Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico

PubMed Central

Che-Mendoza, Azael; Guillermo-May, Guillermo; Herrera-Bojórquez, Josué; Barrera-Pérez, Mario; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Arredondo-Jiménez, Juan I.; Sánchez-Tejeda, Gustavo; Vazquez-Prokopec, Gonzalo; Ranson, Hilary; Lenhart, Audrey; Sommerfeld, Johannes; McCall, Philip J.; Kroeger, Axel; Manrique-Saide, Pablo

2015-01-01

Background Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Methods Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. Results LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. Conclusions These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide. PMID:25604761

The effect of long-lasting insecticidal water container covers on field populations of Aedes aegypti (L.) mosquitoes in Cambodia.

PubMed

Seng, Chang Moh; Setha, To; Nealon, Joshua; Chantha, Ngan; Socheat, Doung; Nathan, Michael B

2008-12-01

Dengue in Cambodia is mainly transmitted by Aedes aegypti (L.) mosquitoes that primarily breed in large, concrete jars (> or =200 liters) used for the storage of water for domestic use. Following a preliminary risk assessment, long-lasting insecticidal netting (LN) treated with deltamethrin was incorporated into the design of the covers for these jars. Their effect on immature and adult female populations of Ae. aegypti in six villages in a peri-urban area of Cambodia were compared with populations in six nearby control villages before and for 22 weeks after distribution of the jar covers. There were significantly fewer pupae per house in intervention villages than in control villages (6.6 and 31.9, respectively, p<0.01). Fewer pupae were recovered from intervention houses than from control houses at every post-intervention assessment. Two weeks after the intervention, the average number of indoor resting female Ae. aegypti per house in the intervention villages had declined approximately three-fold, whereas in the controls there was only a slight reduction (16%). The magnitude of the difference between the two areas diminished over time, which contact bioassays confirmed was likely due to a gradual reduction of insecticidal effect of the jar covers. In the study area, insecticide-treated covers for large concrete water storage jars were efficacious for controlling Ae. aegypti in the protected water jars and with a demonstrable effect on adult densities and survival. Further studies of this targeted container strategy in Cambodia, and elsewhere, are recommended. However, improvements in technology that would extend the duration of insecticidal effectiveness of LN materials may be needed for the development of cost-effective public health applications.

Effects of educational intervention on long-lasting insecticidal nets use in a malarious area, southeast Iran.

PubMed

Soleimani Ahmadi, Mussa; Vatandoost, Hassan; Shaeghi, Mansoreh; Raeisi, Ahmad; Abedi, Farshid; Eshraghian, Mohammad Reza; Aghamolaei, Teimur; Madani, Abdol Hossein; Safari, Reza; Jamshidi, Mahin; Alimorad, Abbas

2012-01-01

Long-lasting insecticidal nets (LLINs) have been advocated as an effective tool against malaria transmission. However, success of this community based intervention largely depends on the knowledge and practice regarding malaria and its prevention. According to the national strategy plan on evaluation of LLINs (Olyset nets), this study was conducted to determine the perceptions and practices about malaria and to improve use of LLINs in Bashagard district, one of the important foci of malaria in southeast Iran. The study area comprised 14 villages that were randomized in two clusters and designated as LLINs and untreated nets. Each of households in both clusters received two bed nets by the free distribution and delivery. After one month quantitative data collection method was used to collect information regarding the objectives of the study. On the basis of this information, an educational program was carried out in both areas to increase motivation for use of bed nets. Community knowledge and practice regarding malaria and LLIN use assessed pre- and post-educational program. The data were analyzed using SPSS ver.16 software. At baseline, 77.5% of respondents in intervention and 69.4 % in control area mentioned mosquito bite as the cause of malaria, this awareness increased significantly in intervention (90.3%) and control areas (87.9%), following the educational program. A significant increase also was seen in the proportion of households who used LLINs the previous night (92.5%) compared with untreated nets (87.1%). Educational status was an important predictor of LLINs use. Regular use of LLIN was considerably higher than the targeted coverage (80%) which recommended by World Heaths Organization. About 81.1% and 85.3% of respondents from LLIN and control areas reported that mosquito nuisance and subsequent malaria transmission were the main determinants of bed net use. These findings highlight a need for educational intervention in implementation of long-lasting

Use and acceptance of long lasting insecticidal net screens for dengue prevention in Acapulco, Guerrero, Mexico.

PubMed

Jones, Catrin H; Benítez-Valladares, David; Guillermo-May, Guillermo; Dzul-Manzanilla, Felipe; Che-Mendoza, Azael; Barrera-Pérez, Mario; Selem-Salas, Celia; Chablé-Santos, Juan; Sommerfeld, Johannes; Kroeger, Axel; O'Dempsey, Timothy; Medina-Barreiro, Anuar; Manrique-Saide, Pablo

2014-08-14

Dengue, recognized by the WHO as the most important mosquito-borne viral disease in the world, is a growing problem. Currently, the only effective way of preventing dengue is vector control. Standard methods have shown limited effect, and there have been calls to develop new integrated vector management approaches. One novel tool, protecting houses with long lasting insecticidal screens on doors and windows, is being trialled in a cluster randomised controlled trial by a joint UADY/WHO TDR/IDRC study in various districts of Acapulco, Mexico, with exceptionally high levels of crime and insecurity.This study investigated the community's perspectives of long lasting insecticidal screens on doors and windows in homes and in schools, in order to ascertain their acceptability, to identify challenges to further implementation and opportunities for future improvements. This was a sequential mixed-methods study. The quantitative arm contained a satisfaction survey administered to 288 houses that had received the intervention examining their perspectives of both the intervention and dengue prevention in general. The qualitative arm consisted of Focus Group Discussions (FGDs) with those who had accepted the intervention and key informant interviews with: schoolteachers to discuss the use of the screens in schools, program staff, and community members who had refused the intervention. Overall satisfaction and acceptance of the screens was very high, with only some operational and technical complaints relating to screen fragility and the installation process. However, the wider social context of urban violence and insecurity was a major barrier to screen acceptance. Lack of information dissemination and community collaboration were identified as project weaknesses. The screens are widely accepted by the population, but the project implementation could be improved by reassuring the community of its legitimacy in the context of insecurity. More community engagement and better

Evaluation of the efficacy of DDT indoor residual spraying and long-lasting insecticidal nets against insecticide resistant populations of Anopheles arabiensis Patton (Diptera: Culicidae) from Ethiopia using experimental huts

PubMed Central

2014-01-01

Background Indoor Residual Spraying (IRS) and Long-Lasting Insecticidal nets (LLINs) are major malaria vector control tools in Ethiopia. However, recent reports from different parts of the country showed that populations of Anopheles arabiensis, the principal malaria vector, have developed resistance to most families of insecticides recommended for public health use which may compromise the efficacy of both of these key vector control interventions. Thus, this study evaluated the efficacy of DDT IRS and LLINs against resistant populations of An. arabiensis using experimental huts in Asendabo area, southwestern Ethiopia. Methods The susceptibility status of populations of An. arabiensis was assessed using WHO test kits to DDT, deltamethrin, malathion, lambda-cyhalothrin, fenitrothion and bendiocarb. The efficacy of LLIN (PermaNet® 2.0), was evaluated using the WHO cone bioassay. Moreover, the effect of the observed resistance against malaria vector control interventions (DDT IRS and LLINs) were assessed using experimental huts. Results The findings of this study revealed that populations of An. arabiensis were resistant to DDT, deltamethrin, lambda-cyhalothrin and malathion with mortality rates of 1.3%, 18.8%, 36.3% and 72.5%, respectively but susceptible to fenitrothion and bendiocarb with mortality rates of 98.81% and 97.5%, respectively. The bio-efficacy test of LLIN (PermaNet® 2.0) against An. arabiensis revealed that the mosquito population showed moderate knockdown (64%) and mortality (78%). Moreover, mosquito mortalities in DDT sprayed huts and in huts with LLINs were not significantly different (p > 0.05) from their respective controls. Conclusion The evaluation of the efficacy of DDT IRS and LLINs using experimental huts showed that both vector control tools had only low to moderate efficacy against An. arabiensis populations from Ethiopia. Despite DDT being replaced by carbamates for IRS, the low efficacy of LLINs against the resistant population of An

Long-term field performance of a polyester-based long-lasting insecticidal mosquito net in rural Uganda

PubMed Central

Kilian, Albert; Byamukama, Wilson; Pigeon, Olivier; Atieli, Francis; Duchon, Stephan; Phan, Chi

2008-01-01

Background In order to evaluate whether criteria for LLIN field performance (phase III) set by the WHO Pesticide Evaluation Scheme are met, first and second generations of one of these products, PermaNet®, a polyester net using the coating technology were tested. Methods A randomized, double blinded study design was used comparing LLIN to conventionally treated nets and following LLIN for three years under regular household use in rural conditions. Primary outcome measures were deltamethrin residue and bioassay performance (60 minute knock-down and 24 hour mortality after a three minute exposure) using a strain of Anopheles gambiae s.s. sensitive to pyrethroid insecticides. Results Baseline concentration of deltamethrin was within targets for all net types but was rapidly lost in conventionally treated nets and first generation PermaNet® with median of 0.7 and 2.5 mg/m2 after six months respectively. In contrast, second generation PermaNet® retained insecticide well and had 41.5% of baseline dose after 36 months (28.7 mg/m2). Similarly, vector mortality and knockdown dropped to 18% and 70% respectively for first generation LLIN after six months but remained high (88.5% and 97.8% respectively) for second generation PermaNet® after 36 months of follow up at which time 90.0% of nets had either a knockdown rate ≥ 95% or mortality rate ≥ 80%. Conclusion Second generation PermaNet® showed excellent results after three years of field use and fulfilled the WHOPES criteria for LLIN. Loss of insecticide on LLIN using coating technology under field conditions was far more influenced by factors associated with handling rather than washing. PMID:18355408

Combination of indoor residual spraying with long-lasting insecticide-treated nets for malaria control in Zambezia, Mozambique: a cluster randomised trial and cost-effectiveness study protocol

PubMed Central

Alonso, Sergi; Zulliger, Rose; Wagman, Joe; Saifodine, Abuchahama; Candrinho, Baltazar; Macete, Eusébio; Brew, Joe; Fornadel, Christen; Kassim, Hidayat; Loch, Lourdes; Sacoor, Charfudin; Varela, Kenyssony; Carty, Cara L; Robertson, Molly; Saute, Francisco

2018-01-01

Background Most of the reduction in malaria prevalence seen in Africa since 2000 has been attributed to vector control interventions. Yet increases in the distribution and intensity of insecticide resistance and higher costs of newer insecticides pose a challenge to sustaining these gains. Thus, endemic countries face challenging decisions regarding the choice of vector control interventions. Methods A cluster randomised trial is being carried out in Mopeia District in the Zambezia Province of Mozambique, where malaria prevalence in children under 5 is high (68% in 2015), despite continuous and campaign distribution of long-lasting insecticide-treated nets (LLINs). Study arm 1 will continue to use the standard, LLIN-based National Malaria Control Programme vector control strategy (LLINs only), while study arm 2 will receive indoor residual spraying (IRS) once a year for 2 years with a microencapsulated formulation of pirimiphos-methyl (Actellic 300 CS), in addition to the standard LLIN strategy (LLINs+IRS). Prior to the 2016 IRS implementation (the first of two IRS campaigns in this study), 146 clusters were defined and stratified per number of households. Clusters were then randomised 1:1 into the two study arms. The public health impact and cost-effectiveness of IRS intervention will be evaluated over 2 years using multiple methods: (1) monthly active malaria case detection in a cohort of 1548 total children aged 6–59 months; (2) enhanced passive surveillance at health facilities and with community health workers; (3) annual cross-sectional surveys; and (4) entomological surveillance. Prospective microcosting of the intervention and provider and societal costs will be conducted. Insecticide resistance status pattern and changes in local Anopheline populations will be included as important supportive outcomes. Discussion By evaluating the public health impact and cost-effectiveness of IRS with a non-pyrethroid insecticide in a high-transmission setting with

