides are often associated with environmental toxicity, adverse effects on human health and the emergence of insect resistance. In the paratransgenic strategy, symbiotic or commensal microbes of host insects are transformed to express gene products that interfere with pathogen transmission. These genetically altered microbes are re-introduced back to the insect where expression of the engineered molecules decreases the host's ability to transmit the pathogen. We have successfully utilized this strategy to reduce carriage rates of Trypanosoma cruzi, the causative agent of Chagas disease, in the triatomine bug, Rhodnius prolixus, and are currently developing this methodology to control the transmission of Leishmania donovani by the sand fly Phlebotomus argentipes. Several effector molecules, including antimicrobial peptides and highly specific single chain antibodies, are currently being explored for their anti-parasite activities in these two systems. In preparation for eventual field use, we are actively engaged in risk assessment studies addressing the issue of horizontal gene transfer from the modified bacteria to environmental microbes. PMID:22110385

Seasonal Changes in the Percentage of Rice Stripe Virus Viruliferous Laodelphax striatellus (Hemiptera: Delphacidae) in Paddy Fields in Japan.

PubMed

Shiba, Takuya; Hirae, Masahiro; Hayano-Saito, Yuriko; Uematsu, Hiroshi; Sasaya, Takahide; Higuchi, Hiroya; Ohto, Yasuo; Okuda, Mitsuru

2016-04-20

Rice stripe disease, which is caused by Rice stripe virus (RSV), is one of the most serious viral diseases of rice. RSV is transmitted in a persistent manner byLaodelphax striatellus(Fallén). The incidence of the disease can be estimated from the density of viruliferous vectors. Understanding seasonal changes of the percentage of viruliferousL. striatelluscan facilitate forecasting and controlling the disease. In paddies, the percentage of viruliferous insects fluctuated in phase with the rate of detection of RSV-infected rice; it gradually increased from July to August, plateaued or temporarily declined in September, and increased sharply on ratoons in October. These findings indicate that horizontal transmission of RSV from diseased plants to vector insects occurred frequently, and the insects acquired RSV from the ratoons. However, the percentages of viruliferous insects overwintering in poaceous weeds, the main hosts forL. striatellusin winter, were lower than those in ratoons. FewL. striatellusthat acquired RSV from ratoons seemed to move to overwintering sites and transmit the virus to the next generation. However, there was a tendency for the percentages of viruliferous overwintering insects to be higher on paddy ridges than in river levees. Insects could probably move from ratoons to poaceous weeds when the weeds were near a paddy. Although increasing percentage of viruliferous insects on ratoons seem to have relatively little impact on RSV dynamics in the next crop season, appropriate weed management around paddies is still needed to reduce the incidence of rice stripe disease. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Handling small arbovirus vectors safely during biosafety level 3 containment: Culicoides variipennis sonorensis (Diptera:Ceratopogonidae) and exotic bluetongue viruses.

PubMed

Hunt, G J; Tabachnick, W J

1996-05-01

Equipment and procedures are described for biosafety level 3 (BL-3) containment work with small, zoophilic arthropods. BL-3 classified pathogens always must be manipulated in biological safety cabinets. Procedures, including physical barriers and handling methods, that prevent the escape of potentially virus-infected insects are discussed, and the use of a monitoring system for insect security is explained. The inability to recover escaped minute, flying insects poses a major difference from similar work with larger insects, such as mosquitoes. Methods were developed for the safe and secure handling of Culicoides variipennis sonorensis Wirth & Jones infected with exotic bluetongue viruses during BL-3 containment.

Filthy Flies? Experiments to Test Flies as Vectors of Bacterial Disease

ERIC Educational Resources Information Center

Shaffer, Julie J.; Warner, Kasey Jo; Hoback, W. Wyatt

2007-01-01

For more than 75 years, flies and other insects have been known to serve as mechanical vectors of infectious disease (Hegner, 1926). Flies have been shown to harbor over 100 different species of potentially pathogenic microorganisms and are known to transmit more than 65 infectious diseases (Greenberg, 1965). This laboratory exercise is a simple…

Chemosensory responses to the repellent nepeta essential oil and its major component nepetalactone by the yellow fever mosquito, aedes aegypti, a vector of zika virus

USDA-ARS?s Scientific Manuscript database

Nepeta essential oil (Neo) (catnip) and its major component, nepetalactone, have long been known to repel insects including mosquitoes. However, the neural mechanisms through which these repellents are detected by mosquitoes, including the yellow fever mosquito Aedes aegypti, an important vector of...

An Overview and History of Glyco-Engineering in Insect Expression Systems.

PubMed

Geisler, Christoph; Mabashi-Asazuma, Hideaki; Jarvis, Donald L

2015-01-01

Insect systems, including the baculovirus-insect cell and Drosophila S2 cell systems are widely used as recombinant protein production platforms. Historically, however, no insect-based system has been able to produce glycoproteins with human-type glycans, which often influence the clinical efficacy of therapeutic glycoproteins and the overall structures and functions of other recombinant glycoprotein products. In addition, some insect cell systems produce N-glycans with immunogenic epitopes. Over the past 20 years, these problems have been addressed by efforts to glyco-engineer insect-based expression systems. These efforts have focused on introducing the capacity to produce complex-type, terminally sialylated N-glycans and eliminating the capacity to produce immunogenic N-glycans. Various glyco-engineering approaches have included genetically engineering insect cells, baculoviral vectors, and/or insects with heterologous genes encoding the enzymes required to produce various glycosyltransferases, sugars, nucleotide sugars, and nucleotide sugar transporters, as well as an enzyme that can deplete GDP-fucose. In this chapter, we present an overview and history of glyco-engineering in insect expression systems as a prelude to subsequent chapters, which will highlight various methods used for this purpose.

Adventitious viruses in insect cell lines used for recombinant protein expression.

PubMed

Geisler, Christoph; Jarvis, Donald L

2018-04-01

Insect cells are widely used for recombinant protein expression, typically as hosts for recombinant baculovirus vectors, but also for plasmid-mediated transient transfection or stable genetic transformation. Insect cells are used to express proteins for research, as well as to manufacture biologicals for human and veterinary medicine. Recently, several insect cell lines used for recombinant protein expression were found to be persistently infected with adventitious viruses. This has raised questions about how these infections might affect research performed using those cell lines. Furthermore, these findings raised serious concerns about the safety of biologicals produced using those cell lines. In response, new insect cell lines lacking adventitious viruses have been isolated for use as improved research tools and safer biological manufacturing platforms. Here, we review the scientific and patent literature on adventitious viruses found in insect cell lines, affected cell lines, and new virus-free cell lines. Copyright © 2017 Elsevier Inc. All rights reserved.

Machine Learning for Characterization of Insect Vector Feeding

PubMed Central

Willett, Nora S.; Stelinski, Lukasz L.; Lapointe, Stephen L.

2016-01-01

Insects that feed by ingesting plant and animal fluids cause devastating damage to humans, livestock, and agriculture worldwide, primarily by transmitting pathogens of plants and animals. The feeding processes required for successful pathogen transmission by sucking insects can be recorded by monitoring voltage changes across an insect-food source feeding circuit. The output from such monitoring has traditionally been examined manually, a slow and onerous process. We taught a computer program to automatically classify previously described insect feeding patterns involved in transmission of the pathogen causing citrus greening disease. We also show how such analysis contributes to discovery of previously unrecognized feeding states and can be used to characterize plant resistance mechanisms. This advance greatly reduces the time and effort required to analyze insect feeding, and should facilitate developing, screening, and testing of novel intervention strategies to disrupt pathogen transmission affecting agriculture, livestock and human health. PMID:27832081

Effects of Climate and Climate Change on Vectors and Vector-Borne Diseases: Ticks Are Different.

PubMed

Ogden, Nick H; Lindsay, L Robbin

2016-08-01

There has been considerable debate as to whether global risk from vector-borne diseases will be impacted by climate change. This has focussed on important mosquito-borne diseases that are transmitted by the vectors from infected to uninfected humans. However, this debate has mostly ignored the biological diversity of vectors and vector-borne diseases. Here, we review how climate and climate change may impact those most divergent of arthropod disease vector groups: multivoltine insects and hard-bodied (ixodid) ticks. We contrast features of the life cycles and behaviour of these arthropods, and how weather, climate, and climate change may have very different impacts on the spatiotemporal occurrence and abundance of vectors, and the pathogens they transmit. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

An innovative ecohealth intervention for Chagas disease vector control in Yucatan, Mexico.

PubMed

Waleckx, Etienne; Camara-Mejia, Javier; Ramirez-Sierra, Maria Jesus; Cruz-Chan, Vladimir; Rosado-Vallado, Miguel; Vazquez-Narvaez, Santos; Najera-Vazquez, Rosario; Gourbière, Sébastien; Dumonteil, Eric

2015-02-01

Non-domiciliated (intrusive) triatomine vectors remain a challenge for the sustainability of Chagas disease vector control as these triatomines are able to transiently (re-)infest houses. One of the best-characterized examples is Triatoma dimidiata from the Yucatan peninsula, Mexico, where adult insects seasonally infest houses between March and July. We focused our study on three rural villages in the state of Yucatan, Mexico, in which we performed a situation analysis as a first step before the implementation of an ecohealth (ecosystem approach to health) vector control intervention. The identification of the key determinants affecting the transient invasion of human dwellings by T. dimidiata was performed by exploring associations between bug presence and qualitative and quantitative variables describing the ecological, biological and social context of the communities. We then used a participatory action research approach for implementation and evaluation of a control strategy based on window insect screens to reduce house infestation by T. dimidiata. This ecohealth approach may represent a valuable alternative to vertically-organized insecticide spraying. Further evaluation may confirm that it is sustainable and provides effective control (in the sense of limiting infestation of human dwellings and vector/human contacts) of intrusive triatomines in the region. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Assessing the Fauna of Aquatic Insects for Possible Use for Malaria Vector Control in Large River, Central Iran.

PubMed

Shayeghi, Mansoureh; Nejati, Jalil; Shirani-Bidabadi, Leila; Koosha, Mona; Badakhshan, Mehdi; Mohammadi Bavani, Mulood; Arzamani, Kourosh; Choubdar, Nayyereh; Bagheri, Fatemeh; Saghafipour, Abedin; Veysi, Arshad; Karimian, Fateh; Akhavan, Amir Ahamd; Vatandoost, Hassan

2015-01-01

Insects with over 30,000 aquatic species are known as very successful arthropods in freshwater habitats. Some of them are applied as biological indicators for water quality control, as well as the main food supply for fishes and amphibians. The faunistic studies are the basic step in entomological researches; the current study was carried out emphasizing on the fauna of aquatic insects in Karaj River, northern Iran. A field study was carried out in six various sampling site of Karaj River during spring 2013. The aquatic insects were collected using several methods such as D-frame nets, dipping and direct search on river floor stones. Specimens were collected and preserved in Ethanol and identified by standard identification keys. Totally, 211 samples were collected belonging to three orders; Plecoptera, Trichoptera and Ephemeroptera. Seven genuses (Perla, Isoperla, Hydropsyche, Cheumatopsyche, Baetis, Heptagenia and Maccafferium) from five families (Perlidae, Perlodidae, Hydropsychidae, Batidae, Heptagenidae) were identified. The most predominant order was Plecoptera followed by Trichoptera. Karaj River is a main and important river, which provides almost all of water of Karaj dam. So, identification of aquatic species which exist in this river is vital and further studies about systematic and ecological investigations should be performed. Also, monitoring of aquatic biota by trained health personnel can be a critical step to describe water quality in this river. Understanding the fauna of aquatic insects will provide a clue for possible biological control of medically important aquatic insects such as Anopheles as the malaria vectors.

Intracellular localization of adeno-associated viral proteins expressed in insect cells.

PubMed

Gallo-Ramírez, Lilí E; Ramírez, Octavio T; Palomares, Laura A

2011-01-01

Production of vectors derived from adeno-associated virus (AAVv) in insect cells represents a feasible option for large-scale applications. However, transducing particles yields obtained in this system are low compared with total capsid yields, suggesting the presence of genome encapsidation bottlenecks. Three components are required for AAVv production: viral capsid proteins (VP), the recombinant AAV genome, and Rep proteins for AAV genome replication and encapsidation. Little is known about the interaction between the three components in insect cells, which have intracellular conditions different to those in mammalian cells. In this work, the localization of AAV proteins in insect cells was assessed for the first time with the purpose of finding potential limiting factors. Unassembled VP were located either in the cytoplasm or in the nucleus. Their transport into the nucleus was dependent on protein concentration. Empty capsids were located in defined subnuclear compartments. Rep proteins expressed individually were efficiently translocated into the nucleus. Their intranuclear distribution was not uniform and differed from VP distribution. While Rep52 distribution and expression levels were not affected by AAV genomes or VP, Rep78 distribution and stability changed during coexpression. Expression of all AAV components modified capsid intranuclear distribution, and assembled VP were found in vesicles located in the nuclear periphery. Such vesicles were related to baculovirus infection, highlighting its role in AAVv production in insect cells. The results obtained in this work suggest that the intracellular distribution of AAV proteins allows their interaction and does not limit vector production in insect cells. Copyright © 2011 American Institute of Chemical Engineers (AIChE).

Silencing of HaAce1 gene by host-delivered artificial microRNA disrupts growth and development of Helicoverpa armigera.

PubMed

Saini, Ravi Prakash; Raman, Venkat; Dhandapani, Gurusamy; Malhotra, Era Vaidya; Sreevathsa, Rohini; Kumar, Polumetla Ananda; Sharma, Tilak R; Pattanayak, Debasis

2018-01-01

The polyphagous insect-pest, Helicoverpa armigera, is a serious threat to a number of economically important crops. Chemical application and/or cultivation of Bt transgenic crops are the two strategies available now for insect-pest management. However, environmental pollution and long-term sustainability are major concerns against these two options. RNAi is now considered as a promising technology to complement Bt to tackle insect-pests menace. In this study, we report host-delivered silencing of HaAce1 gene, encoding the predominant isoform of H. armigera acetylcholinesterase, by an artificial microRNA, HaAce1-amiR1. Arabidopsis pre-miRNA164b was modified by replacing miR164b/miR164b* sequences with HaAce1-amiR1/HaAce1-amiR1* sequences. The recombinant HaAce1-preamiRNA1 was put under the control of CaMV 35S promoter and NOS terminator of plant binary vector pBI121, and the resultant vector cassette was used for tobacco transformation. Two transgenic tobacco lines expressing HaAce1-amiR1 was used for detached leaf insect feeding bioassays. Larval mortality of 25% and adult deformity of 20% were observed in transgenic treated insect group over that control tobacco treated insect group. The reduction in the steady-state level of HaAce1 mRNA was 70-80% in the defective adults compared to control. Our results demonstrate promise for host-delivered amiRNA-mediated silencing of HaAce1 gene for H. armigera management.

Massively parallel pyrosequencing-based transcriptome analyses of small brown planthopper (Laodelphax striatellus), a vector insect transmitting rice stripe virus (RSV)

PubMed Central

2010-01-01

Background The small brown planthopper (Laodelphax striatellus) is an important agricultural pest that not only damages rice plants by sap-sucking, but also acts as a vector that transmits rice stripe virus (RSV), which can cause even more serious yield loss. Despite being a model organism for studying entomology, population biology, plant protection, molecular interactions among plants, viruses and insects, only a few genomic sequences are available for this species. To investigate its transcriptome and determine the differences between viruliferous and naïve L. striatellus, we employed 454-FLX high-throughput pyrosequencing to generate EST databases of this insect. Results We obtained 201,281 and 218,681 high-quality reads from viruliferous and naïve L. striatellus, respectively, with an average read length as 230 bp. These reads were assembled into contigs and two EST databases were generated. When all reads were combined, 16,885 contigs and 24,607 singletons (a total of 41,492 unigenes) were obtained, which represents a transcriptome of the insect. BlastX search against the NCBI-NR database revealed that only 6,873 (16.6%) of these unigenes have significant matches. Comparison of the distribution of GO classification among viruliferous, naïve, and combined EST databases indicated that these libraries are broadly representative of the L. striatellus transcriptomes. Functionally diverse transcripts from RSV, endosymbiotic bacteria Wolbachia and yeast-like symbiotes were identified, which reflects the possible lifestyles of these microbial symbionts that live in the cells of the host insect. Comparative genomic analysis revealed that L. striatellus encodes similar innate immunity regulatory systems as other insects, such as RNA interference, JAK/STAT and partial Imd cascades, which might be involved in defense against viral infection. In addition, we determined the differences in gene expression between vector and naïve samples, which generated a list of candidate genes that are potentially involved in the symbiosis of L. striatellus and RSV. Conclusions To our knowledge, the present study is the first description of a genomic project for L. striatellus. The identification of transcripts from RSV, Wolbachia, yeast-like symbiotes and genes abundantly expressed in viruliferous insect, provided a starting-point for investigating the molecular basis of symbiosis among these organisms. PMID:20462456

Using NextRAD sequencing to infer movement of herbivores among host plants.

PubMed

Fu, Zhen; Epstein, Brendan; Kelley, Joanna L; Zheng, Qi; Bergland, Alan O; Castillo Carrillo, Carmen I; Jensen, Andrew S; Dahan, Jennifer; Karasev, Alexander V; Snyder, William E

2017-01-01

Herbivores often move among spatially interspersed host plants, tracking high-quality resources through space and time. This dispersal is of particular interest for vectors of plant pathogens. Existing molecular tools to track such movement have yielded important insights, but often provide insufficient genetic resolution to infer spread at finer spatiotemporal scales. Here, we explore the use of Nextera-tagmented reductively-amplified DNA (NextRAD) sequencing to infer movement of a highly-mobile winged insect, the potato psyllid (Bactericera cockerelli), among host plants. The psyllid vectors the pathogen that causes zebra chip disease in potato (Solanum tuberosum), but understanding and managing the spread of this pathogen is limited by uncertainty about the insect's host plant(s) outside of the growing season. We identified 1,978 polymorphic loci among psyllids separated spatiotemporally on potato or in patches of bittersweet nightshade (S. dulcumara), a weedy plant proposed to be the source of potato-colonizing psyllids. A subset of the psyllids on potato exhibited genetic similarity to insects on nightshade, consistent with regular movement between these two host plants. However, a second subset of potato-collected psyllids was genetically distinct from those collected on bittersweet nightshade; this suggests that a currently unrecognized source, i.e., other nightshade patches or a third host-plant species, could be contributing to psyllid populations in potato. Oftentimes, dispersal of vectors of pathogens must be tracked at a fine scale in order to understand, predict, and manage disease spread. We demonstrate that emerging sequencing technologies that detect genome-wide SNPs of a vector can be used to infer such localized movement.

Mechanisms by which pesticides affect insect immunity.

PubMed

James, R R; Xu, J

2012-02-01

The current state of knowledge regarding the effect of pesticides on insect immunity is reviewed here. A basic understanding of these interactions is needed for several reasons, including to improve methods for controlling pest insects in agricultural settings, for controlling insect vectors of human diseases, and for reducing mortality in beneficial insects. Bees are particularly vulnerable to sublethal pesticide exposures because they gather nectar and pollen, concentrating environmental toxins in their nests in the process. Pesticides do have effects on immunity. Organophosphates and some botanicals have been found to impact hemocyte number, differentiation, and thus affect phagocytosis. The phenoloxidase cascade and malanization have also been shown to be affected by several insecticides. Many synthetic insecticides increase oxidative stress, and this could have severe impacts on the production of some antimicrobial peptides in insects, but research is needed to determine the actual effects. Pesticides can also affect grooming behaviors, rendering insects more susceptible to disease. Despite laboratory data documenting pesticide/pathogen interactions, little field data is available at the population level. Published by Elsevier Inc.

Using Real-Time PCR to Quantify Aster Yellows Phytoplasma in its Insect Vector; Relationship of Infectivity to Transmissibility in the Aster Leafhopper

USDA-ARS?s Scientific Manuscript database

The aster yellows (AY) index is used to prescribe insecticide sprays that target Macrosteles quadrilineatus, or aster leafhopper (ALH), the vector of the aster yellows phytoplasma (AYp). The AY index metric is the product of the proportion of infective ALHs and the relative ALH population size at a ...

The presence of insect at composting

NASA Astrophysics Data System (ADS)

Mudruňka, J.; Lyčková, B.; Kučerová, R.; Glogarová, V.; Závada, J.; Gibesová, B.; Takač, D.

2017-10-01

During composting biodegradable waste, microbic organisms reproduce massively, most of which belong to serious biopathogens which are able to penetrate various environmental layers. Their vector species include dipterous insect (Diptera) which reaches considerable amounts in composting plant premises as well as home composting units, mainly during summer months. Therefore measures must be taken to eliminate or reduce this unwanted phenomenon (sanitisation, disinfection). For evaluating obtained results, relative abundance calculation was chosen.

Aquatic insect predators and mosquito control.

PubMed

Shaalan, Essam Abdel-Salam; Canyon, Deon V

2009-12-01

Mosquitoes are serious biting pests and obligate vectors of many vertebrate pathogens. Their immature larval and pupal life stages are a common feature in most tropical and many temperate water bodies and often form a significant proportion of the biomass. Control strategies rely primarily on the use of larvicides and environmental modification to reduce recruitment and adulticides during periods of disease transmission. Larvicides are usually chemical but can involve biological toxins, agents or organisms. The use of insect predators in mosquito control has been exploited in a limited fashion and there is much room for further investigation and implementation. Insects that are recognized as having predatorial capacity with regard to mosquito prey have been identified in the Orders Odonata, Coleoptera, Diptera (primarily aquatic predators), and Hemiptera (primarily surface predators). Although their capacity is affected by certain biological and physical factors, they could play a major role in mosquito control. Furthermore, better understanding for the mosquitoes-predators relationship(s) could probably lead to satisfactory reduction of mosquito-borne diseases by utilizing either these predators in control programs, for instance biological and/or integrated control, or their kairomones as mosquitoes' ovipoisting repellents. This review covers the predation of different insect species on mosquito larvae, predator-prey-habitat relationships, co-habitation developmental issues, survival and abundance, oviposition avoidance, predatorial capacity and integrated vector control.

The components of shear stress affecting insect cells used with the baculovirus expression vector system.

PubMed

Weidner, Tobias; Druzinec, Damir; Mühlmann, Martina; Buchholz, Rainer; Czermak, Peter

2017-09-26

Insect-based expression platforms such as the baculovirus expression vector system (BEVS) are widely used for the laboratory- and industrial-scale production of recombinant proteins. Thereby, major drawbacks to gain high-quality proteins are the lytic infection cycle and the shear sensitivity of infected insect cells due to turbulence and aeration. Smaller bubbles were formerly assumed to be more harmful than larger ones, but we found that cell damage is also dependent on the concentration of protective agents such as Pluronic®. At the appropriate concentration, Pluronic forms a layer around air bubbles and hinders the attachment of cells, thus limiting the damage. In this context, we used microaeration to vary bubble sizes and confirmed that size is not the most important factor, but the total gas surface area in the reactor is. If the surface area exceeds a certain threshold, the concentration of Pluronic is no longer sufficient for cell protection. To investigate the significance of shear forces, a second study was carried out in which infected insect cells were cultivated in a hollow fiber module to protect them from shear forces. Both model studies revealed important aspects of the design and scale-up of BEVS processes for the production of recombinant proteins.

A PCR-based survey on Phytomonas (Euglenozoa: Trypanosomatidae) in phytophagous hemipterans of the Amazon region.

PubMed

Godoi, Mara M I; Serrano, Myrna G; Teixeira, Marta M G; Camargo, Erney P

2002-01-01

We have surveyed 244 hemipterans from Western Brazilian Amazĵnia for the presence of trypanosomatids and identification of members of the genus Phytomonas. Examination by phase microscopy of squashes of insect salivary glands (SG) and digestive tubes (DT) revealed that 44% (108/244) of insects from seven families harbored trypanosomatids. Infections were 5 times more frequent in Coreidae than in all other families together. Smears of SG and DT of the dissected insects were fixed on glass slides with methanol and stained with Giemsa for morphological analysis. DNA was recovered from these preparations and submitted to a PCR assay that permitted amplification of all trypanosomatid genera using primers of conserved sequences flanking a segment of the spliced leader (SL) gene. Upon PCR amplification of the recovered DNA, amplicons were hybridized with an oligonucletide probe (SL3') complementary to a SL intron sequence specific for flagellates of the genus Phytomonas. Among the trypanosomatid-positive insects, 38.8% harbored Phytomonas spp., corresponding to an overall Phytomonas prevalence of 17.1% among phytophagous bugs, their putative vectors. Since many Phytomonas are pathogenic in plants, this high prevalence in their vectors emphasizes the permanent risk of exposure to disease by native and cultured plants of the Amazon region.

Darker eggs of mosquitoes resist more to dry conditions: Melanin enhances serosal cuticle contribution in egg resistance to desiccation in Aedes, Anopheles and Culex vectors.

PubMed

Farnesi, Luana C; Vargas, Helena C M; Valle, Denise; Rezende, Gustavo L

2017-10-01

Mosquito vectors lay their white eggs in the aquatic milieu. During early embryogenesis water passes freely through the transparent eggshell, which at this moment is composed of exochorion and endochorion. Within two hours the endochorion darkens via melanization but even so eggs shrink and perish if removed from moisture. However, during mid-embryogenesis, cells of the extraembryonic serosa secrete the serosal cuticle, localized right below the endochorion, becoming the third and innermost eggshell layer. Serosal cuticle formation greatly reduces water flow and allows egg survival outside the water. The degree of egg resistance to desiccation (ERD) at late embryogenesis varies among different species: Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus eggs can survive in a dry environment for ≥ 72, 24 and 5 hours, respectively. In some adult insects, darker-body individuals show greater resistance to desiccation than lighter ones. We asked if egg melanization enhances mosquito serosal cuticle-dependent ERD. Species with higher ERD at late embryogenesis exhibit more melanized eggshells. The melanization-ERD hypothesis was confirmed employing two Anopheles quadrimaculatus strains, the wild type and the mutant GORO, with a dark-brown and a golden eggshell, respectively. In all cases, serosal cuticle formation is fundamental for the establishment of an efficient ERD but egg viability outside the water is much higher in mosquitoes with darker eggshells than in those with lighter ones. The finding that pigmentation influences egg water balance is relevant to understand the evolutionary history of insect egg coloration. Since eggshell and adult cuticle pigmentation ensure insect survivorship in some cases, they should be considered regarding species fitness and novel approaches for vector or pest insects control.

Darker eggs of mosquitoes resist more to dry conditions: Melanin enhances serosal cuticle contribution in egg resistance to desiccation in Aedes, Anopheles and Culex vectors

PubMed Central

Farnesi, Luana C.; Vargas, Helena C. M.; Valle, Denise

2017-01-01

Mosquito vectors lay their white eggs in the aquatic milieu. During early embryogenesis water passes freely through the transparent eggshell, which at this moment is composed of exochorion and endochorion. Within two hours the endochorion darkens via melanization but even so eggs shrink and perish if removed from moisture. However, during mid-embryogenesis, cells of the extraembryonic serosa secrete the serosal cuticle, localized right below the endochorion, becoming the third and innermost eggshell layer. Serosal cuticle formation greatly reduces water flow and allows egg survival outside the water. The degree of egg resistance to desiccation (ERD) at late embryogenesis varies among different species: Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus eggs can survive in a dry environment for ≥ 72, 24 and 5 hours, respectively. In some adult insects, darker-body individuals show greater resistance to desiccation than lighter ones. We asked if egg melanization enhances mosquito serosal cuticle-dependent ERD. Species with higher ERD at late embryogenesis exhibit more melanized eggshells. The melanization-ERD hypothesis was confirmed employing two Anopheles quadrimaculatus strains, the wild type and the mutant GORO, with a dark-brown and a golden eggshell, respectively. In all cases, serosal cuticle formation is fundamental for the establishment of an efficient ERD but egg viability outside the water is much higher in mosquitoes with darker eggshells than in those with lighter ones. The finding that pigmentation influences egg water balance is relevant to understand the evolutionary history of insect egg coloration. Since eggshell and adult cuticle pigmentation ensure insect survivorship in some cases, they should be considered regarding species fitness and novel approaches for vector or pest insects control. PMID:29084225

Role of cyclic di-GMP in Xylella fastidiosa biofilm formation, plant virulence, and insect transmission.

PubMed

Chatterjee, Subhadeep; Killiny, Nabil; Almeida, Rodrigo P P; Lindow, Steven E

2010-10-01

Xylella fastidiosa must coordinately regulate a variety of traits contributing to biofilm formation, host plant and vector colonization, and transmission between plants. Traits such as production of extracellular polysaccharides (EPS), adhesins, extracellular enzymes, and pili are expressed in a cell-density-dependent fashion mediated by a cell-to-cell signaling system involving a fatty acid diffusible signaling factor (DSF). The expression of gene PD0279 (which has a GGDEF domain) is downregulated in the presence of DSF and may be involved in intracellular signaling by modulating the levels of cyclic di-GMP. PD0279, designated cyclic di-GMP synthase A (cgsA), is required for biofilm formation, plant virulence, and vector transmission. cgsA mutants exhibited a hyperadhesive phenotype in vitro and overexpressed gumJ, hxfA, hxfB, xadA, and fimA, which promote attachment of cells to surfaces and, hence, biofilm formation. The mutants were greatly reduced in virulence to grape albeit still transmissible by insect vectors, although at a reduced level compared with transmission rates of the wild-type strain, despite the fact that similar numbers of cells of the cgsA mutant were acquired by the insects from infected plants. High levels of EPS were measured in cgsA mutants compared with wild-type strains, and scanning electron microscopy analysis also revealed a thicker amorphous layer surrounding the mutants. Overexpression of cgsA in a cgsA-complemented mutant conferred the opposite phenotypes in vitro. These results suggest that decreases of cyclic di-GMP result from the accumulation of DSF as cell density increases, leading to a phenotypic transition from a planktonic state capable of colonizing host plants to an adhesive state that is insect transmissible.

Structure of an Insecticide Sequestering Carboxylesterase from the Disease Vector Culex quinquefasciatus: What Makes an Enzyme a Good Insecticide Sponge?

PubMed

Hopkins, Davis H; Fraser, Nicholas J; Mabbitt, Peter D; Carr, Paul D; Oakeshott, John G; Jackson, Colin J

2017-10-17

Carboxylesterase (CBE)-mediated metabolic resistance to organophosphate and carbamate insecticides is a major problem for the control of insect disease vectors, such as the mosquito. The most common mechanism involves overexpression of CBEs that bind to the insecticide with high affinity, thereby sequestering them before they can interact with their target. However, the absence of any structure for an insecticide-sequestering CBE limits our understanding of the molecular basis for this process. We present the first structure of a CBE involved in sequestration, Cqestβ2 1 , from the mosquito disease vector Culex quinquefasciatus. Lysine methylation was used to obtain the crystal structure of Cqestβ2 1 , which adopts a canonical α/β-hydrolase fold that has high similarity to the target of organophosphate and carbamate insecticides, acetylcholinesterase. Sequence similarity networks of the insect carboxyl/cholinesterase family demonstrate that CBEs associated with metabolic insecticide resistance across many species share a level of similarity that distinguishes them from a variety of other classes. This is further emphasized by the structural similarities and differences in the binding pocket and active site residues of Cqestβ2 1 and other insect carboxyl/cholinesterases. Stopped-flow and steady-state inhibition studies support a major role for Cqestβ2 1 in organophosphate resistance and a minor role in carbamate resistance. Comparison with another isoform associated with insecticide resistance, Cqestβ1, showed both enzymes have similar affinity to insecticides, despite 16 amino acid differences between the two proteins. This provides a molecular understanding of pesticide sequestration by insect CBEs and could facilitate the design of CBE-specific inhibitors to circumvent this resistance mechanism in the future.

Genetically Modifying the Insect Gut Microbiota to Control Chagas Disease Vectors through Systemic RNAi

PubMed Central

Taracena, Mabel L.; Oliveira, Pedro L.; Almendares, Olivia; Umaña, Claudia; Lowenberger, Carl; Dotson, Ellen M.; Paiva-Silva, Gabriela O.; Pennington, Pamela M.

2015-01-01

Technologies based on RNA interference may be used for insect control. Sustainable strategies are needed to control vectors of Chagas disease such as Rhodnius prolixus. The insect microbiota can be modified to deliver molecules to the gut. Here, Escherichia coli HT115(DE3) expressing dsRNA for the Rhodnius heme-binding protein (RHBP) and for catalase (CAT) were fed to nymphs and adult triatomine stages. RHBP is an egg protein and CAT is an antioxidant enzyme expressed in all tissues by all developmental stages. The RNA interference effect was systemic and temporal. Concentrations of E. coli HT115(DE3) above 3.35 × 107 CFU/mL produced a significant RHBP and CAT gene knockdown in nymphs and adults. RHBP expression in the fat body was reduced by 99% three days after feeding, returning to normal levels 10 days after feeding. CAT expression was reduced by 99% and 96% in the ovary and the posterior midgut, respectively, five days after ingestion. Mortality rates increased by 24-30% in first instars fed RHBP and CAT bacteria. Molting rates were reduced by 100% in first instars and 80% in third instars fed bacteria producing RHBP or CAT dsRNA. Oviposition was reduced by 43% (RHBP) and 84% (CAT). Embryogenesis was arrested in 16% (RHBP) and 20% (CAT) of laid eggs. Feeding females 105 CFU/mL of the natural symbiont, Rhodococcus rhodnii, transformed to express RHBP-specific hairpin RNA reduced RHBP expression by 89% and reduced oviposition. Modifying the insect microbiota to induce systemic RNAi in R. prolixus may result in a paratransgenic strategy for sustainable vector control. PMID:25675102

Do chimpanzees (Pan troglodytes schweinfurthii) exhibit sleep related behaviors that minimize exposure to parasitic arthropods? A preliminary report on the possible anti-vector function of chimpanzee sleeping platforms.

PubMed

Samson, David R; Muehlenbein, Michael P; Hunt, Kevin D

2013-01-01

Great apes spend half of their lives in a nightly "nest" or sleeping platform (SP), a complex object created by modifying foliage, which functions as a stable substrate on which to sleep. Of the several purported functions of SPs, one hypothesis is that they protect against parasitic infection. Here we investigate the role of SP site choice in avoiding molestation by arthropods. This study presents preliminary data on the insect-repellent properties of preferred sleeping tree species Cynometra alexandri. Insect traps were deployed in gallery forest habitats in which chimpanzees typically "nest." We compared traps placed adjacent to SPs artificially manufactured with C. alexandri trees to an open area within the same habitat. Multiple measures of arthropod counts indicate that simulated C. alexandri SP sites have fewer arthropods than similar non-SP sites. Volatile compounds secreted by C. alexandri foliage are hypothesized to repel annoying arthropods and/or mask chimpanzee olfactory signals. Of the total insects captured (n = 6,318), n = 145 were mosquitoes. Of the total mosquitoes captured, n = 47 were identified as Anopheles (female, n = 12). The prominent malarial vector Anopheles gambiae was identified among the captured mosquito sample. These results suggest that the presence of broken branches of the tree species C. alexandri reduce the amount of insects a chimpanzee is exposed to throughout a night's sleep. This great ape behavioral and socio-technological adaptation may have evolved, in part, to increase quality of sleep as well as decrease exposure to vectors of disease.

Design and construction of functional AAV vectors.

PubMed

Gray, John T; Zolotukhin, Serge

2011-01-01

Using the basic principles of molecular biology and laboratory techniques presented in this chapter, researchers should be able to create a wide variety of AAV vectors for both clinical and basic research applications. Basic vector design concepts are covered for both protein coding gene expression and small non-coding RNA gene expression cassettes. AAV plasmid vector backbones (available via AddGene) are described, along with critical sequence details for a variety of modular expression components that can be inserted as needed for specific applications. Protocols are provided for assembling the various DNA components into AAV vector plasmids in Escherichia coli, as well as for transferring these vector sequences into baculovirus genomes for large-scale production of AAV in the insect cell production system.

Coffee, its roasted form, and their residues cause birth failure and shorten lifespan in dengue vectors.

PubMed

Dieng, Hamady; Ellias, Salbiah Binti; Satho, Tomomitsu; Ahmad, Abu Hassan; Abang, Fatimah; Ghani, Idris Abd; Noor, Sabina; Ahmad, Hamdan; Zuharah, Wan Fatma; Morales Vargas, Ronald E; Morales, Noppawan P; Hipolito, Cirilo N; Attrapadung, Siriluck; Noweg, Gabriel Tonga

2017-06-01

In dengue mosquitoes, successful embryonic development and long lifespan are key determinants for the persistence of both virus and vector. Therefore, targeting the egg stage and vector lifespan would be expected to have greater impacts than larvicides or adulticides, both strategies that have lost effectiveness due to the development of resistance. Therefore, there is now a pressing need to find novel chemical means of vector control. Coffee contains many chemicals, and its waste, which has become a growing environmental concern, is as rich in toxicants as the green coffee beans; these chemicals do not have a history of resistance in insects, but some are lost in the roasting process. We examined whether exposure to coffee during embryonic development could alter larval eclosion and lifespan of dengue vectors. A series of bioassays with different coffee forms and their residues indicated that larval eclosion responses of Aedes albopictus and Ae. aegypti were appreciably lower when embryonic maturation occurred in environments containing coffee, especially roasted coffee crude extract (RCC). In addition, the lifespan of adults derived from eggs that hatched successfully in a coffee milieu was reduced, but this effect was less pronounced with roasted and green coffee extracts (RCU and GCU, respectively). Taken together, these findings suggested that coffee and its residues have embryocidal activities with impacts that are carried over onto the adult lifespan of dengue vectors. These effects may significantly reduce the vectorial capacity of these insects. Reutilizing coffee waste in vector control may also represent a realistic solution to the issues associated with its pollution.

Can invertebrates see the e-vector of polarization as a separate modality of light?

PubMed

Labhart, Thomas

2016-12-15

The visual world is rich in linearly polarized light stimuli, which are hidden from the human eye. But many invertebrate species make use of polarized light as a source of valuable visual information. However, exploiting light polarization does not necessarily imply that the electric (e)-vector orientation of polarized light can be perceived as a separate modality of light. In this Review, I address the question of whether invertebrates can detect specific e-vector orientations in a manner similar to that of humans perceiving spectral stimuli as specific hues. To analyze e-vector orientation, the signals of at least three polarization-sensitive sensors (analyzer channels) with different e-vector tuning axes must be compared. The object-based, imaging polarization vision systems of cephalopods and crustaceans, as well as the water-surface detectors of flying backswimmers, use just two analyzer channels. Although this excludes the perception of specific e-vector orientations, a two-channel system does provide a coarse, categoric analysis of polarized light stimuli, comparable to the limited color sense of dichromatic, 'color-blind' humans. The celestial compass of insects employs three or more analyzer channels. However, that compass is multimodal, i.e. e-vector information merges with directional information from other celestial cues, such as the solar azimuth and the spectral gradient in the sky, masking e-vector information. It seems that invertebrate organisms take no interest in the polarization details of visual stimuli, but polarization vision grants more practical benefits, such as improved object detection and visual communication for cephalopods and crustaceans, compass readings to traveling insects, or the alert 'water below!' to water-seeking bugs. © 2016. Published by The Company of Biologists Ltd.

Can invertebrates see the e-vector of polarization as a separate modality of light?

PubMed Central

2016-01-01

ABSTRACT The visual world is rich in linearly polarized light stimuli, which are hidden from the human eye. But many invertebrate species make use of polarized light as a source of valuable visual information. However, exploiting light polarization does not necessarily imply that the electric (e)-vector orientation of polarized light can be perceived as a separate modality of light. In this Review, I address the question of whether invertebrates can detect specific e-vector orientations in a manner similar to that of humans perceiving spectral stimuli as specific hues. To analyze e-vector orientation, the signals of at least three polarization-sensitive sensors (analyzer channels) with different e-vector tuning axes must be compared. The object-based, imaging polarization vision systems of cephalopods and crustaceans, as well as the water-surface detectors of flying backswimmers, use just two analyzer channels. Although this excludes the perception of specific e-vector orientations, a two-channel system does provide a coarse, categoric analysis of polarized light stimuli, comparable to the limited color sense of dichromatic, ‘color-blind’ humans. The celestial compass of insects employs three or more analyzer channels. However, that compass is multimodal, i.e. e-vector information merges with directional information from other celestial cues, such as the solar azimuth and the spectral gradient in the sky, masking e-vector information. It seems that invertebrate organisms take no interest in the polarization details of visual stimuli, but polarization vision grants more practical benefits, such as improved object detection and visual communication for cephalopods and crustaceans, compass readings to traveling insects, or the alert ‘water below!’ to water-seeking bugs. PMID:27974532

The distance that contaminated aquatic subsidies extend into lake riparian zones.

PubMed

Raikow, David F; Walters, David M; Fritz, Ken M; Mills, Marc A

2011-04-01

Consumption of emergent aquatic insects by terrestrial invertebrates is a poorly resolved, but potentially important, mechanism of contaminant flux across ecosystem borders leading to contaminant exposure in terrestrial invertivores. We characterized the spatial extent and magnitude of contaminant transfer from aquatic sediments to terrestrial invertebrate predators by examining riparian araneid spiders, terrestrial insects, and emergent aquatic insects for stable isotopes and polychlorinated biphenyls (PCBs, sum of 141 congeners) at Lake Hartwell, (Clemson, South Carolina, USA). PCB concentrations in aquatic insects were orders of magnitude higher than in terrestrial insects. Aquatic insect consumption by spiders (as indicated by delta13C and delta15N), PCB concentrations in spiders, and aquatic prey availability were greatest at the shoreline and declined inland, while terrestrial prey availability was invariant with distance. These patterns indicate PCB transfer to spiders through consumption of emergent aquatic insects extending to a distance of 5 m inland. Measurable, but much lower, PCBs were present in insect predators dominated by social wasps up to 30 m inland. These results illustrate the importance of emergent insects as vectors of contaminant transfer from lake sediments to riparian food webs, and that spiders are key predators in this process.

The distance that contaminated aquatic subsidies extend into lake riparian zones

USGS Publications Warehouse

Raikow, D.F.; Walters, D.M.; Fritz, K.M.; Mills, M.A.

2011-01-01

Consumption of emergent aquatic insects by terrestrial invertebrates is a poorly resolved, but potentially important, mechanism of contaminant flux across ecosystem borders leading to contaminant exposure in terrestrial invertivores. We characterized the spatial extent and magnitude of contaminant transfer from aquatic sediments to terrestrial invertebrate predators by examining riparian araneid spiders, terrestrial insects, and emergent aquatic insects for stable isotopes and polychlorinated biphenyls (PCBs, sum of 141 congeners) at Lake Hartwell, (Clemson, South Carolina, USA). PCB concentrations in aquatic insects were orders of magnitude higher than in terrestrial insects. Aquatic insect consumption by spiders (as indicated by ??13C and ??15N), PCB concentrations in spiders, and aquatic prey availability were greatest at the shoreline and declined inland, while terrestrial prey availability was invariant with distance. These patterns indicate PCB transfer to spiders through consumption of emergent aquatic insects extending to a distance of ???5 m inland. Measurable, but much lower, PCBs were present in insect predators dominated by social wasps up to 30 m inland. These results illustrate the importance of emergent insects as vectors of contaminant transfer from lake sediments to riparian food webs, and that spiders are key predators in this process. ?? 2011 by the Ecological Society of America.

Fungal DNA virus infects a mycophagous insect and utilizes it as a transmission vector

PubMed Central

Liu, Si; Xie, Jiatao; Cheng, Jiasen; Li, Bo; Chen, Tao; Fu, Yanping; Li, Guoqing; Wang, Manqun; Jin, Huanan; Wan, Hu; Jiang, Daohong

2016-01-01

Mycoviruses are usually transmitted horizontally via hyphal anastomosis and vertically via sexual/asexual spores. Previously, we reported that a gemycircularvirus, Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), could infect its fungal host extracellularly. Here, we discovered that SsHADV-1 could infect a mycophagous insect, Lycoriella ingenua, and use it as a transmission vector. Virus acquired by larvae feeding on colonies of a virus-infected strain of S. sclerotiorum was replicated and retained in larvae, pupae, adults, and eggs. Virus could be transmitted to insect offspring when larvae were injected with virus particles and allowed to feed on a nonhost fungus. Virus replication in insect cells was further confirmed by inoculating Spodoptera frugiperda cells with virus particles and analyzing with RT-PCR, Northern blot, immunofluorescence, and flow cytometry assays. Larvae could transmit virus once they acquired virus by feeding on virus-infected fungal colony. Offspring larvae hatched from viruliferous eggs were virus carriers and could also successfully transmit virus. Virus transmission between insect and fungus also occurred on rapeseed plants. Virus-infected isolates produced less repellent volatile substances to attract adults of L. ingenua. Furthermore, L. ingenua was easily observed on Sclerotinia lesions in rapeseed fields, and viruliferous adults were captured from fields either sprayed with a virus-infected fungal strain or nonsprayed. Our findings may facilitate the exploration of mycoviruses for control of fungal diseases and enhance our understanding of the ecology of SsHADV-1 and other newly emerging SsHADV-1–like viruses, which were recently found to be widespread in various niches including human HIV-infected blood, human and animal feces, insects, plants, and even sewage. PMID:27791095

Viral RNA Silencing Suppression: The Enigma of Bunyavirus NSs Proteins.

PubMed

Hedil, Marcio; Kormelink, Richard

2016-07-23

The Bunyaviridae is a family of arboviruses including both plant- and vertebrate-infecting representatives. The Tospovirus genus accommodates plant-infecting bunyaviruses, which not only replicate in their plant host, but also in their insect thrips vector during persistent propagative transmission. For this reason, they are generally assumed to encounter antiviral RNA silencing in plants and insects. Here we present an overview on how tospovirus nonstructural NSs protein counteracts antiviral RNA silencing in plants and what is known so far in insects. Like tospoviruses, members of the related vertebrate-infecting bunyaviruses classified in the genera Orthobunyavirus, Hantavirus and Phlebovirus also code for a NSs protein. However, for none of them RNA silencing suppressor activity has been unambiguously demonstrated in neither vertebrate host nor arthropod vector. The second part of this review will briefly describe the role of these NSs proteins in modulation of innate immune responses in mammals and elaborate on a hypothetical scenario to explain if and how NSs proteins from vertebrate-infecting bunyaviruses affect RNA silencing. If so, why this discovery has been hampered so far.

Viral RNA Silencing Suppression: The Enigma of Bunyavirus NSs Proteins

PubMed Central

Hedil, Marcio; Kormelink, Richard

2016-01-01

The Bunyaviridae is a family of arboviruses including both plant- and vertebrate-infecting representatives. The Tospovirus genus accommodates plant-infecting bunyaviruses, which not only replicate in their plant host, but also in their insect thrips vector during persistent propagative transmission. For this reason, they are generally assumed to encounter antiviral RNA silencing in plants and insects. Here we present an overview on how tospovirus nonstructural NSs protein counteracts antiviral RNA silencing in plants and what is known so far in insects. Like tospoviruses, members of the related vertebrate-infecting bunyaviruses classified in the genera Orthobunyavirus, Hantavirus and Phlebovirus also code for a NSs protein. However, for none of them RNA silencing suppressor activity has been unambiguously demonstrated in neither vertebrate host nor arthropod vector. The second part of this review will briefly describe the role of these NSs proteins in modulation of innate immune responses in mammals and elaborate on a hypothetical scenario to explain if and how NSs proteins from vertebrate-infecting bunyaviruses affect RNA silencing. If so, why this discovery has been hampered so far. PMID:27455310

Diverse Array of New Viral Sequences Identified in Worldwide Populations of the Asian Citrus Psyllid (Diaphorina citri) Using Viral Metagenomics

PubMed Central

Nouri, Shahideh; Salem, Nidá; Nigg, Jared C.

2015-01-01

ABSTRACT The Asian citrus psyllid, Diaphorina citri, is the natural vector of the causal agent of Huanglongbing (HLB), or citrus greening disease. Together; HLB and D. citri represent a major threat to world citrus production. As there is no cure for HLB, insect vector management is considered one strategy to help control the disease, and D. citri viruses might be useful. In this study, we used a metagenomic approach to analyze viral sequences associated with the global population of D. citri. By sequencing small RNAs and the transcriptome coupled with bioinformatics analysis, we showed that the virus-like sequences of D. citri are diverse. We identified novel viral sequences belonging to the picornavirus superfamily, the Reoviridae, Parvoviridae, and Bunyaviridae families, and an unclassified positive-sense single-stranded RNA virus. Moreover, a Wolbachia prophage-related sequence was identified. This is the first comprehensive survey to assess the viral community from worldwide populations of an agricultural insect pest. Our results provide valuable information on new putative viruses, some of which may have the potential to be used as biocontrol agents. IMPORTANCE Insects have the most species of all animals, and are hosts to, and vectors of, a great variety of known and unknown viruses. Some of these most likely have the potential to be important fundamental and/or practical resources. In this study, we used high-throughput next-generation sequencing (NGS) technology and bioinformatics analysis to identify putative viruses associated with Diaphorina citri, the Asian citrus psyllid. D. citri is the vector of the bacterium causing Huanglongbing (HLB), currently the most serious threat to citrus worldwide. Here, we report several novel viral sequences associated with D. citri. PMID:26676774

Diverse Array of New Viral Sequences Identified in Worldwide Populations of the Asian Citrus Psyllid (Diaphorina citri) Using Viral Metagenomics.

PubMed

Nouri, Shahideh; Salem, Nidá; Nigg, Jared C; Falk, Bryce W

2015-12-16

The Asian citrus psyllid, Diaphorina citri, is the natural vector of the causal agent of Huanglongbing (HLB), or citrus greening disease. Together; HLB and D. citri represent a major threat to world citrus production. As there is no cure for HLB, insect vector management is considered one strategy to help control the disease, and D. citri viruses might be useful. In this study, we used a metagenomic approach to analyze viral sequences associated with the global population of D. citri. By sequencing small RNAs and the transcriptome coupled with bioinformatics analysis, we showed that the virus-like sequences of D. citri are diverse. We identified novel viral sequences belonging to the picornavirus superfamily, the Reoviridae, Parvoviridae, and Bunyaviridae families, and an unclassified positive-sense single-stranded RNA virus. Moreover, a Wolbachia prophage-related sequence was identified. This is the first comprehensive survey to assess the viral community from worldwide populations of an agricultural insect pest. Our results provide valuable information on new putative viruses, some of which may have the potential to be used as biocontrol agents. Insects have the most species of all animals, and are hosts to, and vectors of, a great variety of known and unknown viruses. Some of these most likely have the potential to be important fundamental and/or practical resources. In this study, we used high-throughput next-generation sequencing (NGS) technology and bioinformatics analysis to identify putative viruses associated with Diaphorina citri, the Asian citrus psyllid. D. citri is the vector of the bacterium causing Huanglongbing (HLB), currently the most serious threat to citrus worldwide. Here, we report several novel viral sequences associated with D. citri. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Museum specimen data reveal emergence of a plant disease may be linked to increases in the insect vector population.

PubMed

Zeilinger, Adam R; Rapacciuolo, Giovanni; Turek, Daniel; Oboyski, Peter T; Almeida, Rodrigo P P; Roderick, George K

2017-09-01

The emergence rate of new plant diseases is increasing due to novel introductions, climate change, and changes in vector populations, posing risks to agricultural sustainability. Assessing and managing future disease risks depends on understanding the causes of contemporary and historical emergence events. Since the mid-1990s, potato growers in the western United States, Mexico, and Central America have experienced severe yield loss from Zebra Chip disease and have responded by increasing insecticide use to suppress populations of the insect vector, the potato psyllid, Bactericera cockerelli (Hemiptera: Triozidae). Despite the severe nature of Zebra Chip outbreaks, the causes of emergence remain unknown. We tested the hypotheses that (1) B. cockerelli occupancy has increased over the last century in California and (2) such increases are related to climate change, specifically warmer winters. We compiled a data set of 87,000 museum specimen occurrence records across the order Hemiptera collected between 1900 and 2014. We then analyzed changes in B. cockerelli distribution using a hierarchical occupancy model using changes in background species lists to correct for collecting effort. We found evidence that B. cockerelli occupancy has increased over the last century. However, these changes appear to be unrelated to climate changes, at least at the scale of our analysis. To the extent that species occupancy is related to abundance, our analysis provides the first quantitative support for the hypothesis that B. cockerelli population abundance has increased, but further work is needed to link B. cockerelli population dynamics to Zebra Chip epidemics. Finally, we demonstrate how this historical macro-ecological approach provides a general framework for comparative risk assessment of future pest and insect vector outbreaks. © 2017 by the Ecological Society of America.

Host group formation decreases exposure to vector-borne disease: a field experiment in a 'hotspot' of West Nile virus transmission.

PubMed

Krebs, Bethany L; Anderson, Tavis K; Goldberg, Tony L; Hamer, Gabriel L; Kitron, Uriel D; Newman, Christina M; Ruiz, Marilyn O; Walker, Edward D; Brawn, Jeffrey D

2014-12-07

Animals can decrease their individual risk of predation by forming groups. The encounter-dilution hypothesis extends the potential benefits of gregariousness to biting insects and vector-borne disease by predicting that the per capita number of insect bites should decrease within larger host groups. Although vector-borne diseases are common and can exert strong selective pressures on hosts, there have been few tests of the encounter-dilution effect in natural systems. We conducted an experimental test of the encounter-dilution hypothesis using the American robin (Turdus migratorius), a common host species for the West Nile virus (WNV), a mosquito-borne pathogen. By using sentinel hosts (house sparrows, Passer domesticus) caged in naturally occurring communal roosts in the suburbs of Chicago, we assessed sentinel host risk of WNV exposure inside and outside of roosts. We also estimated per capita host exposure to infected vectors inside roosts and outside of roosts. Sentinel birds caged inside roosts seroconverted to WNV more slowly than those outside of roosts, suggesting that social groups decrease per capita exposure to infected mosquitoes. These results therefore support the encounter-dilution hypothesis in a vector-borne disease system. Our results suggest that disease-related selective pressures on sociality may depend on the mode of disease transmission. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Modeling the impact of global warming on vector-borne infections

NASA Astrophysics Data System (ADS)

Massad, Eduardo; Coutinho, Francisco Antonio Bezerra; Lopez, Luis Fernandez; da Silva, Daniel Rodrigues

2011-06-01

Global warming will certainly affect the abundance and distribution of disease vectors. The effect of global warming, however, depends on the complex interaction between the human host population and the causative infectious agent. In this work we review some mathematical models that were proposed to study the impact of the increase in ambient temperature on the spread and gravity of some insect-transmitted diseases.

Visual navigation in insects: coupling of egocentric and geocentric information

PubMed

Wehner; Michel; Antonsen

1996-01-01

Social hymenopterans such as bees and ants are central-place foragers; they regularly depart from and return to fixed positions in their environment. In returning to the starting point of their foraging excursion or to any other point, they could resort to two fundamentally different ways of navigation by using either egocentric or geocentric systems of reference. In the first case, they would rely on information continuously collected en route (path integration, dead reckoning), i.e. integrate all angles steered and all distances covered into a mean home vector. In the second case, they are expected, at least by some authors, to use a map-based system of navigation, i.e. to obtain positional information by virtue of the spatial position they occupy within a larger environmental framework. In bees and ants, path integration employing a skylight compass is the predominant mechanism of navigation, but geocentred landmark-based information is used as well. This information is obtained while the animal is dead-reckoning and, hence, added to the vector course. For example, the image of the horizon skyline surrounding the nest entrance is retinotopically stored while the animal approaches the goal along its vector course. As shown in desert ants (genus Cataglyphis), there is neither interocular nor intraocular transfer of landmark information. Furthermore, this retinotopically fixed, and hence egocentred, neural snapshot is linked to an external (geocentred) system of reference. In this way, geocentred information might more and more complement and potentially even supersede the egocentred information provided by the path-integration system. In competition experiments, however, Cataglyphis never frees itself of its homeward-bound vector - its safety-line, so to speak - by which it is always linked to home. Vector information can also be transferred to a longer-lasting (higher-order) memory. There is no need to invoke the concept of the mental analogue of a topographic map - a metric map - assembled by the insect navigator. The flexible use of vectors, snapshots and landmark-based routes suffices to interpret the insect's behaviour. The cognitive-map approach in particular, and the representational paradigm in general, are discussed.

Flying insect detection and classification with inexpensive sensors.

PubMed

Chen, Yanping; Why, Adena; Batista, Gustavo; Mafra-Neto, Agenor; Keogh, Eamonn

2014-10-15

An inexpensive, noninvasive system that could accurately classify flying insects would have important implications for entomological research, and allow for the development of many useful applications in vector and pest control for both medical and agricultural entomology. Given this, the last sixty years have seen many research efforts devoted to this task. To date, however, none of this research has had a lasting impact. In this work, we show that pseudo-acoustic optical sensors can produce superior data; that additional features, both intrinsic and extrinsic to the insect's flight behavior, can be exploited to improve insect classification; that a Bayesian classification approach allows to efficiently learn classification models that are very robust to over-fitting, and a general classification framework allows to easily incorporate arbitrary number of features. We demonstrate the findings with large-scale experiments that dwarf all previous works combined, as measured by the number of insects and the number of species considered.

Insects as weapons of war, terror, and torture.

PubMed

Lockwood, Jeffrey A

2012-01-01

For thousands of years insects have been incorporated into human conflict, with the goals of inflicting pain, destroying food, and transmitting pathogens. Early methods used insects as "found" weapons, functioning as tactical arms (e.g., hurled nests) or in strategic habitats (e.g., mosquito-infested swamps). In the twentieth century the relationship between insects and disease was exploited; vectors were mass-produced to efficiently deliver pathogens to an enemy. The two most sophisticated programs were those of the Japanese in World War II with plague-infected fleas and cholera-coated flies and of the Americans during the Cold War with yellow fever-infected mosquitoes. With continued advances, defenses in the form of insecticides and vaccines meant that insects were no longer considered as battlefield weapons. However, in recent times sociopolitical changes have put insects back into the realm of human conflict through asymmetrical conflicts pitting combatants from nonindustrialized regions against forces from militarily and economically superior nations. Copyright © 2012 by Annual Reviews. All rights reserved.

Co-infection with a wheat rhabdovirus causes a reduction in Mal de Río Cuarto virus titer in its planthopper vector.

PubMed

Dumón, A D; Argüello Caro, E B; Mattio, M F; Alemandri, V; Del Vas, M; Truol, G

2018-04-01

Mal de Río Cuarto virus (MRCV, Fijivirus, Reoviridae) causes one of the most important diseases in maize (Zea mays L.) in Argentina and has been detected in mixed infections with a rhabdovirus closely related to Maize yellow striate virus. In nature both viruses are able to infect maize and several grasses including wheat, and are transmitted in a persistent propagative manner by Delphacodes kuscheli Fennah (Hemiptera: Delphacidae). This work describes the interactions between MRCV and rhabdovirus within their natural vector and the consequences of such co-infection regarding virus transmission and symptom expression. First- and third-instar D. kuscheli nymphs were fed on MRCV-infected wheat plants or MRCV-rhabdovirus-infected oat plants, and two latency periods were considered. Transmission efficiency and viral load of MRCV-transmitting and non-transmitting planthoppers were determined by real-time quantitative polymerase chain reaction analysis (RTqPCR). Vector transmission efficiency was related to treatments (life stages at acquisition and latency periods). Nevertheless, no correlation between transmission efficiency and type of inoculum used to infect insects with MRCV was found. Treatment by third-instar nymphs 17 days after Acquisition Access Period was the most efficient for MRCV transmission, regardless of the type of inoculum. Plants co-infected with MRCV and rhabdovirus showed the typical MRCV symptoms earlier than plants singly infected with MRCV. The transmitting planthoppers showed significantly higher MRCV titers than non-transmitting insects fed on single or mixed inocula, confirming that successful MRCV transmission is positively associated with viral accumulation in the insect. Furthermore, MRCV viral titers were higher in transmitting planthoppers that acquired this virus from a single inoculum than in those that acquired the virus from a mixed inoculum, indicating that the presence of the rhabdovirus somehow impaired MRCV replication and/or acquisition. This is the first study about interactions between MRCV and a rhabdovirus closely related to Maize yellow striate virus in this insect vector (D. kuscheli), and contributes to a better understanding of planthopper-virus interactions and their epidemiological implications.

Insect abundance over Chinese rice fields in relation to environmental parameters, studied with a polarization-sensitive CW near-IR lidar system

NASA Astrophysics Data System (ADS)

Zhu, Shiming; Malmqvist, Elin; Li, Wansha; Jansson, Samuel; Li, Yiyun; Duan, Zheng; Svanberg, Katarina; Feng, Hongqiang; Song, Ziwei; Zhao, Guangyu; Brydegaard, Mikkel; Svanberg, Sune

2017-07-01

Effective monitoring of flying insects is of major societal importance in view of the role of insects as indispensable pollinators, destructive disease vectors and economically devastating agricultural pests. The present paper reports on monitoring of flying agricultural pests using a continuous-wave lidar system in a rice-field location in Southern China. Using a Scheimpflug arrangement, range resolution over several 100 m long observational paths was achieved. The system operates with two perpendicularly polarized near-infrared lasers, which are activated intermittently, and back-scattered radiation from insects was recorded by a linear array detector placed after a linear polarizer. Our polarization sensitive system was used to monitor the flying insect diurnal activity and also the influence of changes in weather conditions, e.g., the occurrence of rain. Activity strongly peaked at dusk and rose again, although to a lower extent, just before dawn. At the onset of rainfall, a strong increase in insect counts occurred which was interpreted as the rain-induced bringing down of high-altitude migrant insects.

Chemical ecology: studies from East Africa.

PubMed

Meinwald, J; Prestwich, G D; Nakanishi, K; Kubo, I

1978-03-17

The International Centre of Insect Physiology and Ecology (ICIPE), in Nairobi, provides a laboratory at which a multinational group of scientists pursues interdisciplinary research. In collaboration with their colleagues in biology, ICIPE chemists have characterized the sex pheromones of the tick which serves as a vector of East Coast fever and have identified a termite queen-cell-building pheromone. The structure of many anthropod defensive chemicals have been determined; most interesting of these are the trinervitenes, structurally novel diterpenoids from nasute termites. Several highly active insect antifeedants were discovered using a simple bioassay to screen selected East African plants. These antifeedants may provide leads for the development of new insect-control techniques.

Gustatory receptor neuron responds to DEET and other insect repellents in the yellow-fever mosquito, Aedes aegypti

NASA Astrophysics Data System (ADS)

Sanford, Jillian L.; Shields, Vonnie D. C.; Dickens, Joseph C.

2013-03-01

Three gustatory receptor neurons were characterized for contact chemoreceptive sensilla on the labella of female yellow-fever mosquitoes, Aedes aegypti. The neuron with the smallest amplitude spike responded to the feeding deterrent, quinine, as well as N, N-diethyl-3-methylbenzamide and other insect repellents. Two other neurons with differing spikes responded to salt (NaCl) and sucrose. This is the first report of a gustatory receptor neuron specific for insect repellents in mosquitoes and may provide a tool for screening chemicals to discover novel or improved feeding deterrents and repellents for use in the management of arthropod disease vectors.

The genome biology of phytoplasma: modulators of plants and insects.

PubMed

Sugio, Akiko; Hogenhout, Saskia A

2012-06-01

Phytoplasmas are bacterial pathogens of plants that are transmitted by insects. These bacteria uniquely multiply intracellularly in both plants (Plantae) and insects (Animalia). Similarly to bacterial endosymbionts, phytoplasmas have reduced genomes with limited metabolic capabilities. Nonetheless, the chromosomes of many phytoplasmas are rich in repeated DNA consisting of mobile elements. Phytoplasmas produce an arsenal of effectors most of which are encoded on these mobile elements and on plasmids. These effectors target conserved plant transcription factors resulting in witches' broom and leafy flower symptoms and suppression of plant defense to insect vectors that transmit the phytoplasmas. Future studies of these fascinating microbes will generate a wealth of new knowledge about forces that shape genomes and microbial interactions with multicellular hosts. Copyright © 2012 Elsevier Ltd. All rights reserved.

Relevance of Assembly-Activating Protein for Adeno-associated Virus Vector Production and Capsid Protein Stability in Mammalian and Insect Cells.

PubMed

Grosse, Stefanie; Penaud-Budloo, Magalie; Herrmann, Anne-Kathrin; Börner, Kathleen; Fakhiri, Julia; Laketa, Vibor; Krämer, Chiara; Wiedtke, Ellen; Gunkel, Manuel; Ménard, Lucie; Ayuso, Eduard; Grimm, Dirk

2017-10-15

The discovery that adeno-associated virus 2 (AAV2) encodes an eighth protein, called assembly-activating protein (AAP), transformed our understanding of wild-type AAV biology. Concurrently, it raised questions about the role of AAP during production of recombinant vectors based on natural or molecularly engineered AAV capsids. Here, we show that AAP is indeed essential for generation of functional recombinant AAV2 vectors in both mammalian and insect cell-based vector production systems. Surprisingly, we observed that AAV2 capsid proteins VP1 to -3 are unstable in the absence of AAP2, likely due to rapid proteasomal degradation. Inhibition of the proteasome led to an increase of intracellular VP1 to -3 but neither triggered assembly of functional capsids nor promoted nuclear localization of the capsid proteins. Together, this underscores the crucial and unique role of AAP in the AAV life cycle, where it rapidly chaperones capsid assembly, thus preventing degradation of free capsid proteins. An expanded analysis comprising nine alternative AAV serotypes (1, 3 to 9, and rh10) showed that vector production always depends on the presence of AAP, with the exceptions of AAV4 and AAV5, which exhibited AAP-independent, albeit low-level, particle assembly. Interestingly, AAPs from all 10 serotypes could cross-complement AAP-depleted helper plasmids during vector production, despite there being distinct intracellular AAP localization patterns. These were most pronounced for AAP4 and AAP5, congruent with their inability to rescue an AAV2/AAP2 knockout. We conclude that AAP is key for assembly of genuine capsids from at least 10 different AAV serotypes, which has implications for vectors derived from wild-type or synthetic AAV capsids. IMPORTANCE Assembly of adeno-associated virus 2 (AAV2) is regulated by the assembly-activating protein (AAP), whose open reading frame overlaps with that of the viral capsid proteins. As the majority of evidence was obtained using virus-like particles composed solely of the major capsid protein VP3, AAP's role in and relevance for assembly of genuine AAV capsids have remained largely unclear. Thus, we established a trans -complementation assay permitting assessment of AAP functionality during production of recombinant vectors based on complete AAV capsids and derived from any serotype. We find that AAP is indeed a critical factor not only for AAV2, but also for generation of vectors derived from nine other AAV serotypes. Moreover, we identify a new role of AAP in maintaining capsid protein stability in mammalian and insect cells. Thereby, our study expands our current understanding of AAV/AAP biology, and it concomitantly provides insights into the importance of AAP for AAV vector production. Copyright © 2017 American Society for Microbiology.

Relevance of Assembly-Activating Protein for Adeno-associated Virus Vector Production and Capsid Protein Stability in Mammalian and Insect Cells

PubMed Central

Grosse, Stefanie; Penaud-Budloo, Magalie; Herrmann, Anne-Kathrin; Börner, Kathleen; Fakhiri, Julia; Laketa, Vibor; Krämer, Chiara; Wiedtke, Ellen; Gunkel, Manuel; Ménard, Lucie; Ayuso, Eduard

2017-01-01

ABSTRACT The discovery that adeno-associated virus 2 (AAV2) encodes an eighth protein, called assembly-activating protein (AAP), transformed our understanding of wild-type AAV biology. Concurrently, it raised questions about the role of AAP during production of recombinant vectors based on natural or molecularly engineered AAV capsids. Here, we show that AAP is indeed essential for generation of functional recombinant AAV2 vectors in both mammalian and insect cell-based vector production systems. Surprisingly, we observed that AAV2 capsid proteins VP1 to -3 are unstable in the absence of AAP2, likely due to rapid proteasomal degradation. Inhibition of the proteasome led to an increase of intracellular VP1 to -3 but neither triggered assembly of functional capsids nor promoted nuclear localization of the capsid proteins. Together, this underscores the crucial and unique role of AAP in the AAV life cycle, where it rapidly chaperones capsid assembly, thus preventing degradation of free capsid proteins. An expanded analysis comprising nine alternative AAV serotypes (1, 3 to 9, and rh10) showed that vector production always depends on the presence of AAP, with the exceptions of AAV4 and AAV5, which exhibited AAP-independent, albeit low-level, particle assembly. Interestingly, AAPs from all 10 serotypes could cross-complement AAP-depleted helper plasmids during vector production, despite there being distinct intracellular AAP localization patterns. These were most pronounced for AAP4 and AAP5, congruent with their inability to rescue an AAV2/AAP2 knockout. We conclude that AAP is key for assembly of genuine capsids from at least 10 different AAV serotypes, which has implications for vectors derived from wild-type or synthetic AAV capsids. IMPORTANCE Assembly of adeno-associated virus 2 (AAV2) is regulated by the assembly-activating protein (AAP), whose open reading frame overlaps with that of the viral capsid proteins. As the majority of evidence was obtained using virus-like particles composed solely of the major capsid protein VP3, AAP's role in and relevance for assembly of genuine AAV capsids have remained largely unclear. Thus, we established a trans-complementation assay permitting assessment of AAP functionality during production of recombinant vectors based on complete AAV capsids and derived from any serotype. We find that AAP is indeed a critical factor not only for AAV2, but also for generation of vectors derived from nine other AAV serotypes. Moreover, we identify a new role of AAP in maintaining capsid protein stability in mammalian and insect cells. Thereby, our study expands our current understanding of AAV/AAP biology, and it concomitantly provides insights into the importance of AAP for AAV vector production. PMID:28768875

Evolutionary decay and the prospects for long-term disease intervention using engineered insect vectors

PubMed Central

2015-01-01

After a long history of applying the sterile insect technique to suppress populations of disease vectors and agricultural pests, there is growing interest in using genetic engineering both to improve old methods and to enable new methods. The two goals of interventions are to suppress populations, possibly eradicating a species altogether, or to abolish the vector’s competence to transmit a parasite. New methods enabled by genetic engineering include the use of selfish genes toward either goal as well as a variety of killer-rescue systems that could be used for vector competence reduction. This article reviews old and new methods with an emphasis on the potential for evolution of resistance to these strategies. Established methods of population suppression did not obviously face a problem from resistance evolution, but newer technologies might. Resistance to these newer interventions will often be mechanism-specific, and while it is too early to know where resistance evolution will become a problem, it is at least possible to propose properties of interventions that will be more or less effective in blocking resistance evolution. PMID:26160736

The exopolysaccharide of Xylella fastidiosa is essential for biofilm formation, plant virulence, and vector transmission.

PubMed

Killiny, N; Martinez, R Hernandez; Dumenyo, C Korsi; Cooksey, D A; Almeida, R P P

2013-09-01

Exopolysaccharides (EPS) synthesized by plant-pathogenic bacteria are generally essential for virulence. The role of EPS produced by the vector-transmitted bacterium Xylella fastidiosa was investigated by knocking out two genes implicated in the EPS biosynthesis, gumD and gumH. Mutant strains were affected in growth characteristics in vitro, including adhesion to surfaces and biofilm formation. In addition, different assays were used to demonstrate that the mutant strains produced significantly less EPS compared with the wild type. Furthermore, gas chromatography-mass spectrometry showed that both mutant strains did not produce oligosaccharides. Biologically, the mutants were deficient in movement within plants, resulting in an avirulent phenotype. Additionally, mutant strains were affected in transmission by insects: they were very poorly transmitted by and retained within vectors. The gene expression profile indicated upregulation of genes implicated in cell-to-cell signaling and adhesins while downregulation in genes was required for within-plant movement in EPS-deficient strains. These results suggest an essential role for EPS in X. fastidiosa interactions with both plants and insects.

Review of insecticide resistance and behavioral avoidance of vectors of human diseases in Thailand

PubMed Central

2013-01-01

Physiological resistance and behavioral responses of mosquito vectors to insecticides are critical aspects of the chemical-based disease control equation. The complex interaction between lethal, sub-lethal and excitation/repellent ('excito-repellent’) properties of chemicals is typically overlooked in vector management and control programs. The development of “physiological” resistance, metabolic and/or target site modifications, to insecticides has been well documented in many insect groups and disease vectors around the world. In Thailand, resistance in many mosquito populations has developed to all three classes of insecticidal active ingredients currently used for vector control with a majority being synthetic-derived pyrethroids. Evidence of low-grade insecticide resistance requires immediate countermeasures to mitigate further intensification and spread of the genetic mechanisms responsible for resistance. This can take the form of rotation of a different class of chemical, addition of a synergist, mixtures of chemicals or concurrent mosaic application of different classes of chemicals. From the gathered evidence, the distribution and degree of physiological resistance has been restricted in specific areas of Thailand in spite of long-term use of chemicals to control insect pests and disease vectors throughout the country. Most surprisingly, there have been no reported cases of pyrethroid resistance in anopheline populations in the country from 2000 to 2011. The precise reasons for this are unclear but we assume that behavioral avoidance to insecticides may play a significant role in reducing the selection pressure and thus occurrence and spread of insecticide resistance. The review herein provides information regarding the status of physiological resistance and behavioral avoidance of the primary mosquito vectors of human diseases to insecticides in Thailand from 2000 to 2011. PMID:24294938

Effects of infection by Trypanosoma cruzi and Trypanosoma rangeli on the reproductive performance of the vector Rhodnius prolixus.

PubMed

Fellet, Maria Raquel; Lorenzo, Marcelo Gustavo; Elliot, Simon Luke; Carrasco, David; Guarneri, Alessandra Aparecida

2014-01-01

The insect Rhodnius prolixus is responsible for the transmission of Trypanosoma cruzi, which is the etiological agent of Chagas disease in areas of Central and South America. Besides this, it can be infected by other trypanosomes such as Trypanosoma rangeli. The effects of these parasites on vectors are poorly understood and are often controversial so here we focussed on possible negative effects of these parasites on the reproductive performance of R. prolixus, specifically comparing infected and uninfected couples. While T. cruzi infection did not delay pre-oviposition time of infected couples at either temperature tested (25 and 30°C) it did, at 25°C, increase the e-value in the second reproductive cycle, as well as hatching rates. Meanwhile, at 30°C, T. cruzi infection decreased the e-value of insects during the first cycle and also the fertility of older insects. When couples were instead infected with T. rangeli, pre-oviposition time was delayed, while reductions in the e-value and hatching rate were observed in the second and third cycles. We conclude that both T. cruzi and T. rangeli can impair reproductive performance of R. prolixus, although for T. cruzi, this is dependent on rearing temperature and insect age. We discuss these reproductive costs in terms of potential consequences on triatomine behavior and survival.

Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission.

PubMed

Ordax, Mónica; Piquer-Salcedo, Jaime E; Santander, Ricardo D; Sabater-Muñoz, Beatriz; Biosca, Elena G; López, María M; Marco-Noales, Ester

2015-01-01

Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae), one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i) E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii) medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle.

Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission

PubMed Central

Ordax, Mónica; Piquer-Salcedo, Jaime E.; Santander, Ricardo D.; Sabater-Muñoz, Beatriz; Biosca, Elena G.; López, María M.; Marco-Noales, Ester

2015-01-01

Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae), one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i) E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii) medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle. PMID:25978369

Flower-visiting behavior of male bees is triggered by nectar-feeding insects.

PubMed

Sugiura, Shinji; Abe, Tetsuto; Yamaura, Yuichi; Makino, Shun'ichi

2007-08-01

Bees are important pollinators for many flowering plants. Female bees are thought to be more effective pollinators than male bees because they carry much more pollen than males. Males of some solitary bee species are known to patrol near flowers that females visit. Because patrolling males visit flowers to mate or defend their territories, they may function as pollinators. However, the significance of patrolling males to pollination has not been studied. We studied males of a solitary bee, Heriades fulvohispidus (Megachilidae), patrolling near flowers and visiting flowers that attracted nectar-feeding insects, including conspecifics, on the Ogasawara (Bonin) Islands. To test the hypothesis that patrolling male bees may function as pollen vectors, we compared the frequency of visits by H. fulvohispidus to flowers of an endemic plant, Schima mertensiana (Theaceae); comparisons were made among flowers with a dead H. fulvohispidus, a dead beetle, a piece of plastic, and nothing (control flowers). Patrolling H. fulvohispidus more frequently visited flowers with a dead conspecific, a dead beetle, or a piece of plastic than the control flowers. Our experiment demonstrates that nectar-feeding insects (including conspecifics and other insects) enhance the flower-visiting frequency of patrolling H. fulvohispidus males on S. mertensiana flowers. Furthermore, we observed S. mertensiana pollen on patrolling males as well as females, suggesting that male bees may also function as pollen vectors.

Flower-visiting behavior of male bees is triggered by nectar-feeding insects

NASA Astrophysics Data System (ADS)

Sugiura, Shinji; Abe, Tetsuto; Yamaura, Yuichi; Makino, Shun'ichi

2007-08-01

Bees are important pollinators for many flowering plants. Female bees are thought to be more effective pollinators than male bees because they carry much more pollen than males. Males of some solitary bee species are known to patrol near flowers that females visit. Because patrolling males visit flowers to mate or defend their territories, they may function as pollinators. However, the significance of patrolling males to pollination has not been studied. We studied males of a solitary bee, Heriades fulvohispidus (Megachilidae), patrolling near flowers and visiting flowers that attracted nectar-feeding insects, including conspecifics, on the Ogasawara (Bonin) Islands. To test the hypothesis that patrolling male bees may function as pollen vectors, we compared the frequency of visits by H. fulvohispidus to flowers of an endemic plant, Schima mertensiana (Theaceae); comparisons were made among flowers with a dead H. fulvohispidus, a dead beetle, a piece of plastic, and nothing (control flowers). Patrolling H. fulvohispidus more frequently visited flowers with a dead conspecific, a dead beetle, or a piece of plastic than the control flowers. Our experiment demonstrates that nectar-feeding insects (including conspecifics and other insects) enhance the flower-visiting frequency of patrolling H. fulvohispidus males on S. mertensiana flowers. Furthermore, we observed S. mertensiana pollen on patrolling males as well as females, suggesting that male bees may also function as pollen vectors.

Analysis of expressed sequence tags for Frankliniella occidentalis, the western flower thrips.

PubMed

Rotenberg, D; Whitfield, A E

2010-08-01

Thrips are members of the insect order Thysanoptera and Frankliniella occidentalis (the western flower thrips) is the most economically important pest within this order. F. occidentalis is both a direct pest of crops and an efficient vector of plant viruses, including Tomato spotted wilt virus (TSWV). Despite the world-wide importance of thrips in agriculture, there is little knowledge of the F. occidentalis genome or gene functions at this time. A normalized cDNA library was constructed from first instar thrips and 13 839 expressed sequence tags (ESTs) were obtained. Our EST data assembled into 894 contigs and 11 806 singletons (12 700 nonredundant sequences). We found that 31% of these sequences had significant similarity (E< or = 10(-10)) to protein sequences in the National Center for Biotechnology Information nonredundant (nr) protein database, and 25% were functionally annotated using Blast 2GO. We identified 74 sequences with putative homology to proteins associated with insect innate immunity. Sixteen sequences had significant similarity to proteins associated with small RNA-mediated gene silencing pathways (RNA interference; RNAi), including the antiviral pathway (short interfering RNA-mediated pathway). Our EST collection provides new sequence resources for characterizing gene functions in F. occidentalis and other thrips species with regards to vital biological processes, studying the mechanism of interactions with the viruses harboured and transmitted by the vector, and identifying new insect gene-centred targets for plant disease and insect control.

Trypanosoma avium of raptors (Falconiformes): phylogeny and identification of vectors.

PubMed

Votýpka, J; Oborník, M; Volf, P; Svobodová, M; Lukes, J

2002-09-01

Avian trypanosomes are widespread parasites of birds, the transmission of which remains mostly unclear, with various blood-sucking insects mentioned as possible vectors. A search for vectors of trypanosomes of sparrowhawk (Accipiter nisus), buzzard (Buteo buteo), lesser-spotted eagle (Aquila pomarina) and kestrel (Falco tinnunculus) was performed in Czech and Slovak Republics. Black flies (Eusimulium spp.), hippoboscid flies (Ornithomyia avicularia), mosquitoes (Culex pipiens pipiens) and biting midges (Culicoides spp.), trapped while attempting to feed on raptor nestlings, were found to contain trypanosomatids in their intestine. Trypanosomes from the raptors and blood-sucking insects were isolated, and their 18S rRNA sequences were used for species identification and for the inference of intra- and interspecific relationships. Together with the trypanosome isolated from a black fly, the bird trypanosomes formed a well-supported Trypanosoma avium clade. The isolates derived from hippoboscid flies and mosquitoes are most likely also avian trypanosomes infecting birds other than the studied raptors. Analysis of the kinetoplast, that has features characteristic for the avian trypanosomes (minicircle size; dimensions of the kinetoplast disc), provided further evidence for the identification of vectors. It is suggested that all trypanosomes isolated from raptors included in this study belong to the T. avium complex and are transmitted by the ornithophilic simuliids such as Eusimulium securiforme.

Integrative proteomics to understand the transmission mechanism of Barley yellow dwarf virus-GPV by its insect vector Rhopalosiphum padi

PubMed Central

Wang, Hui; Wu, Keke; Liu, Yan; Wu, Yunfeng; Wang, Xifeng

2015-01-01

Barley yellow dwarf virus-GPV (BYDV-GPV) is transmitted by Rhopalosiphum padi and Schizaphis graminum in a persistent nonpropagative manner. To improve our understanding of its transmission mechanism by aphid vectors, we used two approaches, isobaric tags for relative and absolute quantitation (iTRAQ) and yeast two-hybrid (YTH) system, to identify proteins in R. padi that may interact with or direct the spread of BYDV-GPV along the circulative transmission pathway. Thirty-three differential aphid proteins in viruliferous and nonviruliferous insects were identified using iTRAQ coupled to 2DLC-MS/MS. With the yeast two-hybrid system, 25 prey proteins were identified as interacting with the readthrough protein (RTP) and eight with the coat protein (CP), which are encoded by BYDV-GPV. Among the aphid proteins identified, most were involved in primary energy metabolism, synaptic vesicle cycle, the proteasome pathway and the cell cytoskeleton organization pathway. In a systematic comparison of the two methods, we found that the information generated by the two methods was complementary. Taken together, our findings provide useful information on the interactions between BYDV-GPV and its vector R. padi to further our understanding of the mechanisms regulating circulative transmission in aphid vectors. PMID:26161807

Improved Production Efficiency of Virus-Like Particles by the Baculovirus Expression Vector System

PubMed Central

Bárcena, Juan; Nuñez, Maria del Carmen; Martínez-Alonso, Diego; Dudognon, Benoit; Guijarro, Eva; Escribano, José M.