The Economic Value of Long-Lasting Insecticidal Nets and Indoor Residual Spraying Implementation in Mozambique

PubMed Central

Lee, Bruce Y.; Bartsch, Sarah M.; Stone, Nathan T. B.; Zhang, Shufang; Brown, Shawn T.; Chatterjee, Chandrani; DePasse, Jay V.; Zenkov, Eli; Briët, Olivier J. T.; Mendis, Chandana; Viisainen, Kirsi; Candrinho, Baltazar; Colborn, James

2017-01-01

Malaria-endemic countries have to decide how much of their limited resources for vector control to allocate toward implementing long-lasting insecticidal nets (LLINs) versus indoor residual spraying (IRS). To help the Mozambique Ministry of Health use an evidence-based approach to determine funding allocation toward various malaria control strategies, the Global Fund convened the Mozambique Modeling Working Group which then used JANUS, a software platform that includes integrated computational economic, operational, and clinical outcome models that can link with different transmission models (in this case, OpenMalaria) to determine the economic value of vector control strategies. Any increase in LLINs (from 80% baseline coverage) or IRS (from 80% baseline coverage) would be cost-effective (incremental cost-effectiveness ratios ≤ $114/disability-adjusted life year averted). However, LLIN coverage increases tend to be more cost-effective than similar IRS coverage increases, except where both pyrethroid resistance is high and LLIN usage is low. In high-transmission northern regions, increasing LLIN coverage would be more cost-effective than increasing IRS coverage. In medium-transmission central regions, changing from LLINs to IRS would be more costly and less effective. In low-transmission southern regions, LLINs were more costly and less effective than IRS, due to low LLIN usage. In regions where LLINs are more cost-effective than IRS, it is worth considering prioritizing LLIN coverage and use. However, IRS may have an important role in insecticide resistance management and epidemic control. Malaria intervention campaigns are not a one-size-fits-all solution, and tailored approaches are necessary to account for the heterogeneity of malaria epidemiology. PMID:28719286

The Economic Value of Long-Lasting Insecticidal Nets and Indoor Residual Spraying Implementation in Mozambique.

PubMed

Lee, Bruce Y; Bartsch, Sarah M; Stone, Nathan T B; Zhang, Shufang; Brown, Shawn T; Chatterjee, Chandrani; DePasse, Jay V; Zenkov, Eli; Briët, Olivier J T; Mendis, Chandana; Viisainen, Kirsi; Candrinho, Baltazar; Colborn, James

2017-06-01

AbstractMalaria-endemic countries have to decide how much of their limited resources for vector control to allocate toward implementing long-lasting insecticidal nets (LLINs) versus indoor residual spraying (IRS). To help the Mozambique Ministry of Health use an evidence-based approach to determine funding allocation toward various malaria control strategies, the Global Fund convened the Mozambique Modeling Working Group which then used JANUS, a software platform that includes integrated computational economic, operational, and clinical outcome models that can link with different transmission models (in this case, OpenMalaria) to determine the economic value of vector control strategies. Any increase in LLINs (from 80% baseline coverage) or IRS (from 80% baseline coverage) would be cost-effective (incremental cost-effectiveness ratios ≤ $114/disability-adjusted life year averted). However, LLIN coverage increases tend to be more cost-effective than similar IRS coverage increases, except where both pyrethroid resistance is high and LLIN usage is low. In high-transmission northern regions, increasing LLIN coverage would be more cost-effective than increasing IRS coverage. In medium-transmission central regions, changing from LLINs to IRS would be more costly and less effective. In low-transmission southern regions, LLINs were more costly and less effective than IRS, due to low LLIN usage. In regions where LLINs are more cost-effective than IRS, it is worth considering prioritizing LLIN coverage and use. However, IRS may have an important role in insecticide resistance management and epidemic control. Malaria intervention campaigns are not a one-size-fits-all solution, and tailored approaches are necessary to account for the heterogeneity of malaria epidemiology.

Estimation of insecticide persistence, biological activity and mosquito resistance to PermaNet® 2 long-lasting insecticidal nets over three to 32 months of use in Ethiopia.

PubMed

Anshebo, Gedeon Yohannes; Graves, Patricia M; Smith, Stephen C; Wills, Aprielle B; Damte, Mesele; Endeshaw, Tekola; Shargie, Estifanos Biru; Gebre, Teshome; Mosher, Aryc W; Patterson, Amy E; Emerson, Paul M

2014-03-06

Information is needed on the expected durability of insecticidal nets under operational conditions. The persistence of insecticidal efficacy is important to estimate the median serviceable life of nets under field conditions and to plan for net replacement. Deltamethrin residue levels were evaluated by the proxy method of X-ray fluorescence spectrometry on 189 nets used for three to six months from nine sites, 220 nets used for 14-20 months from 11 sites, and 200 nets used for 26-32 months from ten sites in Ethiopia. A random sample of 16.5-20% of nets from each time period (total 112 of 609 nets) were tested by bioassay with susceptible mosquitoes, and nets used for 14-20 months and 26-32 months were also tested with wild caught mosquitoes. Mean insecticide levels estimated by X-ray fluorescence declined by 25.9% from baseline of 66.2 (SD 14.6) mg/m2 at three to six months to 44.1 (SD 21.2) mg/m2 at 14-20 months and by 30.8% to 41.1 (SD 18.9) mg/m2 at 26-32 months. More than 95% of nets retained greater than 10 mg/m2 of deltamethrin and over 79% had at least 25 mg/m2 at all time periods. By bioassay with susceptible Anopheles, mortality averaged 89.0% on 28 nets tested at three to six months, 93.3% on 44 nets at 14-20 months and 94.1% on 40 nets at 26-32 months. With wild caught mosquitoes, mortality averaged 85.4% (range 79.1 to 91.7%) at 14-20 months but had dropped significantly to 47.2% (39.8 to 54.7%) at 26-32 months. Insecticide residue level, as estimated by X-ray fluorescence, declined by about one third between three and six months and 14-20 months, but remained relatively stable and above minimum requirements thereafter up to 26-32 months. The insecticidal activity of PermaNet® 2.0 long-lasting insecticidal nets in the specified study area may be considered effective to susceptible mosquitoes at least for the duration indicated in this study (32 months). However, results indicated that resistance in the wild population is already rendering nets with

Impact of operational effectiveness of long-lasting insecticidal nets (LLINs) on malaria transmission in pyrethroid-resistant areas

PubMed Central

2013-01-01

Background A dynamic study on the transmission of malaria was conducted in two areas (R+ area: Low resistance area; R+++ area: High resistance area) in the department of Plateau in South Eastern Benin, where the population is protected by Long Lasting Insecticidal Nets (LLINs). The aim of this study was to determine if the resistance of malaria vectors to insecticides has an impact on their behavior and on the effectiveness of LLINs in the reduction of malaria transmission. Methods Populations of Anopheles gambiae s.l. were sampled monthly by human landing catch in the two areas to evaluate human biting rates (HBR). Collected mosquitoes were identified morphologically and female Anopheles mosquitoes were tested for the presence of Plasmodium falciparum antigen as assessed using ELISA. The entomological inoculation rate (EIR) was also calculated (EIR = HBR x sporozoitic index [S]). We estimated the parity rate by dissecting the females of An. gambiae. Finally, window catch and spray catch were conducted in order to assess the blood feeding rate and the exophily rate of vectors. Results After 6 months of tracking the mosquito's behavior in contact with the LLINs (Olyset) in R+++ and R+ areas, the entomological indicators of the transmission of malaria (parity rate and sporozoitic index) were similar in the two areas. Also, An. gambiae populations showed the same susceptibility to P. falciparum in both R+ and R+++ areas. The EIR and the exophily rate are higher in R+ area than in R+++ area. But the blood-feeding rate is lower in R+ area comparing to R+++. Conclusion The highest entomological inoculation rate observed in R+ area is mostly due to the strong aggressive density of An. gambiae recorded in one of the study localities. On the other hand, the highest exophily rate and the low blood-feeding rate recorded in R+ area compared to R+++ area are not due to the resistance status of An. gambiae, but due to the differences in distribution and availability of

A qualitative study on the acceptability and preference of three types of long-lasting insecticide-treated bed nets in Solomon Islands: implications for malaria elimination

PubMed Central

Atkinson, Jo-An; Bobogare, Albino; Fitzgerald, Lisa; Boaz, Leonard; Appleyard, Bridget; Toaliu, Hilson; Vallely, Andrew

2009-01-01

Background In March 2008, the Solomon Islands and Vanuatu governments raised the goal of their National Malaria Programmes from control to elimination. Vector control measures, such as indoor residual spraying (IRS) and long-lasting insecticidal bed nets (LLINs) are key integral components of this programme. Compliance with these interventions is dependent on their acceptability and on the socio-cultural context of the local population. These factors need to be investigated locally prior to programme implementation. Method Twelve focus group discussions (FGDs) were carried out in Malaita and Temotu Provinces, Solomon Islands in 2008. These discussions explored user perceptions of acceptability and preference for three brands of long-lasting insecticide-treated bed nets (LLINs) and identified a number of barriers to their proper and consistent use. Results Mosquito nuisance and perceived threat of malaria were the main determinants of bed net use. Knowledge of malaria and the means to prevent it were not sufficient to guarantee compliance with LLIN use. Factors such as climate, work and evening social activities impact on the use of bed nets, particularly in men. LLIN acceptability plays a varying role in compliance with their use in villages involved in this study. Participants in areas of reported high and year round mosquito nuisance and perceived threat of malaria reported LLIN use regardless of any reported unfavourable characteristics. Those in areas of low or seasonal mosquito nuisance were more likely to describe the unfavourable characteristics of LLINs as reasons for their intermittent or non-compliance. The main criterion for LLIN brand acceptability was effectiveness in preventing mosquito bites and malaria. Discussions highlighted considerable confusion around LLIN care and washing which may be impacting on their effectiveness and reducing their acceptability in Solomon Islands. Conclusion Providing LLINs that are acceptable will be more important for

Africa's largest long-lasting insecticide-treated net producer: lessons from A to Z Textiles.