2015-01-01

Vaccines based on virus-like particles (VLPs) have proven effective in humans and animals. In this regard, the baculovirus expression vector system (BEVS) is one of the technologies of choice to generate such highly immunogenic vaccines. The extended use of these vaccines for human and animal populations is constrained because of high production costs, therefore a significant improvement in productivity is crucial to ensure their commercial viability. Here we describe the use of the previously described baculovirus expression cassette, called TB, to model the production of two VLP-forming vaccine antigens in insect cells. Capsid proteins from porcine circovirus type 2 (PCV2 Cap) and from the calicivirus that causes rabbit hemorrhagic disease (RHDV VP60) were expressed in insect cells using baculoviruses genetically engineered with the TB expression cassette. Productivity was compared to that obtained using standard counterpart vectors expressing the same proteins under the control of the polyhedrin promoter. Our results demonstrate that the use of the TB expression cassette increased the production yields of these vaccine antigens by around 300% with respect to the standard vectors. The recombinant proteins produced by TB-modified vectors were fully functional, forming VLPs identical in size and shape to those generated by the standard baculoviruses, as determined by electron microscopy analysis. The use of the TB expression cassette implies a simple modification of the baculovirus vectors that significantly improves the cost efficiency of VLP-based vaccine production, thereby facilitating the commercial viability and broad application of these vaccines for human and animal health. PMID:26458221

Improved Production Efficiency of Virus-Like Particles by the Baculovirus Expression Vector System.

PubMed

López-Vidal, Javier; Gómez-Sebastián, Silvia; Bárcena, Juan; Nuñez, Maria del Carmen; Martínez-Alonso, Diego; Dudognon, Benoit; Guijarro, Eva; Escribano, José M

2015-01-01

Vaccines based on virus-like particles (VLPs) have proven effective in humans and animals. In this regard, the baculovirus expression vector system (BEVS) is one of the technologies of choice to generate such highly immunogenic vaccines. The extended use of these vaccines for human and animal populations is constrained because of high production costs, therefore a significant improvement in productivity is crucial to ensure their commercial viability. Here we describe the use of the previously described baculovirus expression cassette, called TB, to model the production of two VLP-forming vaccine antigens in insect cells. Capsid proteins from porcine circovirus type 2 (PCV2 Cap) and from the calicivirus that causes rabbit hemorrhagic disease (RHDV VP60) were expressed in insect cells using baculoviruses genetically engineered with the TB expression cassette. Productivity was compared to that obtained using standard counterpart vectors expressing the same proteins under the control of the polyhedrin promoter. Our results demonstrate that the use of the TB expression cassette increased the production yields of these vaccine antigens by around 300% with respect to the standard vectors. The recombinant proteins produced by TB-modified vectors were fully functional, forming VLPs identical in size and shape to those generated by the standard baculoviruses, as determined by electron microscopy analysis. The use of the TB expression cassette implies a simple modification of the baculovirus vectors that significantly improves the cost efficiency of VLP-based vaccine production, thereby facilitating the commercial viability and broad application of these vaccines for human and animal health.

Sources of Blood Meals of Sylvatic Triatoma guasayana near Zurima, Bolivia, Assayed with qPCR and 12S Cloning

PubMed Central

Lucero, David E.; Ribera, Wilma; Pizarro, Juan Carlos; Plaza, Carlos; Gordon, Levi W.; Peña, Reynaldo; Morrissey, Leslie A.; Rizzo, Donna M.; Stevens, Lori

2014-01-01

Background In this study we compared the utility of two molecular biology techniques, cloning of the mitochondrial 12S ribosomal RNA gene and hydrolysis probe-based qPCR, to identify blood meal sources of sylvatic Chagas disease insect vectors collected with live-bait mouse traps (also known as Noireau traps). Fourteen T. guasayana were collected from six georeferenced trap locations in the Andean highlands of the department of Chuquisaca, Bolivia. Methodology/Principal Findings We detected four blood meals sources with the cloning assay: seven samples were positive for human (Homo sapiens), five for chicken (Gallus gallus) and unicolored blackbird (Agelasticus cyanopus), and one for opossum (Monodelphis domestica). Using the qPCR assay we detected chicken (13 vectors), and human (14 vectors) blood meals as well as an additional blood meal source, Canis sp. (4 vectors). Conclusions/Significance We show that cloning of 12S PCR products, which avoids bias associated with developing primers based on a priori knowledge, detected blood meal sources not previously considered and that species-specific qPCR is more sensitive. All samples identified as positive for a specific blood meal source by the cloning assay were also positive by qPCR. However, not all samples positive by qPCR were positive by cloning. We show the power of combining the cloning assay with the highly sensitive hydrolysis probe-based qPCR assay provides a more complete picture of blood meal sources for insect disease vectors. PMID:25474154

Chromobacterium Csp_P reduces malaria and dengue infection in vector mosquitoes and has entomopathogenic and in vitro anti-pathogen activities.

PubMed

Ramirez, Jose Luis; Short, Sarah M; Bahia, Ana C; Saraiva, Raul G; Dong, Yuemei; Kang, Seokyoung; Tripathi, Abhai; Mlambo, Godfree; Dimopoulos, George

2014-10-01

Plasmodium and dengue virus, the causative agents of the two most devastating vector-borne diseases, malaria and dengue, are transmitted by the two most important mosquito vectors, Anopheles gambiae and Aedes aegypti, respectively. Insect-bacteria associations have been shown to influence vector competence for human pathogens through multi-faceted actions that include the elicitation of the insect immune system, pathogen sequestration by microbes, and bacteria-produced anti-pathogenic factors. These influences make the mosquito microbiota highly interesting from a disease control perspective. Here we present a bacterium of the genus Chromobacterium (Csp_P), which was isolated from the midgut of field-caught Aedes aegypti. Csp_P can effectively colonize the mosquito midgut when introduced through an artificial nectar meal, and it also inhibits the growth of other members of the midgut microbiota. Csp_P colonization of the midgut tissue activates mosquito immune responses, and Csp_P exposure dramatically reduces the survival of both the larval and adult stages. Ingestion of Csp_P by the mosquito significantly reduces its susceptibility to Plasmodium falciparum and dengue virus infection, thereby compromising the mosquito's vector competence. This bacterium also exerts in vitro anti-Plasmodium and anti-dengue activities, which appear to be mediated through Csp_P -produced stable bioactive factors with transmission-blocking and therapeutic potential. The anti-pathogen and entomopathogenic properties of Csp_P render it a potential candidate for the development of malaria and dengue control strategies.

New scenarios of Trypanosoma cruzi transmission in the Orinoco region of Colombia

PubMed Central

Rendón, Lina María; Guhl, Felipe; Cordovez, Juan Manuel; Erazo, Diana

2015-01-01

Rhodnius prolixus, a blood-sucking triatomine with domiciliary anthropophilic habits, is the main vector of Chagas disease. The current paradigm of Trypanosoma cruzi transmission in Columbia includes a sylvatic and domiciliary cycle co-existing with domestic and sylvatic populations of reservoirs. The aim of this study is to evaluate the population densities and relative abundance of triatomines and mammals that may be involved in the sylvatic cycle of Chagas disease to clarify the epidemiological scenario in an endemic area in the province of Casanare. Insect vectors on Attalea butyracea palms were captured using both manual searches and bait traps. The capture of mammals was performed using Sherman and Tomahawk traps. We report an infestation index of 88.5% in 148 palms and an index of T. cruzi natural infection of 60.2% in 269 dissected insects and 11.9% in 160 captured mammals. High population densities of triatomines were observed in the sylvatic environment and there was a high relative abundance of reservoirs in the area, suggesting a stable enzootic cycle. We found no evidence of insect domiciliation. Taken together, these observations suggest that eco-epidemiological factors shape the transmission dynamics of T. cruzi, creating diverse scenarios of disease transmission. PMID:25830543

Toxicity of non-pyrethroid insecticides against Triatoma infestans (Hemiptera: Reduviidae).

PubMed

Carvajal, Guillermo; Mougabure-Cueto, Gastón; Toloza, Ariel Ceferino

2012-08-01

Triatoma infestans (Klug) is the main vector of Chagas disease, which is a public health concern in most Latin American countries. The prevention of Chagas disease is based on the chemical control of the vector using pyrethroid insecticides. In the last decade, different levels of deltamethrin resistance have been detected in certain areas of Argentina and Bolivia. Because of this, alternative non-pyrethroid insecticides from different chemical groups were evaluated against two T. infestans populations, NFS and El Malá, with the objective of finding new insecticides to control resistant insect populations. Toxicity to different insecticides was evaluated in a deltamethrin-susceptible and a deltamethrin-resistant population. Topical application of the insecticides fenitrothion and imidacloprid to first nymphs had lethal effects on both populations, producing 50% lethal dose (LD50) values that ranged from 5.2-28 ng/insect. However, amitraz, flubendiamide, ivermectin, indoxacarb and spinosad showed no insecticidal activity in first instars at the applied doses (LD50 > 200 ng/insect). Fenitrothion and imidacloprid were effective against both deltamethrin-susceptible and deltamethrin-resistant populations of T. infestans. Therefore, they may be considered alternative non-pyrethroid insecticides for the control of Chagas disease.

Construction of baculovirus expression vector of miRNAs and its expression in insect cells.

PubMed

Huang, Yong; Zou, Quan; Shen, Xing Jia; Yu, Xue Li; Wang, Zhan Bin; Cheng, Xiang Chao

2012-01-01

MicroRNAs (miRNAs) are endogenous small non-protein coding RNAs that play important regulatory roles in animals and plants by binding to target transcripts for cleavage or translational repression. The miR-9a is very conservative in animals from flies to humans. Studies indicated that miR-9a is involved in the regulation of neurogenesis in animals. In our study, the baculovirus expression system was used to transcribe a recombinant vector containing miR-9a for further analysis the function ofmiR-9a. The sequence ofpre-miR-9a from silkworm DNA was first cloned into the donor pFastBac. The enhanced green fluorescent protein (EGFP) was used as reporter gene. The recombinant donor plasmid pFastBac-miR-9a was transformed into E.coli DH10Bac/AcNPV forming Bacmid-9a which was transfected into insect cells with cational lipofectin. The transcription of mature miR-9a was detected by Real-time PCR. The results show the recombinant Bacmid-9a was successfully constructed and effectively transcribed miR-9a in infected Sf21 insect cells.

Rhodnius prolixus Life History Outcomes Differ when Infected with Different Trypanosoma cruzi I Strains

PubMed Central

Peterson, Jennifer K.; Graham, Andrea L.; Dobson, Andrew P.; Chávez, Omar Triana

2015-01-01

The effect of a parasite on the life history of its vector is important for understanding and predicting disease transmission. Chagas disease agent Trypanosoma cruzi is a generalist parasite that is diverse across scales from its genetic diversity to the 100s of mammal and vector species it infects. Its vertebrate hosts show quite variable responses to infection, however, to date there are no studies looking at how T. cruzi variability might result in variable outcomes in its invertebrate host. Therefore, we investigated the effect of different T. cruzi I strains on Rhodnius prolixus survival and development. We found significant variation between insects infected with different strains, with some strains having no effect, as compared with uninfected insects, and others with significantly lower survival and development. We also found that different variables had varying importance between strains, with the effect of time postinfection and the blood:weight ratio of the infective meal significantly affecting the survival of insects infected with some strains, but not others. Our results suggest that T. cruzi can be pathogenic not only to its vertebrate hosts but also to its invertebrate hosts. PMID:26078316

Differential gene expression in Xylella fastidiosa 9a5c during co-cultivation with the endophytic bacterium Methylobacterium mesophilicum SR1.6/6.

PubMed

Dourado, Manuella Nóbrega; Santos, Daiene Souza; Nunes, Luiz Roberto; Costa de Oliveira, Regina Lúcia Batista da; de Oliveira, Marcus Vinicius; Araújo, Welington Luiz

2015-12-01

Xylella fastidiosa, the causal agent of citrus variegated chlorosis (CVC), colonizes plant xylem, reducing sap flow, and inducing internerval chlorosis, leaf size reduction, necrosis, and harder and smaller fruits. This bacterium may be transmitted from plant to plant by sharpshooter insects, including Bucephalogonia xanthopis. The citrus endophytic bacterium Methylobacterium mesophilicum SR1.6/6 colonizes citrus xylem and previous studies showed that this strain is also transferred from plant to plant by B. xanthopis (Insecta), suggesting that this endophytic bacterium may interact with X. fastidiosa in planta and inside the insect vector during co-transmission by the same insect vector. To better understand the X. fastidiosa behavior in the presence of M. mesophilicum, we evaluated the X. fastidiosa transcriptional profile during in vitro interaction with M. mesophilicum SR1.6/6. The results showed that during co-cultivation, X. fastidiosa down-regulated genes related to growth and up-regulated genes related to energy production, stress, transport, and motility, suggesting the existence of a specific adaptive response to the presence of M. mesophilicum in the culture medium. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

History of domestication and spread of Aedes aegypti--a review.

PubMed

Powell, Jeffrey R; Tabachnick, Walter J

2013-01-01

The adaptation of insect vectors of human diseases to breed in human habitats (domestication) is one of the most important phenomena in medical entomology. Considerable data are available on the vector mosquito Aedes aegypti in this regard and here we integrate the available information including genetics, behaviour, morphology, ecology and biogeography of the mosquito, with human history. We emphasise the tremendous amount of variation possessed by Ae. aegypti for virtually all traits considered. Typological thinking needs to be abandoned to reach a realistic and comprehensive understanding of this important vector of yellow fever, dengue and Chikungunya.

History of domestication and spread of Aedes aegypti - A Review

PubMed Central

Powell, Jeffrey R; Tabachnick, Walter J

2013-01-01

The adaptation of insect vectors of human diseases to breed in human habitats (domestication) is one of the most important phenomena in medical entomology. Considerable data are available on the vector mosquito Aedes aegypti in this regard and here we integrate the available information including genetics, behaviour, morphology, ecology and biogeography of the mosquito, with human history. We emphasise the tremendous amount of variation possessed by Ae. aegypti for virtually all traits considered. Typological thinking needs to be abandoned to reach a realistic and comprehensive understanding of this important vector of yellow fever, dengue and Chikungunya. PMID:24473798

Modeling the impact of global warming on vector-borne infections.

PubMed

Massad, Eduardo; Coutinho, Francisco Antonio Bezerra; Lopez, Luis Fernandez; da Silva, Daniel Rodrigues

2011-06-01

Global warming will certainly affect the abundance and distribution of disease vectors. The effect of global warming, however, depends on the complex interaction between the human host population and the causative infectious agent. In this work we review some mathematical models that were proposed to study the impact of the increase in ambient temperature on the spread and gravity of some insect-transmitted diseases. Copyright © 2011 Elsevier B.V. All rights reserved.

Novel and viable acetylcholinesterase target site for developing effective and environmentally safe insecticides.

PubMed

Pang, Yuan-Ping; Brimijoin, Stephen; Ragsdale, David W; Zhu, Kun Yan; Suranyi, Robert

2012-04-01

Insect pests are responsible for human suffering and financial losses worldwide. New and environmentally safe insecticides are urgently needed to cope with these serious problems. Resistance to current insecticides has resulted in a resurgence of insect pests, and growing concerns about insecticide toxicity to humans discourage the use of insecticides for pest control. The small market for insecticides has hampered insecticide development; however, advances in genomics and structural genomics offer new opportunities to develop insecticides that are less dependent on the insecticide market. This review summarizes the literature data that support the hypothesis that an insect-specific cysteine residue located at the opening of the acetylcholinesterase active site is a promising target site for developing new insecticides with reduced off-target toxicity and low propensity for insect resistance. These data are used to discuss the differences between targeting the insect-specific cysteine residue and targeting the ubiquitous catalytic serine residue of acetylcholinesterase from the perspective of reducing off-target toxicity and insect resistance. Also discussed is the prospect of developing cysteine-targeting anticholinesterases as effective and environmentally safe insecticides for control of disease vectors, crop damage, and residential insect pests within the financial confines of the present insecticide market.

A Vision-Based Counting and Recognition System for Flying Insects in Intelligent Agriculture.

PubMed

Zhong, Yuanhong; Gao, Junyuan; Lei, Qilun; Zhou, Yao

2018-05-09

Rapid and accurate counting and recognition of flying insects are of great importance, especially for pest control. Traditional manual identification and counting of flying insects is labor intensive and inefficient. In this study, a vision-based counting and classification system for flying insects is designed and implemented. The system is constructed as follows: firstly, a yellow sticky trap is installed in the surveillance area to trap flying insects and a camera is set up to collect real-time images. Then the detection and coarse counting method based on You Only Look Once (YOLO) object detection, the classification method and fine counting based on Support Vector Machines (SVM) using global features are designed. Finally, the insect counting and recognition system is implemented on Raspberry PI. Six species of flying insects including bee, fly, mosquito, moth, chafer and fruit fly are selected to assess the effectiveness of the system. Compared with the conventional methods, the test results show promising performance. The average counting accuracy is 92.50% and average classifying accuracy is 90.18% on Raspberry PI. The proposed system is easy-to-use and provides efficient and accurate recognition data, therefore, it can be used for intelligent agriculture applications.

Novel and Viable Acetylcholinesterase Target Site for Developing Effective and Environmentally Safe Insecticides

PubMed Central

Pang, Yuan-Ping; Brimijoin, Stephen; Ragsdale, David W; Zhu, Kun Yan; Suranyi, Robert

2012-01-01

Insect pests are responsible for human suffering and financial losses worldwide. New and environmentally safe insecticides are urgently needed to cope with these serious problems. Resistance to current insecticides has resulted in a resurgence of insect pests, and growing concerns about insecticide toxicity to humans discourage the use of insecticides for pest control. The small market for insecticides has hampered insecticide development; however, advances in genomics and structural genomics offer new opportunities to develop insecticides that are less dependent on the insecticide market. This review summarizes the literature data that support the hypothesis that an insect-specific cysteine residue located at the opening of the acetylcholinesterase active site is a promising target site for developing new insecticides with reduced off-target toxicity and low propensity for insect resistance. These data are used to discuss the differences between targeting the insect-specific cysteine residue and targeting the ubiquitous catalytic serine residue of acetylcholinesterase from the perspective of reducing off-target toxicity and insect resistance. Also discussed is the prospect of developing cysteine-targeting anticholinesterases as effective and environmentally safe insecticides for control of disease vectors, crop damage, and residential insect pests within the financial confines of the present insecticide market. PMID:22280344

A Vision-Based Counting and Recognition System for Flying Insects in Intelligent Agriculture

PubMed Central

Zhong, Yuanhong; Gao, Junyuan; Lei, Qilun; Zhou, Yao

2018-01-01

Rapid and accurate counting and recognition of flying insects are of great importance, especially for pest control. Traditional manual identification and counting of flying insects is labor intensive and inefficient. In this study, a vision-based counting and classification system for flying insects is designed and implemented. The system is constructed as follows: firstly, a yellow sticky trap is installed in the surveillance area to trap flying insects and a camera is set up to collect real-time images. Then the detection and coarse counting method based on You Only Look Once (YOLO) object detection, the classification method and fine counting based on Support Vector Machines (SVM) using global features are designed. Finally, the insect counting and recognition system is implemented on Raspberry PI. Six species of flying insects including bee, fly, mosquito, moth, chafer and fruit fly are selected to assess the effectiveness of the system. Compared with the conventional methods, the test results show promising performance. The average counting accuracy is 92.50% and average classifying accuracy is 90.18% on Raspberry PI. The proposed system is easy-to-use and provides efficient and accurate recognition data, therefore, it can be used for intelligent agriculture applications. PMID:29747429

Combinatorial Codes and Labeled Lines: How Insects Use Olfactory Cues to Find and Judge Food, Mates, and Oviposition Sites in Complex Environments

PubMed Central

Haverkamp, Alexander; Hansson, Bill S.; Knaden, Markus

2018-01-01

Insects, including those which provide vital ecosystems services as well as those which are devastating pests or disease vectors, locate their resources mainly based on olfaction. Understanding insect olfaction not only from a neurobiological but also from an ecological perspective is therefore crucial to balance insect control and conservation. However, among all sensory stimuli olfaction is particularly hard to grasp. Our chemical environment is made up of thousands of different compounds, which might again be detected by our nose in multiple ways. Due to this complexity, researchers have only recently begun to explore the chemosensory ecology of model organisms such as Drosophila, linking the tools of chemical ecology to those of neurogenetics. This cross-disciplinary approach has enabled several studies that range from single odors and their ecological relevance, via olfactory receptor genes and neuronal processing, up to the insects' behavior. We learned that the insect olfactory system employs strategies of combinatorial coding to process general odors as well as labeled lines for specific compounds that call for an immediate response. These studies opened new doors to the olfactory world in which insects feed, oviposit, and mate. PMID:29449815

Isolation of fungi from dead arthropods and identification of a new mosquito natural pathogen.

PubMed

Jaber, Sana; Mercier, Alex; Knio, Khouzama; Brun, Sylvain; Kambris, Zakaria

2016-09-05

Insects are well known vectors of human and animal pathogens and millions of people are killed by mosquito-borne diseases every year. The use of insecticides to target insect vectors has been hampered by the issues of toxicity to the environment and by the selection of resistant insects. Therefore, biocontrol strategies based on naturally occurring microbial pathogens emerged as a promising control alternative. The entomopathogenic fungus Beauveria bassiana is well characterized and have been approved by the United States Environmental Protection Agency as a pest biological control method. However, thousands of other fungi are unexploited and it is important to identify and use different fungi for biocontrol with possibly some vector specific strains. The aim of this study was to identify new fungal entomopathogens that may be used as potential mosquito biocontrol agents. Cadavers of arthropods were collected from pesticide free areas and the fungi associated isolated, cultured and identified. Then the ability of each isolate to kill laboratory insects was assayed and compared to that of B. bassiana. In total we have isolated and identified 42 fungal strains from 17 different arthropod cadavers. Twenty four fungal isolates were cultivated in the laboratory and were able to induce sporulation. When fungal spores were microinjected into Drosophila melanogaster, eight isolates proved to be highly pathogenic while the remaining strains showed moderate or no pathogenicity. Then a selection of isolates was tested against Aedes mosquitoes in a model mimicking natural infections. Only one fungus (Aspergillus nomius) was as pathogenic as B. bassiana and able to kill 100 % of the mosquitoes. The obtained results are encouraging and demonstrate the feasibility of this simple approach for the identification of new potential mosquito killers. Indeed, it is essential to anticipate and prepare biocontrol methods to fight the expansion of mosquitoes' habitat predicted in certain geographical areas in association with the occurring climatic changes.

Community-Based Entomological Surveillance Reveals Urban Foci of Chagas Disease Vectors in Sobral, State of Ceará, Northeastern Brazil.

PubMed

Parente, Cynara Carvalho; Bezerra, Fernando S M; Parente, Plutarco I; Dias-Neto, Raimundo V; Xavier, Samanta C C; Ramos, Alberto N; Carvalho-Costa, Filipe A; Lima, Marli M

2017-01-01

The aim of this work was to explore the potential risk of vector-borne Chagas disease in urban districts in northeastern Brazil, by analyzing the spatiotemporal distributions and natural infection rates with Trypanosoma cruzi of triatomine species captured in recent years. The main motivation of this work was an acute human case of Chagas disease reported in 2008 in the municipality of Sobral. We analyzed data from community-based entomological surveillance carried out from 2010 to 2014. Triatomine natural T. cruzi infection was assessed by examination of insect feces by optical microscopy. Sites of triatomine capture were georeferenced through Google Earth and analyzed with ArcGIS. A total of 191 triatomines were collected, consisting of 82.2% Triatoma pseudomaculata, 7.9% Rhodnius nasutus, 5.8% T. brasiliensis, 3.7% Panstrongylus lutzi, and 0.5% P. megistus, with an overall natural infection index of 17.8%. Most infestations were reported in the districts of Dom José (36.2%), Padre Palhano (24.7%), and Alto do Cristo (10.6%). The overwhelming majority of insects (185/96.9%) were captured inside houses, and most insects tended to be collected in intermittent peaks. Moreover, captured triatomines tended to constitute colonies. The acute case reported in 2008 was found to be situated within a T. pseudomaculata hotspot. The triatomine collection events carried out by dwellers were aggregated in time and space into distinct foci, suggesting that insects are intermittently and artificially introduced into the city, possibly via accidental migration from their natural reservoirs. The relatively high T. cruzi infection rate indicates considerable circulation of the parasite in these areas, increasing the risk of vector-borne Chagas disease infection. These data suggest a need to strengthen epidemiological surveillance and integrate appropriate control actions targeting triatomines, T. cruzi reservoirs, and human populations. Our data also identify Chagas disease transmission as a hazard in urban areas of Sobral.

Cytorhabdovirus phosphoprotein shows RNA silencing suppressor activity in plants, but not in insect cells.

PubMed

Mann, Krin S; Johnson, Karyn N; Dietzgen, Ralf G

2015-02-01

RNA silencing in plants and insects provides an antiviral defense and as a countermeasure most viruses encode RNA silencing suppressors (RSS). For the family Rhabdoviridae, no detailed functional RSS studies have been reported in plant hosts and insect vectors. In agroinfiltrated Nicotiana benthamiana leaves we show for the first time for a cytorhabdovirus, lettuce necrotic yellows virus (LNYV), that one of the nucleocapsid core proteins, phosphoprotein (P) has relatively weak local RSS activity and delays systemic silencing of a GFP reporter. Analysis of GFP small RNAs indicated that the P protein did not prevent siRNA accumulation. To explore RSS activity in insects, we used a Flock House virus replicon system in Drosophila S2 cells. In contrast to the plant host, LNYV P protein did not exhibit RSS activity in the insect cells. Taken together our results suggest that P protein may target plant-specific components of RNA silencing post siRNA biogenesis. Copyright © 2014 Elsevier Inc. All rights reserved.

Maize rhabdovirus-vector transmission

USDA-ARS?s Scientific Manuscript database

oth of the plant-infecting rhabdovirus genera, Nucleorhabdovirus and Cytorhabdovirus, contain viruses that infect maize (Zea mays L.). The maize infecting rhabdoviruses are transmitted by hemipteran insects in the families Cicadellidae and Delphacidae in a persistent propagative manner. This chapt...

Toward exascale production of recombinant adeno-associated virus for gene transfer applications.

PubMed

Cecchini, S; Negrete, A; Kotin, R M

2008-06-01

To gain acceptance as a medical treatment, adeno-associated virus (AAV) vectors require a scalable and economical production method. Recent developments indicate that recombinant AAV (rAAV) production in insect cells is compatible with current good manufacturing practice production on an industrial scale. This platform can fully support development of rAAV therapeutics from tissue culture to small animal models, to large animal models, to toxicology studies, to Phase I clinical trials and beyond. Efforts to characterize, optimize and develop insect cell-based rAAV production have culminated in successful bioreactor-scale production of rAAV, with total yields potentially capable of approaching the exa-(10(18)) scale. These advances in large-scale AAV production will allow us to address specific catastrophic, intractable human diseases such as Duchenne muscular dystrophy, for which large amounts of recombinant vector are essential for successful outcome.

[New public health challenges in vector management: black flies in Murcia (Spain)].

PubMed

Sánchez-López, Pedro F; Ruiz-Arrondo, Ignacio; Kotter, Heiko; Pacheco Martínez, Francisco; Segovia Hernández, Manuel; Gómez Campoy, M Elisa

Historically, no black fly (Diptera: Simuliidae) nuisance has been reported in the Murcia Region. Back in September 2016 the Ojós City Council has contacted the Regional Public Health General Directorate for help regarding a local insect nuisance, most probably based on mosquitoes. After sampling with a BG-sentinel 2 trap, collecting adult specimens with an entomological aspirator, and collect larvae and pupae on submerged giant cane stalks at the river, it turned out that Simulium sergenti was the insect species causing the nuisance. This species is not considered particularly anthropophilic; therefore, a low vector risk for human health was considered. However, the high fly density impaired the life quality of the people at the village. A management plan was recommended, treating the river with Bacillus thuringiensis var israelensis. Copyright © 2017 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

Survival relative to new and ancestral host plants, phytoplasma infection, and genetic constitution in host races of a polyphagous insect disease vector

PubMed Central

Maixner, Michael; Albert, Andreas; Johannesen, Jes

2014-01-01

Dissemination of vectorborne diseases depends strongly on the vector's host range and the pathogen's reservoir range. Because vectors interact with pathogens, the direction and strength of a vector's host shift is vital for understanding epidemiology and is embedded in the framework of ecological specialization. This study investigates survival in host-race evolution of a polyphagous insect disease vector, Hyalesthes obsoletus, whether survival is related to the direction of the host shift (from field bindweed to stinging nettle), the interaction with plant-specific strains of obligate vectored pathogens/symbionts (stolbur phytoplasma), and whether survival is related to genetic differentiation between the host races. We used a twice repeated, identical nested experimental design to study survival of the vector on alternative hosts and relative to infection status. Survival was tested with Kaplan–Meier analyses, while genetic differentiation between vector populations was quantified with microsatellite allele frequencies. We found significant direct effects of host plant (reduced survival on wrong hosts) and sex (males survive longer than females) in both host races and relative effects of host (nettle animals more affected than bindweed animals) and sex (males more affected than females). Survival of bindweed animals was significantly higher on symptomatic than nonsymptomatic field bindweed, but in the second experiment only. Infection potentially had a positive effect on survival in nettle animals but due to low infection rates the results remain suggestive. Genetic differentiation was not related to survival. Greater negative plant-transfer effect but no negative effect of stolbur in the derived host race suggests preadaptation to the new pathogen/symbiont strain before strong diversifying selection during the specialization process. Physiological maladaptation or failure to accept the ancestral plant will have similar consequences, namely positive assortative mating within host races and a reduction in the likelihood of oviposition on the alternative plant and thus the acquisition of alternative stolbur strains. PMID:25247065

Survival relative to new and ancestral host plants, phytoplasma infection, and genetic constitution in host races of a polyphagous insect disease vector.

PubMed

Maixner, Michael; Albert, Andreas; Johannesen, Jes

2014-08-01

Dissemination of vectorborne diseases depends strongly on the vector's host range and the pathogen's reservoir range. Because vectors interact with pathogens, the direction and strength of a vector's host shift is vital for understanding epidemiology and is embedded in the framework of ecological specialization. This study investigates survival in host-race evolution of a polyphagous insect disease vector, Hyalesthes obsoletus, whether survival is related to the direction of the host shift (from field bindweed to stinging nettle), the interaction with plant-specific strains of obligate vectored pathogens/symbionts (stolbur phytoplasma), and whether survival is related to genetic differentiation between the host races. We used a twice repeated, identical nested experimental design to study survival of the vector on alternative hosts and relative to infection status. Survival was tested with Kaplan-Meier analyses, while genetic differentiation between vector populations was quantified with microsatellite allele frequencies. We found significant direct effects of host plant (reduced survival on wrong hosts) and sex (males survive longer than females) in both host races and relative effects of host (nettle animals more affected than bindweed animals) and sex (males more affected than females). Survival of bindweed animals was significantly higher on symptomatic than nonsymptomatic field bindweed, but in the second experiment only. Infection potentially had a positive effect on survival in nettle animals but due to low infection rates the results remain suggestive. Genetic differentiation was not related to survival. Greater negative plant-transfer effect but no negative effect of stolbur in the derived host race suggests preadaptation to the new pathogen/symbiont strain before strong diversifying selection during the specialization process. Physiological maladaptation or failure to accept the ancestral plant will have similar consequences, namely positive assortative mating within host races and a reduction in the likelihood of oviposition on the alternative plant and thus the acquisition of alternative stolbur strains.

Factors Affecting the Initial Adhesion and Retention of the Plant Pathogen Xylella fastidiosa in the Foregut of an Insect Vector

PubMed Central

Almeida, Rodrigo P. P.

2014-01-01

Vector transmission of bacterial plant pathogens involves three steps: pathogen acquisition from an infected host, retention within the vector, and inoculation of cells into susceptible tissue of an uninfected plant. In this study, a combination of plant and artificial diet systems were used to determine the importance of several genes on the initial adhesion and retention of the bacterium Xylella fastidiosa to an efficient insect vector. Mutant strains included fimbrial (fimA and pilB) and afimbrial (hxfA and hxfB) adhesins and three loci involved in regulatory systems (rpfF, rpfC, and cgsA). Transmission assays with variable retention time indicated that HxfA and HxfB were primarily important for early adhesion to vectors, while FimA was necessary for both adhesion and retention. The long pilus protein PilB was not deficient in initial adhesion but may be important for retention. Genes upregulated under the control of rpfF are important for both initial adhesion and retention, as transmission rates of this mutant strain were initially low and decreased over time, while disruption of rpfC and cgsA yielded trends similar to that shown by the wild-type control. Because induction of an X. fastidiosa transmissible state requires pectin, a series of experiments were used to test the roles of a polygalacturonase (pglA) and the pectin and galacturonic acid carbohydrates on the transmission of X. fastidiosa. Results show that galacturonic acid, or PglA activity breaking pectin into its major subunit (galacturonic acid), is required for X. fastidiosa vector transmission using an artificial diet system. This study shows that early adhesion and retention of X. fastidiosa are mediated by different factors. It also illustrates that the interpretation of results of vector transmission experiments, in the context of vector-pathogen interaction studies, is highly dependent on experimental design. PMID:24185853

Factors affecting the initial adhesion and retention of the plant pathogen Xylella fastidiosa in the foregut of an insect vector.

PubMed

Killiny, Nabil; Almeida, Rodrigo P P

2014-01-01

Vector transmission of bacterial plant pathogens involves three steps: pathogen acquisition from an infected host, retention within the vector, and inoculation of cells into susceptible tissue of an uninfected plant. In this study, a combination of plant and artificial diet systems were used to determine the importance of several genes on the initial adhesion and retention of the bacterium Xylella fastidiosa to an efficient insect vector. Mutant strains included fimbrial (fimA and pilB) and afimbrial (hxfA and hxfB) adhesins and three loci involved in regulatory systems (rpfF, rpfC, and cgsA). Transmission assays with variable retention time indicated that HxfA and HxfB were primarily important for early adhesion to vectors, while FimA was necessary for both adhesion and retention. The long pilus protein PilB was not deficient in initial adhesion but may be important for retention. Genes upregulated under the control of rpfF are important for both initial adhesion and retention, as transmission rates of this mutant strain were initially low and decreased over time, while disruption of rpfC and cgsA yielded trends similar to that shown by the wild-type control. Because induction of an X. fastidiosa transmissible state requires pectin, a series of experiments were used to test the roles of a polygalacturonase (pglA) and the pectin and galacturonic acid carbohydrates on the transmission of X. fastidiosa. Results show that galacturonic acid, or PglA activity breaking pectin into its major subunit (galacturonic acid), is required for X. fastidiosa vector transmission using an artificial diet system. This study shows that early adhesion and retention of X. fastidiosa are mediated by different factors. It also illustrates that the interpretation of results of vector transmission experiments, in the context of vector-pathogen interaction studies, is highly dependent on experimental design.

Oligonucleotide Based Magnetic Bead Capture of Onchocerca volvulus DNA for PCR Pool Screening of Vector Black Flies

PubMed Central

Gopal, Hemavathi; Hassan, Hassan K.; Rodríguez-Pérez, Mario A.; Toé, Laurent D.; Lustigman, Sara; Unnasch, Thomas R.

2012-01-01

Background Entomological surveys of Simulium vectors are an important component in the criteria used to determine if Onchocerca volvulus transmission has been interrupted and if focal elimination of the parasite has been achieved. However, because infection in the vector population is quite rare in areas where control has succeeded, large numbers of flies need to be examined to certify transmission interruption. Currently, this is accomplished through PCR pool screening of large numbers of flies. The efficiency of this process is limited by the size of the pools that may be screened, which is in turn determined by the constraints imposed by the biochemistry of the assay. The current method of DNA purification from pools of vector black flies relies upon silica adsorption. This method can be applied to screen pools containing a maximum of 50 individuals (from the Latin American vectors) or 100 individuals (from the African vectors). Methodology/Principal Findings We have evaluated an alternative method of DNA purification for pool screening of black flies which relies upon oligonucleotide capture of Onchocerca volvulus genomic DNA from homogenates prepared from pools of Latin American and African vectors. The oligonucleotide capture assay was shown to reliably detect one O. volvulus infective larva in pools containing 200 African or Latin American flies, representing a two-four fold improvement over the conventional assay. The capture assay requires an equivalent amount of technical time to conduct as the conventional assay, resulting in a two-four fold reduction in labor costs per insect assayed and reduces reagent costs to $3.81 per pool of 200 flies, or less than $0.02 per insect assayed. Conclusions/Significance The oligonucleotide capture assay represents a substantial improvement in the procedure used to detect parasite prevalence in the vector population, a major metric employed in the process of certifying the elimination of onchocerciasis. PMID:22724041

Effect of the urease-derived peptide Jaburetox on the central nervous system of Triatoma infestans (Insecta: Heteroptera).

PubMed

Galvani, Gerónimo L; Fruttero, Leonardo L; Coronel, María F; Nowicki, Susana; Demartini, Diogo R; Defferrari, Marina S; Postal, Melissa; Canavoso, Lilián E; Carlini, Célia R; Settembrini, Beatriz P

2015-02-01

Triatoma infestans is the main vector of Chagas'disease in Southern Cone countries. In triatomines, symptoms suggesting neurotoxicity were observed after treatment with Jaburetox (Jbtx), the entomotoxic peptide obtained from jackbean urease. Here, we study its effect in the central nervous system (CNS) of this species. Immunohistochemistry, Western blots, immunoprecipitation, two-dimensional electrophoresis, tandem mass spectrometry and enzymatic assays were performed. Anti-Jbtx antibody labeled somata of the antennal lobe only in Jbtx-treated insects. Western blot assays of nervous tissue using the same antibody reacted with a 61kDa protein band only in peptide-injected insects. Combination of immunoprecipitation, two-dimensional electrophoresis and tandem mass spectrometry identified UDP-N-acetylglucosamine pyrophosphorylase (UDP-GlcNAcP) as a molecular target for Jbtx. The activity of UDP-GlcNAcP increased significantly in the CNS of Jbtx-treated insects. The effect of Jbtx on the activity of nitric oxide synthase (NOS) and NO production was investigated as NO is a recognized messenger molecule in the CNS of T. infestans. NOS activity and NO levels decreased significantly in CNS homogenates of Jbtx-treated insects. UDP-GlcNAcP is a molecular target of Jbtx. Jbtx impaired the activity of T. infestans nitrergic system, which may be related with early behavioral effects. We report that the CNS of Triatoma infestans is a target for the entomotoxic peptide and propose that a specific area of the brain is involved. Besides potentially providing tools for control strategies of Chagas' disease vectors our data may be relevant in various fields of research as insect physiology, neurobiology and protein function. Copyright © 2014 Elsevier B.V. All rights reserved.

Evidence that a laminin-like insect protein mediates early events in the interaction of a Phytoparasite with its vector's salivary gland.

PubMed

de Almeida Dias, Felipe; Souza dos Santos, Andre Luis; Santos Lery, Letícia Miranda; Alves e Silva, Thiago Luiz; Oliveira, Mauricio Martins; Bisch, Paulo Mascarello; Saraiva, Elvira Maria; Souto-Padrón, Thaïs Cristina; Lopes, Angela Hampshire

2012-01-01

Phytomonas species are plant parasites of the family Trypanosomatidae, which are transmitted by phytophagous insects. Some Phytomonas species cause major agricultural damages. The hemipteran Oncopeltus fasciatus is natural and experimental host for several species of trypanosomatids, including Phytomonas spp. The invasion of the insect vectors' salivary glands is one of the most important events for the life cycle of Phytomonas species. In the present study, we show the binding of Phytomonas serpens at the external face of O. fasciatus salivary glands by means of scanning electron microscopy and the in vitro interaction of living parasites with total proteins from the salivary glands in ligand blotting assays. This binding occurs primarily through an interaction with a 130 kDa salivary gland protein. The mass spectrometry of the trypsin-digest of this protein matched 23% of human laminin-5 β3 chain precursor sequence by 16 digested peptides. A protein sequence search through the transcriptome of O. fasciatus embryo showed a partial sequence with 51% similarity to human laminin β3 subunit. Anti-human laminin-5 β3 chain polyclonal antibodies recognized the 130 kDa protein by immunoblotting. The association of parasites with the salivary glands was strongly inhibited by human laminin-5, by the purified 130 kDa insect protein, and by polyclonal antibodies raised against the human laminin-5 β3 chain. This is the first report demonstrating that a laminin-like molecule from the salivary gland of O. fasciatus acts as a receptor for Phytomonas binding. The results presented in this investigation are important findings that will support further studies that aim at developing new approaches to prevent the transmission of Phytomonas species from insects to plants and vice-versa.

Evidence That a Laminin-Like Insect Protein Mediates Early Events in the Interaction of a Phytoparasite with Its Vector's Salivary Gland

PubMed Central

Dias, Felipe de Almeida; dos Santos, Andre Luis Souza; Lery, Letícia Miranda Santos; Alves e Silva, Thiago Luiz; Oliveira, Mauricio Martins; Bisch, Paulo Mascarello; Saraiva, Elvira Maria; Souto-Padrón, Thaïs Cristina; Lopes, Angela Hampshire

2012-01-01

Phytomonas species are plant parasites of the family Trypanosomatidae, which are transmitted by phytophagous insects. Some Phytomonas species cause major agricultural damages. The hemipteran Oncopeltus fasciatus is natural and experimental host for several species of trypanosomatids, including Phytomonas spp. The invasion of the insect vectors' salivary glands is one of the most important events for the life cycle of Phytomonas species. In the present study, we show the binding of Phytomonas serpens at the external face of O. fasciatus salivary glands by means of scanning electron microscopy and the in vitro interaction of living parasites with total proteins from the salivary glands in ligand blotting assays. This binding occurs primarily through an interaction with a 130 kDa salivary gland protein. The mass spectrometry of the trypsin-digest of this protein matched 23% of human laminin-5 β3 chain precursor sequence by 16 digested peptides. A protein sequence search through the transcriptome of O. fasciatus embryo showed a partial sequence with 51% similarity to human laminin β3 subunit. Anti-human laminin-5 β3 chain polyclonal antibodies recognized the 130 kDa protein by immunoblotting. The association of parasites with the salivary glands was strongly inhibited by human laminin-5, by the purified 130 kDa insect protein, and by polyclonal antibodies raised against the human laminin-5 β3 chain. This is the first report demonstrating that a laminin-like molecule from the salivary gland of O. fasciatus acts as a receptor for Phytomonas binding. The results presented in this investigation are important findings that will support further studies that aim at developing new approaches to prevent the transmission of Phytomonas species from insects to plants and vice-versa. PMID:23118944

Implication of the Bacterial Endosymbiont Rickettsia spp. in Interactions of the Whitefly Bemisia tabaci with Tomato yellow leaf curl virus

PubMed Central

Kliot, Adi; Cilia, Michelle; Czosnek, Henryk

2014-01-01

ABSTRACT Numerous animal and plant viruses are transmitted by arthropod vectors in a persistent, circulative manner. Tomato yellow leaf curl virus (TYLCV) is transmitted by the sweet potato whitefly Bemisia tabaci. We report here that infection with Rickettsia spp., a facultative endosymbiont of whiteflies, altered TYLCV-B. tabaci interactions. A B. tabaci strain infected with Rickettsia acquired more TYLCV from infected plants, retained the virus longer, and exhibited nearly double the transmission efficiency compared to an uninfected B. tabaci strain with the same genetic background. Temporal and spatial antagonistic relationships were discovered between Rickettsia and TYLCV within the whitefly. In different time course experiments, the levels of virus and Rickettsia within the insect were inversely correlated. Fluorescence in situ hybridization analysis of Rickettsia-infected midguts provided evidence for niche exclusion between Rickettsia and TYLCV. In particular, high levels of the bacterium in the midgut resulted in higher virus concentrations in the filter chamber, a favored site for virus translocation along the transmission pathway, whereas low levels of Rickettsia in the midgut resulted in an even distribution of the virus. Taken together, these results indicate that Rickettsia, by infecting the midgut, increases TYLCV transmission efficacy, adding further insights into the complex association between persistent plant viruses, their insect vectors, and microorganism tenants that reside within these insects. IMPORTANCE Interest in bacterial endosymbionts in arthropods and many aspects of their host biology in agricultural and human health systems has been increasing. A recent and relevant studied example is the influence of Wolbachia on dengue virus transmission by mosquitoes. In parallel with our recently studied whitefly-Rickettsia-TYLCV system, other studies have shown that dengue virus levels in the mosquito vector are inversely correlated with bacterial load. Our work here presents evidence of unifying principles between vectors of plant and animal viruses in a role for endosymbionts in manipulating vector biology and pathogen transmission. Our results demonstrate the influence of an interesting and prominent bacterial endosymbiont in Bemisia tabaci in TYLCV transmission, a worldwide disease infecting tomatoes. Besides its agricultural importance, this system provides interesting insights into Bemisia interaction with these newly discovered endosymbionts. PMID:24600010

Comparative and functional triatomine genomics reveals reductions and expansions in insecticide resistance-related gene families.

PubMed

Traverso, Lucila; Lavore, Andrés; Sierra, Ivana; Palacio, Victorio; Martinez-Barnetche, Jesús; Latorre-Estivalis, José Manuel; Mougabure-Cueto, Gaston; Francini, Flavio; Lorenzo, Marcelo G; Rodríguez, Mario Henry; Ons, Sheila; Rivera-Pomar, Rolando V

2017-02-01

Triatomine insects are vectors of Trypanosoma cruzi, a protozoan parasite that is the causative agent of Chagas' disease. This is a neglected disease affecting approximately 8 million people in Latin America. The existence of diverse pyrethroid resistant populations of at least two species demonstrates the potential of triatomines to develop high levels of insecticide resistance. Therefore, the incorporation of strategies for resistance management is a main concern for vector control programs. Three enzymatic superfamilies are thought to mediate xenobiotic detoxification and resistance: Glutathione Transferases (GSTs), Cytochromes P450 (CYPs) and Carboxyl/Cholinesterases (CCEs). Improving our knowledge of key triatomine detoxification enzymes will strengthen our understanding of insecticide resistance processes in vectors of Chagas' disease. The discovery and description of detoxification gene superfamilies in normalized transcriptomes of three triatomine species: Triatoma dimidiata, Triatoma infestans and Triatoma pallidipennis is presented. Furthermore, a comparative analysis of these superfamilies among the triatomine transcriptomes and the genome of Rhodnius prolixus, also a triatomine vector of Chagas' disease, and other well-studied insect genomes was performed. The expression pattern of detoxification genes in R. prolixus transcriptomes from key organs was analyzed. The comparisons reveal gene expansions in Sigma class GSTs, CYP3 in CYP superfamily and clade E in CCE superfamily. Moreover, several CYP families identified in these triatomines have not yet been described in other insects. Conversely, several groups of insecticide resistance related enzymes within each enzyme superfamily are reduced or lacking in triatomines. Furthermore, our qRT-PCR results showed an increase in the expression of a CYP4 gene in a T. infestans population resistant to pyrethroids. These results could point to an involvement of metabolic detoxification mechanisms on the high levels of pyrethroid resistance detected in triatomines from the Gran Chaco ecoregion. Our results help to elucidate the potential insecticide resistance mechanisms in vectors of Chagas' disease and provide new relevant information for this field. This study shows that metabolic resistance might be a contributing cause of the high pyrethroid resistance observed in wild T. infestans populations from the Gran Chaco ecoregion, area in which although subjected to intense pyrethroid treatments, vector control has failed. This study opens new avenues for further functional studies on triatomine detoxification mechanisms.

Comparative and functional triatomine genomics reveals reductions and expansions in insecticide resistance-related gene families

PubMed Central

Traverso, Lucila; Lavore, Andrés; Sierra, Ivana; Palacio, Victorio; Martinez-Barnetche, Jesús; Latorre-Estivalis, José Manuel; Mougabure-Cueto, Gaston; Francini, Flavio; Lorenzo, Marcelo G.; Rodríguez, Mario Henry; Ons, Sheila; Rivera-Pomar, Rolando V.

2017-01-01

Background Triatomine insects are vectors of Trypanosoma cruzi, a protozoan parasite that is the causative agent of Chagas’ disease. This is a neglected disease affecting approximately 8 million people in Latin America. The existence of diverse pyrethroid resistant populations of at least two species demonstrates the potential of triatomines to develop high levels of insecticide resistance. Therefore, the incorporation of strategies for resistance management is a main concern for vector control programs. Three enzymatic superfamilies are thought to mediate xenobiotic detoxification and resistance: Glutathione Transferases (GSTs), Cytochromes P450 (CYPs) and Carboxyl/Cholinesterases (CCEs). Improving our knowledge of key triatomine detoxification enzymes will strengthen our understanding of insecticide resistance processes in vectors of Chagas’ disease. Methods and findings The discovery and description of detoxification gene superfamilies in normalized transcriptomes of three triatomine species: Triatoma dimidiata, Triatoma infestans and Triatoma pallidipennis is presented. Furthermore, a comparative analysis of these superfamilies among the triatomine transcriptomes and the genome of Rhodnius prolixus, also a triatomine vector of Chagas’ disease, and other well-studied insect genomes was performed. The expression pattern of detoxification genes in R. prolixus transcriptomes from key organs was analyzed. The comparisons reveal gene expansions in Sigma class GSTs, CYP3 in CYP superfamily and clade E in CCE superfamily. Moreover, several CYP families identified in these triatomines have not yet been described in other insects. Conversely, several groups of insecticide resistance related enzymes within each enzyme superfamily are reduced or lacking in triatomines. Furthermore, our qRT-PCR results showed an increase in the expression of a CYP4 gene in a T. infestans population resistant to pyrethroids. These results could point to an involvement of metabolic detoxification mechanisms on the high levels of pyrethroid resistance detected in triatomines from the Gran Chaco ecoregion. Conclusions and significance Our results help to elucidate the potential insecticide resistance mechanisms in vectors of Chagas’ disease and provide new relevant information for this field. This study shows that metabolic resistance might be a contributing cause of the high pyrethroid resistance observed in wild T. infestans populations from the Gran Chaco ecoregion, area in which although subjected to intense pyrethroid treatments, vector control has failed. This study opens new avenues for further functional studies on triatomine detoxification mechanisms. PMID:28199333

A Field Study in Benin to Investigate the Role of Mosquitoes and Other Flying Insects in the Ecology of Mycobacterium ulcerans

PubMed Central

Zogo, Barnabas; Djenontin, Armel; Carolan, Kevin; Babonneau, Jeremy; Guegan, Jean-François; Eyangoh, Sara; Marion, Estelle

2015-01-01

Background Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. There is at present no clear understanding of the exact mode(s) of transmission of M. ulcerans. Populations affected by Buruli ulcer are those living close to humid and swampy zones. The disease is associated with the creation or the extension of swampy areas, such as construction of dams or lakes for the development of agriculture. Currently, it is supposed that insects (water bugs and mosquitoes) are host and vector of M. ulcerans. The role of water bugs was clearly demonstrated by several experimental and environmental studies. However, no definitive conclusion can yet be drawn concerning the precise importance of this route of transmission. Concerning the mosquitoes, DNA was detected only in mosquitoes collected in Australia, and their role as host/vector was never studied by experimental approaches. Surprisingly, no specific study was conducted in Africa. In this context, the objective of this study was to investigate the role of mosquitoes (larvae and adults) and other flying insects in ecology of M. ulcerans. This study was conducted in a highly endemic area of Benin. Methodology/Principal Findings Mosquitoes (adults and larvae) were collected over one year, in Buruli ulcer endemic in Benin. In parallel, to monitor the presence of M. ulcerans in environment, aquatic insects were sampled. QPCR was used to detected M. ulcerans DNA. DNA of M. ulcerans was detected in around 8.7% of aquatic insects but never in mosquitoes (larvae or adults) or in other flying insects. Conclusion/Significance This study suggested that the mosquitoes don't play a pivotal role in the ecology and transmission of M. ulcerans in the studied endemic areas. However, the role of mosquitoes cannot be excluded and, we can reasonably suppose that several routes of transmission of M. ulcerans are possible through the world. PMID:26196901

A Field Study in Benin to Investigate the Role of Mosquitoes and Other Flying Insects in the Ecology of Mycobacterium ulcerans.

PubMed

Zogo, Barnabas; Djenontin, Armel; Carolan, Kevin; Babonneau, Jeremy; Guegan, Jean-François; Eyangoh, Sara; Marion, Estelle

2015-01-01

Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. There is at present no clear understanding of the exact mode(s) of transmission of M. ulcerans. Populations affected by Buruli ulcer are those living close to humid and swampy zones. The disease is associated with the creation or the extension of swampy areas, such as construction of dams or lakes for the development of agriculture. Currently, it is supposed that insects (water bugs and mosquitoes) are host and vector of M. ulcerans. The role of water bugs was clearly demonstrated by several experimental and environmental studies. However, no definitive conclusion can yet be drawn concerning the precise importance of this route of transmission. Concerning the mosquitoes, DNA was detected only in mosquitoes collected in Australia, and their role as host/vector was never studied by experimental approaches. Surprisingly, no specific study was conducted in Africa. In this context, the objective of this study was to investigate the role of mosquitoes (larvae and adults) and other flying insects in ecology of M. ulcerans. This study was conducted in a highly endemic area of Benin. Mosquitoes (adults and larvae) were collected over one year, in Buruli ulcer endemic in Benin. In parallel, to monitor the presence of M. ulcerans in environment, aquatic insects were sampled. QPCR was used to detected M. ulcerans DNA. DNA of M. ulcerans was detected in around 8.7% of aquatic insects but never in mosquitoes (larvae or adults) or in other flying insects. This study suggested that the mosquitoes don't play a pivotal role in the ecology and transmission of M. ulcerans in the studied endemic areas. However, the role of mosquitoes cannot be excluded and, we can reasonably suppose that several routes of transmission of M. ulcerans are possible through the world.

Comparative field trial of alternative vector control strategies for non-domiciliated Triatoma dimidiata.

PubMed

Ferral, Jhibran; Chavez-Nuñez, Leysi; Euan-Garcia, Maria; Ramirez-Sierra, Maria Jesus; Najera-Vazquez, M Rosario; Dumonteil, Eric

2010-01-01

Chagas disease is a major vector-borne disease, and regional initiatives based on insecticide spraying have successfully controlled domiciliated vectors in many regions. Non-domiciliated vectors remain responsible for a significant transmission risk, and their control is a challenge. We performed a proof-of-concept field trial to test alternative strategies in rural Yucatan, Mexico. Follow-up of house infestation for two seasons following the interventions confirmed that insecticide spraying should be performed annually for the effective control of Triatoma dimidiata; however, it also confirmed that insect screens or long-lasting impregnated curtains may represent good alternative strategies for the sustained control of these vectors. Ecosystemic peridomicile management would be an excellent complementary strategy to improve the cost-effectiveness of interventions. Because these strategies would also be effective against other vector-borne diseases, such as malaria or dengue, they could be integrated within a multi-disease control program.

Morphometric evidence for a possible role of Rhodnius prolixus from palm trees in house re-infestation in the State of Barinas (Venezuela).

PubMed

Feliciangeli, M Dora; Sanchez-Martin, Maria; Marrero, Rosalba; Davies, Clive; Dujardin, Jean-Pierre

2007-02-01

The main vector of Chagas disease in Venezuela is Rhodnius prolixus. Specimens of Rhodnius sp., identified elsewhere as R. prolixus by molecular tools, were collected in Barinas State (Venezuela) before insecticide application, and compared by morphometric techniques with post-spraying, re-infesting insects after control. Geometric morphometry was applied, allowing separate analyses of shape and size. The idea of a single species sharing silvatic and domestic/peri-domestic ecotopes was supported, suggesting new evolutionary scenarios for the controversial R. prolixus origins. The same data allowed to understand the possible mechanisms of villages re-infestation after a control campaign, either recolonization by local recovery of survivors or re-infestation by external migrants. Both mechanisms were apparent. Although shape properties could distinguish very close subpopulations such as insects from houses and insects from peri-domestic shelters, they were unable to identify the insects from palm trees as a distinct subpopulation. This strongly suggested that human environment could receive immigrants from palm trees. The pattern of size variation supported the hypothesis of a one-way exchange from silvatic to human environments, but did not support the reverse movement. Thus, morphometric data indicated that a silvatic population of the local vector is probably responsible for re-infesting villages after insecticide application, and they also pointed to the existence of re-infestation by local recovery of survivors. According to this interpretation, new epidemiological scenarios must be considered to improve Chagas disease control in Venezuela.

Nanoformulation of poly(ethylene glycol) polymerized organic insect repellent by PIT emulsification method and its application for Japanese encephalitis vector control.

PubMed

Balaji, A P B; Mishra, Prabhakar; Suresh Kumar, R S; Mukherjee, Amitava; Chandrasekaran, Natarajan

2015-04-01

The utilization of increased dosage of insect repellents to overcome mosquito resistance has raised environmental concerns globally. In accord to this, we have formulated an efficacious, water-dispersive, nanometric formulation of a poor water-soluble insect repellent, diethylphenylacetamide (DEPA) by poly(ethylene glycol) (PEG) polymerization followed by PIT emulsification method. The critical micelle concentration of PEG in the spontaneously emulsified conventional DEPA droplets was determined, based on the droplets physical stability. Subjecting them to PIT emulsification yielded monodispersed polymeric nanomicelles of DEPA (Nano DEPA) with hydrodynamic mean diameter of 153.74 nm. The high-resolution scanning and transmission electron microscopic studies revealed the characteristic core-shell structure of micelle. The comparative efficacy of Bulk DEPA and Nano DEPA was evaluated by larvicidal and WHO cone bioassay against the Japanese encephalitis vector Culex tritaeniorhynchus. The median lethal concentrations (48 h) for 3rd instars C. tritaeniorhynchus larvae were found to be 0.416 mg/L for Bulk DEPA and 0.052 mg/L for Nano DEPA, respectively. The median knockdown concentrations (60 min) for the two to three-day-old, sucrose-fed, female adult mosquitoes were 5.372% (v/v) and 3.471% (v/v) for Bulk and Nano DEPA, respectively. Further investigation by histopathological and biochemical studies propound that Nano DEPA exerted better bioefficacy as comparative to its bulk form even at minimal exposure concentrations. Hence, Nano DEPA will serve as an effective alternate in controlling the vector expansion with reduced dosage. Copyright © 2015 Elsevier B.V. All rights reserved.

A cell–cell signaling sensor is required for virulence and insect transmission of Xylella fastidiosa

PubMed Central

Chatterjee, Subhadeep; Wistrom, Christina; Lindow, Steven E.

2008-01-01

Cell–cell signaling in Xylella fastidiosa, a xylem-colonizing plant pathogenic bacterium, mediated by a fatty acid Diffusible Signaling Factor (DSF), is required to colonize insect vectors and to suppress virulence to grape. Here, we show that a hybrid two-component regulatory protein RpfC is involved in negative regulation of DSF synthesis by RpfF in X. fastidiosa. X. fastidiosa rpfC mutants hyperexpress rpfF and overproduce DSF and are deficient in virulence and movement in the xylem vessels of grape. The expression of the genes encoding the adhesins FimA, HxfA, and HxfB is much higher in rpfC mutants, which also exhibit a hyperattachment phenotype in culture that is associated with their inability to migrate in xylem vessels and cause disease. rpfF mutants deficient in DSF production have the opposite phenotypes for all of these traits. RpfC is also involved in the regulation of other signaling components including rpfG, rpfB, a GGDEF domain protein that may be involved in intracellular signaling by modulating the levels of cyclic-di-GMP, and the virulence factors tolC and pglA required for disease. rpfC mutants are able to colonize the mouthparts of insect vectors and wild-type strains but are not transmitted as efficiently to new host plants, apparently because of their high levels of adhesiveness. Because of the conflicting contributions of adhesiveness and other traits to movement within plants and vectoring to new host plants, X. fastidiosa apparently coordinates these traits in a population-size-dependent fashion involving accumulation of DSF. PMID:18268318

A cell-cell signaling sensor is required for virulence and insect transmission of Xylella fastidiosa.

PubMed

Chatterjee, Subhadeep; Wistrom, Christina; Lindow, Steven E

2008-02-19

Cell-cell signaling in Xylella fastidiosa, a xylem-colonizing plant pathogenic bacterium, mediated by a fatty acid Diffusible Signaling Factor (DSF), is required to colonize insect vectors and to suppress virulence to grape. Here, we show that a hybrid two-component regulatory protein RpfC is involved in negative regulation of DSF synthesis by RpfF in X. fastidiosa. X. fastidiosa rpfC mutants hyperexpress rpfF and overproduce DSF and are deficient in virulence and movement in the xylem vessels of grape. The expression of the genes encoding the adhesins FimA, HxfA, and HxfB is much higher in rpfC mutants, which also exhibit a hyperattachment phenotype in culture that is associated with their inability to migrate in xylem vessels and cause disease. rpfF mutants deficient in DSF production have the opposite phenotypes for all of these traits. RpfC is also involved in the regulation of other signaling components including rpfG, rpfB, a GGDEF domain protein that may be involved in intracellular signaling by modulating the levels of cyclic-di-GMP, and the virulence factors tolC and pglA required for disease. rpfC mutants are able to colonize the mouthparts of insect vectors and wild-type strains but are not transmitted as efficiently to new host plants, apparently because of their high levels of adhesiveness. Because of the conflicting contributions of adhesiveness and other traits to movement within plants and vectoring to new host plants, X. fastidiosa apparently coordinates these traits in a population-size-dependent fashion involving accumulation of DSF.

The autophagy pathway participates in resistance to tomato yellow leaf curl virus infection in whiteflies.

PubMed

Wang, Lan-Lan; Wang, Xin-Ru; Wei, Xue-Mei; Huang, Huang; Wu, Jian-Xiang; Chen, Xue-Xin; Liu, Shu-Sheng; Wang, Xiao-Wei

2016-09-01

Macroautophagy/autophagy plays an important role against pathogen infection in mammals and plants. However, little has been known about the role of autophagy in the interactions of insect vectors with the plant viruses, which they transmit. Begomoviruses are a group of single-stranded DNA viruses and are exclusively transmitted by the whitefly Bemisia tabaci in a circulative manner. In this study, we found that the infection of a begomovirus, tomato yellow leaf curl virus (TYLCV) could activate the autophagy pathway in the Middle East Asia Minor 1 (MEAM1) species of the B. tabaci complex as evidenced by the formation of autophagosomes and ATG8-II. Interestingly, the activation of autophagy led to the subsequent degradation of TYLCV coat protein (CP) and genomic DNA. While feeding the whitefly with 2 autophagy inhibitors (3-methyladenine and bafilomycin A1) and silencing the expression of Atg3 and Atg9 increased the viral load; autophagy activation via feeding of rapamycin notably decreased the amount of viral CP and DNA in the whitefly. Furthermore, we found that activation of whitefly autophagy could inhibit the efficiency of virus transmission; whereas inhibiting autophagy facilitated virus transmission. Taken together, these results indicate that TYLCV infection can activate the whitefly autophagy pathway, which leads to the subsequent degradation of virus. Furthermore, our report proves that an insect vector uses autophagy as an intrinsic antiviral program to repress the infection of a circulative-transmitted plant virus. Our data also demonstrate that TYLCV may replicate and trigger complex interactions with the insect vector.

Improving mycoinsecticides for insect biological control.

PubMed

Ortiz-Urquiza, Almudena; Luo, Zhibing; Keyhani, Nemat O

2015-02-01

The desire for decreased reliance on chemical pesticides continues to fuel interest in alternative means for pest control including the use of naturally occurring microbial insect pathogens. Insects, as vectors of disease causing agents or as agricultural pests, are responsible for millions of deaths and significant economic losses worldwide, placing stresses on productivity (GDP) and human health and welfare. In addition, alterations in climate change are likely to affect insect ranges, expanding their access to previously constrained geographic areas, a potentially worrisome outcome. Metarhizium anisopliae and Beauveria bassiana, two cosmopolitan fungal pathogens of insects found in almost all ecosystems, are the most commonly applied mycoinsecticides for a variety of insect control purposes. The availability of the complete genomes for both organisms coupled to robust technologies for their transformation has led to several advances in engineering these fungi for greater efficacy and/or utility in pest control applications. Here, we will provide an overview of the fungal-insect and fungal-plant interactions that occur and highlight recent advances in the genetic engineering of these fungi. The latter work has resulted in the development of strains displaying (1) increased resistance to abiotic stress, (2) increased cuticular targeting and degradation, (3) increased virulence via expression of insecticidal protein/peptide toxins, (4) the ability to block transmission of disease causing agents, and (5) the ability to target specific insect hosts, decrease host fecundity, and/or alter insect behaviors.

Development and Evaluation of a Pyriproxyfen-treated Device to Control the Dengue Vector, Aedes aegypti (L.) (Diptera: Culicidae)

DTIC Science & Technology

2013-03-01

Jersey: John Wiley & Sons, 2011. Fradin MS, Day JF. Comparative efficacy of insect repellents against mosquito bites. N Engl J Med 2002; 347: 13-8...control of Aedes aegypti mosquitoes , the vectors of these diseases, critically important. We developed and evaluated an Ae. aegypti control device...that is visually-attractive to mosquitoes . This pyriproxyfen-treated device was evaluated for its impact on Ae. aegypti egg production and population

Tracking contaminant flux from aquatic to terrestrial food webs

EPA Science Inventory

Aquatic insects provide a critical energy subsidy to riparian food webs, yet their role as vectors of contaminants to terrestrial ecosystems is poorly understood. We investigated aquatic resource utilization and contaminant exposure among riparian invertivores (spiders and herpt...

A tool for developing an automatic insect identification system based on wing outlines

PubMed Central

Yang, He-Ping; Ma, Chun-Sen; Wen, Hui; Zhan, Qing-Bin; Wang, Xin-Li

2015-01-01

For some insect groups, wing outline is an important character for species identification. We have constructed a program as the integral part of an automated system to identify insects based on wing outlines (DAIIS). This program includes two main functions: (1) outline digitization and Elliptic Fourier transformation and (2) classifier model training by pattern recognition of support vector machines and model validation. To demonstrate the utility of this program, a sample of 120 owlflies (Neuroptera: Ascalaphidae) was split into training and validation sets. After training, the sample was sorted into seven species using this tool. In five repeated experiments, the mean accuracy for identification of each species ranged from 90% to 98%. The accuracy increased to 99% when the samples were first divided into two groups based on features of their compound eyes. DAIIS can therefore be a useful tool for developing a system of automated insect identification. PMID:26251292

Flying Insect Detection and Classification with Inexpensive Sensors

PubMed Central

Chen, Yanping; Why, Adena; Batista, Gustavo; Mafra-Neto, Agenor; Keogh, Eamonn

2014-01-01

An inexpensive, noninvasive system that could accurately classify flying insects would have important implications for entomological research, and allow for the development of many useful applications in vector and pest control for both medical and agricultural entomology. Given this, the last sixty years have seen many research efforts devoted to this task. To date, however, none of this research has had a lasting impact. In this work, we show that pseudo-acoustic optical sensors can produce superior data; that additional features, both intrinsic and extrinsic to the insect’s flight behavior, can be exploited to improve insect classification; that a Bayesian classification approach allows to efficiently learn classification models that are very robust to over-fitting, and a general classification framework allows to easily incorporate arbitrary number of features. We demonstrate the findings with large-scale experiments that dwarf all previous works combined, as measured by the number of insects and the number of species considered. PMID:25350921

Identification of Wolbachia Strains in Mosquito Disease Vectors

PubMed Central

Osei-Poku, Jewelna; Han, Calvin; Mbogo, Charles M.; Jiggins, Francis M.

2012-01-01

Wolbachia bacteria are common endosymbionts of insects, and some strains are known to protect their hosts against RNA viruses and other parasites. This has led to the suggestion that releasing Wolbachia-infected mosquitoes could prevent the transmission of arboviruses and other human parasites. We have identified Wolbachia in Kenyan populations of the yellow fever vector Aedes bromeliae and its relative Aedes metallicus, and in Mansonia uniformis and Mansonia africana, which are vectors of lymphatic filariasis. These Wolbachia strains cluster together on the bacterial phylogeny, and belong to bacterial clades that have recombined with other unrelated strains. These new Wolbachia strains may be affecting disease transmission rates of infected mosquito species, and could be transferred into other mosquito vectors as part of control programs. PMID:23185484

Triatoma maculata, the Vector of Trypanosoma cruzi, in Venezuela. Phenotypic and Genotypic Variability as Potential Indicator of Vector Displacement into the Domestic Habitat

PubMed Central

García-Alzate, Roberto; Lozano-Arias, Daisy; Reyes-Lugo, Rafael Matías; Morocoima, Antonio; Herrera, Leidi; Mendoza-León, Alexis

2014-01-01

Triatoma maculata is a wild vector of Trypanosoma cruzi, the causative agent of Chagas disease; its incursion in the domestic habitat is scant. In order to establish the possible domestic habitat of T. maculata, we evaluated wing variability and polymorphism of genotypic markers in subpopulations of T. maculata that live in different habitats in Venezuela. As markers, we used the mtCyt b gene, previously apply to evaluate population genetic structure in triatomine species, and the β-tubulin gene region, a marker employed to study genetic variability in Leishmania subgenera. Adults of T. maculata were captured in the period 2012–2013 at domestic, peridomestic (PD), and wild areas of towns in the Venezuelan states of Anzoátegui, Bolívar, Portuguesa, Monagas, Nueva Esparta, and Sucre. The phenotypic analysis was conducted through the determination of the isometric size and conformation of the left wing of each insect (492 individuals), using the MorphoJ program. Results reveal that insects of the domestic habitat showed significant reductions in wing size and variations in anatomical characteristics associated with flying, in relation to the PD and wild habitats. The largest variability was found in Anzoátegui and Monagas. The genotypic variability was assessed by in silico sequence comparison of the molecular markers and PCR-RFLP assays, demonstrating a marked polymorphism for the markers in insects of the domestic habitat in comparison with the other habitats. The highest polymorphism was found for the β-tubulin marker with enzymes BamHI and KpnI. Additionally, the infection rate by T. cruzi was higher in Monagas and Sucre (26.8 and 37.0%, respectively), while in domestic habitats the infestation rate was highest in Anzoátegui (22.3%). Results suggest domestic habitat colonization by T. maculata that in epidemiological terms, coupled with the presence in this habitat of nymphs of the vector, represents a high risk of transmission of Chagas disease. PMID:25325053

Induced Release of a Plant-Defense Volatile ‘Deceptively’ Attracts Insect Vectors to Plants Infected with a Bacterial Pathogen

PubMed Central

Mann, Rajinder S.; Ali, Jared G.; Hermann, Sara L.; Tiwari, Siddharth; Pelz-Stelinski, Kirsten S.; Alborn, Hans T.; Stelinski, Lukasz L.

2012-01-01

Transmission of plant pathogens by insect vectors is a complex biological process involving interactions between the plant, insect, and pathogen. Pathogen-induced plant responses can include changes in volatile and nonvolatile secondary metabolites as well as major plant nutrients. Experiments were conducted to understand how a plant pathogenic bacterium, Candidatus Liberibacter asiaticus (Las), affects host preference behavior of its psyllid (Diaphorina citri Kuwayama) vector. D. citri were attracted to volatiles from pathogen-infected plants more than to those from non-infected counterparts. Las-infected plants were more attractive to D. citri adults than non-infected plants initially; however after feeding, psyllids subsequently dispersed to non-infected rather than infected plants as their preferred settling point. Experiments with Las-infected and non-infected plants under complete darkness yielded similar results to those recorded under light. The behavior of psyllids in response to infected versus non-infected plants was not influenced by whether or not they were carriers of the pathogen. Quantification of volatile release from non-infected and infected plants supported the hypothesis that odorants mediate psyllid preference. Significantly more methyl salicylate, yet less methyl anthranilate and D-limonene, was released by infected than non-infected plants. Methyl salicylate was attractive to psyllids, while methyl anthranilate did not affect their behavior. Feeding on citrus by D. citri adults also induced release of methyl salicylate, suggesting that it may be a cue revealing location of conspecifics on host plants. Infected plants were characterized by lower levels of nitrogen, phosphorus, sulfur, zinc, and iron, as well as, higher levels of potassium and boron than non-infected plants. Collectively, our results suggest that host selection behavior of D. citri may be modified by bacterial infection of plants, which alters release of specific headspace volatiles and plant nutritional contents. Furthermore, we show in a laboratory setting that this apparent pathogen-mediated manipulation of vector behavior may facilitate pathogen spread. PMID:22457628

Conceptual framework and rationale

PubMed Central

Robinson, Alan S; Knols, Bart GJ; Voigt, Gabriella; Hendrichs, Jorge

2009-01-01

The sterile insect technique (SIT) has been shown to be an effective and sustainable genetic approach to control populations of selected major pest insects, when part of area-wide integrated pest management (AW-IPM) programmes. The technique introduces genetic sterility in females of the target population in the field following their mating with released sterile males. This process results in population reduction or elimination via embryo lethality caused by dominant lethal mutations induced in sperm of the released males. In the past, several field trials have been carried out for mosquitoes with varying degrees of success. New technology and experience gained with other species of insect pests has encouraged a reassessment of the use of the sterility principle as part of integrated control of malaria vectors. Significant technical and logistic hurdles will need to be overcome to develop the technology and make it effective to suppress selected vector populations, and its application will probably be limited to specific ecological situations. Using sterile males to control mosquito vector populations can only be effective as part of an AW-IPM programme. The area-wide concept entails the targeting of the total mosquito population within a defined area. It requires, therefore, a thorough understanding of the target pest population biology especially as regards mating behaviour, population dynamics, dispersal and level of reproductive isolation. The key challenges for success are: 1) devising methods to monitor vector populations and measuring competitiveness of sterile males in the field, 2) designing mass rearing, sterilization and release strategies that maintain competitiveness of the sterile male mosquitoes, 3) developing methods to separate sexes in order to release only male mosquitoes and 4) adapting suppression measures and release rates to take into account the high reproductive rate of mosquitoes. Finally, success in area-wide implementation in the field can only be achieved if close attention is paid to political, socio-economic and environmental sensitivities and an efficient management organization is established taking into account the interests of all potential stakeholders of an AW-IPM programme. PMID:19917070

Induced release of a plant-defense volatile 'deceptively' attracts insect vectors to plants infected with a bacterial pathogen.

PubMed

Mann, Rajinder S; Ali, Jared G; Hermann, Sara L; Tiwari, Siddharth; Pelz-Stelinski, Kirsten S; Alborn, Hans T; Stelinski, Lukasz L

2012-01-01

Transmission of plant pathogens by insect vectors is a complex biological process involving interactions between the plant, insect, and pathogen. Pathogen-induced plant responses can include changes in volatile and nonvolatile secondary metabolites as well as major plant nutrients. Experiments were conducted to understand how a plant pathogenic bacterium, Candidatus Liberibacter asiaticus (Las), affects host preference behavior of its psyllid (Diaphorina citri Kuwayama) vector. D. citri were attracted to volatiles from pathogen-infected plants more than to those from non-infected counterparts. Las-infected plants were more attractive to D. citri adults than non-infected plants initially; however after feeding, psyllids subsequently dispersed to non-infected rather than infected plants as their preferred settling point. Experiments with Las-infected and non-infected plants under complete darkness yielded similar results to those recorded under light. The behavior of psyllids in response to infected versus non-infected plants was not influenced by whether or not they were carriers of the pathogen. Quantification of volatile release from non-infected and infected plants supported the hypothesis that odorants mediate psyllid preference. Significantly more methyl salicylate, yet less methyl anthranilate and D-limonene, was released by infected than non-infected plants. Methyl salicylate was attractive to psyllids, while methyl anthranilate did not affect their behavior. Feeding on citrus by D. citri adults also induced release of methyl salicylate, suggesting that it may be a cue revealing location of conspecifics on host plants. Infected plants were characterized by lower levels of nitrogen, phosphorus, sulfur, zinc, and iron, as well as, higher levels of potassium and boron than non-infected plants. Collectively, our results suggest that host selection behavior of D. citri may be modified by bacterial infection of plants, which alters release of specific headspace volatiles and plant nutritional contents. Furthermore, we show in a laboratory setting that this apparent pathogen-mediated manipulation of vector behavior may facilitate pathogen spread.

Leishmania, microbiota and sand fly immunity.

PubMed

Telleria, Erich Loza; Martins-da-Silva, Andrea; Tempone, Antonio Jorge; Traub-Csekö, Yara Maria

2018-06-20

In this review, we explore the state-of-the-art of sand fly relationships with microbiota, viruses and Leishmania, with particular emphasis on the vector immune responses. Insect-borne diseases are a major public health problem in the world. Phlebotomine sand flies are proven vectors of several aetiological agents including viruses, bacteria and the trypanosomatid Leishmania, which are responsible for diseases such as viral encephalitis, bartonellosis and leishmaniasis, respectively. All metazoans in nature coexist intimately with a community of commensal microorganisms known as microbiota. The microbiota has a fundamental role in the induction, maturation and function of the host immune system, which can modulate host protection from pathogens and infectious diseases. We briefly review viruses of public health importance present in sand flies and revisit studies done on bacterial and fungal gut contents of these vectors. We bring this information into the context of sand fly development and immune responses. We highlight the immunity mechanisms that the insect utilizes to survive the potential threats involved in these interactions and discuss the recently discovered complex interactions among microbiota, sand fly, Leishmania and virus. Additionally, some of the alternative control strategies that could benefit from the current knowledge are considered.

Dembo polymerase chain reaction technique for detection of bovine abortion, diarrhea, and respiratory disease complex infectious agents in potential vectors and reservoirs.

PubMed

Rahpaya, Sayed Samim; Tsuchiaka, Shinobu; Kishimoto, Mai; Oba, Mami; Katayama, Yukie; Nunomura, Yuka; Kokawa, Saki; Kimura, Takashi; Kobayashi, Atsushi; Kirino, Yumi; Okabayashi, Tamaki; Nonaka, Nariaki; Mekata, Hirohisa; Aoki, Hiroshi; Shiokawa, Mai; Umetsu, Moeko; Morita, Tatsushi; Hasebe, Ayako; Otsu, Keiko; Asai, Tetsuo; Yamaguchi, Tomohiro; Makino, Shinji; Murata, Yoshiteru; Abi, Ahmad Jan; Omatsu, Tsutomu; Mizutani, Tetsuya

2018-05-31

Bovine abortion, diarrhea, and respiratory disease complexes, caused by infectious agents, result in high and significant economic losses for the cattle industry. These pathogens are likely transmitted by various vectors and reservoirs including insects, birds, and rodents. However, experimental data supporting this possibility are scarce. We collected 117 samples and screened them for 44 bovine abortive, diarrheal, and respiratory disease complex pathogens by using Dembo polymerase chain reaction (PCR), which is based on TaqMan real-time PCR. Fifty-seven samples were positive for at least one pathogen, including bovine viral diarrhea virus, bovine enterovirus, Salmonella enterica ser. Dublin, Salmonella enterica ser. Typhimurium, and Neospora caninum ; some samples were positive for multiple pathogens. Bovine viral diarrhea virus and bovine enterovirus were the most frequently detected pathogens, especially in flies, suggesting an important role of flies in the transmission of these viruses. Additionally, we detected the N. caninum genome from a cockroach sample for the first time. Our data suggest that insects (particularly flies), birds, and rodents are potential vectors and reservoirs of abortion, diarrhea, and respiratory infectious agents, and that they may transmit more than one pathogen at the same time.

Viruses vector control proposal: genus Aedes emphasis.

PubMed

Reis, Nelson Nogueira; Silva, Alcino Lázaro da; Reis, Elma Pereira Guedes; Silva, Flávia Chaves E; Reis, Igor Guedes Nogueira

The dengue fever is a major public health problem in the world. In Brazil, in 2015, there were 1,534,932 cases, being 20,320 cases of severe form, and 811 deaths related to this disease. The distribution of Aedes aegypti, the vector, is extensive. Recently, Zika and Chikungunya viruses had arisen, sharing the same vector as dengue and became a huge public health issue. Without specific treatment, it is urgently required as an effective vector control. This article is focused on reviewing vector control strategies, their effectiveness, viability and economical impact. Among all, the Sterile Insect Technique is highlighted as the best option to be adopted in Brazil, once it is largely effectively used in the USA and Mexico for plagues related to agribusiness. Copyright © 2017 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.

Parasite-mediated interactions within the insect vector: Trypanosoma rangeli strategies.

PubMed

Garcia, Eloi S; Castro, Daniele P; Figueiredo, Marcela B; Azambuja, Patrícia

2012-05-30

Trypanosoma rangeli is a protozoan that is non-pathogenic for humans and other mammals but causes pathology in the genus Rhodnius. T. rangeli and R. prolixus is an excellent model for studying the parasite-vector interaction, but its cycle in invertebrates remains unclear. The vector becomes infected on ingesting blood containing parasites, which subsequently develop in the gut, hemolymph and salivary glands producing short and large epimastigotes and metacyclic trypomastigotes, which are the infective forms. The importance of the T. rangeli cycle is the flagellate penetration into the gut cells and invasion of the salivary glands. The establishment of the parasite depends on the alteration of some vector defense mechanisms. Herein, we present our understanding of T. rangeli infection on the vector physiology, including gut and salivary gland invasions, hemolymph reactions and behavior alteration.

Malaria vector control: from past to future.