PubMed

Masum, Hassan; Shah, Ronak; Schroeder, Karl; Daar, Abdallah S; Singer, Peter A

2010-12-13

Field trials have demonstrated the efficacy of insecticide-treated nets, and the WHO has recently endorsed a shift toward Long-Lasting Insecticide Treated nets (LLINs) due to factors such as reduced distribution costs. However, the need for LLINs poses several challenges. Is it possible to manufacture LLINs in large quantities in the African continent, where malaria is most endemic? When production is located in low-income countries, what role is played by local funding and employment, scaling up manufacturing, and partnerships? What factors influence availability and pricing? A case study of A to Z Textiles was undertaken to answer the question of how large-scale production of LLINs can occur in a low income setting. One of the largest sources of bed nets for Africa, A to Z Textiles is Africa-based, and its Tanzanian operations have a production capacity of 30 million LLINs per year, along with full WHO recommendation for its nets. Our analysis is based on semi-structured interviews with key informants familiar with A to Z, site visits in Tanzania, and literature reviews.This paper discusses the history and current status of A to Z Textiles, identifies the factors that led to its success, and suggests policy considerations that could support similar initiatives in the future. Local funding, scaling up manufacturing, technology transfer, and partnerships all played important roles in A to Z's ascent, as did perceived benefits of local employment and capacity-building. Regulatory issues and procurement rules acted as barriers. A to Z cost-effectively manufactures high-quality LLINs where malaria is most endemic. With a production capacity of 30 million LLINs per year, and full WHOPES (WHO Pesticide Evaluation Scheme) certification, A to Z Textiles demonstrates how key health goods can be successfully produced in the low-income countries that use them. Its example may be instructive and of high interest to readers in the malaria community, especially in developing

Social Determinants of Long Lasting Insecticidal Hammock-Use Among the Ra-Glai Ethnic Minority in Vietnam: Implications for Forest Malaria Control

PubMed Central

Muela Ribera, Joan; Ngo Duc, Thang; van Bortel, Wim; Truong Ba, Nhat; Van, Ky Pham; Le Xuan, Hung; D'Alessandro, Umberto; Erhart, Annette

2012-01-01

Background Long-lasting insecticidal hammocks (LLIHs) are being evaluated as an additional malaria prevention tool in settings where standard control strategies have a limited impact. This is the case among the Ra-glai ethnic minority communities of Ninh Thuan, one of the forested and mountainous provinces of Central Vietnam where malaria morbidity persist due to the sylvatic nature of the main malaria vector An. dirus and the dependence of the population on the forest for subsistence - as is the case for many impoverished ethnic minorities in Southeast Asia. Methods A social science study was carried out ancillary to a community-based cluster randomized trial on the effectiveness of LLIHs to control forest malaria. The social science research strategy consisted of a mixed methods study triangulating qualitative data from focused ethnography and quantitative data collected during a malariometric cross-sectional survey on a random sample of 2,045 study participants. Results To meet work requirements during the labor intensive malaria transmission and rainy season, Ra-glai slash and burn farmers combine living in government supported villages along the road with a second home at their fields located in the forest. LLIH use was evaluated in both locations. During daytime, LLIH use at village level was reported by 69.3% of all respondents, and in forest fields this was 73.2%. In the evening, 54.1% used the LLIHs in the villages, while at the fields this was 20.7%. At night, LLIH use was minimal, regardless of the location (village 4.4%; forest 6.4%). Discussion Despite the free distribution of insecticide-treated nets (ITNs) and LLIHs, around half the local population remains largely unprotected when sleeping in their forest plot huts. In order to tackle forest malaria more effectively, control policies should explicitly target forest fields where ethnic minority farmers are more vulnerable to malaria. PMID:22253852

Implications of bio-efficacy and persistence of insecticides when indoor residual spraying and long-lasting insecticide nets are combined for malaria prevention.

PubMed

Okumu, Fredros O; Chipwaza, Beatrice; Madumla, Edith P; Mbeyela, Edgar; Lingamba, Geoffrey; Moore, Jason; Ntamatungro, Alex J; Kavishe, Deo R; Moore, Sarah J

2012-11-19

Bio-efficacy and residual activity of insecticides used for indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs) were assessed against laboratory-reared and wild populations of the malaria vector, Anopheles arabiensis in south eastern Tanzania. Implications of the findings are examined in the context of potential synergies and redundancies where IRS and LLINs are combined. Bioassays were conducted monthly for six months on three LLIN types (Olyset® PermaNet 2.0®,and Icon Life®) and three IRS treatments (2 g/m2 pirimiphos-methyl, 2 g/m2 DDT and 0.03 g/m2 lambda-cyhalothrin, sprayed on mud walls and palm ceilings of experimental huts). Tests used susceptible laboratory-reared An. arabiensis exposed in cones (nets and IRS) or wire balls (nets only). Susceptibility of wild populations was assessed using WHO diagnostic concentrations and PCR for knock-down resistance (kdr) genes. IRS treatments killed ≥ 85% of mosquitoes exposed on palm ceilings and ≥ 90% of those exposed on mud walls, but up to 50% of this toxicity decayed within 1-3 months, except for DDT. By 6th month, only 7.5%, 42.5% and 30.0% of mosquitoes died when exposed to ceilings sprayed with pirimiphos-methyl, DDT or lambda-cyhalothrin respectively, while 12.5%, 36.0% and 27.5% died after exposure to mud walls sprayed with the same insecticides. In wire-ball assays, mortality decreased from 98.1% in 1st month to 92.6% in 6th month in tests on PermaNet 2.0®, from 100% to 61.1% on Icon Life® and from 93.2% to 33.3% on Olyset® nets. In cone bioassays, mortality reduced from 92.8% in 1st month to 83.3% in 6th month on PermaNet 2.0®, from 96.9% to 43.80% on Icon Life® and from 85.6% to 14.6% on Olyset®. Wild An. arabiensis were 100% susceptible to DDT, 95.8% to deltamethrin, 90.2% to lambda cyhalothrin and 95.2% susceptible to permethrin. No kdr gene mutations were detected. In bioassays where sufficient contact with treated surfaces is assured, LLINs and IRS kill high

Assessing bed net use and non-use after long-lasting insecticidal net distribution: a simple framework to guide programmatic strategies

PubMed Central

2010-01-01

Background Insecticide-treated nets (ITNs) are becoming increasingly available to vulnerable populations at risk for malaria. Their appropriate and consistent use is essential to preventing malaria, but ITN use often lags behind ITN ownership. In order to increase ITN use, it is necessary to devise strategies that accurately identify, differentiate, and target the reasons and types of non-use. Methods A simple method based on the end-user as the denominator was employed to classify each individual into one of four ITN use categories: 1) living in households not owning an ITN; 2) living in households owning, but not hanging an ITN; 3) living in households owning and hanging an ITN, but who are not sleeping under one; and 4) sleeping under an ITN. This framework was applied to survey data designed to evaluate long-lasting insecticidal nets (LLINs) distributions following integrated campaigns in five countries: Togo, Sierra Leone, Madagascar, Kenya and Niger. Results The percentage of children <5 years of age sleeping under an ITN ranged from 51.5% in Kenya to 81.1% in Madagascar. Among the three categories of non-use, children living in households without an ITN make up largest group (range: 9.4%-30.0%), despite the efforts of the integrated child health campaigns. The percentage of children who live in households that own but do not hang an ITN ranged from 5.1% to 16.1%. The percentage of children living in households where an ITN was suspended, but who were not sleeping under it ranged from 4.3% to 16.4%. Use by all household members in Sierra Leone (39.9%) and Madagascar (60.4%) indicate that integrated campaigns reach beyond their desired target populations. Conclusions The framework outlined in this paper provides a helpful tool to examine the deficiencies in ITN use. Monitoring and evaluation strategies designed to assess ITN ownership and use can easily incorporate this approach using existing data collection instruments that measure the standard indicators

Are Long-Lasting Insecticidal Nets Effective for Preventing Childhood Deaths among Non-Net Users? A Community-Based Cohort Study in Western Kenya

PubMed Central

Komazawa, Osuke; Kaneko, Satoshi; K’Opiyo, James; Kiche, Ibrahim; Wanyua, Sheru; Shimada, Masaaki; Karama, Mohamed

2012-01-01

Background Increasing the distribution and use of insecticide-treated nets (ITNs) in Sub-Saharan Africa has made controlling malaria with ITNs more practical. We evaluated community effects induced by ITNs, specifically long-lasting insecticidal nets (LLINs), under ordinary conditions in an endemic malaria area of Western Kenya. Methods Using the database from Mbita Health and Demographic Surveillance System (HDSS), children younger than 5 years old were assessed over four survey periods. We analyzed the effect of bed net usage, LLIN density and population density of young people around a child on all-cause child mortality (ACCM) rates using Cox PH models. Results During the study, 14,554 children were followed and 250 deaths were recorded. The adjusted hazard ratios (HRs) for LLIN usage compared with no net usage were not significant among the models: 1.08 (95%CI 0.76–1.52), 1.19 (95%CI 0.69–2.08) and 0.92 (95%CI 0.42–2.02) for LLIN users, untreated net users, and any net users, respectively. A significant increasing linear trend in risk across LLIN density quartiles (HR = 1.25; 95%CI 1.03–1.51) and a decreasing linear trend in risk across young population density quartiles among non-net user children (HR = 0.77; 95%CI 0.63–0.94) were observed. Conclusions Although our data showed that current LLIN coverage level (about 35%) could induce a community effect to protect children sleeping without bed nets even in a malaria-endemic area, it appears that a better system is needed to monitor the current malaria situation globally in order to optimize malaria control programs with limited resources. PMID:23185378

Bio-efficacy, physical integrity, community usage and washing practices of mosquito nets treated with ICON MAXX long-lasting insecticidal treatment in India

PubMed Central

Sahu, Sudhansu Sekhar; Gunasekaran, Kasinathan; Vijayakumar, Kilakootil Narayanan; Jambulingam, Purushothaman

2017-01-01

BACKGROUND New brands of potential long lasting insecticide nets (LLINs) and LLIN treatment kits require field evaluation before they are used in a vector control programme. OBJECTIVES The aim of this study was to evaluate the bio-efficacy, usage, washing practice and physical integrity of nets treated with LLIN treatment kit, ICON MAXX in a phase III field trial in Odisha state, India. METHODS A total of 300 polyester nets treated with ICON MAXX and 140 polyester nets treated conventionally with lambda-cyhalothrin CS 2.5% ITNs were distributed. The bio-efficacy was evaluated with WHO cone bioassay. The chemical analysis of netting pieces was done at the beginning, after 12 and 36 months of the trial. FINDINGS After one year of distribution of nets, the bioassay showed 100% mortality on both ITNs and ICON MAXX treated nets. At 36 months, the overall pass rate was 58.8% and the mean lambda-cyhalothrin content of LLINs was 34.5 mg ai/m2, showing a loss of 44.4% of the original concentration. CONCLUSION ICON MAXX treated LLIN was found to retain bio-efficacy causing 97% knockdown of Anopheles stephensi up to 30 months and met the WHOPES criteria. However, the desired bio-efficacy was not sustained up to 36 months. PMID:28125134

Insecticidal, acaricidal and repellent effects of DEET- and IR3535-impregnated bed nets using a novel long-lasting polymer-coating technique.

PubMed

Faulde, Michael K; Albiez, Gunther; Nehring, Oliver

2010-03-01

A novel long-lasting repellent-treated net (LLRTN) has been designed by binding the skin repellents N,N-diethyl-m-toluamide (DEET), or IR3535, onto the fibres of bed net fabric using a new polymer-coating technique. The repellent toxicological effectiveness and residual activity of a factory-based repellent-impregnated fabric has been evaluated by laboratory testing against adult Aedes aegypti mosquitoes and nymphal Ixodes ricinus ticks. By using this repellent-embedding impregnation technique, concentrations exceeding 10 g/m(2) could be achieved with one single polymer layer. Both DEET- and IR3535-impregnated fabrics revealed a dose-dependent insecticidal as well as acaricidal activity. One hundred percent knockdown times of DEET-treated bed nets ranged from 187.5 +/- 31.8 to 27.5 +/- 3.5 min against A. aegypti, and between 214 +/- 47 and 22.6 +/- 5 min against nymphal I. ricinus, linked to a DEET concentration of 1.08 and 10.58 g/m(2), respectively. With IR3535, A. aegypti produced dose-dependent 100% knockdown times varying from 87.5 +/- 10.6 to 57.5 +/- 3.5 min and between 131.4 +/- 6.5 and 33.8 +/- 5 min against nymphal I. ricinus, respectively, linked to concentrations between 1.59 and 10.02 g/m(2). One hundred percent repellency measured by complete landing and biting protection of impregnated fabric by using the arm-in-cage test could be achieved at DEET concentrations exceeding 3.7 to 3.9 g/m(2), and for IR3535 concentrations over 10 g/m(2). One hundred percent landing and biting protection could be preserved with DEET-treated fabrics for 29 weeks at an initial concentration of 4.66 g/m(2), 54 weeks at 8.8 g/m(2), 58 weeks at 9.96 g/m(2) and 61 weeks at 10.48 g/m(2) for DEET, and 23 weeks for IR3535-treated fabric at a concentration of 10.02 g/m(2). Unlike repellent-treated fabric, a brand of a commercially available long-lasting insecticide-treated net tested containing 500 mg permethrin/m(2) did not protect from mosquito bites. First results on

Malaria in Dielmo, a Senegal village: Is its elimination possible after seven years of implementation of long-lasting insecticide-treated nets?

PubMed

Wotodjo, Amélé Nyedzie; Doucoure, Souleymane; Gaudart, Jean; Diagne, Nafissatou; Diene Sarr, Fatoumata; Faye, Ngor; Tall, Adama; Raoult, Didier; Sokhna, Cheikh

2017-01-01

The malaria burden has decreased significantly in recent years in Africa through the widespread use of artemisinin-based combination therapy (ACT) and long-lasting insecticide-treated nets (LLINs). However, the occurrence of malaria resurgences, the loss of immunity of exposed populations constitute among other factors, serious concerns about the future of malaria elimination efforts. This study investigated the evolution of malaria morbidity in Dielmo (Senegal) before and after the implementation of LLINs. A longitudinal study was carried out in Dielmo over eight years, from July 2007 to July 2015. In July 2008, LLINs were offered to all villagers, and in July 2011 and August 2014 the LLINs were renewed. A survey on LLINs use was done each quarter of the year. Thick smears stained with Giemsa, a rapid diagnostic test (RDT) and quantitative polymerase chain reaction (PCR) methods were performed for all cases of fever to assess malaria clinical attacks. Malaria cases were treated with ACT since June 2006. Malaria morbidity has decreased significantly since the implementation of LLINs in Dielmo, together with ACT. However, malaria resurgences have occurred twice during the seven years of LLINs use. These resurgences occurred the first time during the third year after the introduction of LLINs (aIRR (adjusted incidence-rate ratio) [95%CI] = 5.90 [3.53; 9.88] p< 0.001) and a second time during the third year after the renewal of LLINs (aIRR [95%CI] = 5.60 [3.34; 9.39] p< 0.001). Sixty-nine percent (69%) of the nets tested for their long-lasting insecticidal activity remained effective after 3 years of use. Good management of malaria cases by the use of ACT as first-line treatment against malaria in addition to the use of LLINs has significantly reduced malaria in Dielmo and allowed to reach the phase of pre-elimination of the disease. However, the occurrence of malaria resurgences raised serious concerns about malaria elimination, which would require additional tools

Country-level operational implementation of the Global Plan for Insecticide Resistance Management

PubMed Central

Hemingway, Janet; Vontas, John; Poupardin, Rodolphe; Raman, Jaishree; Lines, Jo; Schwabe, Chris; Matias, Abrahan; Kleinschmidt, Immo

2013-01-01

Malaria control is reliant on the use of long-lasting pyrethroid-impregnated nets and/or indoor residual spraying (IRS) of insecticide. The rapid selection and spread of operationally significant pyrethroid resistance in African malaria vectors threatens our ability to sustain malaria control. Establishing whether resistance is operationally significant is technically challenging. Routine monitoring by bioassay is inadequate, and there are limited data linking resistance selection with changes in disease transmission. The default is to switch insecticides when resistance is detected, but limited insecticide options and resistance to multiple insecticides in numerous locations make this approach unsustainable. Detailed analysis of the resistance situation in Anopheles gambiae on Bioko Island after pyrethroid resistance was detected in this species in 2004, and the IRS program switched to carbamate bendiocarb, has now been undertaken. The pyrethroid resistance selected is a target-site knock-down resistance kdr-form, on a background of generally elevated metabolic activity, compared with insecticide-susceptible A. gambiae, but the major cytochrome P450-based metabolic pyrethroid resistance mechanisms are not present. The available evidence from bioassays and infection data suggests that the pyrethroid resistance mechanisms in Bioko malaria vectors are not operationally significant, and on this basis, a different, long-lasting pyrethroid formulation is now being reintroduced for IRS in a rotational insecticide resistance management program. This will allow control efforts to be sustained in a cost-effective manner while reducing the selection pressure for resistance to nonpyrethroid insecticides. The methods used provide a template for evidence-based insecticide resistance management by malaria control programs. PMID:23696658

Country-level operational implementation of the Global Plan for Insecticide Resistance Management.

PubMed

Hemingway, Janet; Vontas, John; Poupardin, Rodolphe; Raman, Jaishree; Lines, Jo; Schwabe, Chris; Matias, Abrahan; Kleinschmidt, Immo

2013-06-04

Malaria control is reliant on the use of long-lasting pyrethroid-impregnated nets and/or indoor residual spraying (IRS) of insecticide. The rapid selection and spread of operationally significant pyrethroid resistance in African malaria vectors threatens our ability to sustain malaria control. Establishing whether resistance is operationally significant is technically challenging. Routine monitoring by bioassay is inadequate, and there are limited data linking resistance selection with changes in disease transmission. The default is to switch insecticides when resistance is detected, but limited insecticide options and resistance to multiple insecticides in numerous locations make this approach unsustainable. Detailed analysis of the resistance situation in Anopheles gambiae on Bioko Island after pyrethroid resistance was detected in this species in 2004, and the IRS program switched to carbamate bendiocarb, has now been undertaken. The pyrethroid resistance selected is a target-site knock-down resistance kdr-form, on a background of generally elevated metabolic activity, compared with insecticide-susceptible A. gambiae, but the major cytochrome P450-based metabolic pyrethroid resistance mechanisms are not present. The available evidence from bioassays and infection data suggests that the pyrethroid resistance mechanisms in Bioko malaria vectors are not operationally significant, and on this basis, a different, long-lasting pyrethroid formulation is now being reintroduced for IRS in a rotational insecticide resistance management program. This will allow control efforts to be sustained in a cost-effective manner while reducing the selection pressure for resistance to nonpyrethroid insecticides. The methods used provide a template for evidence-based insecticide resistance management by malaria control programs.

Examining equity in access to long-lasting insecticide nets and artemisinin-based combination therapy in Anambra state, Nigeria

PubMed Central

2012-01-01

Background In order to achieve universal health coverage, the government of Anambra State, southeast Nigeria has distributed free Long-lasting Insecticide treated Nets (LLINs) to the general population and delivered free Artemisinin-based Combination Therapy (ACT) to pregnant women and children less than 5 years. However, the levels of coverage with LLINS and ACTs is not clear, especially coverage of different socio-economic status (SES) population groups. This study was carried out to determine the level of coverage and access to LLINs and ACTs amongst different SES groups. Methods A questionnaire was used to collect data from randomly selected households in 19 local government areas of the State. Selected households had a pregnant woman and/or a child less than 5 years. The lot quality assurance sampling (LQAS) methodology was used in sampling. The questionnaire explored the availability and utilization of LLINs and ACTs from 2394 households. An asset-based SES index was used to examine the level of access of LLINS and ACTs to different SES quintiles. Results It was found that 80.5 % of the households had an LLIN and 64.4 % of the households stated that they actually used the nets the previous night. The findings showed that 42.3 % of pregnant women who had fever within the past month received ACTs, while 37.5 % of children ≪5 years old who had malaria in the past month had received ACTs. There was equity in ownership of nets for the range 1–5 nets per household. No significant SES difference was found in use of ACTs for treatment of malaria in children under five years old and in pregnant women. Conclusions The free distribution of LLINs and ACTs increased household coverage of both malaria control interventions and bridged the equity gap in access to them among the most vulnerable groups. PMID:22545723

Insecticide-impregnated netting as a potential tool for long-lasting control of the leishmaniasis vector Lutzomyia longipalpis in animal shelters

PubMed Central

2013-01-01

Background Leishmaniasis remains a serious neglected disease, with more than 350 million people potentially at risk worldwide. Control strategies often rely on spraying residual insecticides to target populations of the sand fly vectors that transmit Leishmania parasites when blood-feeding. These programmes are often difficult to sustain effectively, as sand fly resting sites must be resprayed on a regular basis. Here, we investigate whether application of insecticide-impregnated netting to a surface could act as an alternative to residual spraying for controlling the American visceral leishmaniasis vector Lutzomyia longipalpis. Methods Female L. longipalpis from our laboratory colony were exposed for 1 h to three treatments applied to plywood surfaces: 2% permethrin-impregnated netting (Olyset®), 20 mg a.i.m-2 micro-encapsulated lambda-cyhalothrin (Demand CS®) and a no-treatment control. We compared the speed at which these treatments acted, by measuring the percentage of sand flies killed both immediately after exposure to the treatment for 1 hour, as well as the number that had died 24 h after the 1 hour exposure. We repeated the experiment at 6 and 12 months following application to test the effectiveness of each treatment over time. Results When first applied, the lambda-cyhalothrin killed more sand flies in the first hour than the permethrin-impregnated netting. However, the effectiveness of the lambda-cyhalothrin diminished over time, so that there was no difference between the two treatments at 12 months. Both killed more sand flies than the control. When measured 24 h following exposure, both test treatments had killed close to 100% of sand flies when first applied, but while the lethal effect of the netting was maintained at close to 100% over 12 months, the effectiveness of the residual insecticide diminished to approximately 80% after 6 months. Conclusions The results of these initial laboratory experiments indicate that covering surfaces

Impact of mass distribution of free long-lasting insecticidal nets on childhood malaria morbidity: The Togo National Integrated Child Health Campaign

PubMed Central

2010-01-01

Background An evaluation of the short-term impact on childhood malaria morbidity of mass distribution of free long-lasting insecticidal nets (LLINs) to households with children aged 9-59 months as part of the Togo National Integrated Child Health Campaign. Methods The prevalence of anaemia and malaria in children aged zero to 59 months was measured during two cross-sectional household cluster-sample surveys conducted during the peak malaria transmission, three months before (Sept 2004, n = 2521) and nine months after the campaign (Sept 2005, n = 2813) in three districts representative of Togo's three epidemiological malaria transmission regions: southern tropical coastal plains (Yoto), central fertile highlands (Ogou) and northern semi-arid savannah (Tone). Results In households with children <5 years of age, insecticide-treated net (ITN) ownership increased from <1% to >65% in all 3 districts. Reported ITN use by children during the previous night was 35.9%, 43.8% and 80.6% in Yoto, Ogou and Tone, respectively. Rainfall patterns were comparable in both years. The overall prevalence of moderate to severe anaemia (Hb < 8.0 g/dL) was reduced by 28% (prevalence ratio [PR] 0.72, 95% CI 0.62-0.84) and mean haemoglobin was increased by 0.35 g/dL (95% CI 0.25-0.45). The effect was predominantly seen in children aged 18-59 months and in the two southern districts: PR (95% CI) for moderate to severe anaemia and clinical malaria: Yoto 0.62 (0.44-0.88) and 0.49 (0.35-0.75); Ogou 0.54 (0.37-0.79) and 0.85 (0.57-1.27), respectively. Similar reductions occurred in children <18 months in Ogou, but not in Yoto. No effect was seen in the semi-arid northern district despite a high malaria burden and ITN coverage. Conclusions A marked reduction in childhood malaria associated morbidity was observed in the year following mass distribution of free LLINs in two of the three districts in Togo. Sub-national level impact evaluations will contribute to a better understanding of the impact

Ownership and utilisation of long lasting insecticide treated nets following free distribution campaign in South West Nigeria.

PubMed

Aderibigbe, Sunday Adedeji; Olatona, Foluke Adenike; Sogunro, Oluremi; Alawode, Gafar; Babatunde, Oluwole Adeyemi; Onipe, Ambrose Itopa; Bolarinwa, Oladimeji Akeem; Ameen, Hafsat Abolore; Osagbemi, Gordon Kayode; Sanya, Emmanuel Olatunde; Olarinoye, Adebunmi Oyeladun; Akande, Tanimola Makanjuola

2014-01-01

Malaria has proven to be the most horrendous and intractable amongst the health problems confronting countries in the sub-Saharan Africa. This study aims to determine the ownership and utilisation of long lasting insecticide treated nets following free distribution campaign in a state in South West Nigeria. Multi-stage sampling technique was used to recruit 2560 households spread across the 16 LGAs of the state. Interviewer administered standardized questionnaire was used for the survey. Data analysis was done using Stata 10 software. Sixty eight point six percent (68.6%) of the households had at least one under-five child living in the household while 32.6% had at least one pregnant woman living in the household. A total of 2440 (95.3%) households received LLIN during the campaign. Overall, the utilization rate for all respondents was 58.5%. Despite the fact that 2440 households received LLINs during the campaign, only 84.3% of them were seen to have hung theirs during the survey. Coverage and ownership of LLINs increased significantly following the free distribution campaign. There was a discrepancy between net possession and net use with rate of use lower than possession. Post distribution educational campaign should be incorporated into future distribution campaigns to help increase net utilisation.