PubMed

Raghavendra, Kamaraju; Barik, Tapan K; Reddy, B P Niranjan; Sharma, Poonam; Dash, Aditya P

2011-04-01

Malaria is one of the most common vector-borne diseases widespread in the tropical and subtropical regions. Despite considerable success of malaria control programs in the past, malaria still continues as a major public health problem in several countries. Vector control is an essential part for reducing malaria transmission and became less effective in recent years, due to many technical and administrative reasons, including poor or no adoption of alternative tools. Of the different strategies available for vector control, the most successful are indoor residual spraying and insecticide-treated nets (ITNs), including long-lasting ITNs and materials. Earlier DDT spray has shown spectacular success in decimating disease vectors but resulted in development of insecticide resistance, and to control the resistant mosquitoes, organophosphates, carbamates, and synthetic pyrethroids were introduced in indoor residual spraying with needed success but subsequently resulted in the development of widespread multiple insecticide resistance in vectors. Vector control in many countries still use insecticides in the absence of viable alternatives. Few developments for vector control, using ovitraps, space spray, biological control agents, etc., were encouraging when used in limited scale. Likewise, recent introduction of safer vector control agents, such as insect growth regulators, biocontrol agents, and natural plant products have yet to gain the needed scale of utility for vector control. Bacterial pesticides are promising and are effective in many countries. Environmental management has shown sufficient promise for vector control and disease management but still needs advocacy for inter-sectoral coordination and sometimes are very work-intensive. The more recent genetic manipulation and sterile insect techniques are under development and consideration for use in routine vector control and for these, standardized procedures and methods are available but need thorough understanding of biology, ethical considerations, and sufficiently trained manpower for implementation being technically intensive methods. All the methods mentioned in the review that are being implemented or proposed for implementation needs effective inter-sectoral coordination and community participation. The latest strategy is evolution-proof insecticides that include fungal biopesticides, Wolbachia, and Denso virus that essentially manipulate the life cycle of the mosquitoes were found effective but needs more research. However, for effective vector control, integrated vector management methods, involving use of combination of effective tools, is needed and is also suggested by Global Malaria Control Strategy. This review article raises issues associated with the present-day vector control strategies and state opportunities with a focus on ongoing research and recent advances to enable to sustain the gains achieved so far.

Can antibodies against flies alter malaria transmission in birds by changing vector behavior?

PubMed

Ghosh, Suma; Waite, Jessica L; Clayton, Dale H; Adler, Frederick R

2014-10-07

Transmission of insect-borne diseases is shaped by the interactions among parasites, vectors, and hosts. Any factor that alters movement of infected vectors from infected to uninfeced hosts will in turn alter pathogen spread. In this paper, we study one such pathogen-vector-host system, avian malaria in pigeons transmitted by fly ectoparasites, where both two-way and three-way interactions play a key role in shaping disease spread. Bird immune defenses against flies can decrease malaria prevalence by reducing fly residence time on infected birds or increase disease prevalence by enhancing fly movement and thus infection transmission. We develop a mathematical model that illustrates how these changes in vector behavior influence pathogen transmission and show that malaria prevalence is maximized at an intermediate level of defense avoidance by the flies. Understanding how host immune defenses indirectly alter disease transmission by influencing vector behavior has implications for reducing the transmission of human malaria and other vectored pathogens. Published by Elsevier Ltd.

New Insights on the Inflammatory Role of Lutzomyia longipalpis Saliva in Leishmaniasis

PubMed Central

Prates, Deboraci Brito; Araújo-Santos, Théo; Brodskyn, Cláudia; Barral-Netto, Manoel; Barral, Aldina; Borges, Valéria Matos

2012-01-01

When an haematophagous sand fly vector insect bites a vertebrate host, it introduces its mouthparts into the skin and lacerates blood vessels, forming a hemorrhagic pool which constitutes an intricate environment of cell interactions. In this scenario, the initial performance of host, parasite, and vector “authors” will heavily influence the course of Leishmania infection. Recent advances in vector-parasite-host interaction have elucidated “co-authors” and “new roles” not yet described. We review here the stimulatory role of Lutzomyia longipalpis saliva leading to inflammation and try to connect them in an early context of Leishmania infection. PMID:22506098

Playback interference of glassy-winged sharp shooter communication

USDA-ARS?s Scientific Manuscript database

Animal communication is vital to reproduction, particularly for securing a mate. Insects commonly communicate by exchanging vibrational signals that are transmitted through host plants. The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is an important vector of Xylella fastidiosa, a pl...

Disrupting mating behavior of Diaphorina citri (Liviidae)

USDA-ARS?s Scientific Manuscript database

Severe economic damage from citrus greening disease, caused by ‘Candidatus Liberibacter asiaticus’ bacteria, has stimulated development of methods to reduce mating and reproduction in populations of its insect vector, Diaphorina citri (Hemiptera: Liviidae). Male D. citri find mating partners by walk...

Pollination by brood-site deception.

PubMed

Urru, Isabella; Stensmyr, Marcus C; Hansson, Bill S

2011-09-01

Pollination is often regarded as a mutualistic relationship between flowering plants and insects. In such a relationship, both partners gain a fitness benefit as a result of their interaction. The flower gets pollinated and the insect typically gets a food-related reward. However, flower-insect communication is not always a mutualistic system, as some flowers emit deceitful signals. Insects are thus fooled by irresistible stimuli and pollination is accomplished. Such deception requires very fine tuning, as insects in their typically short life span, try to find mating/feeding breeding sites as efficiently as possible, and following deceitful signals thus is both costly and time-consuming. Deceptive flowers have thus evolved the ability to emit signals that trigger obligate innate or learned responses in the targeted insects. The behavior, and thus the signals, exploited are typically involved in reproduction, from attracting pheromones to brood/food-site cues. Chemical mimicry is one of the main modalities through which flowers trick their pollen vectors, as olfaction plays a pivotal role in insect-insect and insect-plant interactions. Here we focus on floral odors that specifically mimic an oviposition substrate, i.e., brood-site mimicry. The phenomenon is wide spread across unrelated plant lineages of Angiosperm, Splachnaceae and Phallaceae. Targeted insects are mainly beetles and flies, and flowers accordingly often emit, to the human nose, highly powerful and fetid smells that are conversely extremely attractive to the duped insects. Brood-site deceptive plants often display highly elaborate flowers and have evolved a trap-release mechanism. Chemical cues often act in unison with other sensory cues to refine the imitation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Comparative ultrastructural characterization of African horse sickness virus-infected mammalian and insect cells reveals a novel potential virus release mechanism from insect cells.

PubMed

Venter, E; van der Merwe, C F; Buys, A V; Huismans, H; van Staden, V

2014-03-01

African horse sickness virus (AHSV) is an arbovirus capable of successfully replicating in both its mammalian host and insect vector. Where mammalian cells show a severe cytopathic effect (CPE) following AHSV infection, insect cells display no CPE. These differences in cell death could be linked to the method of viral release, i.e. lytic or non-lytic, that predominates in a specific cell type. Active release of AHSV, or any related orbivirus, has, however, not yet been documented from insect cells. We applied an integrated microscopy approach to compare the nanomechanical and morphological response of mammalian and insect cells to AHSV infection. Atomic force microscopy revealed plasma membrane destabilization, integrity loss and structural deformation of the entire surface of infected mammalian cells. Infected insect cells, in contrast, showed no morphological differences from mock-infected cells other than an increased incidence of circular cavities present on the cell surface. Transmission electron microscopy imaging identified a novel large vesicle-like compartment within infected insect cells, not present in mammalian cells, containing viral proteins and virus particles. Extracellular clusters of aggregated virus particles were visualized adjacent to infected insect cells with intact plasma membranes. We propose that foreign material is accumulated within these vesicles and that their subsequent fusion with the cell membrane releases entrapped viruses, thereby facilitating a non-lytic virus release mechanism different from the budding previously observed in mammalian cells. This insect cell-specific defence mechanism contributes to the lack of cell damage observed in AHSV-infected insect cells.

Combining stable insect cell lines with baculovirus-mediated expression for multi-HA influenza VLP production.

PubMed

Sequeira, Daniela P; Correia, Ricardo; Carrondo, Manuel J T; Roldão, António; Teixeira, Ana P; Alves, Paula M

2018-05-24

Safer and broadly protective vaccines are needed to cope with the continuous evolution of circulating influenza virus strains and promising approaches based on the expression of multiple hemagglutinins (HA) in a virus-like particle (VLP) have been proposed. However, expression of multiple genes in the same vector can lead to its instability due to tandem repetition of similar sequences. By combining stable with transient expression systems we can rationally distribute the number of genes to be expressed per platform and thus mitigate this risk. In this work, we developed a modular system comprising stable and baculovirus-mediated expression in insect cells for production of multi-HA influenza enveloped VLPs. First, a stable insect High Five cell population expressing two different HA proteins from subtype H3 was established. Infection of this cell population with a baculovirus vector encoding three other HA proteins from H3 subtype proved to be as competitive as traditional co-infection approaches in producing a pentavalent H3 VLP. Aiming at increasing HA expression, the stable insect cell population was infected at increasingly higher cell concentrations (CCI). However, cultures infected at CCI of 3×10 6 cells/mL showed lower HA titers per cell in comparison to standard CCI of 2×10 6 cells/mL, a phenomenon named "cell density effect". To lessen the negative impact of this phenomenon, a tailor-made refeed strategy was designed based on the exhaustion of key nutrients during cell growth. Noteworthy, cultures supplemented and infected at a CCI of 4×10 6 cells/mL showed comparable HA titers per cell to those of CCI of 2×10 6 cells/mL, thus leading to an increase of up to 4-fold in HA titers per mL. Scalability of the modular strategy herein proposed was successfully demonstrated in 2L stirred tank bioreactors with comparable HA protein levels observed between bioreactor and shake flasks cultures. Overall, this work demonstrates the suitability of combining stable with baculovirus-mediated expression in insect cells as an efficient platform for production of multi-HA influenza VLPs, surpassing the drawbacks of traditional co-infection strategies and/or the use of larger, unstable vectors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Epidemiological Implications of Host Biodiversity and Vector Biology: Key Insights from Simple Models.

PubMed

Dobson, Andrew D M; Auld, Stuart K J R

2016-04-01

Models used to investigate the relationship between biodiversity change and vector-borne disease risk often do not explicitly include the vector; they instead rely on a frequency-dependent transmission function to represent vector dynamics. However, differences between classes of vector (e.g., ticks and insects) can cause discrepancies in epidemiological responses to environmental change. Using a pair of disease models (mosquito- and tick-borne), we simulated substitutive and additive biodiversity change (where noncompetent hosts replaced or were added to competent hosts, respectively), while considering different relationships between vector and host densities. We found important differences between classes of vector, including an increased likelihood of amplified disease risk under additive biodiversity change in mosquito models, driven by higher vector biting rates. We also draw attention to more general phenomena, such as a negative relationship between initial infection prevalence in vectors and likelihood of dilution, and the potential for a rise in density of infected vectors to occur simultaneously with a decline in proportion of infected hosts. This has important implications; the density of infected vectors is the most valid metric for primarily zoonotic infections, while the proportion of infected hosts is more relevant for infections where humans are a primary host.

Joint torques in a freely walking insect reveal distinct functions of leg joints in propulsion and posture control

PubMed Central

2016-01-01

Determining the mechanical output of limb joints is critical for understanding the control of complex motor behaviours such as walking. In the case of insect walking, the neural infrastructure for single-joint control is well described. However, a detailed description of the motor output in form of time-varying joint torques is lacking. Here, we determine joint torques in the stick insect to identify leg joint function in the control of body height and propulsion. Torques were determined by measuring whole-body kinematics and ground reaction forces in freely walking animals. We demonstrate that despite strong differences in morphology and posture, stick insects show a functional division of joints similar to other insect model systems. Propulsion was generated by strong depression torques about the coxa–trochanter joint, not by retraction or flexion/extension torques. Torques about the respective thorax–coxa and femur–tibia joints were often directed opposite to fore–aft forces and joint movements. This suggests a posture-dependent mechanism that counteracts collapse of the leg under body load and directs the resultant force vector such that strong depression torques can control both body height and propulsion. Our findings parallel propulsive mechanisms described in other walking, jumping and flying insects, and challenge current control models of insect walking. PMID:26791608

Lipophorin Drives Lipid Incorporation and Metabolism in Insect Trypanosomatids.

PubMed

Ximenes, Aline dos Anjos; Silva-Cardoso, Lívia; De Cicco, Nuccia Nicole T; Pereira, Miria G; Lourenço, Daniela C; Fampa, Patricia; Folly, Evelize; Cunha-e-Silva, Narcisa L; Silva-Neto, Mario A C; Atella, Georgia C

2015-07-01

Insect trypanosomatids are inhabitants of the insect digestive tract. These parasites can be either monoxenous or dixenous. Plant trypanosomatids are known as insect trypanosomatids once they and are transmitted by phytophagous insects. Such parasites can be found in latex, phloem, fruits and seeds of many plant families. Infections caused by these pathogens are a major cause of serious economic losses. Studies by independent groups have demonstrated the metabolic flow of lipids from the vertebrate host to trypanosomatids. This mechanism is usually present when parasites possess an incomplete de novo lipid biosynthesis pathway. Here, we show that both insect trypanosomatids Phytomonas françai and Leptomonas wallacei incorporate (3)H-palmitic acid and inorganic phosphate. These molecules are used for lipid biosynthesis. Moreover, we have isolated the main hemolymphatic lipoprotein, Lipophorin (Lp) from Oncopeltus fasciatus, the natural insect vector of such parasites. Both parasites were able to incorporate Lp to be utilized both as a lipid and protein source for their metabolism. Also, we have observed the presence of Lp binding sites in the membrane of a parasite. In conclusion, we believe that the elucidation of trypanosomatid metabolic pathways will lead to a better understanding of parasite-host interactions and the identification of novel potential chemotherapy targets. Copyright © 2015 Elsevier GmbH. All rights reserved.

Genome scale transcriptomics of baculovirus-insect interactions.

PubMed

Nguyen, Quan; Nielsen, Lars K; Reid, Steven

2013-11-12

Baculovirus-insect cell technologies are applied in the production of complex proteins, veterinary and human vaccines, gene delivery vectors' and biopesticides. Better understanding of how baculoviruses and insect cells interact would facilitate baculovirus-based production. While complete genomic sequences are available for over 58 baculovirus species, little insect genomic information is known. The release of the Bombyx mori and Plutella xylostella genomes, the accumulation of EST sequences for several Lepidopteran species, and especially the availability of two genome-scale analysis tools, namely oligonucleotide microarrays and next generation sequencing (NGS), have facilitated expression studies to generate a rich picture of insect gene responses to baculovirus infections. This review presents current knowledge on the interaction dynamics of the baculovirus-insect system' which is relatively well studied in relation to nucleocapsid transportation, apoptosis, and heat shock responses, but is still poorly understood regarding responses involved in pro-survival pathways, DNA damage pathways, protein degradation, translation, signaling pathways, RNAi pathways, and importantly metabolic pathways for energy, nucleotide and amino acid production. We discuss how the two genome-scale transcriptomic tools can be applied for studying such pathways and suggest that proteomics and metabolomics can produce complementary findings to transcriptomic studies.

A CRISPR-Cas9 sex-ratio distortion system for genetic control

PubMed Central

Galizi, Roberto; Hammond, Andrew; Kyrou, Kyros; Taxiarchi, Chrysanthi; Bernardini, Federica; O’Loughlin, Samantha M.; Papathanos, Philippos-Aris; Nolan, Tony; Windbichler, Nikolai; Crisanti, Andrea

2016-01-01

Genetic control aims to reduce the ability of insect pest populations to cause harm via the release of modified insects. One strategy is to bias the reproductive sex ratio towards males so that a population decreases in size or is eliminated altogether due to a lack of females. We have shown previously that sex ratio distortion can be generated synthetically in the main human malaria vector Anopheles gambiae, by selectively destroying the X-chromosome during spermatogenesis, through the activity of a naturally-occurring endonuclease that targets a repetitive rDNA sequence highly-conserved in a wide range of organisms. Here we describe a CRISPR-Cas9 sex distortion system that targets ribosomal sequences restricted to the member species of the Anopheles gambiae complex. Expression of Cas9 during spermatogenesis resulted in RNA-guided shredding of the X-chromosome during male meiosis and produced extreme male bias among progeny in the absence of any significant reduction in fertility. The flexibility of CRISPR-Cas9 combined with the availability of genomic data for a range of insects renders this strategy broadly applicable for the species-specific control of any pest or vector species with an XY sex-determination system by targeting sequences exclusive to the female sex chromosome. PMID:27484623

Broad Surveys of DNA Viral Diversity Obtained through Viral Metagenomics of Mosquitoes

PubMed Central

Ng, Terry Fei Fan; Willner, Dana L.; Lim, Yan Wei; Schmieder, Robert; Chau, Betty; Nilsson, Christina; Anthony, Simon; Ruan, Yijun; Rohwer, Forest; Breitbart, Mya

2011-01-01

Viruses are the most abundant and diverse genetic entities on Earth; however, broad surveys of viral diversity are hindered by the lack of a universal assay for viruses and the inability to sample a sufficient number of individual hosts. This study utilized vector-enabled metagenomics (VEM) to provide a snapshot of the diversity of DNA viruses present in three mosquito samples from San Diego, California. The majority of the sequences were novel, suggesting that the viral community in mosquitoes, as well as the animal and plant hosts they feed on, is highly diverse and largely uncharacterized. Each mosquito sample contained a distinct viral community. The mosquito viromes contained sequences related to a broad range of animal, plant, insect and bacterial viruses. Animal viruses identified included anelloviruses, circoviruses, herpesviruses, poxviruses, and papillomaviruses, which mosquitoes may have obtained from vertebrate hosts during blood feeding. Notably, sequences related to human papillomaviruses were identified in one of the mosquito samples. Sequences similar to plant viruses were identified in all mosquito viromes, which were potentially acquired through feeding on plant nectar. Numerous bacteriophages and insect viruses were also detected, including a novel densovirus likely infecting Culex erythrothorax. Through sampling insect vectors, VEM enables broad survey of viral diversity and has significantly increased our knowledge of the DNA viruses present in mosquitoes. PMID:21674005

Silencing of ecdysone receptor, insect intestinal mucin and sericotropin genes by bacterially produced double-stranded RNA affects larval growth and development in Plutella xylostella and Helicoverpa armigera.

PubMed

Israni, B; Rajam, M V

2017-04-01

RNA interference mediated gene silencing, which is triggered by double-stranded RNA (dsRNA), has become a important tool for functional genomics studies in various systems, including insects. Bacterially produced dsRNA employs the use of a bacterial strain lacking in RNaseIII activity and harbouring a vector with dual T7 promoter sites, which allow the production of intact dsRNA molecules. Here, we report an assessment of the functional relevance of the ecdysone receptor, insect intestinal mucin and sericotropin genes through silencing by dsRNA in two lepidopteran insect pests, Helicoverpa armigera and Plutella xylostella, both of which cause serious crop losses. Oral feeding of dsRNA led to significant reduction in transcripts of the target insect genes, which caused significant larval mortality with various moulting anomalies and an overall developmental delay. We also found a significant decrease in reproductive potential in female moths, with a drop in egg laying and compromised egg hatching from treated larvae as compared to controls. dsRNA was stable in the insect gut and was efficiently processed into small interfering RNAs (siRNAs), thus accounting for the phenotypes observed in the present work. The study revealed the importance of these genes in core insect processes, which are essential for insect development and survival. © 2016 The Royal Entomological Society.

Insecticide resistance in Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) and Anopheles gambiae Giles (Diptera: Culicidae) could compromise the sustainability of malaria vector control strategies in West Africa.

PubMed

Gnankiné, Olivier; Bassolé, Imael H N; Chandre, Fabrice; Glitho, Isabelle; Akogbeto, Martin; Dabiré, Roch K; Martin, Thibaud

2013-10-01

Insecticides from the organophosphate (OP) and pyrethroid (PY) chemical families, have respectively, been in use for 50 and 30 years in West Africa, mainly against agricultural pests, but also against vectors of human disease. The selection pressure, with practically the same molecules year after year (mainly on cotton), has caused insecticide resistance in pest populations such as Bemisia tabaci, vector of harmful phytoviruses on vegetables. The evolution toward insecticide resistance in malaria vectors such as Anopheles gambiae sensus lato (s.l.) is probably related to the current use of these insecticides in agriculture. Thus, successful pest and vector control in West Africa requires an investigation of insect susceptibility, in relation to the identification of species and sub species, such as molecular forms or biotypes. Identification of knock down resistance (kdr) and acetylcholinesterase gene (Ace1) mutations modifying insecticide targets in individual insects and measure of enzymes activity typically involved in insecticide metabolism (oxidase, esterase and glutathion-S-transferase) are indispensable in understanding the mechanisms of resistance. Insecticide resistance is a good example in which genotype-phenotype links have been made successfully. Insecticides used in agriculture continue to select new resistant populations of B. tabaci that could be from different biotype vectors of plant viruses. As well, the evolution of insecticide resistance in An. gambiae threatens the management of malaria vectors in West Africa. It raises the question of priority in the use of insecticides in health and/or agriculture, and more generally, the question of sustainability of crop protection and vector control strategies in the region. Here, we review the susceptibility tests, biochemical and molecular assays data for B. tabaci, a major pest in cotton and vegetable crops, and An. gambiae, main vector of malaria. The data reviewed was collected in Benin and Burkina Faso between 2008 and 2010 under the Corus 6015 research program. This review aims to show: (i) the insecticide resistance in B. tabaci as well as in An. gambiae; and (ii) due to this, the impact of selection of resistant populations on malaria vector control strategies. Some measures that could be beneficial for crop protection and vector control strategies in West Africa are proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Digital PCR for detection of citrus pathogens

USDA-ARS?s Scientific Manuscript database

Citrus trees are often infected with multiple pathogens of economic importance, especially those with insect or mite vectors. Real-time/quantitative PCR (qPCR) has been used for high-throughput detection and relative quantification of pathogens; however, target reference or standards are required. I...

SPATIAL DYNAMICS OF LAND COVER AND INFECTIOUS DISEASE RISK

EPA Science Inventory

Climate changes may allow for vector-transmitted tropical diseases to spread into temperate areas. Areas of low ecological diversity are at higher risk of infectious disease transmission due to decreased zooprophylaxis, the diversion of disease carrying insects from humans to
...

Experimental transmission of Corynebacterium pseudotuberculosis biovar equi in horses by house flies

USDA-ARS?s Scientific Manuscript database

The route of Corynebacterium pseudotuberculosis infection in horses remains undetermined, but transmission by insects is suspected. Scientists from CMAVE and Auburn University investigated house flies (Musca domestica L.) as possible vectors. Three ponies were directly inoculated with C. pseudotuber...

Mating behavior and vibrational mimicry in the glassy-winged sharpshooter, Homalodisca vitripennis

USDA-ARS?s Scientific Manuscript database

Vibrational communication is widespread in insects, particularly in leafhoppers where the pair formation process is mediated by species-specific vibrational signals. One important pest using vibrational communication, glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is a vector of Xylella...

Detection of phytoplasmas of temperate fruit trees.

PubMed

Laimer, Margit

2009-01-01

Phytoplasmas are associated with hundreds of plant diseases globally. Many fruit tree phytoplasmas are transmitted by insect vectors or grafting, are considered quarantine organisms and a major economic threat to orchards. Diagnosis can be difficult, but immunochemical and molecular methods have been developed.

Physalin B inhibits Trypanosoma cruzi infection in the gut of Rhodnius prolixus by affecting the immune system and microbiota.

PubMed

Castro, Daniele P; Moraes, Caroline S; Gonzalez, Marcelo S; Ribeiro, Ivone M; Tomassini, Therezinha C B; Azambuja, Patrícia; Garcia, Eloi S

2012-12-01

Physalin B is a natural secosteroidal, extracted from the Solanaceae plant, Physalis angulata, and it presents immune-modulator effects on the bloodsucking bug, Rhodnius prolixus. In this work, R. prolixus was treated with physalin B at a concentration of 1 mg/ml of blood meal (oral application), or 20 ng/insect (applied topically) or 57 ng/cm(2) of filter paper (contact treatment), and infected with Trypanosoma cruzi Dm28c clone (2×10(6) epimastigotes/insect). The three types of applications significantly decreased the number of T. cruzi Dm28c in the gut comparing with the non-treated infected insects (controls). All groups of infected insects treated with physalin B had higher numbers of bacterial microbiota in the gut than the non-treated controls infected with T. cruzi. We observed that the infected physalin B insects with topical and contact treatments had a lower antibacterial activity in the gut when compared with control infected insects. Furthermore, infected insects with the physalin B oral treatment produced higher levels of nitrite and nitrate in the gut than control infected insects. These results demonstrate that physalin B decreases the T. cruzi transmission by inhibiting the parasite development in the insect vector R. prolixus. Herein the importance of physalin B modulation on the immune system and microbiota population in terms of parasite development and transmission are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Faunistic Study of the Aquatic Arthropods in a Tourism Area in Northern Iran.

PubMed

Shaeghi, Mansoureh; Dehghan, Hossein; Pakdad, Kamran; Nikpour, Fatemeh; Absavaran, Azad; Sofizadeh, Aioub; Akhavan, Amir Ahmad; Vatandoost, Hassan; Aghai-Afshar, Abbass

2017-06-01

Aquatic insects are very abundant and divers groups of insects that are associated with an aquatic or semiaquatic environment in one or more of their life stages. These insects have been, in some cases, well studied because they are vectors of several diseases. This is the first comprehensive faunistic study of aquatic insects from Babol County. The results may provide basic data for further taxonomic and ecological studies of aquatic insects as biological control agent or classification of water quality for the country. The specimens were collected using different methods including: D-frame net collector, standard mosquito dipper (350ml), Sweep-Netting and plastic pipette. Sampling carried out in different part of breading places in several times. During this study a total of 196 aquatic specimens were collected from different habitats and were morphologically identified including 18 families classified in 6 orders: Diptera, Trichoptera, Ephemeroptera, Plecoptera, Hemiptera and Odonata. Babol and Amol district in Mazandaran Province are located in humid climate regions with suitable ecological factors of humidity, moderate temperature and the variety of plant species. There are different species of aquatic insects in different habitats. The results will provide information for biodeveristy, species richness, their role for biological control as well as calcification of rivers based on abundance of aquatic insects. Therefore the understanding of ecological specifications of aquatic insects could provide a clue for further Arthropod-borne disease control. Additionally aquatic insect could be used for classification of water bodies.

Faunistic Study of the Aquatic Arthropods in a Tourism Area in Northern Iran

PubMed Central

Shaeghi, Mansoureh; Dehghan, Hossein; Pakdad, Kamran; Nikpour, Fatemeh; Absavaran, Azad; Sofizadeh, Aioub; Akhavan, Amir Ahmad; Vatandoost, Hassan; Aghai-Afshar, Abbass

2017-01-01

Background: Aquatic insects are very abundant and divers groups of insects that are associated with an aquatic or semiaquatic environment in one or more of their life stages. These insects have been, in some cases, well studied because they are vectors of several diseases. This is the first comprehensive faunistic study of aquatic insects from Babol County. The results may provide basic data for further taxonomic and ecological studies of aquatic insects as biological control agent or classification of water quality for the country. Methods: The specimens were collected using different methods including: D-frame net collector, standard mosquito dipper (350ml), Sweep-Netting and plastic pipette. Sampling carried out in different part of breading places in several times. Results: During this study a total of 196 aquatic specimens were collected from different habitats and were morphologically identified including 18 families classified in 6 orders: Diptera, Trichoptera, Ephemeroptera, Plecoptera, Hemiptera and Odonata. Babol and Amol district in Mazandaran Province are located in humid climate regions with suitable ecological factors of humidity, moderate temperature and the variety of plant species. There are different species of aquatic insects in different habitats. Conclusion: The results will provide information for biodeveristy, species richness, their role for biological control as well as calcification of rivers based on abundance of aquatic insects. Therefore the understanding of ecological specifications of aquatic insects could provide a clue for further Arthropod-borne disease control. Additionally aquatic insect could be used for classification of water bodies PMID:29062853

Persistent, circulative transmission of begomoviruses by whitefly vectors.

PubMed

Rosen, Ran; Kanakala, Surapathrudu; Kliot, Adi; Cathrin Pakkianathan, Britto; Farich, Basheer Abu; Santana-Magal, Nadine; Elimelech, Meytar; Kontsedalov, Svetlana; Lebedev, Galina; Cilia, Michelle; Ghanim, Murad

2015-12-01

Begomoviruses comprise an emerging and economically important group of plant viruses exclusively transmitted by the sweetpotato whitefly Bemisia tabaci in many regions of the world. The past twenty years have witnessed significant progress in studying the molecular interactions between members of this virus group and B. tabaci. Mechanisms and proteins encoded by the insect vector and its bacterial symbionts, which have been shown to be important for virus transmission, have been identified and thoroughly studied. Despite the economic importance of this group of viruses and their impact on the global agriculture, progress in investigating the virus-vector interactions is moving slowly when compared with similar virus-vector systems in plants and animals. Major advances in this field and future perspectives will be discussed in this review. Copyright © 2015 Elsevier B.V. All rights reserved.

Infection of aquatic insects with trematode metacercariae carrying Ehrlichia risticii, the cause of Potomac horse fever.

PubMed

Chae, J S; Pusterla, N; Johnson, E; Derock, E; Lawler, S P; Madigan, J E

2000-07-01

We provide evidence of Ehrlichia risticii Holland, the agent of Potomac horse fever, in trematode stages found in aquatic insects collected from a pasture stream in northern California, using nested polymerase chain reaction (PCR) amplification and sequence analyses of the 16S rRNA, 51 kDa major antigen and groEL heat shock protein genes. E. risticii was detected in metacercariae found in the immatures and adults of the following insects: caddisflies (Trichoptera), mayflies (Ephemeroptera), damselflies (Odonata, Zygoptera), dragonflies (Odonata, Anisoptera), and stoneflies (Plecoptera). The prevalence of E. risticii was 31.9% (n = 454 individuals) in aquatic insects (13 of 17 species were positive). Prevalence within orders was as follows: 43.5% (n = 207) in caddisflies, 15.2% (n = 92) in mayflies, 13.9% (n = 115) in damselflies, 10.0% (n = 10) in dragonflies, and 80.0% (n = 30) in stoneflies. This study demonstrates a broad intermediate host range for trematodes that act as vector for E. risticii. Insects are likely to play an important role in the epidemiology of this disease.

Black fly involvement in the epidemic transmission of vesicular stomatitis New Jersey virus (Rhabdoviridae: Vesiculovirus).

PubMed

Mead, Daniel G; Howerth, Elizabeth W; Murphy, Molly D; Gray, Elmer W; Noblet, Raymond; Stallknecht, David E

2004-01-01

The transmission routes of Vesicular stomatitis New Jersey virus (VSNJV), a causative agent of vesicular stomatitis, an Office International des Epizooties List-A disease, are not completely understood. Epidemiological and entomological studies conducted during the sporadic epidemics in the western United States have identified potential virus transmission routes involving insect vectors and animal-to-animal contact. In the present study we experimentally tested the previously proposed transmission routes which were primarily based on field observations. Results obtained provide strong evidence for the following: (1) hematophagous insects acquire VSNJV by unconventional routes while blood feeding on livestock, (2) clinical course of VSNJV infection in livestock following transmission by an infected insect is related to insect bite site, (3) infection of livestock via insect bite can result in multiple transmission possibilities, including animal-to-animal contact. Taken together, these data significantly add to our understanding of the transmission routes of a causative agent of one of the oldest known infectious diseases of livestock, for which the details have remained largely unknown despite decades of research.

Rift valley fever virus infection of human cells and insect hosts is promoted by protein kinase C epsilon.

PubMed

Filone, Claire Marie; Hanna, Sheri L; Caino, M Cecilia; Bambina, Shelly; Doms, Robert W; Cherry, Sara

2010-11-24

As an arthropod-borne human pathogen, Rift Valley fever virus (RVFV) cycles between an insect vector and mammalian hosts. Little is known about the cellular requirements for infection in either host. Here we developed a tissue culture model for RVFV infection of human and insect cells that is amenable to high-throughput screening. Using this approach we screened a library of 1280 small molecules with pharmacologically defined activities and identified 59 drugs that inhibited RVFV infection with 15 inhibiting RVFV replication in both human and insect cells. Amongst the 15 inhibitors that blocked infection in both hosts was a subset that inhibits protein kinase C. Further studies found that infection is dependent upon the novel protein kinase C isozyme epsilon (PKCε) in both human and insect cells as well as in adult flies. Altogether, these data show that inhibition of cellular factors required for early steps in the infection cycle including PKCε can block RVFV infection, and may represent a starting point for the development of anti-RVFV therapeutics.

Virus infection of a weed increases vector attraction to and vector fitness on the weed.

PubMed

Chen, Gong; Pan, Huipeng; Xie, Wen; Wang, Shaoli; Wu, Qingjun; Fang, Yong; Shi, Xiaobin; Zhang, Youjun

2013-01-01

Weeds are important in the ecology of field crops, and when crops are harvested, weeds often become the main hosts for plant viruses and their insect vectors. Few studies, however, have examined the relationships between plant viruses, vectors, and weeds. Here, we investigated how infection of the weed Datura stramonium L. by tomato yellow leaf curl virus (TYLCV) affects the host preference and performance of the TYLCV vector, Bemisia tabaci (Gennadius) Q. The results of a choice experiment indicated that B. tabaci Q preferentially settled and oviposited on TYLCV-infected plants rather than on healthy plants. In addition, B. tabaci Q performed better on TYLCV-infected plants than on healthy plants. These results demonstrate that TYLCV is indirectly mutualistic to B. tabaci Q. The mutually beneficial interaction between TYLCV and B. tabaci Q may help explain the concurrent outbreaks of TYLCV and B. tabaci Q in China.

Chitin utilization by the insect-transmitted bacterium Xylella fastidiosa.

PubMed

Killiny, Nabil; Prado, Simone S; Almeida, Rodrigo P P

2010-09-01

Xylella fastidiosa is an insect-borne bacterium that colonizes xylem vessels of a large number of host plants, including several crops of economic importance. Chitin is a polysaccharide present in the cuticle of leafhopper vectors of X. fastidiosa and may serve as a carbon source for this bacterium. Biological assays showed that X. fastidiosa reached larger populations in the presence of chitin. Additionally, chitin induced phenotypic changes in this bacterium, notably increasing adhesiveness. Quantitative PCR assays indicated transcriptional changes in the presence of chitin, and an enzymatic assay demonstrated chitinolytic activity by X. fastidiosa. An ortholog of the chitinase A gene (chiA) was identified in the X. fastidiosa genome. The in silico analysis revealed that the open reading frame of chiA encodes a protein of 351 amino acids with an estimated molecular mass of 40 kDa. chiA is in a locus that consists of genes implicated in polysaccharide degradation. Moreover, this locus was also found in the genomes of closely related bacteria in the genus Xanthomonas, which are plant but not insect associated. X. fastidiosa degraded chitin when grown on a solid chitin-yeast extract-agar medium and grew in liquid medium with chitin as the sole carbon source; ChiA was also determined to be secreted. The gene encoding ChiA was cloned into Escherichia coli, and endochitinase activity was detected in the transformant, showing that the gene is functional and involved in chitin degradation. The results suggest that X. fastidiosa may use its vectors' foregut surface as a carbon source. In addition, chitin may trigger X. fastidiosa's gene regulation and biofilm formation within vectors. Further work is necessary to characterize the role of chitin and its utilization in X. fastidiosa.

Hyaluronidase activity in the salivary glands of tabanid flies.

PubMed

Volfova, Vera; Tothova, Viktorie; Volf, Petr

2016-06-01

Tabanids are haematophagous insects that act as biological and mechanical vectors of various diseases, including viruses, bacteria and parasites. The saliva of these insects contains strong anticoagulant and vasodilatory activities as well as immunoregulatory peptides. Here we demonstrate pronounced hyaluronidase (hyase) activity in ten tabanid species of the genera Chrysops, Haematopota, Hybomitra and Tabanus. Compared to other haematophagous insects, the ability of tabanid hyases to hydrolyze hyaluronic acid (HA) is extremely high, for example the enzyme activity of Hybomitra muehlfeldi was found to be 32-fold higher than the salivary hyase activity of the sand fly Phlebotomus papatasi. Hyases of all ten tabanid species tested also cleaved chondroitin sulfate A, another glycosaminoglycan present in the extracellular matrix of vertebrates. The pH optimum of the enzyme activity was measured in eight tabanid species; the hyase of Haemopota pluvialis was the only one with optimum at pH 4.0, while in the other seven species the activity optimum was at 5.0. SDS PAGE zymography showed the monomeric character of the enzymes in all tabanid species tested. Under non-reducing conditions the activities were visible as single bands with estimated MW between 35 and 52 kDa. The very high hyaluronidase activity in tabanid saliva might be related to their aggressive biting behavior as well as to their high efficiency as mechanical vectors. As they are supposedly involved in the enlargement of feeding hematomas, hyases might contribute to the mechanical transmission of pathogens. Pathogens present in vector mouthparts are co-inoculated into the vertebrate host together with saliva and may benefit from increased tissue permeability and the immunomodulatory activity of the salivary hyase. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

A plant pathogenic bacterium exploits the tricarboxylic acid cycle metabolic pathway of its insect vector

PubMed Central

Nehela, Yasser; Hijaz, Faraj; Vincent, Christopher I.

2018-01-01

ABSTRACT Huanglongbing in citrus is caused by a phloem-limited, uncultivable, gram-negative α-proteobacterium, Candidatus Liberibacter asiaticus (CLas). CLas is transmitted by the phloem-sucking insect, Diaphorina citri (Hemiptera: Liviidae), in a persistent, circulative, and propagative manner. In this study, we investigated the metabolomic and respiration rates changes in D. citri upon infection with CLas using gas chromatography-mass spectrometry (GC-MS) and gas exchange analysis. The level of glycine, L-serine, L-threonine, and gamma-amino butyric acid were higher in CLas-infected D. citri, while L-proline, L-aspartic acid, and L-pyroglutamic acid were lower in CLas-infected D. citri compared with the control. Citric acid was increased in CLas-infected D. citri, whereas malic and succinic acids were reduced. Interestingly, most of the reduced metabolites such as malate, succinate, aspartate, and L-proline are required for the growth of CLas. The increase in citric acid, serine, and glycine indicated that CLas induced glycolysis and the tricarboxylic acid cycle (TCA) in its vector. In agreement with the GC-MS results, the gene expression results also indicated that glycolysis and TCA were induced in CLas-infected D. citri and this was accompanied with an increases in respiration rate. Phosphoric acid and most of the sugar alcohols were higher in CLas-infected D. citri, indicating a response to the biotic stress or cell damage. Only slight increases in the levels of few sugars were observed in CLas-infected D. citri, which indicated that sugars are tightly regulated by D. citri. Our results indicated that CLas induces nutrient and energetic stress in its host insect. This study may provide some insights into the mechanism of colonization of CLas in its vector. PMID:28594267

A plant pathogenic bacterium exploits the tricarboxylic acid cycle metabolic pathway of its insect vector.

PubMed

Killiny, Nabil; Nehela, Yasser; Hijaz, Faraj; Vincent, Christopher I

2018-01-01

Huanglongbing in citrus is caused by a phloem-limited, uncultivable, gram-negative α-proteobacterium, Candidatus Liberibacter asiaticus (CLas). CLas is transmitted by the phloem-sucking insect, Diaphorina citri (Hemiptera: Liviidae), in a persistent, circulative, and propagative manner. In this study, we investigated the metabolomic and respiration rates changes in D. citri upon infection with CLas using gas chromatography-mass spectrometry (GC-MS) and gas exchange analysis. The level of glycine, L -serine, L -threonine, and gamma-amino butyric acid were higher in CLas-infected D. citri, while L -proline, L -aspartic acid, and L -pyroglutamic acid were lower in CLas-infected D. citri compared with the control. Citric acid was increased in CLas-infected D. citri, whereas malic and succinic acids were reduced. Interestingly, most of the reduced metabolites such as malate, succinate, aspartate, and L -proline are required for the growth of CLas. The increase in citric acid, serine, and glycine indicated that CLas induced glycolysis and the tricarboxylic acid cycle (TCA) in its vector. In agreement with the GC-MS results, the gene expression results also indicated that glycolysis and TCA were induced in CLas-infected D. citri and this was accompanied with an increases in respiration rate. Phosphoric acid and most of the sugar alcohols were higher in CLas-infected D. citri, indicating a response to the biotic stress or cell damage. Only slight increases in the levels of few sugars were observed in CLas-infected D. citri, which indicated that sugars are tightly regulated by D. citri. Our results indicated that CLas induces nutrient and energetic stress in its host insect. This study may provide some insights into the mechanism of colonization of CLas in its vector.

Chitin Utilization by the Insect-Transmitted Bacterium Xylella fastidiosa▿ †

PubMed Central

Killiny, Nabil; Prado, Simone S.; Almeida, Rodrigo P. P.

2010-01-01

Xylella fastidiosa is an insect-borne bacterium that colonizes xylem vessels of a large number of host plants, including several crops of economic importance. Chitin is a polysaccharide present in the cuticle of leafhopper vectors of X. fastidiosa and may serve as a carbon source for this bacterium. Biological assays showed that X. fastidiosa reached larger populations in the presence of chitin. Additionally, chitin induced phenotypic changes in this bacterium, notably increasing adhesiveness. Quantitative PCR assays indicated transcriptional changes in the presence of chitin, and an enzymatic assay demonstrated chitinolytic activity by X. fastidiosa. An ortholog of the chitinase A gene (chiA) was identified in the X. fastidiosa genome. The in silico analysis revealed that the open reading frame of chiA encodes a protein of 351 amino acids with an estimated molecular mass of 40 kDa. chiA is in a locus that consists of genes implicated in polysaccharide degradation. Moreover, this locus was also found in the genomes of closely related bacteria in the genus Xanthomonas, which are plant but not insect associated. X. fastidiosa degraded chitin when grown on a solid chitin-yeast extract-agar medium and grew in liquid medium with chitin as the sole carbon source; ChiA was also determined to be secreted. The gene encoding ChiA was cloned into Escherichia coli, and endochitinase activity was detected in the transformant, showing that the gene is functional and involved in chitin degradation. The results suggest that X. fastidiosa may use its vectors' foregut surface as a carbon source. In addition, chitin may trigger X. fastidiosa's gene regulation and biofilm formation within vectors. Further work is necessary to characterize the role of chitin and its utilization in X. fastidiosa. PMID:20656858

Survival and immune response of the Chagas vector Meccus pallidipennis (Hemiptera: Reduviidae) against two entomopathogenic fungi, Metarhizium anisopliae and Isaria fumosorosea.

PubMed

Flores-Villegas, A Laura; Cabrera-Bravo, Margarita; Toriello, Conchita; Bucio-Torres, Martha I; Salazar-Schettino, Paz María; Córdoba-Aguilar, Alex

2016-03-24

Chagas disease is a key health problem in Latin America and is caused and transmitted by Trypanosoma cruzi and triatomine bugs, respectively. Control of triatomines has largely relied on the use pyrethroids, which has proved to be ineffective in the long term. Alternatively, the use of entomopathogenic fungi has been implemented to control triatomine bugs. These fungi are highly efficient as they induce a reduction in immune response on insects. Meccus pallidipennis is the main triatomine vector of Chagas disease in Mexico. In this work we investigated the effects of two entomopathogenic fungi, Metarhizium anisopliae and Isaria fumosorosea, on M. pallidipennis nymphs in terms of insect survival and immune response. We had an infected and a control group for each fungal species and assessed: a) insect survival during 30 days; and, b) phenoloxidase (PO) and prophenoloxidase (proPO; two key traits in insect immune response) at 24, 48, 96 and 144 h. For survival we used Kaplan-Meier survival analysis while for immune response we used factorial, repeated-measures ANOVA for each fungal species. Animals treated with M. anisopliae died sooner than animals treated with I. fumosorosea. Infected animals showed lower PO and proPO values than sham individuals, with a clear decrease in these parameters at 24 h with no further changes after this time. Our study widens the possibility of entomopathogenic fungi being used for triatomine control. The negative effect on PO and proPO seems mediated by a down-regulation of the triatomine immune response.

Factors influencing aquatic-to-terrestrial contaminant transport to terrestrial arthropod consumers in a multiuse river system.

PubMed

Alberts, Jeremy M; Sullivan, S Mažeika P

2016-06-01

Emerging aquatic insects are important vectors of contaminant transfer from aquatic to terrestrial food webs. However, the environmental factors that regulate contaminant body burdens in nearshore terrestrial consumers remain largely unexplored. We investigated the relative influences of riparian landscape composition (i.e., land use and nearshore vegetation structure) and contaminant flux via the emergent aquatic insect subsidy on selenium (Se) and mercury (Hg) body burdens of riparian ants (Formica subsericea) and spiders of the family Tetragnathidae along 11 river reaches spanning an urban-rural land-use gradient in Ohio, USA. Model-selection results indicated that fine-scale land cover (e.g., riparian zone width, shrub cover) in the riparian zone was positively associated with reach-wide body burdens of Se and Hg in both riparian F. subsericea and tetragnathid spiders (i.e., total magnitude of Hg and Se concentrations in ant and spider populations, respectively, for each reach). River distance downstream of Columbus, Ohio - where study reaches were impounded and flow through a large urban center - was also implicated as an important factor. Although stable-isotope analysis suggested that emergent aquatic insects were likely vectors of Se and Hg to tetragnathid spiders (but not to F. subsericea), emergent insect contaminant flux did not emerge as a significant predictor for either reach-wide body burdens of spider Hg or Se. Improved understanding of the pathways and influences that control aquatic-to-terrestrial contaminant transport will be critical for effective risk management and remediation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Insect-specific viruses and their potential impact on arbovirus transmission

PubMed Central

Vasilakis, Nikos; Tesh, Robert B.

2015-01-01

Arthropod-borne viruses (arboviruses) are the causative agents of significant morbidity and mortality among humans and animals globally. In the last few years, the widespread adoption of next generation sequencing and metagenomics has led to a new era of virus discovery, where many novel viruses have been documented, exhibiting a restricted host-range in mosquitoes. They represent a wide-range of insect-specific viruses within the families of Bunyaviridae, Flaviviridae, Mesoniviridae, Reoviridae, Rhabdoviridae, Togaviridae, and the newly recognized taxon of Negeviruses. Collectively, their discovery has opened new vistas about the extent of viral diversity and evolution, their influence on vector competence and ability of their insect hosts to transmit human pathogens (e.g. arboviruses), and their potential development as biological control agents or novel vaccine platforms. PMID:26322695

Insect cells-baculovirus system for the production of difficult to express proteins.

PubMed

Osz-Papai, Judit; Radu, Laura; Abdulrahman, Wassim; Kolb-Cheynel, Isabelle; Troffer-Charlier, Nathalie; Birck, Catherine; Poterszman, Arnaud

2015-01-01

The production of sufficient quantities of homogenous protein not only is an essential prelude for structural investigations but also represents a rate-limiting step for many human functional studies. Although technologies for expression of recombinant proteins and complexes have been improved tremendously, in many cases, protein production remains a challenge and can be associated with considerable investment. This chapter describes simple and efficient protocols for expression screening and optimization of protein production in insect cells using the baculovirus expression system. We describe the procedure, starting from the cloning of a gene of interest into an expression transfer baculovirus vector, followed by generation of the recombinant virus by homologous recombination, evaluation of protein expression, and scale-up. Handling of insect cell cultures and preparation of bacmid for co-transfection are also detailed.

Tissue-specific expression of silkmoth chorion genes in vivo using Bombyx mori nuclear polyhedrosis virus as a transducing vector.

PubMed Central

Iatrou, K; Meidinger, R G

1990-01-01

A pair of silkmoth chorion chromosomal genes, HcA.12-HcB.12, was inserted into a baculovirus transfer vector, pBmp2, derived from the nuclear polyhedrosis virus of Bombyx mori. This vector, which permits the insertion of foreign genetic material in the vicinity of a mutationally inactivated polyhedrin gene, was used to acquire the corresponding recombinant virus. Injection of mutant silkmoth pupae that lack all Hc chorion genes with the recombinant virus resulted in the infection of all internal organs including follicular tissue. Analysis of RNA from infected tissues has demonstrated that the two chorion genes present in the viral genome are correctly transcribed under the control of their own promoter in follicular cells, the tissue in which chorion genes are normally expressed. The chorion primary transcripts are also correctly processed in the infected follicular cells and yield mature mRNAs indistinguishable from authentic chorion mRNAs present in wild-type follicles. These results demonstrate that recombinant nuclear polyhedrosis viruses can be used as transducing vectors for introducing genetic material of host origin into the cells of the organism and that the transduced genes are transiently expressed in a tissue-specific manner under the control of their resident regulatory sequences. Thus we show the in vivo expression of cloned genes under cellular promoter control in an insect other than Drosophila melanogaster. The approach should be applicable to all insect systems that are subject to nuclear polyhedrosis virus infection. Images PMID:2187186

Pollination Research Methods with Apis mellifera

USDA-ARS?s Scientific Manuscript database

This chapter describes field and lab procedures for doing experiments on honey bee pollination. Most of the methods apply to any insect for whom pollen vectoring capacity is the question. What makes honey bee pollination distinctive is its historic emphasis on agricultural applications; hence one fi...

Assessing transmission of ‘Candidatus Liberibacter solanacearum’ haplotypes through seed potato

USDA-ARS?s Scientific Manuscript database

Conflicting data has previously been reported concerning the impact of zebra chip disease transmission through seed tubers. These discrepancies may be due to the experimental design of each study, whereby different pathogen haplotypes, insect vector haplotypes, and potato plant varieties were used....

P53-mediated rapid induction of apoptosis conveys resistance to viral infection in Drosophila melanogaster

USDA-ARS?s Scientific Manuscript database

Arthropod-borne pathogens account for millions of deaths each year. Understanding the genetic mechanisms controlling vector susceptibility to pathogens has profound implications for developing novel strategies for controlling insect transmitted infectious diseases. The fact that many viruses carry...

Developing resistance to HLB

USDA-ARS?s Scientific Manuscript database

Huanglongbing (HLB) disease of citrus is caused by Candidatus Liberibacter asiaticus (CLas) a bacterium that is transmitted among citrus trees by its insect vector, the Asian citrus psyllid (ACP). HLB has had negative impact on citrus production in the far east for over one hundred years, but not c...

The fungal aroma gene ATF1 promotes dispersal of yeast cells through insect vectors.

PubMed

Christiaens, Joaquin F; Franco, Luis M; Cools, Tanne L; De Meester, Luc; Michiels, Jan; Wenseleers, Tom; Hassan, Bassem A; Yaksi, Emre; Verstrepen, Kevin J

2014-10-23

Yeast cells produce various volatile metabolites that are key contributors to the pleasing fruity and flowery aroma of fermented beverages. Several of these fruity metabolites, including isoamyl acetate and ethyl acetate, are produced by a dedicated enzyme, the alcohol acetyl transferase Atf1. However, despite much research, the physiological role of acetate ester formation in yeast remains unknown. Using a combination of molecular biology, neurobiology, and behavioral tests, we demonstrate that deletion of ATF1 alters the olfactory response in the antennal lobe of fruit flies that feed on yeast cells. The flies are much less attracted to the mutant yeast cells, and this in turn results in reduced dispersal of the mutant yeast cells by the flies. Together, our results uncover the molecular details of an intriguing aroma-based communication and mutualism between microbes and their insect vectors. Similar mechanisms may exist in other microbes, including microbes on flowering plants and pathogens. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Dual Insect specific virus infection limits Arbovirus replication in Aedes mosquito cells.

PubMed

Schultz, Michaela J; Frydman, Horacio M; Connor, John H

2018-05-01

Aedes mosquitoes are vectors for many pathogenic viruses. Cell culture systems facilitate the investigation of virus growth in the mosquito vector. We found Zika virus (ZIKV) growth to be consistent in A. albopictus cells but hypervariable in A. aegypti cell lines. As a potential explanation of this variability, we tested the hypothesis that our cells harbored opportunistic viruses. We screened Aedes cell lines for the presence of insect specific viruses (ISVs), Cell-fusing agent virus (CFAV) and Phasi charoen-like virus (PCLV). PCLV was present in the ZIKV-growth-variable A. aegypti cell lines but absent in A. albopictus lines, suggesting that these ISVs may interfere with ZIKV growth. In support of this hypothesis, PCLV infection of CFAV-positive A. albopictus cells inhibited the growth of ZIKV, dengue virus and La Crosse virus. These data suggest ISV infection of cell lines can impact arbovirus growth leading to significant changes in cell permissivity to arbovirus infection. Copyright © 2018 Elsevier Inc. All rights reserved.

Assessing gene expression during pathogenesis: Use of qRT-PCR to follow toxin production in the entomopathogenic fungus Beauveria bassiana during infection and immune response of the insect host Triatoma infestans.

PubMed

Lobo, Luciana S; Luz, Christian; Fernandes, Éverton K K; Juárez, M Patricia; Pedrini, Nicolás

2015-06-01

Entomopathogenic fungi secrete toxic secondary metabolites during the invasion of the insect hemocoel as part of the infection process. Although these compounds have been frequently mentioned as virulence factors, the roles of many of them remain poorly understood, including the question of whether they are expressed during the infection process. A major hurdle to this issue remains the low sensitivity of biochemical detection techniques (e.g., HPLC) within the complex samples that may contain trace quantities of fungal molecules inside the insect. In this study, quantitative reverse transcription real-time PCR (qRT-PCR) was used to measure the transcript levels within the insect fungal pathogen Beauveria bassiana, that encode for the synthetase enzymes of the secondary metabolites tenellin (BbtenS), beauvericin (BbbeaS) and bassianolide (BbbslS) during the infection of Triatoma infestans, a Chagas disease insect vector. Absolute quantification was performed at different time periods after insect treatment with various concentrations of propagules, either by immersing the insects in conidial suspensions or by injecting them with blastospores. Both BbtenS and BbbeaS were highly expressed in conidia-treated insects at days 3 and 12 post-treatment. In blastospore-injected insects, BbtenS and BbbeaS expression peaked at 24h post-injection and were also highly expressed in insect cadavers. The levels of BbbslS transcripts were much lower in all conditions tested. The expression patterns of insect genes encoding proteins that belong to the T. infestans humoral immune system were also evaluated with the same technique. This qPCR-based methodology can contribute to decifering the dynamics of entomopathogenic fungal infection at the molecular level. Copyright © 2015 Elsevier Inc. All rights reserved.

Virus diseases of peppers (Capsicum spp.) and their control.

PubMed

Kenyon, Lawrence; Kumar, Sanjeet; Tsai, Wen-Shi; Hughes, Jacqueline d'A

2014-01-01

The number of virus species infecting pepper (Capsicum spp.) crops and their incidences has increased considerably over the past 30 years, particularly in tropical and subtropical pepper production systems. This is probably due to a combination of factors, including the expansion and intensification of pepper cultivation in these regions, the increased volume and speed of global trade of fresh produce (including peppers) carrying viruses and vectors to new locations, and perhaps climate change expanding the geographic range suitable for the viruses and vectors. With the increased incidences of diverse virus species comes increased incidences of coinfection with two or more virus species in the same plant. There is then greater chance of synergistic interactions between virus species, increasing symptom severity and weakening host resistance, as well as the opportunity for genetic recombination and component exchange and a possible increase in aggressiveness, virulence, and transmissibility. The main virus groups infecting peppers are transmitted by aphids, whiteflies, or thrips, and a feature of many populations of these vector groups is that they can develop resistance to some of the commonly used insecticides relatively quickly. This, coupled with the increasing concern over the impact of over- or misuse of insecticides on the environment, growers, and consumers, means that there should be less reliance on insecticides to control the vectors of viruses infecting pepper crops. To improve the durability of pepper crop protection measures, there should be a shift away from the broadscale use of insecticides and the use of single, major gene resistance to viruses. Instead, integrated and pragmatic virus control measures should be sought that combine (1) cultural practices that reduce sources of virus inoculum and decrease the rate of spread of viruliferous vectors into the pepper crop, (2) synthetic insecticides, which should be used judiciously and only when the plants are young and most susceptible to infection, (3) appropriate natural products and biocontrol agents to induce resistance in the plants, affect the behavior of the vector insects, or augment the local populations of parasites or predators of the virus vectors, and (4) polygenic resistances against viruses and vector insects with pyramided single-gene virus resistances to improve resistance durability.

Biting midges (Culicoides, Diptera) transmit Haemoproteus parasites of owls: evidence from sporogony and molecular phylogeny.

PubMed

Bukauskaitė, Dovilė; Žiegytė, Rita; Palinauskas, Vaidas; Iezhova, Tatjana A; Dimitrov, Dimitar; Ilgūnas, Mikas; Bernotienė, Rasa; Markovets, Mikhail Yu; Valkiūnas, Gediminas

2015-06-04

Haemoproteus parasites are widespread, and several species cause diseases both in birds and blood-sucking insects. These pathogens are transmitted by dipterans belonging to the Ceratopogonidae and Hippoboscidae, however certain vector species remain unknown for the majority of Haemoproteus spp. Owls are often infected by Haemoproteus parasites, but experimental studies on vectors of these infections are lacking. The aim of this study was to investigate sporogonic development of two widespread Haemoproteus parasites of owls, H. noctuae and H. syrnii in experimentally infected biting midges Culicoides impunctatus and Culicoides nubeculosus. We also followed in vitro sporogonic development of these infections and determined their phylogenetic relationships with Haemoproteus spp., for which vectors have been identified. Wild-caught C. impunctatus and laboratory reared C. nubeculosus were infected experimentally by allowing them to take blood meals on one individual long-eared owl (Asio otus) and one tawny owl (Strix aluco) harbouring mature gametocytes of H. noctuae (lineage hCIRCUM01) and H. syrnii (hCULCIB01), respectively. The engorged insects were maintained in the laboratory at 16-18 °C, and dissected at intervals in order to follow the development of ookinetes, oocysts and sporozoites. We also observed in vitro development of sexual stages of both parasites by exposure of infected blood to air. The parasite lineages were determined by polymerase chain reaction-based methods. Bayesian phylogeny was constructed in order to determine the relationships of owl parasites with other avian Haemoproteus spp., for which vectors have been identified. Both H. noctuae and H. syrnii completed sporogony in C. nubeculosus, and H. noctuae completed sporogony in C. impunctatus. Ookinetes, oocysts and sporozoites of these parasites were reported and described. Gametes and ookinetes of both species readily developed in vitro. In accordance with sporogony data, the phylogenetic analysis placed both parasite lineages in a clade of Culicoides spp.-transmitted avian Haemoproteus (Parahaemoproteus) spp. Culicoides nubeculosus and C. impunctatus are vectors of H. noctuae and H. syrnii. Phylogenies based on cytochrome b gene indicate parasite-vector relationships, and we recommend using them in predicting possible parasite-vector relationships and planning research on avian Haemoproteus spp. vectors in wildlife.

Dynamics of Huanglongbing-associated Bacterium Candidatus Liberibacter asiaticus in Citrus aurantifolia Swingle (Mexican Lime).

PubMed

Abel Lopez-Buenfil, Jose; Abrahan Ramirez-Pool, Jose; Ruiz-Medrano, Roberto; Del Carmen Montes-Horcasitas, Maria; Chavarin-Palacio, Claudio; Moya-Hinojosa, Jesus; Javier Trujillo-Arriaga, Francisco; Carmona, Rosalia Lira; Xoconostle-Cazares, Beatriz

2017-01-01

The bacterial disease citrus huanglongbing (HLB), associated with "Candidatus Liberibacter asiaticus" (C.Las) has severely impacted the citrus industry, causing a significant reduction in production and fruit quality. In the present study, it was monitored the C.Las population dynamics in symptomatic, HLB-positive Mexican lime trees (Citrus aurantifolia Swingle) in a tropical, citrus-producing area of Mexico. The objective of this study was to identify the dynamics of the population of huanglongbing-associated bacterium Candidatus Liberibacter asiaticus and its insect vector in Citrus aurantifolia Swingle (Mexican lime). Leaf samples were collected every 2 months over a period of 26 months for quantification of bacterial titers and young and mature leaves were collected in each season to determine preferential sites of bacterial accumulation. The proportion of living and dead bacterial cells could be determined through the use of quantitative real-time PCR in the presence of ethidium monoazide (EMA-qPCR). It was observed a lower bacterial titer at high temperatures in the infected trees relative to titers in mild weather, despite a higher accumulation of the insect vector Diaphorina citri in these conditions. This study also revealed seasonal fluctuations in the titers of bacteria in mature leaves when compared to young leaves. No statistically significant correlation between any meteorological variable, C.Las concentration and D. citri population could be drawn. Although, HLB management strategies have focused on vector control, host tree phenology may be important. The evaluation of citrus phenology, C.Las concentration, ACP population and environmental conditions provides insights into the cyclical, seasonal variations of both the HLB pathogen and its vector. These findings should help in the design of integrative HLB control strategies that take into account the accumulation of the pathogen and the presence of its vector.

Prevalence of bluetongue virus antibodies and associated risk factors among cattle in East Darfur State, Western Sudan

PubMed Central

2014-01-01

Background Bluetongue virus (BTV) is an insect-transmitted virus, which causes bluetongue disease (BT) in sheep and a fatal hemorrhagic infection in North American white-tailed deer. However, in cattle the disease is typically asymptomatic and no overt clinical signs of disease appear to be associated with BTV infection. Serological evidence and isolation of different BTV serotypes have been reported in Sudan, however, no information is currently available in regard to previous exposure of Sudanese livestock to BTV infection in East Darfur State, Sudan. Aims To determine the prevalence of BTV antibodies and to identify the potential risk factors associated with BTV infection among cattle in East Darfur State, Sudan. Methods A total of 224 blood samples were collected randomly from five localities in East Darfur State, Sudan. The serum samples were screened for detection of BTV-specific immunoglobulin G (IgG) antibodies using a competitive enzyme-linked immunosorbent assay (c-ELISA). Results Serological evidence of BTV infection was observed in 150 out of 224 animals accounting for a 67% prevalence rate among cattle in East Darfur State. Older cattle (>2 years of age) were six times more likely to be infected with BTV (OR = 6.62, CI = 2.87-15.26, p-value = 0.01). Regarding animal source (contact with other herds) as a risk factor, it was shown that cattle purchased from market or introduced from other herds were 3 times at higher risk of being infected with BTV (OR = 3.87, CI = 1.07-13.87, p value = 0.03). Exposure of cattle to the insect vector increased the risk of contracting BTV infection by six times compared to non-exposed cattle (OR = 6.44, CI = 1.53-27.08, p value = 0.01). Conclusion The present study indicated that age, animal source and the intensity of the insect vector are influential risk factors for BTV infection in cattle in the Darfur region. Surveillance for BTV infection should be extended to include other susceptible ruminants and to study the distribution of the insect vectors to better predict and respond to a possible BTV outbreak in the State of East Darfur, Sudan. PMID:24507448

Prevalence of bluetongue virus antibodies and associated risk factors among cattle in East Darfur State, Western Sudan.

PubMed

Khair, Hadia Om; Adam, Ibrahim A; Bushara, Shakir B; Eltom, Kamal H; Musa, Nasreen O; Aradaib, Imadeldin E

2014-02-07

Bluetongue virus (BTV) is an insect-transmitted virus, which causes bluetongue disease (BT) in sheep and a fatal hemorrhagic infection in North American white-tailed deer. However, in cattle the disease is typically asymptomatic and no overt clinical signs of disease appear to be associated with BTV infection. Serological evidence and isolation of different BTV serotypes have been reported in Sudan, however, no information is currently available in regard to previous exposure of Sudanese livestock to BTV infection in East Darfur State, Sudan. To determine the prevalence of BTV antibodies and to identify the potential risk factors associated with BTV infection among cattle in East Darfur State, Sudan. A total of 224 blood samples were collected randomly from five localities in East Darfur State, Sudan. The serum samples were screened for detection of BTV-specific immunoglobulin G (IgG) antibodies using a competitive enzyme-linked immunosorbent assay (c-ELISA). Serological evidence of BTV infection was observed in 150 out of 224 animals accounting for a 67% prevalence rate among cattle in East Darfur State. Older cattle (>2 years of age) were six times more likely to be infected with BTV (OR = 6.62, CI = 2.87-15.26, p-value = 0.01). Regarding animal source (contact with other herds) as a risk factor, it was shown that cattle purchased from market or introduced from other herds were 3 times at higher risk of being infected with BTV (OR = 3.87, CI = 1.07-13.87, p value = 0.03). Exposure of cattle to the insect vector increased the risk of contracting BTV infection by six times compared to non-exposed cattle (OR = 6.44, CI = 1.53-27.08, p value = 0.01). The present study indicated that age, animal source and the intensity of the insect vector are influential risk factors for BTV infection in cattle in the Darfur region. Surveillance for BTV infection should be extended to include other susceptible ruminants and to study the distribution of the insect vectors to better predict and respond to a possible BTV outbreak in the State of East Darfur, Sudan.

Receptive fields of locust brain neurons are matched to polarization patterns of the sky.

PubMed

Bech, Miklós; Homberg, Uwe; Pfeiffer, Keram

2014-09-22

Many animals, including insects, are able to use celestial cues as a reference for spatial orientation and long-distance navigation [1]. In addition to direct sunlight, the chromatic gradient of the sky and its polarization pattern are suited to serve as orientation cues [2-5]. Atmospheric scattering of sunlight causes a regular pattern of E vectors in the sky, which are arranged along concentric circles around the sun [5, 6]. Although certain insects rely predominantly on sky polarization for spatial orientation [7], it has been argued that detection of celestial E vector orientation may not suffice to differentiate between solar and antisolar directions [8, 9]. We show here that polarization-sensitive (POL) neurons in the brain of the desert locust Schistocerca gregaria can overcome this ambiguity. Extracellular recordings from POL units in the central complex and lateral accessory lobes revealed E vector tunings arranged in concentric circles within large receptive fields, matching the sky polarization pattern at certain solar positions. Modeling of neuronal responses under an idealized sky polarization pattern (Rayleigh sky) suggests that these "matched filter" properties allow locusts to unambiguously determine the solar azimuth by relying solely on the sky polarization pattern for compass navigation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterization of Viral Communities of Biting Midges and Identification of Novel Thogotovirus Species and Rhabdovirus Genus

PubMed Central

Temmam, Sarah; Monteil-Bouchard, Sonia; Robert, Catherine; Baudoin, Jean-Pierre; Sambou, Masse; Aubadie-Ladrix, Maxence; Labas, Noémie; Raoult, Didier; Mediannikov, Oleg; Desnues, Christelle

2016-01-01

More than two thirds of emerging viruses are of zoonotic origin, and among them RNA viruses represent the majority. Ceratopogonidae (genus Culicoides) are well-known vectors of several viruses responsible for epizooties (bluetongue, epizootic haemorrhagic disease, etc.). They are also vectors of the only known virus infecting humans: the Oropouche virus. Female midges usually feed on a variety of hosts, leading to possible transmission of emerging viruses from animals to humans. In this context, we report here the analysis of RNA viral communities of Senegalese biting midges using next-generation sequencing techniques as a preliminary step toward the identification of potential viral biohazards. Sequencing of the RNA virome of three pools of Culicoides revealed the presence of a significant diversity of viruses infecting plants, insects and mammals. Several novel viruses were detected, including a novel Thogotovirus species, related but genetically distant from previously described tick-borne thogotoviruses. Novel rhabdoviruses were also detected, possibly constituting a novel Rhabdoviridae genus, and putatively restricted to insects. Sequences related to the major viruses transmitted by Culicoides, i.e., African horse sickness, bluetongue and epizootic haemorrhagic disease viruses were also detected. This study highlights the interest in monitoring the emergence and circulation of zoonoses and epizooties using their arthropod vectors. PMID:26978389

Characterization of Viral Communities of Biting Midges and Identification of Novel Thogotovirus Species and Rhabdovirus Genus.

PubMed

Temmam, Sarah; Monteil-Bouchard, Sonia; Robert, Catherine; Baudoin, Jean-Pierre; Sambou, Masse; Aubadie-Ladrix, Maxence; Labas, Noémie; Raoult, Didier; Mediannikov, Oleg; Desnues, Christelle

2016-03-11

More than two thirds of emerging viruses are of zoonotic origin, and among them RNA viruses represent the majority. Ceratopogonidae (genus Culicoides) are well-known vectors of several viruses responsible for epizooties (bluetongue, epizootic haemorrhagic disease, etc.). They are also vectors of the only known virus infecting humans: the Oropouche virus. Female midges usually feed on a variety of hosts, leading to possible transmission of emerging viruses from animals to humans. In this context, we report here the analysis of RNA viral communities of Senegalese biting midges using next-generation sequencing techniques as a preliminary step toward the identification of potential viral biohazards. Sequencing of the RNA virome of three pools of Culicoides revealed the presence of a significant diversity of viruses infecting plants, insects and mammals. Several novel viruses were detected, including a novel Thogotovirus species, related but genetically distant from previously described tick-borne thogotoviruses. Novel rhabdoviruses were also detected, possibly constituting a novel Rhabdoviridae genus, and putatively restricted to insects. Sequences related to the major viruses transmitted by Culicoides, i.e., African horse sickness, bluetongue and epizootic haemorrhagic disease viruses were also detected. This study highlights the interest in monitoring the emergence and circulation of zoonoses and epizooties using their arthropod vectors.

Polarization-sensitive descending neurons in the locust: connecting the brain to thoracic ganglia.

PubMed

Träger, Ulrike; Homberg, Uwe

2011-02-09

Many animal species, in particular insects, exploit the E-vector pattern of the blue sky for sun compass navigation. Like other insects, locusts detect dorsal polarized light via photoreceptors in a specialized dorsal rim area of the compound eye. Polarized light information is transmitted through several processing stages to the central complex, a brain area involved in the control of goal-directed orientation behavior. To investigate how polarized light information is transmitted to thoracic motor circuits, we studied the responses of locust descending neurons to polarized light. Three sets of polarization-sensitive descending neurons were characterized through intracellular recordings from axonal fibers in the neck connectives combined with single-cell dye injections. Two descending neurons from the brain, one with ipsilaterally and the second with contralaterally descending axon, are likely to bridge the gap between polarization-sensitive neurons in the brain and thoracic motor centers. In both neurons, E-vector tuning changed linearly with daytime, suggesting that they signal time-compensated spatial directions, an important prerequisite for navigation using celestial signals. The third type connects the suboesophageal ganglion with the prothoracic ganglion. It showed no evidence for time compensation in E-vector tuning and might play a role in flight stabilization and control of head movements.

RNA Interference Restricts Rift Valley Fever Virus in Multiple Insect Systems.

PubMed

Dietrich, Isabelle; Jansen, Stephanie; Fall, Gamou; Lorenzen, Stephan; Rudolf, Martin; Huber, Katrin; Heitmann, Anna; Schicht, Sabine; Ndiaye, El Hadji; Watson, Mick; Castelli, Ilaria; Brennan, Benjamin; Elliott, Richard M; Diallo, Mawlouth; Sall, Amadou A; Failloux, Anna-Bella; Schnettler, Esther; Kohl, Alain; Becker, Stefanie C

2017-01-01

The emerging bunyavirus Rift Valley fever virus (RVFV) is transmitted to humans and livestock by a large number of mosquito species. RNA interference (RNAi) has been characterized as an important innate immune defense mechanism used by mosquitoes to limit replication of positive-sense RNA flaviviruses and togaviruses; however, little is known about its role against negative-strand RNA viruses such as RVFV. We show that virus-specific small RNAs are produced in infected mosquito cells, in Drosophila melanogaster cells, and, most importantly, also in RVFV vector mosquitoes. By addressing the production of small RNAs in adult Aedes sp. and Culex quinquefasciatus mosquitoes, we showed the presence of virus-derived Piwi-interacting RNAs (piRNAs) not only in Aedes sp. but also in C. quinquefasciatus mosquitoes, indicating that antiviral RNA interference in C. quinquefasciatus mosquitoes is similar to the described activities of RNAi in Aedes sp. mosquitoes. We also show that these have antiviral activity, since silencing of RNAi pathway effectors enhances viral replication. Moreover, our data suggest that RVFV does not encode a suppressor of RNAi. These findings point toward a significant role of RNAi in the control of RVFV in mosquitoes. IMPORTANCE Rift Valley fever virus (RVFV; Phlebovirus , Bunyaviridae ) is an emerging zoonotic mosquito-borne pathogen of high relevance for human and animal health. Successful strategies of intervention in RVFV transmission by its mosquito vectors and the prevention of human and veterinary disease rely on a better understanding of the mechanisms that govern RVFV-vector interactions. Despite its medical importance, little is known about the factors that govern RVFV replication, dissemination, and transmission in the invertebrate host. Here we studied the role of the antiviral RNA interference immune pathways in the defense against RVFV in natural vector mosquitoes and mosquito cells and draw comparisons to the model insect Drosophila melanogaster . We found that RVFV infection induces both the exogenous small interfering RNA (siRNA) and piRNA pathways, which contribute to the control of viral replication in insects. Furthermore, we demonstrate the production of virus-derived piRNAs in Culex quinquefasciatus mosquitoes. Understanding these pathways and the targets within them offers the potential of the development of novel RVFV control measures in vector-based strategies.

RNA Interference Restricts Rift Valley Fever Virus in Multiple Insect Systems

PubMed Central

Jansen, Stephanie; Fall, Gamou; Lorenzen, Stephan; Rudolf, Martin; Huber, Katrin; Heitmann, Anna; Schicht, Sabine; Ndiaye, El Hadji; Watson, Mick; Castelli, Ilaria; Elliott, Richard M.; Diallo, Mawlouth; Sall, Amadou A.; Failloux, Anna-Bella; Schnettler, Esther

2017-01-01

ABSTRACT The emerging bunyavirus Rift Valley fever virus (RVFV) is transmitted to humans and livestock by a large number of mosquito species. RNA interference (RNAi) has been characterized as an important innate immune defense mechanism used by mosquitoes to limit replication of positive-sense RNA flaviviruses and togaviruses; however, little is known about its role against negative-strand RNA viruses such as RVFV. We show that virus-specific small RNAs are produced in infected mosquito cells, in Drosophila melanogaster cells, and, most importantly, also in RVFV vector mosquitoes. By addressing the production of small RNAs in adult Aedes sp. and Culex quinquefasciatus mosquitoes, we showed the presence of virus-derived Piwi-interacting RNAs (piRNAs) not only in Aedes sp. but also in C. quinquefasciatus mosquitoes, indicating that antiviral RNA interference in C. quinquefasciatus mosquitoes is similar to the described activities of RNAi in Aedes sp. mosquitoes. We also show that these have antiviral activity, since silencing of RNAi pathway effectors enhances viral replication. Moreover, our data suggest that RVFV does not encode a suppressor of RNAi. These findings point toward a significant role of RNAi in the control of RVFV in mosquitoes. IMPORTANCE Rift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is an emerging zoonotic mosquito-borne pathogen of high relevance for human and animal health. Successful strategies of intervention in RVFV transmission by its mosquito vectors and the prevention of human and veterinary disease rely on a better understanding of the mechanisms that govern RVFV-vector interactions. Despite its medical importance, little is known about the factors that govern RVFV replication, dissemination, and transmission in the invertebrate host. Here we studied the role of the antiviral RNA interference immune pathways in the defense against RVFV in natural vector mosquitoes and mosquito cells and draw comparisons to the model insect Drosophila melanogaster. We found that RVFV infection induces both the exogenous small interfering RNA (siRNA) and piRNA pathways, which contribute to the control of viral replication in insects. Furthermore, we demonstrate the production of virus-derived piRNAs in Culex quinquefasciatus mosquitoes. Understanding these pathways and the targets within them offers the potential of the development of novel RVFV control measures in vector-based strategies. PMID:28497117

Age- and bite-structured models for vector-borne diseases.

PubMed

Rock, K S; Wood, D A; Keeling, M J

2015-09-01

The biology and behaviour of biting insects is a vitally important aspect in the spread of vector-borne diseases. This paper aims to determine, through the use of mathematical models, what effect incorporating vector senescence and realistic feeding patterns has on disease. A novel model is developed to enable the effects of age- and bite-structure to be examined in detail. This original PDE framework extends previous age-structured models into a further dimension to give a new insight into the role of vector biting and its interaction with vector mortality and spread of disease. Through the PDE model, the roles of the vector death and bite rates are examined in a way which is impossible under the traditional ODE formulation. It is demonstrated that incorporating more realistic functions for vector biting and mortality in a model may give rise to different dynamics than those seen under a more simple ODE formulation. The numerical results indicate that the efficacy of control methods that increase vector mortality may not be as great as predicted under a standard host-vector model, whereas other controls including treatment of humans may be more effective than previously thought. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Germline Transformation of Drosophila Virilis Mediated by the Transposable Element Hobo

PubMed Central

Lozovskaya, E. R.; Nurminsky, D. I.; Hartl, D. L.; Sullivan, D. T.

1996-01-01

A laboratory strain of Drosophila virilis was genetically transformed with a hobo vector carrying the miniwhite cassette using a helper plasmid with an hsp70-driven hobo transposase-coding sequence. The rate of transformation was 0.5% per fertile G0 animal. Three transgenic insertions were cloned and characterized and found to be authentic hobo insertions. These results, together with the known wide-spread distribution of hobo in diverse insect species, suggest that hobo and related transposable elements may be of considerable utility in the germline transformation of insects other than D. melanogaster. PMID:8770594

Gene drive systems for insect disease vectors.

PubMed

Sinkins, Steven P; Gould, Fred

2006-06-01

The elegant mechanisms by which naturally occurring selfish genetic elements, such as transposable elements, meiotic drive genes, homing endonuclease genes and Wolbachia, spread at the expense of their hosts provide some of the most fascinating and remarkable subjects in evolutionary genetics. These elements also have enormous untapped potential to be used in the control of some of the world's most devastating diseases. Effective gene drive systems for spreading genes that can block the transmission of insect-borne pathogens are much needed. Here we explore the potential of natural gene drive systems and discuss the artificial constructs that could be envisaged for this purpose.

The Anopheles innate immune system in the defense against malaria infection

PubMed Central

Clayton, April M.; Dong, Yuemei; Dimopoulos, George

2014-01-01

The multifaceted innate immune system of insects is capable of fighting infection by a variety of pathogens including those causing human malaria. Malaria transmission by the Anopheles mosquito depends on the Plasmodium parasite’s successful completion of its lifecycle in the insect vector, a process that involves interactions with several tissues and cell types as well as with the mosquito’s innate immune system. This review will discuss our current understanding of the Anopheles mosquito’s innate immune responses against the malaria parasite Plasmodium and the influence of the insect’s intestinal microbiota on parasite infection. PMID:23988482

Density-dependent host choice by disease vectors: epidemiological implications of the ideal free distribution.

PubMed

Basáñez, María-Gloria; Razali, Karina; Renz, Alfons; Kelly, David

2007-03-01

The proportion of vector blood meals taken on humans (the human blood index, h) appears as a squared term in classical expressions of the basic reproduction ratio (R(0)) for vector-borne infections. Consequently, R(0) varies non-linearly with h. Estimates of h, however, constitute mere snapshots of a parameter that is predicted, from evolutionary theory, to vary with vector and host abundance. We test this prediction using a population dynamics model of river blindness assuming that, before initiation of vector control or chemotherapy, recorded measures of vector density and human infection accurately represent endemic equilibrium. We obtain values of h that satisfy the condition that the effective reproduction ratio (R(e)) must equal 1 at equilibrium. Values of h thus obtained decrease with vector density, decrease with the vector:human ratio and make R(0) respond non-linearly rather than increase linearly with vector density. We conclude that if vectors are less able to obtain human blood meals as their density increases, antivectorial measures may not lead to proportional reductions in R(0) until very low vector levels are achieved. Density dependence in the contact rate of infectious diseases transmitted by insects may be an important non-linear process with implications for their epidemiology and control.

Diversity of Scolytinae (Coleoptera: Curculionidae) attracted to avocado, lychee, and essential oil lures

USDA-ARS?s Scientific Manuscript database

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae), is an exotic wood-boring insect that vectors laurel wilt, a lethal vascular disease of trees in the Lauraceae, including avocado (Persea americana) and native Persea species (redbay, swampbay). As part...

Survey and molecular detection of phytoplasmas associated with potato in Romania and southern Russia

USDA-ARS?s Scientific Manuscript database

In recent years, emerging phytoplasma diseases of potato (Solanum tuberosum L.) have increasingly become important in central and eastern Europe. Accurate identification of phytoplasmas and their insect vectors is essential to developing effective management strategies for diseases caused by these p...

The phloem-sap feeding mealybug (Ferrisia virgata) carries 'Candidatus Liberibacter asiaticus' populations without transmitting disease

USDA-ARS?s Scientific Manuscript database

Candidatus Liberibacter asiaticus (Las) is the primary causal agent of huanglongbing (HLB), the most devastating disease of citrus worldwide. Currently the known insect vectors of the HLB-associated bacteria are three species of psyllids, Diaphorina citri (Hemiptera: Sternorrhyncha: Psyllidae), Trio...

[Climate change - a pioneer for the expansion of canine vector-borne diseases?].

PubMed

Krämer, F; Mencke, N

2011-01-01

Vector-transmitted diseases are one of the major contributors to the global burden of disease in humans and animals. Climate change is consistently held responsible for the spread of parasitic acarid and insect vectors such as ticks, fleas, sand flies and mosquitoes, and their transmitted pathogens (in the case of the dog the so-called canine vector-borne diseases [CVBD]). Currently, there is only insufficient data available to prove whether climate change is a major driving force for vector and disease expansion, but the evidence is growing. Other reasons, such as ecological, demographic and socio-economic factors, e.g. pet travel into and pet import from endemic areas, also play a role in this development. Apart from all the controversial discussion of the factors leading to vector and disease expansion, preventative measures should include dog owners' education as they are responsible for individual parasite protection as well as for the minimisation of adverse risk behaviour, e.g. regarding pet travel. Broad-spectrum vector control should be practised by using parasiticides that repel and kill blood feeders in order to minimize the risk of CVBD-pathogen transmission.

Plant and Insect Viruses in Managed and Natural Environments: Novel and Neglected Transmission Pathways.

PubMed

Jones, Roger A C

2018-01-01

The capacity to spread by diverse transmission pathways enhances a virus' ability to spread effectively and survive when circumstances change. This review aims to improve understanding of how plant and insect viruses spread through natural and managed environments by drawing attention to 12 novel or neglected virus transmission pathways whose contribution is underestimated. For plant viruses, the pathways reviewed are vertical and horizontal transmission via pollen, and horizontal transmission by parasitic plants, natural root grafts, wind-mediated contact, chewing insects, and contaminated water or soil. For insect viruses, they are transmission by plants serving as passive "vectors," arthropod vectors, and contamination of pollen and nectar. Based on current understanding of the spatiotemporal dynamics of virus spread, the likely roles of each pathway in creating new primary infection foci, enlarging previously existing infection foci, and promoting generalized virus spread are estimated. All pathways except transmission via parasitic plants, root grafts, and wind-mediated contact transmission are likely to produce new primary infection foci. All 12 pathways have the capability to enlarge existing infection foci, but only to a limited extent when spread occurs via virus-contaminated soil or vertical pollen transmission. All pathways except those via parasitic plant, root graft, contaminated soil, and vertical pollen transmission likely contribute to generalized virus spread, but to different extents. For worst-case scenarios, where mixed populations of host species occur under optimal virus spread conditions, the risk that host species jumps or virus emergence events will arise is estimated to be "high" for all four insect virus pathways considered, and, "very high" or "moderate" for plant viruses transmitted by parasitic plant and root graft pathways, respectively. To establish full understanding of virus spread and thereby optimize effective virus disease management, it is important to examine all transmission pathways potentially involved, regardless of whether the virus' ecology is already presumed to be well understood or otherwise. © 2018 Elsevier Inc. All rights reserved.