Importance of factors determining the effective lifetime of a mass, long-lasting, insecticidal net distribution: a sensitivity analysis.

PubMed

Briët, Olivier J T; Hardy, Diggory; Smith, Thomas A

2012-01-13

Long-lasting insecticidal nets (LLINs) reduce malaria transmission by protecting individuals from infectious bites, and by reducing mosquito survival. In recent years, millions of LLINs have been distributed across sub-Saharan Africa (SSA). Over time, LLINs decay physically and chemically and are destroyed, making repeated interventions necessary to prevent a resurgence of malaria. Because its effects on transmission are important (more so than the effects of individual protection), estimates of the lifetime of mass distribution rounds should be based on the effective length of epidemiological protection. Simulation models, parameterised using available field data, were used to analyse how the distribution's effective lifetime depends on the transmission setting and on LLIN characteristics. Factors considered were the pre-intervention transmission level, initial coverage, net attrition, and both physical and chemical decay. An ensemble of 14 stochastic individual-based model variants for malaria in humans was used, combined with a deterministic model for malaria in mosquitoes. The effective lifetime was most sensitive to the pre-intervention transmission level, with a lifetime of almost 10 years at an entomological inoculation rate of two infectious bites per adult per annum (ibpapa), but of little more than 2 years at 256 ibpapa. The LLIN attrition rate and the insecticide decay rate were the next most important parameters. The lifetime was surprisingly insensitive to physical decay parameters, but this could change as physical integrity gains importance with the emergence and spread of pyrethroid resistance. The strong dependency of the effective lifetime on the pre-intervention transmission level indicated that the required distribution frequency may vary more with the local entomological situation than with LLIN quality or the characteristics of the distribution system. This highlights the need for malaria monitoring both before and during intervention

Evaluation of the association between long-lasting insecticidal nets mass distribution campaigns and child malaria in Nigeria.

PubMed

Kyu, Hmwe Hmwe; Georgiades, Katholiki; Shannon, Harry S; Boyle, Michael H

2013-01-09

Nigeria carries the greatest malaria burden among countries in the world. As part of the National Malaria Control Strategic Plan, free long-lasting insecticidal nets (LLINs) were distributed in 14 states of Nigeria through mass campaigns led by different organizations (the World Bank, UNICEF, or the Global Fund) between May 2009 and August 2010. The objective of this study was to evaluate the association between LLIN distribution campaigns and child malaria in Nigeria. Data were from the Nigeria Malaria Indicator Survey which was carried out from October to December 2010 on a nationally representative sample of households. Participants were women aged 15-49 years and their children aged less than five years (N = 4082). The main outcome measure was the presence or absence of malaria parasites in blood samples of children (6-59 months). Compared with children living in communities with no campaigns, those in the campaign areas were less likely to test positive for malaria after adjusting for geographic locations, community- and individual-level characteristics including child-level use of insecticide-treated nets (ITNs). The protective effects were statistically significant for the World Bank Booster Project areas (OR = 0.18, 95% CI = 0.04-0.73) but did not reach statistical significance for other campaign areas. Results also showed that community-level wealth (OR = 0.51, 95% CI = 0.34-0.76), community-level maternal knowledge regarding malaria prevention (OR = 0.70, 95% CI = 0.50-0.97), and child-level use of ITNs (OR = 0.79, 95% CI = 0.63-0.99) were negatively associated with child malaria. The observed protective effects on child malaria of these campaigns (statistically significant in the World Bank Booster Project areas and non-significant in the other areas) need to be corroborated by future effectiveness studies. Results also show that improving community-level maternal knowledge through appropriate channels might be helpful

Costs and effects of two public sector delivery channels for long-lasting insecticidal nets in Uganda

PubMed Central

2010-01-01

Background In Uganda, long-lasting insecticidal nets (LLIN) have been predominantly delivered through two public sector channels: targeted campaigns or routine antenatal care (ANC) services. Their combination in a mixed-model strategy is being advocated to quickly increase LLIN coverage and maintain it over time, but there is little evidence on the efficiency of each system. This study evaluated the two delivery channels regarding LLIN retention and use, and estimated the associated costs, to contribute towards the evidence-base on LLIN delivery channels in Uganda. Methods Household surveys were conducted 5-7 months after LLIN distribution, combining questionnaires with visual verification of LLIN presence. Focus groups and interviews were conducted to further investigate determinants of LLIN retention and use. Campaign distribution was evaluated in Jinja and Adjumani while ANC distribution was evaluated only in the latter district. Costs were calculated from the provider perspective through retrospective analysis of expenditure data, and effects were estimated as cost per LLIN delivered and cost per treated-net-year (TNY). These effects were calculated for the total number of LLINs delivered and for those retained and used. Results After 5-7 months, over 90% of LLINs were still owned by recipients, and between 74% (Jinja) and 99% (ANC Adjumani) were being used. Costing results showed that delivery was cheapest for the campaign in Jinja and highest for the ANC channel, with economic delivery cost per net retained and used of USD 1.10 and USD 2.31, respectively. Financial delivery costs for the two channels were similar in the same location, USD 1.04 for campaign or USD 1.07 for ANC delivery in Adjumani, but differed between locations (USD 0.67 for campaign delivery in Jinja). Economic cost for ANC distribution were considerably higher (USD 2.27) compared to campaign costs (USD 1.23) in Adjumani. Conclusions Targeted campaigns and routine ANC services can both

Success of Senegal's first nationwide distribution of long-lasting insecticide-treated nets to children under five - contribution toward universal coverage

PubMed Central

2011-01-01

Background In 2009, the first national long-lasting insecticide-treated net (LLIN) distribution campaign in Senegal resulted in the distribution of 2.2 million LLINs in two phases to children aged 6-59 months. Door-to-door teams visited all households to administer vitamin A and mebendazole, and to give a coupon to redeem later for an LLIN. Methods A nationwide community-based two-stage cluster survey was conducted, with clusters selected within regions by probability proportional to size sampling, followed by GPS-assisted mapping, simple random selection of households in each cluster, and administration of a questionnaire using personal digital assistants (PDAs). The questionnaire followed the Malaria Indicator Survey format, with rosters of household members and bed nets, and questions on campaign participation. Results There were 3,280 households in 112 clusters representing 33,993 people. Most (92.1%) guardians of eligible children had heard about the campaign, the primary sources being health workers (33.7%), neighbours (26.2%), and radio (22.0%). Of eligible children, 82.4% received mebendazole, 83.8% received vitamin A, and 75.4% received LLINs. Almost all (91.4%) LLINs received during the campaign remained in the household; of those not remaining, 74.4% had been given away and none were reported sold. At least one insecticide-treated net (ITN) was present in 82.3% of all households, 89.2% of households with a child < 5 years and 57.5% of households without a child < 5 years. Just over half (52.4%) of ITNs had been received during the campaign. Considering possible indicators of universal coverage, 39.8% of households owned at least one ITN per two people, 21.6% owned at least one ITN per sleeping space and 34.7% of the general population slept under an ITN the night before the survey. In addition, 45.6% of children < 5 years, and 49.2% of pregnant women had slept under an ITN. Conclusions The nationwide integrated LLIN distribution campaign allowed

Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial

PubMed Central

Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

2015-01-01

Background Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. Methods A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4–6 weeks after the second intervention (March to April 2014). Results Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Conclusions Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. PMID:25604762

Combination of indoor residual spraying with long-lasting insecticide-treated nets for malaria control in Zambezia, Mozambique: a cluster randomised trial and cost-effectiveness study protocol.

PubMed

Chaccour, Carlos J; Alonso, Sergi; Zulliger, Rose; Wagman, Joe; Saifodine, Abuchahama; Candrinho, Baltazar; Macete, Eusébio; Brew, Joe; Fornadel, Christen; Kassim, Hidayat; Loch, Lourdes; Sacoor, Charfudin; Varela, Kenyssony; Carty, Cara L; Robertson, Molly; Saute, Francisco

2018-01-01

Most of the reduction in malaria prevalence seen in Africa since 2000 has been attributed to vector control interventions. Yet increases in the distribution and intensity of insecticide resistance and higher costs of newer insecticides pose a challenge to sustaining these gains. Thus, endemic countries face challenging decisions regarding the choice of vector control interventions. A cluster randomised trial is being carried out in Mopeia District in the Zambezia Province of Mozambique, where malaria prevalence in children under 5 is high (68% in 2015), despite continuous and campaign distribution of long-lasting insecticide-treated nets (LLINs). Study arm 1 will continue to use the standard, LLIN-based National Malaria Control Programme vector control strategy (LLINs only), while study arm 2 will receive indoor residual spraying (IRS) once a year for 2 years with a microencapsulated formulation of pirimiphos-methyl (Actellic 300 CS), in addition to the standard LLIN strategy (LLINs+IRS). Prior to the 2016 IRS implementation (the first of two IRS campaigns in this study), 146 clusters were defined and stratified per number of households. Clusters were then randomised 1:1 into the two study arms. The public health impact and cost-effectiveness of IRS intervention will be evaluated over 2 years using multiple methods: (1) monthly active malaria case detection in a cohort of 1548 total children aged 6-59 months; (2) enhanced passive surveillance at health facilities and with community health workers; (3) annual cross-sectional surveys; and (4) entomological surveillance. Prospective microcosting of the intervention and provider and societal costs will be conducted. Insecticide resistance status pattern and changes in local Anopheline populations will be included as important supportive outcomes. By evaluating the public health impact and cost-effectiveness of IRS with a non-pyrethroid insecticide in a high-transmission setting with high LLIN ownership, it is

Planning long lasting insecticide treated net campaigns: should households’ existing nets be taken into account?

PubMed Central

2013-01-01

Background Mass distribution of long-lasting insecticide treated bed nets (LLINs) has led to large increases in LLIN coverage in many African countries. As LLIN ownership levels increase, planners of future mass distributions face the challenge of deciding whether to ignore the nets already owned by households or to take these into account and attempt to target individuals or households without nets. Taking existing nets into account would reduce commodity costs but require more sophisticated, and potentially more costly, distribution procedures. The decision may also have implications for the average age of nets in use and therefore on the maintenance of universal LLIN coverage over time. Methods A stochastic simulation model based on the NetCALC algorithm was used to determine the scenarios under which it would be cost saving to take existing nets into account, and the potential effects of doing so on the age profile of LLINs owned. The model accounted for variability in timing of distributions, concomitant use of continuous distribution systems, population growth, sampling error in pre-campaign coverage surveys, variable net ‘decay’ parameters and other factors including the feasibility and accuracy of identifying existing nets in the field. Results Results indicate that (i) where pre-campaign coverage is around 40% (of households owning at least 1 LLIN), accounting for existing nets in the campaign will have little effect on the mean age of the net population and (ii) even at pre-campaign coverage levels above 40%, an approach that reduces LLIN distribution requirements by taking existing nets into account may have only a small chance of being cost-saving overall, depending largely on the feasibility of identifying nets in the field. Based on existing literature the epidemiological implications of such a strategy is likely to vary by transmission setting, and the risks of leaving older nets in the field when accounting for existing nets must be considered

Design, implementation and evaluation of a national campaign to deliver 18 million free long-lasting insecticidal nets to uncovered sleeping spaces in Tanzania

PubMed Central

2013-01-01

Background Since 2004, the Tanzanian National Voucher Scheme has increased availability and accessibility of insecticide-treated nets (ITNs) to pregnant women and infants by subsidizing the cost of nets purchased. From 2008 to 2010, a mass distribution campaign delivered nine million long-lasting insecticidal nets (LLINs) free-of-charge to children under-five years of age in Tanzania mainland. In 2010 and 2011, a Universal Coverage Campaign (UCC) led by the Ministry of Health and Social Welfare (MoHSW) was implemented to cover all sleeping spaces not yet reached through previous initiatives. Methods The UCC was coordinated through a unit within the National Malaria Control Programme. Partners were contracted by the MoHSW to implement different activities in collaboration with local government authorities. Volunteers registered the number of uncovered sleeping spaces in every household in the country. On this basis, LLINs were ordered and delivered to village level, where they were issued over a three-day period in each zone (three regions). Household surveys were conducted in seven districts immediately after the campaign to assess net ownership and use. Results The UCC was chiefly financed by the Global Fund to Fight AIDS, Tuberculosis and Malaria with important contributions from the US President’s Malaria Initiative. A total of 18.2 million LLINs were delivered at an average cost of USD 5.30 per LLIN. Overall, 83% of the expenses were used for LLIN procurement and delivery and 17% for campaign associated activities. Preliminary results of the latest Tanzania HIV Malaria Indicator Survey (2011–12) show that household ownership of at least one ITN increased to 91.5%. ITN use, among children under-five years of age, improved to 72.7% after the campaign. ITN ownership and use data post-campaign indicated high equity across wealth quintiles. Conclusion Close collaboration among the MoHSW, donors, contracted partners, local government authorities and volunteers

Evaluation of a national universal coverage campaign of long-lasting insecticidal nets in a rural district in north-west Tanzania.

PubMed

West, Philippa A; Protopopoff, Natacha; Rowland, Mark W; Kirby, Matthew J; Oxborough, Richard M; Mosha, Franklin W; Malima, Robert; Kleinschmidt, Immo

2012-08-10

Insecticide-treated nets (ITN) are one of the most effective measures for preventing malaria. Mass distribution campaigns are being used to rapidly increase net coverage in at-risk populations. This study had two purposes: to evaluate the impact of a universal coverage campaign (UCC) of long-lasting insecticidal nets (LLINs) on LLIN ownership and usage, and to identify factors that may be associated with inadequate coverage. In 2011 two cross-sectional household surveys were conducted in 50 clusters in Muleba district, north-west Tanzania. Prior to the UCC 3,246 households were surveyed and 2,499 afterwards. Data on bed net ownership and usage, demographics of household members and household characteristics including factors related to socio-economic status were gathered, using an adapted version of the standard Malaria Indicator Survey. Specific questions relating to the UCC process were asked. The proportion of households with at least one ITN increased from 62.6% (95% Confidence Interval (CI) = 60.9-64.2) before the UCC to 90.8% (95% CI = 89.0-92.3) afterwards. ITN usage in all residents rose from 40.8% to 55.7%. After the UCC 58.4% (95% CI = 54.7-62.1) of households had sufficient ITNs to cover all their sleeping places. Households with children under five years (OR = 2.4, 95% CI = 1.9-2.9) and small households (OR = 1.9, 95% CI = 1.5-2.4) were most likely to reach universal coverage. Poverty was not associated with net coverage. Eighty percent of households surveyed received LLINs from the campaign. The UCC in Muleba district of Tanzania was equitable, greatly improving LLIN ownership and, more moderately, usage. However, the goal of universal coverage in terms of the adequate provision of nets was not achieved. Multiple, continuous delivery systems and education activities are required to maintain and improve bed net ownership and usage.

Long-lasting control of Anopheles arabiensis by a single spray application of micro-encapsulated pirimiphos-methyl (Actellic® 300 CS)

PubMed Central

2014-01-01

Background Pyrethroid-resistant mosquitoes are an increasing threat to malaria vector control. The Global Plan for Insecticide Resistance Management (GPIRM) recommends rotation of non-pyrethroid insecticides for indoor residual spraying (IRS). The options from other classes are limited. The carbamate bendiocarb and the organophosphate pirimiphos-methyl (p-methyl) emulsifiable concentrate (EC) have a short residual duration of action, resulting in increased costs due to multiple spray cycles, and user fatigue. Encapsulation (CS) technology was used to extend the residual performance of p-methyl. Methods Two novel p-methyl CS formulations were evaluated alongside the existing EC in laboratory bioassays and experimental hut trials in Tanzania between 2008-2010. Bioassays were carried out monthly on sprayed substrates of mud, concrete, plywood, and palm thatch to assess residual activity. Experimental huts were used to assess efficacy against wild free-flying Anopheles arabiensis, in terms of insecticide-induced mortality and blood-feeding inhibition. Results In laboratory bioassays of An. arabiensis and Culex quinquefasciatus both CS formulations produced high rates of mortality for significantly longer than the EC formulation on all substrates. On mud, the best performing CS killed >80% of An. arabiensis for five months and >50% for eight months, compared with one and two months, respectively, for the EC. In monthly bioassays of experimental hut walls the EC was ineffective shortly after spraying, while the best CS formulation killed more than 80% of An. arabiensis for five months on mud, and seven months on concrete. In experimental huts both CS and EC formulations killed high proportions of free-flying wild An. arabiensis for up to 12 months after spraying. There was no significant difference between treatments. All treatments provided considerable personal protection, with blood-feeding inhibition ranging from 9-49% over time. Conclusions The long residual

Underpinning Sustainable Vector Control through Informed Insecticide Resistance Management

PubMed Central

Hemmings, Kay; Hughes, Angela J.; Chanda, Emmanuel; Musapa, Mulenga; Kamuliwo, Mulakwa; Phiri, Faustina N.; Muzia, Lucy; Chanda, Javan; Kandyata, Alister; Chirwa, Brian; Poer, Kathleen; Hemingway, Janet; Wondji, Charles S.; Ranson, Hilary; Coleman, Michael

2014-01-01

Background There has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to elimination. Zambia's programme reported high levels of resistance to the insecticides it used in 2010, and, as a result, increased its investment in resistance monitoring to support informed resistance management decisions. Methodology/Principal Findings A country-wide survey on insecticide resistance in Zambian malaria vectors was performed using WHO bioassays to detect resistant phenotypes. Molecular techniques were used to detect target-site mutations and microarray to detect metabolic resistance mechanisms. Anopheles gambiae s.s. was resistant to pyrethroids, DDT and carbamates, with potential organophosphate resistance in one population. The resistant phenotypes were conferred by both target-site and metabolic mechanisms. Anopheles funestus s.s. was largely resistant to pyrethroids and carbamates, with potential resistance to DDT in two locations. The resistant phenotypes were conferred by elevated levels of cytochrome p450s. Conclusions/Significance Currently, the Zambia National Malaria Control Centre is using these results to inform their vector control strategy. The methods employed here can serve as a template to all malaria-endemic countries striving to create a sustainable insecticide resistance management plan. PMID:24932861

Decreasing proportion of Anopheles darlingi biting outdoors between long-lasting insecticidal net distributions in peri-Iquitos, Amazonian Peru.

PubMed

Prussing, Catharine; Moreno, Marta; Saavedra, Marlon P; Bickersmith, Sara A; Gamboa, Dionicia; Alava, Freddy; Schlichting, Carl D; Emerson, Kevin J; Vinetz, Joseph M; Conn, Jan E

2018-02-20

In Loreto Department, Peru, a successful 2005-2010 malaria control programme (known as PAMAFRO) included massive distribution of long-lasting insecticidal nets (LLINs). Additional local distribution of LLINs occurred in individual villages, but not between 2012 and 2015. A 2011-2012 study of the primary regional malaria vector Anopheles darlingi detected a trend of increased exophagy compared with pre-PAMAFRO behaviour. For the present study, An. darlingi were collected in three villages in Loreto in 2013-2015 to test two hypotheses: (1) that between LLIN distributions, An. darlingi reverted to pre-intervention biting behaviour; and, (2) that there are separate sub-populations of An. darlingi in Loreto with distinct biting behaviour. In 2013-2015 An. darlingi were collected by human landing catch during the rainy and dry seasons in the villages of Lupuna and Cahuide. The abundance of An. darlingi varied substantially across years, villages and time periods, and there was a twofold decrease in the ratio of exophagic:endophagic An. darlingi over the study period. Unexpectedly, there was evidence of a rainy season population decline in An. darlingi. Plasmodium-infected An. darlingi were detected indoors and outdoors throughout the night, and the monthly An. darlingi human biting rate was correlated with the number of malaria cases. Using nextRAD genotyping-by-sequencing, 162 exophagic and endophagic An. darlingi collected at different times during the night were genotyped at 1021 loci. Based on model-based and non-model-based analyses, all genotyped An. darlingi belonged to a homogeneous population, with no evidence for genetic differentiation by biting location or time. This study identified a decreasing proportion of exophagic An. darlingi in two villages in the years between LLIN distributions. As there was no evidence for genetic differentiation between endophagic and exophagic An. darlingi, this shift in biting behaviour may be the result of behavioural

Social determinants of long lasting insecticidal hammock use among the Ra-glai ethnic minority in Vietnam: implications for forest malaria control.

PubMed

Grietens, Koen Peeters; Xuan, Xa Nguyen; Ribera, Joan; Duc, Thang Ngo; Bortel, Wim van; Ba, Nhat Truong; Van, Ky Pham; Xuan, Hung Le; D'Alessandro, Umberto; Erhart, Annette

2012-01-01

Long-lasting insecticidal hammocks (LLIHs) are being evaluated as an additional malaria prevention tool in settings where standard control strategies have a limited impact. This is the case among the Ra-glai ethnic minority communities of Ninh Thuan, one of the forested and mountainous provinces of Central Vietnam where malaria morbidity persist due to the sylvatic nature of the main malaria vector An. dirus and the dependence of the population on the forest for subsistence--as is the case for many impoverished ethnic minorities in Southeast Asia. A social science study was carried out ancillary to a community-based cluster randomized trial on the effectiveness of LLIHs to control forest malaria. The social science research strategy consisted of a mixed methods study triangulating qualitative data from focused ethnography and quantitative data collected during a malariometric cross-sectional survey on a random sample of 2,045 study participants. To meet work requirements during the labor intensive malaria transmission and rainy season, Ra-glai slash and burn farmers combine living in government supported villages along the road with a second home at their fields located in the forest. LLIH use was evaluated in both locations. During daytime, LLIH use at village level was reported by 69.3% of all respondents, and in forest fields this was 73.2%. In the evening, 54.1% used the LLIHs in the villages, while at the fields this was 20.7%. At night, LLIH use was minimal, regardless of the location (village 4.4%; forest 6.4%). Despite the free distribution of insecticide-treated nets (ITNs) and LLIHs, around half the local population remains largely unprotected when sleeping in their forest plot huts. In order to tackle forest malaria more effectively, control policies should explicitly target forest fields where ethnic minority farmers are more vulnerable to malaria.

Long-lasting insecticide-treated house screens and targeted treatment of productive breeding-sites for dengue vector control in Acapulco, Mexico.