A spatial model with pulsed releases to compare strategies for the sterile insect technique applied to the mosquito Aedes aegypti.

PubMed

Oléron Evans, Thomas P; Bishop, Steven R

2014-08-01

We present a simple mathematical model to replicate the key features of the sterile insect technique (SIT) for controlling pest species, with particular reference to the mosquito Aedes aegypti, the main vector of dengue fever. The model differs from the majority of those studied previously in that it is simultaneously spatially explicit and involves pulsed, rather than continuous, sterile insect releases. The spatially uniform equilibria of the model are identified and analysed. Simulations are performed to analyse the impact of varying the number of release sites, the interval between pulsed releases and the overall volume of sterile insect releases on the effectiveness of SIT programmes. Results show that, given a fixed volume of available sterile insects, increasing the number of release sites and the frequency of releases increases the effectiveness of SIT programmes. It is also observed that programmes may become completely ineffective if the interval between pulsed releases is greater that a certain threshold value and that, beyond a certain point, increasing the overall volume of sterile insects released does not improve the effectiveness of SIT. It is also noted that insect dispersal drives a rapid recolonisation of areas in which the species has been eradicated and we argue that understanding the density dependent mortality of released insects is necessary to develop efficient, cost-effective SIT programmes. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Insect Responses to Linearly Polarized Reflections: Orphan Behaviors Without Neural Circuits.

PubMed

Heinloth, Tanja; Uhlhorn, Juliane; Wernet, Mathias F

2018-01-01

The e-vector orientation of linearly polarized light represents an important visual stimulus for many insects. Especially the detection of polarized skylight by many navigating insect species is known to improve their orientation skills. While great progress has been made towards describing both the anatomy and function of neural circuit elements mediating behaviors related to navigation, relatively little is known about how insects perceive non-celestial polarized light stimuli, like reflections off water, leaves, or shiny body surfaces. Work on different species suggests that these behaviors are not mediated by the "Dorsal Rim Area" (DRA), a specialized region in the dorsal periphery of the adult compound eye, where ommatidia contain highly polarization-sensitive photoreceptor cells whose receptive fields point towards the sky. So far, only few cases of polarization-sensitive photoreceptors have been described in the ventral periphery of the insect retina. Furthermore, both the structure and function of those neural circuits connecting to these photoreceptor inputs remain largely uncharacterized. Here we review the known data on non-celestial polarization vision from different insect species (dragonflies, butterflies, beetles, bugs and flies) and present three well-characterized examples for functionally specialized non-DRA detectors from different insects that seem perfectly suited for mediating such behaviors. Finally, using recent advances from circuit dissection in Drosophila melanogaster , we discuss what types of potential candidate neurons could be involved in forming the underlying neural circuitry mediating non-celestial polarization vision.

Trypanosomatidae: Phytomonas detection in plants and phytophagous insects by PCR amplification of a genus-specific sequence of the spliced leader gene.

PubMed

Serrano, M G; Nunes, L R; Campaner, M; Buck, G A; Camargo, E P; Teixeira, M M

1999-03-01

In this paper we describe a method for the detection of Phytomonas spp. from plants and phytophagous insects using the PCR technique by targeting a genus-specific sequence of the spliced leader (SL) gene. PCR amplification of DNA from 48 plant and insect isolates previously classified as Phytomonas by morphological, biochemical, and molecular criteria resulted in all cases in a 100-bp fragment that hybridized with the Phytomonas-specific spliced leader-derived probe SL3'. Moreover, this Phytomonas-specific PCR could also detect Phytomonas spp. in crude preparations of naturally infected plants and insects. This method shows no reaction with any other trypanosomatid genera or with plant and insect host DNA, revealing it to be able to detect Phytomonas spp. from fruit, latex, or phloem of various host plants as well as from salivary glands and digestive tubes of several species of insect hosts. Results demonstrated that SLPCR is a simple, fast, specific, and sensitive method that can be applied to the diagnosis of Phytomonas among cultured trypanosomatids and directly in plants and putative vector insects. Therefore, the method was shown to be a very specific and sensitive tool for diagnosis of Phytomonas without the need for isolation, culture, and DNA extraction of flagellates, a feature that is very convenient for practical and epidemiological purposes. Copyright 1999 Academic Press.

Flexible metabolism in Metarhizium anisopliae and Beauveria bassiana: role of the glyoxylate cycle during insect pathogenesis.

PubMed

Padilla-Guerrero, Israel Enrique; Barelli, Larissa; González-Hernández, Gloria Angélica; Torres-Guzmán, Juan Carlos; Bidochka, Michael J

2011-01-01

Insect pathogenic fungi such as Metarhizium anisopliae and Beauveria bassiana have an increasing role in the control of agricultural insect pests and vectors of human diseases. Many of the virulence factors are well studied but less is known of the metabolism of these fungi during the course of insect infection or saprobic growth. Here, we assessed enzyme activity and gene expression in the central carbon metabolic pathway, including isocitrate dehydrogenase, aconitase, citrate synthase, malate synthase (MLS) and isocitrate lyase (ICL), with particular attention to the glyoxylate cycle when M. anisopliae and B. bassiana were grown under various conditions. We observed that ICL and MLS, glyoxylate cycle intermediates, were upregulated during growth on 2-carbon compounds (acetate and ethanol) as well as in insect haemolymph. We fused the promoter of the M. anisopliae ICL gene (Ma-icl) to a marker gene (mCherry) and showed that Ma-icl was upregulated when M. anisopliae was grown in the presence of acetate. Furthermore, Ma-icl was upregulated when fungi were engulfed by insect haemocytes as well as during appressorium formation. Addition of the ICL inhibitor 3-nitroproprionate delayed conidial germination and inhibited appressorium formation. These results show that these insect pathogenic fungi have a flexible metabolism that includes the glyoxylate cycle as an integral part of germination, pathogenesis and saprobic growth.

Insect-plant-pathogen interactions as shaped by future climate: effects on biology, distribution, and implications for agriculture.

PubMed

Trębicki, Piotr; Dáder, Beatriz; Vassiliadis, Simone; Fereres, Alberto

2017-12-01

Carbon dioxide (CO 2 ) is the main anthropogenic gas which has drastically increased since the industrial revolution, and current concentrations are projected to double by the end of this century. As a consequence, elevated CO 2 is expected to alter the earths' climate, increase global temperatures and change weather patterns. This is likely to have both direct and indirect impacts on plants, insect pests, plant pathogens and their distribution, and is therefore problematic for the security of future food production. This review summarizes the latest findings and highlights current knowledge gaps regarding the influence of climate change on insect, plant and pathogen interactions with an emphasis on agriculture and food production. Direct effects of climate change, including increased CO 2 concentration, temperature, patterns of rainfall and severe weather events that impact insects (namely vectors of plant pathogens) are discussed. Elevated CO 2 and temperature, together with plant pathogen infection, can considerably change plant biochemistry and therefore plant defense responses. This can have substantial consequences on insect fecundity, feeding rates, survival, population size, and dispersal. Generally, changes in host plant quality due to elevated CO 2 (e.g., carbon to nitrogen ratios in C3 plants) negatively affect insect pests. However, compensatory feeding, increased population size and distribution have also been reported for some agricultural insect pests. This underlines the importance of additional research on more targeted, individual insect-plant scenarios at specific locations to fully understand the impact of a changing climate on insect-plant-pathogen interactions. © 2017 Institute of Zoology, Chinese Academy of Sciences.

The Gut Microbiome of the Vector Lutzomyia longipalpis Is Essential for Survival of Leishmania infantum.

PubMed

Kelly, Patrick H; Bahr, Sarah M; Serafim, Tiago D; Ajami, Nadim J; Petrosino, Joseph F; Meneses, Claudio; Kirby, John R; Valenzuela, Jesus G; Kamhawi, Shaden; Wilson, Mary E

2017-01-17

The vector-borne disease leishmaniasis, caused by Leishmania species protozoa, is transmitted to humans by phlebotomine sand flies. Development of Leishmania to infective metacyclic promastigotes in the insect gut, a process termed metacyclogenesis, is an essential prerequisite for transmission. Based on the hypothesis that vector gut microbiota influence the development of virulent parasites, we sequenced midgut microbiomes in the sand fly Lutzomyia longipalpis with or without Leishmania infantum infection. Sucrose-fed sand flies contained a highly diverse, stable midgut microbiome. Blood feeding caused a decrease in microbial richness that eventually recovered. However, bacterial richness progressively decreased in L. infantum-infected sand flies. Acetobacteraceae spp. became dominant and numbers of Pseudomonadaceae spp. diminished coordinately as the parasite underwent metacyclogenesis and parasite numbers increased. Importantly, antibiotic-mediated perturbation of the midgut microbiome rendered sand flies unable to support parasite growth and metacyclogenesis. Together, these data suggest that the sand fly midgut microbiome is a critical factor for Leishmania growth and differentiation to its infective state prior to disease transmission. Leishmania infantum, a parasitic protozoan causing fatal visceral leishmaniasis, is transmitted to humans through the bite of the sand fly Lutzomyia longipalpis Development of the parasite to its virulent metacyclic state occurs in the sand fly gut. In this study, the microbiota within the Lu. longipalpis midgut was delineated by 16S ribosomal DNA (rDNA) sequencing, revealing a highly diverse community composition that lost diversity as parasites developed to their metacyclic state and increased in abundance in infected flies. Perturbing sand fly gut microbiota with an antibiotic cocktail, which alone had no effect on either the parasite or the fly, arrested both the development of virulent parasites and parasite expansion. These findings indicate the importance of bacterial commensals within the insect vector for the development of virulent pathogens, and raise the possibility that impairing the microbial composition within the vector might represent a novel approach to control of vector-borne diseases. Copyright © 2017 Kelly et al.

Evolutionary and dispersal history of Triatoma infestans, main vector of Chagas disease, by chromosomal markers.

PubMed

Panzera, Francisco; Ferreiro, María J; Pita, Sebastián; Calleros, Lucía; Pérez, Ruben; Basmadjián, Yester; Guevara, Yenny; Brenière, Simone Frédérique; Panzera, Yanina

2014-10-01

Chagas disease, one of the most important vector-borne diseases in the Americas, is caused by Trypanosoma cruzi and transmitted to humans by insects of the subfamily Triatominae. An effective control of this disease depends on elimination of vectors through spraying with insecticides. Genetic research can help insect control programs by identifying and characterizing vector populations. In southern Latin America, Triatoma infestans is the main vector and presents two distinct lineages, known as Andean and non-Andean chromosomal groups, that are highly differentiated by the amount of heterochromatin and genome size. Analyses with nuclear and mitochondrial sequences are not conclusive about resolving the origin and spread of T. infestans. The present paper includes the analyses of karyotypes, heterochromatin distribution and chromosomal mapping of the major ribosomal cluster (45S rDNA) to specimens throughout the distribution range of this species, including pyrethroid-resistant populations. A total of 417 specimens from seven different countries were analyzed. We show an unusual wide rDNA variability related to number and chromosomal position of the ribosomal genes, never before reported in species with holocentric chromosomes. Considering the chromosomal groups previously described, the ribosomal patterns are associated with a particular geographic distribution. Our results reveal that the differentiation process between both T. infestans chromosomal groups has involved significant genomic reorganization of essential coding sequences, besides the changes in heterochromatin and genomic size previously reported. The chromosomal markers also allowed us to detect the existence of a hybrid zone occupied by individuals derived from crosses between both chromosomal groups. Our genetic studies support the hypothesis of an Andean origin for T. infestans, and suggest that pyrethroid-resistant populations from the Argentinean-Bolivian border are most likely the result of recent secondary contact between both lineages. We suggest that vector control programs should make a greater effort in the entomological surveillance of those regions with both chromosomal groups to avoid rapid emergence of resistant individuals. Copyright © 2014 Elsevier B.V. All rights reserved.

Pyrethroid resistance persists after ten years without usage against Aedes aegypti in governmental campaigns: Lessons from São Paulo State, Brazil.

PubMed

Macoris, Maria de Lourdes; Martins, Ademir Jesus; Andrighetti, Maria Teresa Macoris; Lima, José Bento Pereira; Valle, Denise

2018-03-01

Aedes aegypti, vector of dengue, chikungunya and Zika viruses, is found at high densities in tropical urban areas. The dissemination of this vector is partially the consequence of failures in current vector control methods, still mainly relying upon insecticides. In the State of São Paulo (SP), Brazil, public health managers employed pyrethroids against Ae. aegypti adults from 1989 to 2000, when a robust insecticide resistance monitoring system detected resistance to pyrethroids in several Ae. aegypti populations. However, pyrethroids are also the preferred compounds engaged in household applications due to their rapid knockdown effect, lower toxicity to mammals and less irritating smell. We evaluated pyrethroid resistance in Ae. aegypti populations over the course of a decade, from 2004 to 2015, after interruption of pyrethroid public applications in SP. Qualitative bioassays with papers impregnated with a deltamethrin diagnostic dose (DD) performed with insects from seven SP municipalities and evaluated yearly from 2006 to 2014, detected resistance in most of the cases. Quantitative bioassays were also carried out with four populations in 2011, suggesting a positive correlation between resistance level and survivorship in the DD bioassays. Biochemical tests conducted with seven insect populations in 2006 and 2015, detected increasing metabolic alterations of all major classes of detoxifying enzymes, mostly of mixed function oxidases. Genotyping of the voltage-gated sodium channel (AaNaV, the pyrethroid target-site) with a TaqMan real time PCR based technique was performed from 2004 to 2014 in all seven localities. The two kdr mutations, Val1016Ile and Phe1534Cys, known to be spread throughout Brazil, were always present with a severe decrease of the susceptible allele over time. These results are discussed in the context of public and domestic insecticide use, the necessity of implementation of a strong integrated vector control strategy and the conceptual misunderstanding between 'vector control' and 'chemical control of vectors'.

Potential impact of climate change on emerging vector-borne and other infections in the UK.

PubMed

Baylis, Matthew

2017-12-05

Climate is one of several causes of disease emergence. Although half or more of infectious diseases are affected by climate it appears to be a relatively infrequent cause of human disease emergence. Climate mostly affects diseases caused by pathogens that spend part of their lifecycle outside of the host, exposed to the environment. The most important routes of transmission of climate sensitive diseases are by arthropod (insect and tick) vectors, in water and in food. Given the sensitivity of many diseases to climate, it is very likely that at least some will respond to future climate change. In the case of vector-borne diseases this response will include spread to new areas. Several vector-borne diseases have emerged in Europe in recent years; these include vivax malaria, West Nile fever, dengue fever, Chikungunya fever, leishmaniasis, Lyme disease and tick-borne encephalitis. The vectors of these diseases are mosquitoes, sand flies and ticks. The UK has endemic mosquito species capable of transmitting malaria and probably other pathogens, and ticks that transmit Lyme disease. The UK is also threatened by invasive mosquito species known to be able to transmit West Nile, dengue, chikungunya and Zika, and sand flies that spread leishmaniasis. Warmer temperatures in the future will increase the suitability of the UK's climate for these invasive species, and increase the risk that they may spread disease. While much attention is on invasive species, it is important to recognize the threat presented by native species too. Proposed actions to reduce the future impact of emerging vector-borne diseases in the UK include insect control activity at points of entry of vehicles and certain goods, wider surveillance for mosquitoes and sand flies, research into the threat posed by native species, increased awareness of the medical profession of the threat posed by specific diseases, regular risk assessments, and increased preparedness for the occurrence of a disease emergency.

Pyrethroid resistance persists after ten years without usage against Aedes aegypti in governmental campaigns: Lessons from São Paulo State, Brazil

PubMed Central

Andrighetti, Maria Teresa Macoris; Lima, José Bento Pereira; Valle, Denise

2018-01-01

Background Aedes aegypti, vector of dengue, chikungunya and Zika viruses, is found at high densities in tropical urban areas. The dissemination of this vector is partially the consequence of failures in current vector control methods, still mainly relying upon insecticides. In the State of São Paulo (SP), Brazil, public health managers employed pyrethroids against Ae. aegypti adults from 1989 to 2000, when a robust insecticide resistance monitoring system detected resistance to pyrethroids in several Ae. aegypti populations. However, pyrethroids are also the preferred compounds engaged in household applications due to their rapid knockdown effect, lower toxicity to mammals and less irritating smell. Methodology/Principal findings We evaluated pyrethroid resistance in Ae. aegypti populations over the course of a decade, from 2004 to 2015, after interruption of pyrethroid public applications in SP. Qualitative bioassays with papers impregnated with a deltamethrin diagnostic dose (DD) performed with insects from seven SP municipalities and evaluated yearly from 2006 to 2014, detected resistance in most of the cases. Quantitative bioassays were also carried out with four populations in 2011, suggesting a positive correlation between resistance level and survivorship in the DD bioassays. Biochemical tests conducted with seven insect populations in 2006 and 2015, detected increasing metabolic alterations of all major classes of detoxifying enzymes, mostly of mixed function oxidases. Genotyping of the voltage-gated sodium channel (AaNaV, the pyrethroid target-site) with a TaqMan real time PCR based technique was performed from 2004 to 2014 in all seven localities. The two kdr mutations, Val1016Ile and Phe1534Cys, known to be spread throughout Brazil, were always present with a severe decrease of the susceptible allele over time. Conclusions/Significance These results are discussed in the context of public and domestic insecticide use, the necessity of implementation of a strong integrated vector control strategy and the conceptual misunderstanding between 'vector control' and 'chemical control of vectors'. PMID:29601580

Field performance of a genetically engineered strain of pink bollworm.

PubMed

Simmons, Gregory S; McKemey, Andrew R; Morrison, Neil I; O'Connell, Sinead; Tabashnik, Bruce E; Claus, John; Fu, Guoliang; Tang, Guolei; Sledge, Mickey; Walker, Adam S; Phillips, Caroline E; Miller, Ernie D; Rose, Robert I; Staten, Robert T; Donnelly, Christl A; Alphey, Luke

2011-01-01

Pest insects harm crops, livestock and human health, either directly or by acting as vectors of disease. The Sterile Insect Technique (SIT)--mass-release of sterile insects to mate with, and thereby control, their wild counterparts--has been used successfully for decades to control several pest species, including pink bollworm, a lepidopteran pest of cotton. Although it has been suggested that genetic engineering of pest insects provides potential improvements, there is uncertainty regarding its impact on their field performance. Discrimination between released and wild moths caught in monitoring traps is essential for estimating wild population levels. To address concerns about the reliability of current marking methods, we developed a genetically engineered strain of pink bollworm with a heritable fluorescent marker, to improve discrimination of sterile from wild moths. Here, we report the results of field trials showing that this engineered strain performed well under field conditions. Our data show that attributes critical to SIT in the field--ability to find a mate and to initiate copulation, as well as dispersal and persistence in the release area--were comparable between the genetically engineered strain and a standard strain. To our knowledge, these represent the first open-field experiments with a genetically engineered insect. The results described here provide encouragement for the genetic control of insect pests.

[Ovarian development and analysis of mating effects on ovary maturation of Diaphorina citri Kuwayama (Hemiptera: Psyllidae)].

PubMed

Dossi, Fábio C A; Cônsoli, Fernando L

2010-01-01

As many other insects with a restricted diet, the citrus psyllid Diaphorina citri Kuwayama, which vector the causing agent of the Huanglongbing, the bacteria Candidatus Liberibacter spp., is intimately associated with symbiotic microorganisms. These mutualist symbionts play a key role on their host nutritional ecology, and are vertically transmitted to the progeny. However, despite the role symbionts play on host development and reproduction, and the growing opportunities of exploitation of the association insect-symbiont to control insect vectored-pathogens, there are very few studies on the host reproductive biology and on the symbiont transovarial transmission. Therefore, we aimed at analyzing the ovary development during D. citri adulthood, and at verifying for the mating requirement as a trigger to initiate ovary development. Newly-emerged D. citri females were grouped as virgin or mated and ovary development was observed during adulthood. Newly-emerged females have immature ovaries, and ovaries remain without any mature eggs until females mate. Once female mates, the vitellogenesis synthesis and uptake are estimulated, and oocytes are quickly developed. Oocytes maturation in ovarioles is metachronic, with only one oocyte developing at a time in each oogenic cycle. Morphological observations of the reproductive system including the ovaries and spermatheca, after the first cluster of eggs is laid, indicated D. citri is polyandrous, and may require multiple mating to develop additional oogenic maturation cycles.

Lutzomyia umbratilis from an area south of the Negro River is refractory to in vitro interaction with Leishmania guyanensis.

PubMed

Soares, Rodrigo Pedro; Nogueira, Paula Monalisa; Secundino, Nágila Francinete; Marialva, Eric Fabrício; Ríos-Velásquez, Cláudia Maria; Pessoa, Felipe Arley Costa

2018-03-01

Lutzomyia umbratilis, the vector for Leishmania guyanensis in northern South America, has been found naturally infected with L. guyanensis only in areas north of the Negro and Amazon rivers. While populations of this sand fly species are also found in areas south of these rivers, these populations have never been reported to be infected and/or transmitting L. guyanensis. However, no studies on the corresponding host-parasite interactions are available. This study evaluated the interaction between Lu. guyanensis promastigotes and field-collected Lu. umbratilis sand flies from Rio Preto da Eva and Manacapuru, which are located to the north and south, respectively, of the Negro River. Procyclic and metacyclic attachment was quantified using an in vitro system. Low attachment of parasites to the midguts of insects collected from Manacapuru was detected. Conversely, greater binding of metacyclic parasites was observed in the midguts of insects collected from Rio Preto da Eva, and this attachment was more pronounced than that observed for procyclics (p < 0.03). The Lu. umbratilis population from an area south of the Negro River has lower in vitro interaction with L. guyanensis. The higher attachment of L. guyanensis to midguts of insects from Rio Preto da Eva may suggest better vector competence. These findings are in accordance with previously reported epidemiological information of American cutaneous leishmaniasis (ACL) transmission in the Amazon.

Bioactivities of Ketones Terpenes: Antifungal Effect on F. verticillioides and Repellents to Control Insect Fungal Vector, S. zeamais.

PubMed

Pizzolitto, Romina P; Herrera, Jimena M; Zaio, Yesica P; Dambolena, Jose S; Zunino, Maria P; Gallucci, Mauro N; Zygadlo, Julio A

2015-11-12

Maize is one the most important staple foods in the world. However, numerous pests, such as fungal pathogens, e.g., Fusarium verticillioides, and insects, such as Sitophlilus zeamais, attack maize grains during storage. Many F. verticillioides strains produce fumonisins, one of the most important mycotoxin that causes toxic effects on human and animal health. This situation is aggravated by the insect fungal vector, Sitophlilus zeamais, which contributes to the dispersal of fungal spores, and through feeding damage, provide entry points for fungal infections. The aim of this study was to evaluate in vitro bioassays, the antifungal activity on F. verticillioides M3125 and repellent effects against S. zeamais of ketone terpenes. In addition, we performed Quantitative structure-activity relationship (Q-SAR) studies between physico-chemical properties of ketone terpenes and the antifungal effect. Thymoquinone was the most active compound against F. verticillioides (Minimum Inhibitory Concentration, MIC: 0.87) affecting the lag phase and the growth rate showing a total inhibition of growth at concentration higher than 2 mM (p < 0.05). The Q-SAR model revealed that the antifungal activity of ketone compounds is related to the electronic descriptor, Pi energy. Thymoquinone showed a strong repellent effect (-77.8 ± 8.5, p < 0.001) against S. zeamais. These findings make an important contribution to the search for new compounds to control two stored pests of maize.

Triatomicidal effect of new spot-on formulations applied to poultry in semi-field conditions.

PubMed

Juan, Laura W; Seccacini, Emilia A; Zerba, Eduardo N; Canale, Delmi; Alzogaray, Raúl A

2013-01-01

Chagas disease is an endemic disease affecting ten million people in the American continent. Produced by a parasite transmitted by triatomine insects, the main actions for reducing the incidence of this disease are focused on the control of insect vectors. This type of control has produced highly effective results within rural homes, but not in peridomestic areas (kitchens, warehouses, hen houses and other buildings not attached to the houses). The object of the present study was to assess the triatomicidal effect of new spot-on formulations developed by our laboratory in a semi-rural environment. The active ingredients of the formulations were β-cypermethrin, pyriproxyfen, or β-cypermethrin + pyriproxyfen. All formulations were applied to hens and tested in miniature replicas of rural households where experimental populations of Triatoma infestans, the main vector of Chagas disease in Argentina, had been previously released. The experimental populations exposed to formulations containing β-cypermethrin or β-cypermethrin + pyriproxyfen were noticeably reduced compared to non-treated control groups. However, no differences were observed between the effects produced by β-cypermethrin alone and β-cypermethrin + pyriproxyfen. Pyriproxyfen alone produced no significant reduction in the experimental populations of T. infestans. These results suggest that spot-on application of β-cypermethrin could be a useful complementary tool for controlling triatomine insects in the peridomestic areas of rural homes.

Decreasing Global Transcript Levels over Time Suggest that Phytoplasma Cells Enter Stationary Phase during Plant and Insect Colonization

PubMed Central

Pacifico, D.; Galetto, L.; Rashidi, M.; Abbà, S.; Palmano, S.; Firrao, G.; Bosco, D.

2015-01-01

To highlight different transcriptional behaviors of the phytoplasma in the plant and animal host, expression of 14 genes of “Candidatus Phytoplasma asteris,” chrysanthemum yellows strain, was investigated at different times following the infection of a plant host (Arabidopsis thaliana) and two insect vector species (Macrosteles quadripunctulatus and Euscelidius variegatus). Target genes were selected among those encoding antigenic membrane proteins, membrane transporters, secreted proteins, and general enzymes. Transcripts were detected for all analyzed genes in the three hosts; in particular, those encoding the antigenic membrane protein Amp, elements of the mechanosensitive channel, and two of the four secreted proteins (SAP54 and TENGU) were highly accumulated, suggesting that they play important roles in phytoplasma physiology during the infection cycle. Most transcripts were present at higher abundance in the plant host than in the insect hosts. Generally, transcript levels of the selected genes decreased significantly during infection of A. thaliana and M. quadripunctulatus but were more constant in E. variegatus. Such decreases may be explained by the fact that only a fraction of the phytoplasma population was transcribing, while the remaining part was aging to a stationary phase. This strategy might improve long-term survival, thereby increasing the likelihood that the pathogen may be acquired by a vector and/or inoculated to a healthy plant. PMID:25636844

Identifying environmental drivers of insect phenology across space and time: Culicoides in Scotland as a case study.

PubMed

Searle, K R; Blackwell, A; Falconer, D; Sullivan, M; Butler, A; Purse, B V

2013-04-01

Interpreting spatial patterns in the abundance of species over time is a fundamental cornerstone of ecological research. For many species, this type of analysis is hampered by datasets that contain a large proportion of zeros, and data that are overdispersed and spatially autocorrelated. This is particularly true for insects, for which abundance data can fluctuate from zero to many thousands in the space of weeks. Increasingly, an understanding of the ways in which environmental variation drives spatial and temporal patterns in the distribution, abundance and phenology of insects is required for management of pests and vector-borne diseases. In this study, we combine the use of smoothing techniques and generalised linear mixed models to relate environmental drivers to key phenological patterns of two species of biting midges, Culicoides pulicaris and C. impunctatus, of which C. pulicaris has been implicated in transmission of bluetongue in Europe. In so doing, we demonstrate analytical tools for linking the phenology of species with key environmental drivers, despite using a relatively small dataset containing overdispersed and zero-inflated data. We demonstrate the importance of landcover and climatic variables in determining the seasonal abundance of these two vector species, and highlight the need for more empirical data on the effects of temperature and precipitation on the life history traits of palearctic Culicoides spp. in Europe.

Where do these bugs come from? Phenotypic structure of Triatoma infestans populations after control interventions in the Argentine Chaco

PubMed Central

Gaspe, María Sol; Provecho, Yael Mariana; Piccinali, Romina Valeria; Gürtler/, Ricardo Esteban

2015-01-01

House re-invasion by native triatomines after insecticide-based control campaigns represents a major threat for Chagas disease vector control. We conducted a longitudinal intervention study in a rural section (Area III, 407 houses) of Pampa del Indio, northeastern Argentina, and used wing geometric morphometry to compare pre-spray and post-spray (re-infestant bugs) Triatoma infestans populations. The community-wide spraying with pyrethroids reduced the prevalence of house infestation by T. infestans from 31.9% to < 1% during a four-year follow-up, unlike our previous studies in the neighbouring Area I. Two groups of bug collection sites differing in wing shape variables before interventions (including 221 adults from 11 domiciles) were used as a reference for assigning 44 post-spray adults. Wing shape variables from post-spray, high-density bug colonies and pre-spray groups were significantly different, suggesting that re-infestant insects had an external origin. Insects from one house differed strongly in wing shape variables from all other specimens. A further comparison between insects from both areas supported the existence of independent re-infestation processes within the same district. These results point to local heterogeneities in house re-infestation dynamics and emphasise the need to expand the geographic coverage of vector surveillance and control operations to the affected region. PMID:25946158

Plants traditionally used as mosquito repellents and the implication for their use in vector control.

PubMed

Tisgratog, Rungarun; Sanguanpong, Unchalee; Grieco, John P; Ngoen-Kluan, Ratchadawan; Chareonviriyaphap, Theeraphap

2016-05-01

Numerous plants with insect repelling properties are native to the tropics where they are produced for a wide range of medicinal purposes. In Thailand, these native plant species have a history of use for personal protection against biting insects. From our investigation we identified 37 plant species within 14 plant families that showed some mosquito repellent properties. Of these, 9 plant species were characterized using an excito-repellency test system against several Thai mosquito species. Results from these studies revealed that five essential oils extracted from plants demonstrated promising insect repellent activity. These active ingredients show promise for further development into formulations that may serve as alternatives to DEET or possibly be used as natural bio-pesticides to kill mosquitoes. Copyright © 2016 Elsevier B.V. All rights reserved.

Insect-specific viruses and their potential impact on arbovirus transmission.

PubMed

Vasilakis, Nikos; Tesh, Robert B

2015-12-01

Arthropod-borne viruses (arboviruses) are the causative agents of significant morbidity and mortality among humans and animals globally. In the past few years, the widespread adoption of next generation sequencing and metagenomics has led to a new era of virus discovery, where many novel viruses have been documented, exhibiting a restricted host-range in mosquitoes. They represent a wide-range of insect-specific viruses within the families of Bunyaviridae, Flaviviridae, Mesoniviridae, Reoviridae, Rhabdoviridae, Togaviridae, and the newly recognized taxon of Negeviruses. Collectively, their discovery has opened new vistas about the extent of viral diversity and evolution, their influence on vector competence and ability of their insect hosts to transmit human pathogens (e.g. arboviruses), and their potential development as biological control agents or novel vaccine platforms. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection and typing of Xylella fastidiosa from glassy-winged sharpshooter for Pierce’s disease epidemiology

USDA-ARS?s Scientific Manuscript database

Epidemiology of Pierce’s disease of grape, caused by the bacterial pathogen Xylella fastidiosa (Xf), is largely dependent on populations of insect vectors such as the invasive glassy-winged sharpshooter (GWSS) (Homalodisca vitripennis). In the grape-growing regions of the southern San Joaquin Valley...

Acetylcholinesterase mutations and organophosphate resistance in sand flies and mosquitoes

USDA-ARS?s Scientific Manuscript database

Leishmaniasis is an insect-borne disease caused by several protozoan species in the genus Leishmania, which are vectored by sand fly species in the genera Phlebotomus or Lutzomyia, depending on the sand fly species geographic range. Sand fly bites and leishmaniasis significantly impacted U.S. milita...

Spray characterization of thermal fogging equipment typically used in vector control

USDA-ARS?s Scientific Manuscript database

The generation of insecticide laden fogs provides an effective method for controlling flying insects. One of the critical factors affecting the effectiveness of a thermal fogging application is the generation of droplets that will remain aloft in the fogging cloud and moves into the area where the ...

Vector-borne viruses of pulse crops, with a particular emphasis on North American cropping systems

USDA-ARS?s Scientific Manuscript database

Pulse crop production in the USA has increased dramatically over the past decade, in part due to their nutritional value and ability to form symbiotic associations with rhizobacteria that fix atmospheric nitrogen. There are several insect-transmitted viruses that are prevalent and periodically quite...

Cold Tolerance of Pityophthorus juglandis (Coleoptera: Scolytidae) From Northern California

Treesearch

Andrea R. Hefty; Steven J. Seybold; Brian H. Aukema; Robert C. Venette

2017-01-01

Winter survivorship of insects is determined by a combination of physiological, behavioral, and microhabitat characteristics. We characterized the cold tolerance of the walnut twig beetle, Pityophthorus juglandis Blackman, a domestic alien invasive bark beetle that vectors a phytopathogenic fungus. The beetle and fungus cause thousand cankers...

CAPA-gene products in the haematophagous sandfly Phlebotomus papatasi (Scopoli) - Vector for leishmaniasis disease

USDA-ARS?s Scientific Manuscript database

Sandflies (Phlebotominae, Nematocera, Diptera) are responsible for transmission of leishmaniasis and other protozoan-borne diseases in humans, and these insects depend on the regulation of water balance to cope with the sudden and enormous intake of blood over a very short time period. The sandfly ...

From rags to riches: insights from the first genomic sequence of a plant pathogenic bacterium

PubMed Central

Keen, Noel T; Korsi Dumenyo, C; Yang, Ching-Hong; Cooksey, Donald A

2000-01-01

The recently published genomic sequence of Xylella fastidiosa is the first for a free-living plant pathogen and provides clues to mechanisms of pathogenesis and survival in insect vectors. The sequence data should lead to improved control of this pathogen. PMID:11178244

Habitat Effects on Population Density and Movement of Insect Vectors of Xylella fastidiosa in California, USA

USDA-ARS?s Scientific Manuscript database

Xylella fastidiosa is a xylem-limited bacterium that causes disease in grapevines, almonds, citrus, pear, alfalfa, and many other economically important plants. In California, USA, the bacteria are transmitted by several species of leafhoppers including the cicadellids Draeculacephala minerva Ball a...

Micro-CT study of the anatomy of the Leafhopper Homalodisca vitripennis (Hemiptera: Cicadellidae)

USDA-ARS?s Scientific Manuscript database

A Digital Anatomy Library, DAL, was produced to the anatomy of the glassy-winged sharpshooter adult, Homalodisca vitripennis (Hemiptera: Cicadellidae), vector of bacteria which cause Pierce’s disease of grapevines. The insect anatomy was elucidated using a high resolution Bruker Skyscan 1172 micro t...

Electrophysiological responses of male and female Amyelois transitella antennae to pistachio and almond host plant volatiles

USDA-ARS?s Scientific Manuscript database

The polyphagous navel orangeworm, Amyelois transitella (Lepidoptera: Pyralidae), is a major insect pest of California tree nuts. The larvae of A. transitella feed on kernels inflicting damage and lowering nut kernel quality. Moreover, larvae vector aflatoxigenic aspergilli resulting in internationa...

Chapter 15. transforming lepidopteran insect cells for continuous recombinant protein expression

USDA-ARS?s Scientific Manuscript database

The baculovirus expression vector system (BEVS) is widely used to produce large quantities of recombinant proteins. However, yields of extracellular and membrane-bound proteins obtained with this system often are very low, possibly due to the adverse effects of baculovirus infection on the host ins...

Phytoplasmas and their insect vectors: Implications for date palm

USDA-ARS?s Scientific Manuscript database

Date palm is affected by a variety of plant diseases and those associated with phytoplasma presence are increasingly recognised as an emerging threat to the crop. Phytoplasmas are bacteria characterised by a small genome size and the lack of a cell wall. Unlike other bacteria, they are transmitted c...

A leucokinin mimic elicits aversive behavior in mosquito Aedes aegypti (L.) and inhibits the sugar taste neuron

USDA-ARS?s Scientific Manuscript database

Insect kinins (leucokinins) are multifunctional peptides acting as neurohormones and neurotransmitters. In females of the mosquito vector Aedes aegypti (L.), aedeskinins are known to stimulate fluid secretion from the renal organs (Malpighian tubules) and hindgut contractions by activating a G prot...

Host-pathogen interactions and genome evolution in two generalist and specialist microsporidian pathogens of mosquitoes

USDA-ARS?s Scientific Manuscript database

The adaptation of two distantly related microsporidia to their mosquito hosts was investigated. Edhazardia aedis is a specialist pathogen that infects Aedes aegypti, the main vector of dengue and yellow fever arboviruses. Vavraia culicis is a generalist pathogen of several insects including Anophele...

Promising Aedes aegypti repellent chemotypes identified through integrated QSAE, virtual screening, synthesis, and bioassay

USDA-ARS?s Scientific Manuscript database

Molecular field topology analysis, scaffold hopping, and molecular docking were used as complementary computational tools for the design of repellents for Aedes aegypti, the insect vector for yellow fever, West Nile fever, and dengue fever. A large number of analogues were evaluated by virtual scree...

Ovicidal efficacy of Ageratina adenophora (Family: Asteraceae) against Anopheles stephensi (Diptera: Culicidae)

USDA-ARS?s Scientific Manuscript database

Mosquitoes are blood-feeding insects and serve as the most important vectors for spreading human diseases such as malaria, yellow fever, dengue fever, and filariasis. The continued use of synthetic insecticides has resulted in resistance in mosquitoes. Synthetic insecticides are toxic and affect the...

Effect of sulfuryl fluoride on the pinewood nematode in pine wood

Treesearch

L. David Dwinell; E. Thoms; S. Prabhakaran

2003-01-01

The pinewood nematode (PUTN) (Bursaphelenchus xylophilus), the causal agent of pine wilt disease, has been intercepted in pine chips, unseasoned pine lumber, and wood packing material (WPM). Likewise, the PWN's insect vectors, Monochamus spp. (pine sawyers), have been found in pallets, crates and dunnage. The PWN, which is...

Epidemiology and Association of Four Insect-Vectored Viruses in Florida Watermelon

USDA-ARS?s Scientific Manuscript database

Whitefly-transmitted Squash vein yellowing virus (SqVYV), Cucurbit leaf crumple virus (CuLCrV), Cucurbit yellow stunting disorder virus (CYSDV) and aphid-transmitted Papaya ringspot virus type W (PRSV-W) have had serious impact on watermelon production in southwest and west-central Florida in the pa...

Program review of the USDA Center for Medical, Agricultural and Veterinary Entomology

USDA-ARS?s Scientific Manuscript database

The USDA-ARS Center for Medical, Agricultural and Veterinary Entomology (CMAVE) has a history that starts in 1932 in Orlando to develop methods to control mosquitoes, including malaria vectors under conditions simulating those of the south Pacific jungles, and other insects affecting man and animals...

Investigations with misting systems, barrier treatments, and space sprays operationalized with a mobile pesticide app

USDA-ARS?s Scientific Manuscript database

US military operations in field conditions face significant negative impacts on mission readiness from disease-vector and nuisance populations of filth flies, mosquitoes, and sand flies. Although measures are in place to protect personnel in the field from these insect threats, experiences from rece...

Matrimony vine and potato psyllid in the Pacific Northwest: a worrisome marriage?

USDA-ARS?s Scientific Manuscript database

Managing zebra chip disease in the potato growing regions of Washington, Oregon, and Idaho is complicated by confusion about the source of the insect vector (potato psyllid) as it colonizes potato fields in these growing regions. Not knowing where the psyllid is before arriving in Washington potato...

Gut content analysis of a phloem-feeding insect, Bactericera cockerelli (Sulc) (Hemiptera: Triozidae)

USDA-ARS?s Scientific Manuscript database

Potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) is a key pest of potato (Solanum tuberosum L., Solanales: Solanaceae) and a vector of "Candidatus Liberibacter solanacearum," the pathogen associated with zebra chip disease. In addition to its presence on cultivated crops, the p...

Jack bean (Canavalia ensiformis) urease induces eicosanoid-modulated hemocyte aggregation in the Chagas' disease vector Rhodnius prolixus.

PubMed

Defferrari, M S; da Silva, R; Orchard, I; Carlini, C R

2014-05-01

Ureases are multifunctional proteins that display biological activities independently of their enzymatic function, such as induction of exocytosis and insecticidal effects. Rhodnius prolixus, a major vector of Chagas' disease, is a model for studies on the entomotoxicity of jack bean urease (JBU). We have previously shown that JBU induces the production of eicosanoids in isolated tissues of R. prolixus. In insects, the immune response comprises cellular and humoral reactions, and is centrally modulated by eicosanoids. Cyclooxygenase products signal immunity in insects, mainly cellular reactions, such as hemocyte aggregation. In searching for a link between JBU's toxic effects and immune reactions in insects, we have studied the effects of this toxin on R. prolixus hemocytes. JBU triggers aggregation of hemocytes after injection into the hemocoel and when applied to isolated cells. On in vitro assays, the eicosanoid synthesis inhibitors dexamethasone (phospholipase A2 indirect inhibitor) and indomethacin (cyclooxygenase inhibitor) counteracted JBU's effect, indicating that eicosanoids, more specifically cyclooxygenase products, are likely to mediate the aggregation response. Contrarily, the inhibitors esculetin and baicalein were inactive, suggesting that lipoxygenase products are not involved in JBU's effect. Extracellular calcium was also necessary for JBU's effect, in agreement to other cell models responsive to ureases. A progressive darkening of the medium of JBU-treated hemocytes was observed, suggestive of a humoral response. JBU was immunolocalized in the cultured cells upon treatment along with cytoskeleton damage. The highest concentration of JBU tested on cultured cells also led to nuclei aggregation of adherent hemocytes. This is the first time urease has been shown to affect insect hemocytes, contributing to our understanding of the entomotoxic mechanisms of action of this protein. Copyright © 2014 Elsevier Ltd. All rights reserved.