PubMed

Che-Mendoza, Azael; Guillermo-May, Guillermo; Herrera-Bojórquez, Josué; Barrera-Pérez, Mario; Dzul-Manzanilla, Felipe; Gutierrez-Castro, Cipriano; Arredondo-Jiménez, Juan I; Sánchez-Tejeda, Gustavo; Vazquez-Prokopec, Gonzalo; Ranson, Hilary; Lenhart, Audrey; Sommerfeld, Johannes; McCall, Philip J; Kroeger, Axel; Manrique-Saide, Pablo

2015-02-01

Long-lasting insecticidal net screens (LLIS) fitted to domestic windows and doors in combination with targeted treatment (TT) of the most productive Aedes aegypti breeding sites were evaluated for their impact on dengue vector indices in a cluster-randomised trial in Mexico between 2011 and 2013. Sequentially over 2 years, LLIS and TT were deployed in 10 treatment clusters (100 houses/cluster) and followed up over 24 months. Cross-sectional surveys quantified infestations of adult mosquitoes, immature stages at baseline (pre-intervention) and in four post-intervention samples at 6-monthly intervals. Identical surveys were carried out in 10 control clusters that received no treatment. LLIS clusters had significantly lower infestations compared to control clusters at 5 and 12 months after installation, as measured by adult (male and female) and pupal-based vector indices. After addition of TT to the intervention houses in intervention clusters, indices remained significantly lower in the treated clusters until 18 (immature and adult stage indices) and 24 months (adult indices only) post-intervention. These safe, simple affordable vector control tools were well-accepted by study participants and are potentially suitable in many regions at risk from dengue worldwide. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

To assess whether indoor residual spraying can provide additional protection against clinical malaria over current best practice of long-lasting insecticidal mosquito nets in The Gambia: study protocol for a two-armed cluster-randomised trial

PubMed Central

2011-01-01

Background Recently, there has been mounting interest in scaling-up vector control against malaria in Africa. It needs to be determined if indoor residual spraying (IRS with DDT) will provide significant marginal protection against malaria over current best practice of long-lasting insecticidal nets (LLINs) and prompt treatment in a controlled trial, given that DDT is currently the most persistent insecticide for IRS. Methods A 2 armed cluster-randomised controlled trial will be conducted to assess whether DDT IRS and LLINs combined provide better protection against clinical malaria in children than LLINs alone in rural Gambia. Each cluster will be a village, or a group of small adjacent villages; all clusters will receive LLINs and half will receive IRS in addition. Study children, aged 6 months to 13 years, will be enrolled from all clusters and followed for clinical malaria using passive case detection to estimate malaria incidence for 2 malaria transmission seasons in 2010 and 2011. This will be the primary endpoint. Exposure to malaria parasites will be assessed using light and exit traps followed by detection of Anopheles gambiae species and sporozoite infection. Study children will be surveyed at the end of each transmission season to estimate the prevalence of Plasmodium falciparum infection and the prevalence of anaemia. Discussion Practical issues concerning intervention implementation, as well as the potential benefits and risks of the study, are discussed. Trial Registration ISRCTN01738840 - Spraying And Nets Towards malaria Elimination (SANTE) PMID:21663656

Free mass distribution of long lasting insecticidal nets lead to high levels of LLIN access and use in Madagascar, 2010: A cross-sectional observational study

PubMed Central

Butts, Jessica; Ranaivoharimina, Harilala; Cotte, Annett H.; Ramarosandratana, Benjamin; Rabarijaona, Henintsoa; Tuseo, Luciano; Chang, Michelle; Vanden Eng, Jodi

2017-01-01

Background Madagascar conducted the first two phases of a national free mass distribution campaign of long-lasting insecticidal nets (LLINs) during a political crisis in 2009 aiming to achieve coverage of two LLINs per household as part of the National Malaria Control Strategy. The campaign targeted households in 19 out of 91 total health districts. Methods A community-based cross-sectional household survey using a three-stage cluster sample design was conducted four months post campaign to assess LLIN ownership, access and use. Multivariable logistic regression analysis was used to identify factors associated with household LLIN access and individual LLIN use. Results A total of 2211 households were surveyed representing 8867 people. At least one LLIN was present in 93.5% (95% confidence interval [CI], 91.6–95.5%) of households and 74.8% (95% CI, 71.0–78.6%) owned at least two LLINs. Access measured as the proportion of the population that could potentially be covered by household-owned LLINs was 77.2% (77.2% (95% CI, 72.9–81.3%) and LLIN use by all individuals was 84.2% (95% CI, 81.2–87.2%). LLIN use was associated with knowledge of insecticide treated net use to prevent malaria (OR = 3.58, 95% CI, 1.85–6.94), household ownership of more LLINs (OR 2.82, 95% CI 1.85–4.3), presence of children under five (OR = 2.05, 95% CI, 1.67–2.51), having traveled to the distribution point and receiving information about hanging a bednet (OR = 1.56, 95% CI, 1.41–1.74), and having received a post-campaign visit by a community mobilizer (OR = 1.75, 95% CI, 1.26–2.43). Lower LLIN use was associated with increasing household size (OR = 0.81 95% CI 0.77–0.85) and number of sleeping spaces (OR = 0.55, 95% CI, 0.44–0.68). Conclusions A large scale free mass LLIN distribution campaign was feasible and effective at achieving high LLIN access and use in Madagascar. Campaign process indicators highlighted potential areas for strengthening implementation to optimize

Status of pyrethroid resistance in Anopheles gambiae s. s. M form prior to the scaling up of Long Lasting Insecticidal Nets (LLINs) in Adzopé, Eastern Côte d’Ivoire

PubMed Central

2012-01-01

Background The growing development of pyrethroid resistance constitutes a serious threat to malaria control programmes and if measures are not taken in time, resistance may compromise control efforts in the foreseeable future. Prior to Long Lasting Insecticidal Nets (LLINs) distribution in Eastern Cote d’Ivoire, we conducted bioassays to inform the National Malaria Control Programme of the resistance status of the main malaria vector, Anopheles gambiae s. s. and the need for close surveillance of resistance. Methods Larvae of An. gambiae s. s. were collected in two areas of Adzopé (Port-Bouët and Tsassodji) and reared to adults. WHO susceptibility tests with impregnated filter papers were carried out to detect resistance to three pyrethroids commonly used to develop LLINs: permethrin 1%, deltamethrin 0.05% and lambda-cyhalothrin 0.05%. Molecular assays were conducted to detect M and S forms and the L1014F kdr allele in individual mosquitoes. Results Resistance, at various degrees was detected in both areas of Adzopé. Overall, populations of An. gambiae at both sites surveyed showed equivalent frequency of the L1014F kdr allele (0.67) but for all tested pyrethroids, there were significantly higher survival rates for mosquitoes from Tsassodji (32–58%) than those from Port-Bouët (3–32%) (p < 0.001), indicating the implication of resistance mechanisms other than kdr alone. During the survey period (May–June) in this forested area of Côte d’Ivoire, An. gambiae s. s. found were exclusively of the M form and were apparently selected for pyrethroid resistance through agricultural and household usage of insecticides. Conclusion Prior to LLINs scaling up in Eastern Côte d’Ivoire, resistance was largely present at various levels in An. gambiae. Underlying mechanisms included the high frequency of the L1014F kdr mutation and other unidentified components, probably metabolic detoxifiers. Their impact on the efficacy of the planned strategy (LLINs) in the

Effectiveness of organo-phosphorus insecticides against houseflies and mosquitos

PubMed Central

Lindquist, A. W.

1957-01-01

The paper describes the research being undertaken on organo-phosphorus insecticides for the control of houseflies and mosquitos. The information obtained from laboratory and field tests indicates that these insecticides are at present effective substitutes for DDT and other chlorinated-hydrocarbon insecticides for use against resistant houseflies and culicine mosquitos, but the residual applications are not as long lasting as those of DDT and therefore will probably not be as efficient in anopheline control. PMID:13413645

Cost-effectiveness analysis of vaccinating children in Malawi with RTS,S vaccines in comparison with long-lasting insecticide-treated nets

PubMed Central

2014-01-01

Background New RTS,S malaria vaccines may soon be licensed, yet its cost-effectiveness is unknown. Before the widespread introduction of RTS,S vaccines, cost-effectiveness studies are needed to help inform governments in resource-poor settings about how best to prioritize between the new vaccine and existing malaria interventions. Methods A Markov model simulated malaria progression in a hypothetical Malawian birth cohort. Parameters were based on published data. Three strategies were compared: no intervention, vaccination at one year, and long-lasting, insecticide-treated nets (LLINs) at birth. Both health service and societal perspectives were explored. Health outcomes were measured in disability-adjusted life years (DALYs) averted and costed in 2012 US$. Incremental cost-effectiveness ratios (ICERs) were calculated and extensive sensitivity analyses were conducted. Three times GDP per capita ($1,095) per DALY averted was used for a cost-effectiveness threshold, whilst one times GDP ($365) was considered ‘very cost-effective’. Results From a societal perspective the vaccine strategy was dominant. It averted 0.11 more DALYs than LLINs and 0.372 more DALYs than the no intervention strategy per person, while costing $10.04 less than LLINs and $59.74 less than no intervention. From a health service perspective the vaccine’s ICER was $145.03 per DALY averted, and thus can be considered very cost-effective. The results were robust to changes in all variables except the vaccine and LLINs’ duration of efficacy. Vaccines remained cost-effective even at the lowest assumed efficacy levels of 49.6% (mild malaria) and 14.2% (severe malaria), and the highest price of $15. However, from a societal perspective, if the vaccine duration efficacy was set below 2.69 years or the LLIN duration of efficacy was greater than 4.24 years then LLINs became the more cost-effective strategy. Conclusion The results showed that vaccinating Malawian children with RTS,S vaccines was

Analysing and recommending options for maintaining universal coverage with long-lasting insecticidal nets: the case of Tanzania in 2011

PubMed Central

2013-01-01

Background Tanzania achieved universal coverage with long-lasting insecticidal nets (LLINs) in October 2011, after three years of free mass net distribution campaigns and is now faced with the challenge of maintaining high coverage as nets wear out and the population grows. A process of exploring options for a continuous or “Keep-Up” distribution system was initiated in early 2011. This paper presents for the first time a comprehensive national process to review the major considerations, findings and recommendations for the implementation of a new strategy. Methods Stakeholder meetings and site visits were conducted in five locations in Tanzania to garner stakeholder input on the proposed distribution systems. Coverage levels for LLINs and their decline over time were modelled using NetCALC software, taking realistic net decay rates, current demographic profiles and other relevant parameters into consideration. Costs of the different distribution systems were estimated using local data. Results LLIN delivery was considered via mass campaigns, Antenatal Care-Expanded Programme on Immunization (ANC/EPI), community-based distribution, schools, the commercial sector and different combinations of the above. Most approaches appeared unlikely to maintain universal coverage when used alone. Mass campaigns, even when combined with a continuation of the Tanzania National Voucher Scheme (TNVS), would produce large temporal fluctuations in coverage levels; over 10 years this strategy would require 63.3 million LLINs and a total cost of $444 million USD. Community mechanisms, while able to deliver the required numbers of LLINs, would require a massive scale-up in monitoring, evaluation and supervision systems to ensure accurate application of identification criteria at the community level. School-based approaches combined with the existing TNVS would reach most Tanzanian households and deliver 65.4 million LLINs over 10 years at a total cost of $449 million USD and ensure

Pilot study assessing the effectiveness of long-lasting permethrin-impregnated clothing for the prevention of tick bites.

PubMed

Vaughn, Meagan F; Meshnick, Steven R

2011-07-01

Tick-borne diseases such as Lyme disease, Rocky Mountain spotted fever, and ehrlichiosis are a significant concern for many thousands of workers who have frequent and unavoidable exposure to tick-infested habitats. Many North Carolina state employees with outdoor occupations report multiple tick bites each year, indicating that existing tick preventive strategies may be underutilized or ineffective. Treatment of clothing with permethrin, a nontoxic chemical with insecticidal, knockdown, and repellent properties, is highly effective against ticks. However, most permethrin products must be reapplied after several washings to maintain insecticidal activity. Recently, a factory-based method for long-lasting permethrin impregnation of clothing has been developed by Insect Shield, Inc., that allows clothing to retain insecticidal activity for over 70 washes. A nonrandomized open label pilot study was conducted to determine the effectiveness of Insect Shield-treated clothing for the prevention of tick bites among 16 outdoor workers from the North Carolina Division of Water Quality under actual field conditions. Participants completed questionnaires at the start of follow-up (March, 2008) and at the end of follow-up (September, 2008), and tick bites and outdoor work hours were reported on weekly tick bite logs for the entire follow-up period. Subjects wearing Insect Shield-treated clothing had a 93% reduction (p < 0.0001) in the total incidence of tick bites compared to subjects using standard tick bite prevention measures. This study provides preliminary evidence that long-lasting permethrin-impregnated clothing may be highly effective against tick bites.