Phytoplasma Effector SAP54 Hijacks Plant Reproduction by Degrading MADS-box Proteins and Promotes Insect Colonization in a RAD23-Dependent Manner

PubMed Central

MacLean, Allyson M.; Orlovskis, Zigmunds; Kowitwanich, Krissana; Zdziarska, Anna M.; Angenent, Gerco C.; Immink, Richard G. H.; Hogenhout, Saskia A.

2014-01-01

Pathogens that rely upon multiple hosts to complete their life cycles often modify behavior and development of these hosts to coerce them into improving pathogen fitness. However, few studies describe mechanisms underlying host coercion. In this study, we elucidate the mechanism by which an insect-transmitted pathogen of plants alters floral development to convert flowers into vegetative tissues. We find that phytoplasma produce a novel effector protein (SAP54) that interacts with members of the MADS-domain transcription factor (MTF) family, including key regulators SEPALLATA3 and APETALA1, that occupy central positions in the regulation of floral development. SAP54 mediates degradation of MTFs by interacting with proteins of the RADIATION SENSITIVE23 (RAD23) family, eukaryotic proteins that shuttle substrates to the proteasome. Arabidopsis rad23 mutants do not show conversion of flowers into leaf-like tissues in the presence of SAP54 and during phytoplasma infection, emphasizing the importance of RAD23 to the activity of SAP54. Remarkably, plants with SAP54-induced leaf-like flowers are more attractive for colonization by phytoplasma leafhopper vectors and this colonization preference is dependent on RAD23. An effector that targets and suppresses flowering while simultaneously promoting insect herbivore colonization is unprecedented. Moreover, RAD23 proteins have, to our knowledge, no known roles in flower development, nor plant defence mechanisms against insects. Thus SAP54 generates a short circuit between two key pathways of the host to alter development, resulting in sterile plants, and promotes attractiveness of these plants to leafhopper vectors helping the obligate phytoplasmas reproduce and propagate (zombie plants). PMID:24714165

Selection of Reference Genes for Expression Studies in Diaphorina citri (Hemiptera: Liviidae).

PubMed

Bassan, Meire Menezes; Angelotti-Mendonc A, Je Ssika; Alves, Gustavo Rodrigues; Yamamoto, Pedro Takao; Moura O Filho, Francisco de Assis Alves

2017-12-05

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is considered the main vector of the bacteria associated with huanglongbing, a very serious disease that has threatened the world citrus industry. The absence of efficient control management protocols, including a lack of resistant cultivars, has led to the development of different approaches to study this pathosystem. The production of resistant genotypes relies on D. citri gene expression analyses by RT-qPCR to assess control of the vector population. High-quality, reliable RT-qPCR analyses depend upon proper reference gene selection and validation. However, adequate D. citri reference genes have not yet been identified. In the present study, we evaluated the genes EF 1-α, ACT, GAPDH, RPL7, RPL17, and TUB as candidate reference genes for this insect. Gene expression stability was evaluated using the mathematical algorithms deltaCt, NormFinder, BestKeeper, and geNorm, at five insect developmental stages, grown on two different plant hosts [Citrus sinensis (L.) Osbeck (Sapindales: Rutaceae) and Murraya paniculata (L.) Jack (Sapindales: Rutaceae)]. The final gene ranking was calculated using RefFinder software, and the V-ATPase-A gene was selected for validation. According to our results, two reference genes are recommended when different plant hosts and developmental stages are considered. Considering gene expression studies in D. citri grown on M. paniculata, regardless of the insect developmental stage, GAPDH and RPL7 have the best fit as reference genes in RT-qPCR analyses, whereas GAPDH and EF 1-α are recommended as reference genes in insect studies using C. sinensis. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Urbanization, land tenure security and vector-borne Chagas disease.

PubMed

Levy, Michael Z; Barbu, Corentin M; Castillo-Neyra, Ricardo; Quispe-Machaca, Victor R; Ancca-Juarez, Jenny; Escalante-Mejia, Patricia; Borrini-Mayori, Katty; Niemierko, Malwina; Mabud, Tarub S; Behrman, Jere R; Naquira-Velarde, Cesar

2014-08-22

Modern cities represent one of the fastest growing ecosystems on the planet. Urbanization occurs in stages; each stage characterized by a distinct habitat that may be more or less susceptible to the establishment of disease vector populations and the transmission of vector-borne pathogens. We performed longitudinal entomological and epidemiological surveys in households along a 1900 × 125 m transect of Arequipa, Peru, a major city of nearly one million inhabitants, in which the transmission of Trypanosoma cruzi, the aetiological agent of Chagas disease, by the insect vector Triatoma infestans, is an ongoing problem. The transect spans a cline of urban development from established communities to land invasions. We find that the vector is tracking the development of the city, and the parasite, in turn, is tracking the dispersal of the vector. New urbanizations are free of vector infestation for decades. T. cruzi transmission is very recent and concentrated in more established communities. The increase in land tenure security during the course of urbanization, if not accompanied by reasonable and enforceable zoning codes, initiates an influx of construction materials, people and animals that creates fertile conditions for epidemics of some vector-borne diseases. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Vector independent transmission of the vector-borne bluetongue virus.

PubMed

van der Sluijs, Mirjam Tineke Willemijn; de Smit, Abraham J; Moormann, Rob J M

2016-01-01

Bluetongue is an economically important disease of ruminants. The causative agent, Bluetongue virus (BTV), is mainly transmitted by insect vectors. This review focuses on vector-free BTV transmission, and its epizootic and economic consequences. Vector-free transmission can either be vertical, from dam to fetus, or horizontal via direct contract. For several BTV-serotypes, vertical (transplacental) transmission has been described, resulting in severe congenital malformations. Transplacental transmission had been mainly associated with live vaccine strains. Yet, the European BTV-8 strain demonstrated a high incidence of transplacental transmission in natural circumstances. The relevance of transplacental transmission for the epizootiology is considered limited, especially in enzootic areas. However, transplacental transmission can have a substantial economic impact due to the loss of progeny. Inactivated vaccines have demonstrated to prevent transplacental transmission. Vector-free horizontal transmission has also been demonstrated. Since direct horizontal transmission requires close contact of animals, it is considered only relevant for within-farm spreading of BTV. The genetic determinants which enable vector-free transmission are present in virus strains circulating in the field. More research into the genetic changes which enable vector-free transmission is essential to better evaluate the risks associated with outbreaks of new BTV serotypes and to design more appropriate control measures.

Flight behavior and performance of Rhodnius pallescens (Hemiptera: Reduviidae) on a tethered flight mill.

PubMed

Castro, Lauren A; Peterson, Jennifer K; Saldana, Azael; Perea, Milixa Y; Calzada, Jose E; Pineda, Vanessa; Dobson, Andrew P; Gottdenker, Nicole L

2014-09-01

ABSTRACT Flight dispersal of the triatomine bug species Rhodnius pallescens Barber, the principal vector of Chagas disease in Panama, is an important mechanism for spreading Trypanosoma cruzi, causative agent of Chagas disease. This study measures R. pallescens flight performance using a tethered flight mill both when uninfected, and when infected with T. cruzi or Trypanosoma rangeli. Forty-four out of the 48 (91.7%) insects initiated flight across all treatments, and trypanosome infection did not significantly impact flight initiation. Insects from all treatments flew a cumulative distance ranging from 0.5 to 5 km before fatiguing. The median cumulative distance flown before insect fatigue was higher in T. cruzi- and T. rangeli-infected insects than in control insects; however, this difference was not statistically significant. There was a positive relationship between parasite load ingested and time until flight initiation in T. rangeli-infected bugs, and T. rangeli- and T. cruzi-infected females flew significantly faster than males at different time points. These novel findings allow for a better understanding of R. pallescens dispersal ability and peridomestic management strategies for the prevention of Chagas disease in Panama.

The NS3 protein of Rice hoja blanca tenuivirus suppresses RNA silencing in plant and insect hosts by efficiently binding both siRNAs and miRNAs

PubMed Central

Hemmes, Hans; Lakatos, Lóránt; Goldbach, Rob; Burgyán, József; Prins, Marcel

2007-01-01

RNA silencing plays a key role in antiviral defense as well as in developmental processes in plants and insects. Negative strand RNA viruses such as the plant virus Rice hoja blanca tenuivirus (RHBV) replicate in plants and in their insect transmission vector. Like most plant-infecting viruses, RHBV encodes an RNA silencing suppressor, the NS3 protein, and here it is demonstrated that this protein is capable of suppressing RNA silencing in both plants and insect cells. Biochemical analyses showed that NS3 efficiently binds siRNA as well as miRNA molecules. Binding of NS3 is greatly influenced by the size of small RNA molecules, as 21 nucleotide (nt) siRNA molecules are bound > 100 times more efficiently than 26 nt species. Competition assays suggest that the activity of NS3 is based on binding to siRNAs prior to strand separation during the assembly of the RNA-induced silencing complex. In addition, NS3 has a high affinity for miRNA/miRNA* duplexes, indicating that its activity might also interfere with miRNA-regulated gene expression in both insects and plants. PMID:17513697

Constant-dose microwave irradiation of insect pupae

NASA Astrophysics Data System (ADS)

Olsen, Richard G.

Pupae of the yellow mealworm Tenebrio molitor L. were subjected to microwave irradiation for 1.5-24 hours at power density levels adjusted to produce a total dosage of approximately 1123 J/g in each insect for every experiment. Insects without visible blemishes were exposed in a standing wave irradiation system such that half of them were exposed in the plane of maximum electric field (E field) and the other half were exposed in the plane of maximum magnetic field (H field). Both E field and H field insects exhibited nearly the same specific absorption rate (SAR) for pupal orientation parallel to the magnetic field vector at 5.95 GHz. Irradiations were conducted both with and without the use of a ventilating fan to control the temperature rise in the irradiation chamber. Abnormal development as a result of the microwave exposure was seen only in the high-power, short-duration experiment without chamber ventilation. This result suggests a thermal interaction mechanism for explanation of observed microwave-induced abnormalities. A study of the time course of the average temperature rise in the irradiated insects indicates that teratological effects for this configuration have a temperature threshold of approximately 40°C.

Tyrosine Detoxification Is an Essential Trait in the Life History of Blood-Feeding Arthropods.

PubMed

Sterkel, Marcos; Perdomo, Hugo D; Guizzo, Melina G; Barletta, Ana Beatriz F; Nunes, Rodrigo D; Dias, Felipe A; Sorgine, Marcos H F; Oliveira, Pedro L

2016-08-22

Blood-feeding arthropods are vectors of infectious diseases such as dengue, Zika, Chagas disease, and malaria [1], and vector control is essential to limiting disease spread. Because these arthropods ingest very large amounts of blood, a protein-rich meal, huge amounts of amino acids are produced during digestion. Previous work on Rhodnius prolixus, a vector of Chagas disease, showed that, among all amino acids, only tyrosine degradation enzymes were overexpressed in the midgut compared to other tissues [2]. Here we demonstrate that tyrosine detoxification is an essential trait in the life history of blood-sucking arthropods. We found that silencing Rhodnius tyrosine aminotransferase (TAT) and 4-hydroxyphenylpyruvate dioxygenase (HPPD), the first two enzymes of the phenylalanine/tyrosine degradation pathway, caused the death of insects after a blood meal. This was confirmed by using the HPPD inhibitor mesotrione, which selectively killed hematophagous arthropods but did not affect non-hematophagous insects. In addition, mosquitoes and kissing bugs died after feeding on mice that had previously received a therapeutic effective oral dose (1 mg/kg) of nitisinone, another HPPD inhibitor used in humans for the treatment of tyrosinemia type I [3]. These findings indicate that HPPD (and TAT) can be a target for the selective control of blood-sucking disease vector populations. Because HPPD inhibitors are extensively used as herbicides and in medicine, these compounds may provide an alternative less toxic to humans and more environmentally friendly than the conventional neurotoxic insecticides that are currently used, with the ability to affect only hematophagous arthropods. Copyright © 2016 Elsevier Ltd. All rights reserved.

Vector development and vitellogenin determine the transovarial transmission of begomoviruses.

PubMed

Wei, Jing; He, Ya-Zhou; Guo, Qi; Guo, Tao; Liu, Yin-Quan; Zhou, Xue-Ping; Liu, Shu-Sheng; Wang, Xiao-Wei

2017-06-27

The majority of plant viruses are transmitted by insect vectors between hosts, and transovarial transmission of viruses from vector parents to offspring has great significance to their epidemiology. Begomoviruses are transmitted by the whitefly Bemisia tabaci in a circulative manner and are maintained through a plant-insect-plant cycle. Other routes of begomovirus transmission are not clearly known. Here, we report that transovarial transmission from female whiteflies to offspring often happens for one begomovirus, Tomato yellow leaf curl virus (TYLCV), and may have contributed significantly to its global spread. We found that TYLCV entry of the reproductive organ of its vector mainly depended on the developmental stage of the whitefly ovary, and the transovarial transmission of TYLCV to offspring increased with whitefly adult age. The specific interaction between virus coat protein (CP) and whitefly vitellogenin (Vg) was vital for virus entry into whitefly ovary. When knocking down the expression of Vg, the entry of TYLCV into ovary was inhibited and the transovarial transmission efficiency decreased. In contrast, another begomovirus, Papaya leaf curl China virus (PaLCuCNV), CP did not interact with whitefly Vg, and PaLCuCNV could not be transovarially transmitted by whiteflies. We further showed that TYLCV could be maintained for at least two generations in the absence of virus-infected plants, and the adult progenies were able to infect healthy plants in both the laboratory and field. This study reports the transovarial transmission mechanism of begomoviruses, and it may help to explain the evolution and global spread of some begomoviruses.

More than one rabbit out of the hat: Radiation, transgenic and symbiont-based approaches for sustainable management of mosquito and tsetse fly populations.

PubMed

Bourtzis, Kostas; Lees, Rosemary Susan; Hendrichs, Jorge; Vreysen, Marc J B

2016-05-01

Mosquitoes (Diptera: Culicidae) and tsetse flies (Diptera: Glossinidae) are bloodsucking vectors of human and animal pathogens. Mosquito-borne diseases (malaria, filariasis, dengue, zika, and chikungunya) cause severe mortality and morbidity annually, and tsetse fly-borne diseases (African trypanosomes causing sleeping sickness in humans and nagana in livestock) cost Sub-Saharan Africa an estimated US$ 4750 million annually. Current reliance on insecticides for vector control is unsustainable: due to increasing insecticide resistance and growing concerns about health and environmental impacts of chemical control there is a growing need for novel, effective and safe biologically-based methods that are more sustainable. The integration of the sterile insect technique has proven successful to manage crop pests and disease vectors, particularly tsetse flies, and is likely to prove effective against mosquito vectors, particularly once sex-separation methods are improved. Transgenic and symbiont-based approaches are in development, and more advanced in (particularly Aedes) mosquitoes than in tsetse flies; however, issues around stability, sustainability and biosecurity have to be addressed, especially when considering population replacement approaches. Regulatory issues and those relating to intellectual property and economic cost of application must also be overcome. Standardised methods to assess insect quality are required to compare and predict efficacy of the different approaches. Different combinations of these three approaches could be integrated to maximise their benefits, and all have the potential to be used in tsetse and mosquito area-wide integrated pest management programmes. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Campylobacter jejuni in Musca domestica: An examination of survival and transmission potential in light of the innate immune responses of the house flies.

PubMed

Gill, Carson; Bahrndorff, Simon; Lowenberger, Carl

2017-08-01

The house fly, Musca domestica, has been implicated as a vector of Campylobacter spp., a major cause of human disease. Little is known whether house flies serve as biological amplifying hosts or mechanical vectors for Campylobacter jejuni. We investigated the period after C. jejuni had been ingested by house flies in which viable C. jejuni colonies could be isolated from whole bodies, the vomitus and the excreta of adult M. domestica and evaluated the activation of innate immune responses of house flies to ingested C. jejuni over time. C. jejuni could be cultured from infected houseflies soon after ingestion but no countable C. jejuni colonies were observed > 24 h postingestion. We detected viable C. jejuni in house fly vomitus and excreta up to 4 h after ingestion, but no viable bacteria were detected ≥ 8 h. Suppression subtractive hybridization identified pathogen-induced gene expression in the intestinal tracts of adult house flies 4-24 h after ingesting C. jejuni. We measured the expression of immune regulatory (thor, JNK, and spheroide) and effector (cecropin, diptericin, attacin, defensing, and lysozyme) genes in C. jejuni-infected and -uninfected house flies using quantitative real time PCR. Some house fly factor, or combination of factors, eliminates C. jejuni within 24 h postingestion. Because C. jejuni is not amplified within the body of the housefly, this insect likely serves as a mechanical vector rather than as a true biological, amplifying vector for C. jejuni, and adds to our understanding of insect-pathogen interactions. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Neem cake as a promising larvicide and adulticide against the rural malaria vector Anopheles culicifacies (Diptera: Culicidae): a HPTLC fingerprinting approach.

PubMed

Benelli, Giovanni; Chandramohan, Balamurugan; Murugan, Kadarkarai; Madhiyazhagan, Pari; Kovendan, Kalimuthu; Panneerselvam, Chellasamy; Dinesh, Devakumar; Govindarajan, Marimuthu; Higuchi, Akon; Toniolo, Chiara; Canale, Angelo; Nicoletti, Marcello

2017-05-01

Mosquitoes are insects of huge public health importance, since they act as vectors for important pathogens and parasites. Here, we focused on the possibility of using the neem cake in the fight against mosquito vectors. The neem cake chemical composition significantly changes among producers, as evidenced by our HPTLC (High performance thin layer chromatography) analyses of different marketed products. Neem cake extracts were tested to evaluate the ovicidal, larvicidal and adulticidal activity against the rural malaria vector Anopheles culicifacies. Ovicidal activity of both types of extracts was statistically significant, and 150 ppm completely inhibited egg hatching. LC 50 values were extremely low against fourth instar larvae, ranging from 1.321 (NM1) to 1.818 ppm (NA2). Adulticidal activity was also high, with LC 50 ranging from 3.015 (NM1) to 3.637 ppm (NM2). This study pointed out the utility of neem cake as a source of eco-friendly mosquitocides in Anopheline vector control programmes.

Bed Bugs (Cimex lectularius) as Vectors of Trypanosoma cruzi

PubMed Central

Salazar, Renzo; Castillo-Neyra, Ricardo; Tustin, Aaron W.; Borrini-Mayorí, Katty; Náquira, César; Levy, Michael Z.

2015-01-01

Populations of the common bed bug, Cimex lectularius, have recently undergone explosive growth. Bed bugs share many important traits with triatomine insects, but it remains unclear whether these similarities include the ability to transmit Trypanosoma cruzi, the etiologic agent of Chagas disease. Here, we show efficient and bidirectional transmission of T. cruzi between hosts and bed bugs in a laboratory environment. Most bed bugs that fed on experimentally infected mice acquired the parasite. A majority of previously uninfected mice became infected after a period of cohabitation with exposed bed bugs. T. cruzi was also transmitted to mice after the feces of infected bed bugs were applied directly to broken host skin. Quantitative bed bug defecation measures were similar to those of important triatomine vectors. Our findings suggest that the common bed bug may be a competent vector of T. cruzi and could pose a risk for vector-borne transmission of Chagas disease. PMID:25404068

Spatial distribution of an infectious disease in a small mammal community

NASA Astrophysics Data System (ADS)

Correa, Juana P.; Bacigalupo, Antonella; Fontúrbel, Francisco E.; Oda, Esteban; Cattan, Pedro E.; Solari, Aldo; Botto-Mahan, Carezza

2015-10-01

Chagas disease is a zoonosis caused by the parasite Trypanosoma cruzi and transmitted by insect vectors to several mammals, but little is known about its spatial epidemiology. We assessed the spatial distribution of T. cruzi infection in vectors and small mammals to test if mammal infection status is related to the proximity to vector colonies. During four consecutive years we captured and georeferenced the locations of mammal species and colonies of Mepraia spinolai, a restricted-movement vector. Infection status on mammals and vectors was evaluated by molecular techniques. To examine the effect of vector colonies on mammal infection status, we constructed an infection distance index using the distance between the location of each captured mammal to each vector colony and the average T. cruzi prevalence of each vector colony, weighted by the number of colonies assessed. We collected and evaluated T. cruzi infection in 944 mammals and 1976 M. spinolai. We found a significant effect of the infection distance index in explaining their infection status, when considering all mammal species together. By examining the most abundant species separately, we found this effect only for the diurnal and gregarious rodent Octodon degus. Spatially explicit models involving the prevalence and location of infected vectors and hosts had not been reported previously for a wild disease.

Host structural carbohydrate induces vector transmission of a bacterial plant pathogen.

PubMed

Killiny, Nabil; Almeida, Rodrigo P P

2009-12-29

Many insect-borne pathogens have complex life histories because they must colonize both hosts and vectors for successful dissemination. In addition, the transition from host to vector environments may require changes in gene expression before the pathogen's departure from the host. Xylella fastidiosa is a xylem-limited plant-pathogenic bacterium transmitted by leafhopper vectors that causes diseases in a number of economically important plants. We hypothesized that factors of host origin, such as plant structural polysaccharides, are important in regulating X. fastidiosa gene expression and mediating vector transmission of this pathogen. The addition of pectin and glucan to a simple defined medium resulted in dramatic changes in X. fastidiosa's phenotype and gene-expression profile. Cells grown in the presence of pectin became more adhesive than in other media tested. In addition, the presence of pectin and glucan in media resulted in significant changes in the expression of several genes previously identified as important for X. fastidiosa's pathogenicity in plants. Furthermore, vector transmission of X. fastidiosa was induced in the presence of both polysaccharides. Our data show that host structural polysaccharides mediate gene regulation in X. fastidiosa, which results in phenotypic changes required for vector transmission. A better understanding of how vector-borne pathogens transition from host to vector, and vice versa, may lead to previously undiscovered disease-control strategies.

Sex pheromones and their impact on pest management.

PubMed

Witzgall, Peter; Kirsch, Philipp; Cork, Alan

2010-01-01

The idea of using species-specific behavior-modifying chemicals for the management of noxious insects in agriculture, horticulture, forestry, stored products, and for insect vectors of diseases has been a driving ambition through five decades of pheromone research. Hundreds of pheromones and other semiochemicals have been discovered that are used to monitor the presence and abundance of insects and to protect plants and animals against insects. The estimated annual production of lures for monitoring and mass trapping is on the order of tens of millions, covering at least 10 million hectares. Insect populations are controlled by air permeation and attract-and-kill techniques on at least 1 million hectares. Here, we review the most important and widespread practical applications. Pheromones are increasingly efficient at low population densities, they do not adversely affect natural enemies, and they can, therefore, bring about a long-term reduction in insect populations that cannot be accomplished with conventional insecticides. A changing climate with higher growing season temperatures and altered rainfall patterns makes control of native and invasive insects an increasingly urgent challenge. Intensified insecticide use will not provide a solution, but pheromones and other semiochemicals instead can be implemented for sustainable area-wide management and will thus improve food security for a growing population. Given the scale of the challenges we face to mitigate the impacts of climate change, the time is right to intensify goal-oriented interdisciplinary research on semiochemicals, involving chemists, entomologists, and plant protection experts, in order to provide the urgently needed, and cost-effective technical solutions for sustainable insect management worldwide.

[Triatominae and Cactaceae: a risk for the transmission of the American trypanosomiasis in the peridomicilary space (Northeast Brazil)].

PubMed

Emperaire, L; Romaña, C A

2006-06-01

Field observations carried in semi-arid Brazil Northeast point out the frequent association, in the peridomiciliary space, between a cactus, Cereus jamacaru, the occurrence of nests in its branches and the occurrence of two species of insects vectors of Trypanosoma cruzi, pathogenic agent of Chagas disease: Rhodnius neglectus and Triatoma pseudomaculata. The analysis of the architectural variables of this Cactaceae shows that the presence of nests, and thus of insects, depends on the traditional practices of management of this cactus. This study underlines the relevance of an integrated approach of the ecology of Triatominae for the identification of factors of risk.

Stability and Activities of Antibiotics Produced during Infection of the Insect Galleria mellonella by Two Isolates of Xenorhabdus nematophilus

PubMed Central

Maxwell, Philip W.; Chen, Genhui; Webster, John M.; Dunphy, Gary B.

1994-01-01

Xenorhabdus nematophilus subsp. dutki, an entomopathogenic bacterium, is vectored by steinernematid nematodes into insects, where it produces broad-spectrum antibiotics. The use of the nematode-bacterium complex against soil-dwelling pest insects could introduce antibiotics into the soil via the dead insect fragments during the emergence phase of the nematodes. Studies on the stability and activities of these antibiotics produced in the insect Galleria mellonella may contribute to assessing the possible impact of antibiotics on soil bacteria. Two isolates of X. nematophilus subsp. dutki (isolates GI and SFU) produced xenocoumacins 1 and 2 in cadavers of G. mellonella larvae in a 1:1 ratio. Total xenocoumacin 1 and 2 production was 800 ng/200 mg (wet weight) of insect tissue for the GI isolate. Antibiotic activity of water extracts from insects that had been infected with X. nematophilus was stable at 60°C for 1 h and after repeated freeze-thaw cycles. The antibiotic titer of extracts held at 27°C declined by day 10. The spectrum of bacterial species killed by antibiotics produced in insect cadavers varied with the isolate of X. nematophilus. Levels of antibiotic activity were greater in vivo than in tryptic soy broth, which may represent a nutrient effect. The bacterial isolate, culture condition, and presence of nematodes influenced the total antibiotic production in vivo. However, the levels of activity were not correlated with bacterial levels in the different growth environments. Insect cadavers with antibiotic activity transiently lowered the numbers of the bacteria in the soil, the extent of decline varying with the strain of X. nematophilus and the time of sampling. PMID:16349198

Seasonal abundance and spatio-temporal distribution of dominant xylem fluid-feeding hemiptera in vineyards of central Texas and surrounding habitats.

PubMed

Lauzière, Isabelle; Sheather, Simon; Mitchell, Forrest

2008-08-01

A survey of xylem fluid-feeding insects (Hemiptera) exhibiting potential for transmission of Xylella fastidiosa, the bacterium causing Pierce's disease of grapevine, was conducted from 2004 to 2006 in the Hill Country grape growing region of central Texas. Nineteen insect species were collected from yellow sticky traps. Among these, two leafhoppers and one spittlebug comprised 94.57% of the xylem specialists caught in this region. Homalodisca vitripennis (Germar), Graphocephala versuta (Say), and Clastoptera xanthocephala Germar trap catches varied significantly over time, with greatest counts usually recorded between May or June and August and among localities. A comparison of insect counts from traps placed inside and outside vineyards indicated that G. versuta is always more likely captured on the vegetation adjacent to the vineyard. C. xanthocephala was caught inside the vineyard during the summer. Between October and December, the natural habitat offers more suitable host plants, and insects were absent from the vineyards after the first freezes. H. vitripennis was caught in higher numbers inside the vineyards throughout the grape vegetative season. However, insects were also caught in the habitat near the affected crop throughout the year, and residual populations overwintering near vineyards were also recorded. This study shed new light on the fauna of xylem fluid-feeding insects of Texas. These results also provide critical information to vineyard managers for timely applications of insecticides before insect feeding and vectoring to susceptible grapevines.

Transmission of Ehrlichia risticii, the agent of Potomac horse fever, using naturally infected aquatic insects and helminth vectors: preliminary report.

PubMed

Madigan, J E; Pusterla, N; Johnson, E; Chae, J S; Pusterla, J B; Derock, E; Lawler, S P

2000-07-01

Ehrlichia risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in snail secretions and in aquatic insects. Based on these findings, horses could conceivably be exposed to E. risticii by skin penetration with infected cercariae, by ingestion of infected cercariae in water or via metacercariae in a second intermediate host, such as an aquatic insect. In order to test this hypothesis, horses were challenged with infectious snail secretions and aquatic insects collected from a PHF endemic region in northern California. Two horses stood with their front feet in water harbouring E. risticii-infected cercariae, 2 horses drank water harbouring E. risticii-infected cercariae, and 6 horses were fed pools of different aquatic insects harbouring E. risticii-infected metacercariae. In this preliminary study, only the one horse infected orally with mature caddisflies (Dicosmoecus gilvipes) developed the clinical and haematological disease syndrome of PHF. The agent was isolated from the blood of the infected horse in a continuous cell line and identified as E. risticii by characterisation of the 16S rRNA gene. Therefore, E. risticii is maintained in nature in a complex aquatic ecosystem and transmission to horses can occur through accidental ingestion of insects such as caddisflies containing infected metacercariae. At present, the small number of horses used in this study does not exclude other insects and free trematode stages as potential sources of infection.

Insect Responses to Linearly Polarized Reflections: Orphan Behaviors Without Neural Circuits

PubMed Central

Heinloth, Tanja; Uhlhorn, Juliane; Wernet, Mathias F.

2018-01-01

The e-vector orientation of linearly polarized light represents an important visual stimulus for many insects. Especially the detection of polarized skylight by many navigating insect species is known to improve their orientation skills. While great progress has been made towards describing both the anatomy and function of neural circuit elements mediating behaviors related to navigation, relatively little is known about how insects perceive non-celestial polarized light stimuli, like reflections off water, leaves, or shiny body surfaces. Work on different species suggests that these behaviors are not mediated by the “Dorsal Rim Area” (DRA), a specialized region in the dorsal periphery of the adult compound eye, where ommatidia contain highly polarization-sensitive photoreceptor cells whose receptive fields point towards the sky. So far, only few cases of polarization-sensitive photoreceptors have been described in the ventral periphery of the insect retina. Furthermore, both the structure and function of those neural circuits connecting to these photoreceptor inputs remain largely uncharacterized. Here we review the known data on non-celestial polarization vision from different insect species (dragonflies, butterflies, beetles, bugs and flies) and present three well-characterized examples for functionally specialized non-DRA detectors from different insects that seem perfectly suited for mediating such behaviors. Finally, using recent advances from circuit dissection in Drosophila melanogaster, we discuss what types of potential candidate neurons could be involved in forming the underlying neural circuitry mediating non-celestial polarization vision. PMID:29615868

Alien Insects in Italy: Comparing Patterns from the Regional to European Level

PubMed Central

Inghilesi, Alberto F.; Mazza, Giuseppe; Cervo, Rita; Gherardi, Francesca; Sposimo, Paolo; Tricarico, Elena; Zapparoli, Marzio

2013-01-01

The introduction of species outside their native range contributes to the loss of biodiversity, alters the structure and functioning of ecosystems, and damages economy and human health. Insects are one of the taxa with the highest frequency of introduction due to their high diversity, biological properties, and close association with human activities. Here, the allodiversity of Italian entomofauna was analyzed, with a focus on Tuscany (Central Italy). A list of alien insects in Tuscany is included. The status of the alien entomofauna in Italy was updated. The number of alien insects amounts to 122 in Tuscany and 923 in Italy. An introduction rate of 98 species per decade was estimated in Italy. In Tuscany, alien insects belong to 10 orders, mostly Coleoptera (38%), Hemiptera (Sternorrhyncha and Auchenorrhyncha) (23%), and Hymenoptera (13%). They have been most often introduced through vegetable items (ornamental plants or crops). Most species come from the Nearctic region (26%) and are both phytophagous (63%) and amphigonic (80%). Differences and similarities in introduction patterns and in insect abundances across orders among regional, national, and European scales, also considering worldwide abundances, are discussed. Finally, a paucity of information regarding the negative impacts of many species, except for economic pests, phytosanitary threats, and vectors of disease, is underlined. A deeper understanding of the alien insects' ecological impact might help designate policies aimed at preventing further introductions and control the invasive populations of already established species. PMID:24219427

Pyrethroid Susceptibility Has Been Maintained in the Dengue Vector, Aedes aegypti (Diptera: Culicidae), in Queensland, Australia.

PubMed

Endersby-Harshman, Nancy M; Wuliandari, Juli Rochmijati; Harshman, Lawrence G; Frohn, Verena; Johnson, Brian J; Ritchie, Scott A; Hoffmann, Ary A

2017-11-07

Although pesticide resistance is common in insect vectors of human diseases, the evolution of resistance might be delayed if management practices are adopted that limit selection of resistance alleles. Outbreaks of dengue fever have occurred in Queensland, Australia, since the late 1800s, leading to ongoing attempts to control the mosquito vector, Aedes aegypti (L.). Since the 1990s, pyrethroid insecticides have been used for this purpose, but have been applied in a strategic manner with a variety of delivery methods including indoor residual spraying, lethal ovitraps, and use of insect growth regulators as larvicides. Separate selection experiments on mosquitoes from Queensland using Type I and Type II pyrethroids did not produce resistant lines of Ae. aegypti, and bioassays of field material from Queensland showed only weak tolerance in comparison with a susceptible line. There was no evidence of knockdown resistance (kdr) mutations in Ae. aegypti from Queensland, in stark contrast to the situation in nearby southeast Asia. We suspect that careful management of pyrethroid insecticide use combined with surveillance and interception of exotic incursions has helped to maintain pyrethroid (and particularly kdr-based) susceptibility in Ae. aegypti in Australia. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

EAG responses to host-based attractants and temporal patterns in host-seeking flight of Xyleborus glabratus, X. affinis, and X. ferrugineus

USDA-ARS?s Scientific Manuscript database

The redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is an exotic wood-boring insect that vectors the mycopathogen responsible for laurel wilt, a lethal vascular disease of trees in the Lauraceae, including avocado (Persea americana Mill.). Effective semiochemical-based detection and control p...

Checklist of available generic names for Microsporidia with type species and type host

USDA-ARS?s Scientific Manuscript database

The science of microsporidiology encompasses a diverse assemblage of pathogens from a large and varied group of hosts. Many members of this group have been studied and exploited for their role in the control of insect pests and vectors as well as their detrimental impact on vertebrates including ma...

Maintenance of primary cell cultures of immunocytes from Cacopsylla sp. psyllids: a new in vitrio tool for the study of pest insects

USDA-ARS?s Scientific Manuscript database

Psyllid species are major vectors of plant pathogens, such as phytoplasmas and Liberibacter bacteria, which threaten economic stability of fruit tee crops and vegetable production worldwide. Primary cell cultures of immunocytes have been developed from the three psyllid species, Cacopsylla melanone...

Deciphering the bacterial microbiome of citrus plants in response to ‘Candidatus Liberibacter asiaticus’-infection and antibiotic treatment

USDA-ARS?s Scientific Manuscript database

Huanglongbing (HLB), the most devastating citrus disease worldwide, is vectored by phloem-feeding insects, and the pathogen in the USA is Candidatus Liberibacter asiaticus (Las). The bacterial microbiome of citrus after Las-infection and treatments with ampicillin (Amp) and gentamicin (Gm) was chara...

Reproduction of walnut twig beetle in black walnut and butternut

Treesearch

Andrea R. Hefty; Mark V. Coggeshall; Brian H. Aukema; Robert C. Venette; Steven J. Seybold

2016-01-01

The walnut twig beetle [WTB (Pityophthorus juglandis Blackman)] is the primary insect vector for a pathogen that causes thousand cankers disease (TCD), a disease complex that leads to mortality in species of walnut (Juglans L.). We performed field and laboratory trials to determine if reproduction by WTB varies between two...

A Review of Knowledge Gaps and Tools for Orbivirus Research

USDA-ARS?s Scientific Manuscript database

Although recognized as causing emerging and re-emerging disease outbreaks world-wide since the late 1800’s, there has been growing interest in the U.S. and Europe in recent years in orbiviruses, their insect vectors, and the diseases they cause in domestic livestock and wildlife. This is due, in par...

Metabolic interplay between the Asian citrus psyllid and its Profftella symbiont: An Achilles’ heel of the citrus greening insect vector

USDA-ARS?s Scientific Manuscript database

‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including ‘Candidatus Profftella armatura’, are likely to impact tra...

El virus de la mancha clorótica del tomate: Tomato chlorotic spot virus (TCSV)

USDA-ARS?s Scientific Manuscript database

Tomato chlorotic spot virus has emerged as a major pathogen of vegetables in Puerto Rico, the Caribbean and Florida. This virus is transmitted by thrips making management difficult. Growers must be aware of the distribution, host range, insect vectors, symptoms, modes of transmission to successfully...

Site Selection, Acquisition, and Planning for Aquaculture in Dredged Material Containment Areas

DTIC Science & Technology

1993-08-01

LCUIRSETTIWVIN Figure ACUAT 6. Fowhr o ei gnpoeuefrstln n nta trg RAEQUREDt S RACErmadWd 98 18~RE FORte 2- SiteA Selej) Site characteristics Table 1 lists...seeds, spores, organisms, etc.) (5) Effects on preserves, etc. Imvact f Attraction of vectors ( insects or rodents) due to creation of favorable

Arbovirus Detection in Insect Vectors by Rapid, High-Throughput Pyrosequencing

DTIC Science & Technology

2010-11-09

large contigs that by BLAST had their best hit to a rRNA of various fungal origins (including the genera Penicillium and Aspergillus ) and in all five...bioinformatic workflows need to be streamlined for non-expert users. For this approach to ever become part of the public health arsenal, our calculations

Variation in Tomato Spotted Wilt Virus Titer in Frankliniella Occidentalis and Its Association with Frequency of Transmission

USDA-ARS?s Scientific Manuscript database

Tomato spotted wilt virus (TSWV) is transmitted in a persistent propagative manner by Frankliniella occidentalis, the Western flower thrips. While it is well established that vector competence depends on TSWV acquisition by young larvae and virus replication within the insect, the biological factor...

Development of single chain variable fragment (scFv) antibodies against Xylella fastidiosa subsp. pauca by phage display

USDA-ARS?s Scientific Manuscript database

Xylella fastidiosa is a member of the gamma proteobacteria. It is fastidious, insect-vectored and xylem-limited and causes a variety of diseases, some severe, on a wide range of economically important perennial crops, including grape and citrus. Xylella fastidiosa subsp pauca causes citrus variegat...

Degradation products of citrus volatile organic compounds (VOCs) acting as phagostimulants that increase probing behavior of Asian citrus psyllid

USDA-ARS?s Scientific Manuscript database

Volatile phytochemicals play a role in orientation by phytophagous insects. We studied antennal and behavioral responses of the Asian citrus psyllid, Diaphorina citri Kuwayama, vector of the citrus greening disease pathogen. Little or no response to citrus leaf volatiles was detected by electroanten...

Cell lines derived from the squash bug, anasa tristis (coreidae: hemiptera)

USDA-ARS?s Scientific Manuscript database

The squash bug, Anasa tristis, is a pest of cucurbits that exerts direct damage on crops and is a vector of plant pathogens. We established cell lines from this insect to serve as tools for basic biology, such as virology and immunology, as well as applied studies, such as insecticide development pr...

Germline transformation of the olive fruit fly, Bactrocera oleae (Rossi)(Diptera:Tephritidae) with a piggyBac transposon vector

USDA-ARS?s Scientific Manuscript database

The olive fruit fly, Bactrocera oleae, is a highly significant pest in olive growing countries whose control may be enhanced by the use of genetically-modified strains, especially for sterile insect technique programs. To improve and expand this technology, piggyBac-mediated germline transformation ...

Biochemical analysis of leaf waxes and thrips resistance in onion selections

USDA-ARS?s Scientific Manuscript database

Thrips (Thrips tabaci) is a serious insect pest of onion and is a vector for Iris yellow spot virus (IYSV). Lower amounts of epicuticular waxes on onion leaves have been associated with fewer thrips, less feeding damage, and lower incidence of IYSV. In this study, 10 onion selections that showed les...

The transmission of oak wilt.

Treesearch

J.N. Gibbs; D.W. French

1980-01-01

Provides an up-to-date review of factors affecting the transmission of oak wilt, Ceratocystis fagacearum. Discusses the history and severity of the disease, the saprophytic existence of the fungus in the dying tree, seasonal susceptibility of trees to infection, overland and underground spread, the role of animals and insects as vectors or tree wounders, and the...

Influence of temperature and humidity on the viability of Ophiognomonia clavigignenti-juglandacearum Conidia

Treesearch

M.J. Moore; M.E. Ostry

2015-01-01

Butternut canker, caused by the fungus Ophiognomonia clavigignenti-juglandacearum, primarily kills butternut (Juglans cinerea). Rain splash and local air currents are the primary means of conidia dispersal but that does not explain its long-distance spread and infection of isolated trees. Dispersal by insect or animal vectors...

Vibrational duetting mimics to trap and disrupt mating of the devastating Asian citrus psyllid insect pest

USDA-ARS?s Scientific Manuscript database

The Asian citrus psyllid (ACP) is the primary vector of a bacterium that produces a devastating disease of citrus, huanglongbing. Efficient surveillance of ACP at low population densities is essential for timely pest management programs. ACP males search for mates on tree branches by producing vibra...