Rapid Increase in Ownership and Use of Long-Lasting Insecticidal Nets and Decrease in Prevalence of Malaria in Three Regional States of Ethiopia (2006-2007)

PubMed Central

Shargie, Estifanos Biru; Ngondi, Jeremiah; Graves, Patricia M.; Getachew, Asefaw; Hwang, Jimee; Gebre, Teshome; Mosher, Aryc W.; Ceccato, Pietro; Endeshaw, Tekola; Jima, Daddi; Tadesse, Zerihun; Tenaw, Eskindir; Reithinger, Richard; Emerson, Paul M.; Richards, Frank O.; Ghebreyesus, Tedros Adhanom

2010-01-01

Following recent large scale-up of malaria control interventions in Ethiopia, this study aimed to compare ownership and use of long-lasting insecticidal nets (LLIN), and the change in malaria prevalence using two population-based household surveys in three regions of the country. Each survey used multistage cluster random sampling with 25 households per cluster. Household net ownership tripled from 19.6% in 2006 to 68.4% in 2007, with mean LLIN per household increasing from 0.3 to 1.2. Net use overall more than doubled from 15.3% to 34.5%, but in households owning LLIN, use declined from 71.7% to 48.3%. Parasitemia declined from 4.1% to 0.4%. Large scale-up of net ownership over a short period of time was possible. However, a large increase in net ownership was not necessarily mirrored directly by increased net use. Better targeting of nets to malaria-risk areas and sustained behavioural change communication are needed to increase and maintain net use. PMID:20936103

Evaluation of the 2011 long-lasting, insecticide-treated net distribution for universal coverage in Togo.

PubMed

Stevens, Elizabeth R; Aldridge, Abigail; Degbey, Yawo; Pignandi, Akou; Dorkenoo, Monique A; Hugelen-Padin, Justin

2013-05-16

Malaria remains a substantial public health problem in Togo. An integrated child health campaign was conducted in Togo in October 2011. This campaign included a component of free distribution of 2,799,800 long-lasting, insecticide-treated nets (LLINs) to households throughout Togo. This distribution marked the first effort in Togo at universal LLIN coverage and was not targeted specifically to children under five years and pregnant women, but to all household members. This study reports the results of the LLIN distribution campaign in terms of bed net possession and utilization. A representative household survey was implemented during the rainy season nine months after the LLIN distribution component of the campaign. Some 6,015 households selected through two stages of probability proportion to size stratified random sampling were interviewed using a brief questionnaire that included a demographic section with questions on the number of household members and sleeping spaces, and a campaign participation section with questions used to evaluate non-LLIN aspects of the campaign. A net roster listed all nets and their characteristics, and a household roster listed all members and visitors with information about bed net use. The questions addressed different aspects of bed net and LLIN possession and utilization. Crude weighted frequencies, percentages, and t- tests of association were calculated using the Stata 12.0 Survey features. Possession of at least one bed net and/or LLIN increased from 41.3% to 96.7% (P <0.001). Household possession of at least one campaign LLIN was 93.3%. Report LLIN among pregnant women was 77.5% and 79.3% for children under five. For the general population LLIN use was 68.3%. Due to the gap in LLIN possession and use and the significant number of individuals reporting a lack of nets as a reason for non-use, additional national LLIN distribution campaigns with a stronger educational component need to be implemented in order increase the use

Trials of Improved Practices (TIPs): A Strategy for Making Long-Lasting Nets Last Longer?

PubMed Central

Harvey, Steven A.; Paredes Olórtegui, Maribel; Leontsini, Elli; Ramal Asayag, César; Scott, Kerry; Winch, Peter J.

2013-01-01

Long-lasting insecticidal net (LLIN) use is a proven malaria prevention method. Mass distribution has greatly expanded LLIN access in sub-Saharan Africa, but a gap remains between LLIN ownership and use. Furthermore, LLINs wear out more quickly than anticipated. This paper suggests a participatory research strategy—trials of improved practices (TIPs)—that could identify locally appropriate approaches to prolonging net life and increasing effective use. We used TIPs to overcome barriers to optimal net use in the Peruvian Amazon. Working with 15 families in three villages, we tested home treatment of cotton nets, use of an alternative netting fabric, and alternative washing and care instructions. TIPs helped confirm feasibility of these interventions. Although our findings are time- and context-specific, TIPs could help improve consistency and effectiveness of current LLIN use and prolong net lifespan in sub-Saharan Africa and elsewhere. This would help maximize the value of shrinking donor resources for malaria. PMID:23530074

A household randomized, controlled trial of the efficacy of 0.03% transfluthrin coils alone and in combination with long-lasting insecticidal nets on the incidence of Plasmodium falciparum and Plasmodium vivax malaria in Western Yunnan Province, China.

PubMed

Hill, Nigel; Zhou, Hong Ning; Wang, Piyu; Guo, Xiaofang; Carneiro, Ilona; Moore, Sarah J

2014-05-31

Mosquito coils are the most commonly used household insecticidal product in the world with sales exceeding 50 billion coils, used by two billion people worldwide annually. Despite strong evidence that coils prevent mosquito bites a systematic review concluded that there is no evidence that burning mosquito coils prevents malaria acquisition. Therefore, the current trial was designed to measure and compare prevention of malaria infection by mosquito coils or long-lasting insecticidal net (LLIN) or a combination of the two in Yunnan, China in the Greater Mekong sub-region. A four-arm single blind household-randomized design was chosen as coils emanate insecticide throughout the household. Households enrolled at baseline were randomly allocated by the lottery method to one of the four intervention arms: (i) nothing, (ii) 0.03% transfluthrin coils alone, (iii) deltamethrin long-lasting insecticide treated nets, (LLINs) alone or (iv) a combination of transfluthrin coils and deltamethrin LLINs. All household members were recruited to the study, with only those households excluded with pregnant or breastfeeding mothers, members with chest complaints or allergies or members that regularly slept away from home. The main outcome of interest was Plasmodium falciparum malaria prevalence detected by rapid diagnostic tests (RDTs) during six repeated monthly cross-sectional surveys. The secondary outcome of interest was the effect on Plasmodium vivax prevalence detected in the same way. A total of 2,052 households were recruited into the study, comprising 7,341 individuals The odds ratios of testing positive by RDT with P. falciparum or P. vivax were >75% lower for all intervention arms compared with the control arm. Coils alone provided 77% protection (95% CI: 50%-89%), LLINs provided 91% protection (95% CI: 72%-97%) and the combination of coils and LLINs provided 94% protection (95% CI: 77%-99%) against P. falciparum compared with the control arm. There was no statistically

When intensity of deltamethrin resistance in Anopheles gambiae s.l. leads to loss of Long Lasting Insecticidal Nets bio-efficacy: a case study in north Cameroon.

PubMed

Etang, Josiane; Pennetier, Cédric; Piameu, Michael; Bouraima, Aziz; Chandre, Fabrice; Awono-Ambene, Parfait; Marc, Coosemans; Corbel, Vincent

2016-03-08

In Cameroon, insecticide resistance in Anopheles (An.) gambiae s.l. has been reported in several foci, prompting further investigations on associated patterns of Long-Lasting Insecticidal Nets (LLINs) bio-efficacy. The current study, conducted from June to August 2011, explored the intensity of deltamethrin resistance in An. gambiae s.l. from Pitoa and its impact on the residual bio-efficacy of LifeNet, a LLIN with deltamethrin incorporated into polypropylene nets (PND). Two-four days old females An. gambiae s.l. reared from larval collections in Pitoa were tested for susceptibility to DDT, permethrin and deltamethrin, using standard World Health Organization (WHO) tube assays. Intensity of deltamethrin resistance was explored using WHO tube assays, but across six working concentrations from 0.001 % to 0.5 %. Bio-efficacy of unwashed and washed PND was assessed using WHO cone test. Species identification and kdr 1014 genotyping were performed on mosquito samples that were not exposed to insecticides, using PCR-RFLP and HOLA methods respectively. The Kisumu reference susceptible strain of An. gambiae s.s. was used for comparisons. A total of 1895 An. gambiae s.l. specimens from Pitoa were used for resistance and PND bio-efficacy testing. This mosquito population was resistant to DDT, permethrin and deltamethrin, with 18-40 min knockdown times for 50 % of tested mosquitoes and 59-77 % mortality. Deltamethrin Resistance Ratio compared with the Kisumu strain was estimated at ≥500 fold. LifeNets were effective against the susceptible Kisumu (100 % knockdown (KD60min) and mortality) and the resistant Pitoa samples (95 % KD60min, 83-95 % mortality). However, the bio-efficacy gradually dropped against the Pitoa samples when nets were washed (X (2) = 35.887, df = 8, p < 0.001), and fell under the WHO efficacy threshold (80 % mortality and/or 95 % KD60min) between 10 and 15 washes. The Pitoa samples were composed of three sibling species: An. arabiensis (132

Effectiveness of post-campaign, door-to-door, hang-up, and communication interventions to increase long-lasting, insecticidal bed net utilization in Togo (2011–2012): a cluster randomized, control trial

PubMed Central

2014-01-01

Background It is well established that insecticide-treated bed nets (ITNs), in particular long-lasting, insecticidal nets (LLINs), can be used as one of the primary interventions for effective malaria control. A consistent gap between net ownership and use has been observed, indicating that factors exist that prevent an owned mosquito net from being used. One approach used in the context of LLIN campaigns is a post-distribution, door-to-door visit of households with educational messages and to physically assist with hang-up of nets. Methods A cluster randomized trial was conducted in the Plateaux Region of Togo to evaluate the effectiveness of different approaches to post-LLIN campaign home visits (number of visits and timing) by volunteers to enhance LLIN hang-up and utilization. Results It was found that, in general, households that received intervention visits, particularly the most recent intervention visit, had levels of use that were typically 5 to 10% higher than the control households, while access did not differ among control and intervention households. Eight months post-campaign, ITN use by all individuals, children under five years and women of reproductive age was 11.3 to 14.4 percentage points greater in the study arm that received all three intervention visits than in the control communities. In households that received one or two additional door-to-door visits, the majority of respondents indicated that the volunteer provided new information during the visit regarding the use and importance of ITNs despite having received previous multiple visits. Conclusions The impact of the interventions appears to have been primarily through the delivery and reinforcement of key behaviour-change communication (BCC) messages regarding the importance of using an ITN and its care. Regardless of whether the respondents in fact received new information or had forgotten earlier information, this suggests that regular visits from community agents are useful in

Examining equity in access to long-lasting insecticide nets and artemisinin-based combination therapy in Anambra State, Nigeria.

PubMed

Mbachu, Chinyere O; Onwujekwe, Obinna E; Uzochukwu, Benjamin S C; Uchegbu, Eloka; Oranuba, Joseph; Ilika, Amobi L

2012-05-22

In order to achieve universal health coverage, the government of Anambra State, southeast Nigeria has distributed free Long-lasting Insecticide treated Nets (LLINs) to the general population and delivered free Artemisinin-based Combination Therapy (ACT) to pregnant women and children less than 5 years. However, the levels of coverage with LLINS and ACTs is not clear, especially coverage of different socio-economic status (SES) population groups. This study was carried out to determine the level of coverage and access to LLINs and ACTs amongst different SES groups. A questionnaire was used to collect data from randomly selected households in 19 local government areas of the State. Selected households had a pregnant woman and/or a child less than 5 years. The lot quality assurance sampling (LQAS) methodology was used in sampling. The questionnaire explored the availability and utilization of LLINs and ACTs from 2394 households. An asset-based SES index was used to examine the level of access of LLINS and ACTs to different SES quintiles. It was found that 80.5% of the households had an LLIN and 64.4% of the households stated that they actually used the nets the previous night. The findings showed that 42.3% of pregnant women who had fever within the past month received ACTs, while 37.5% of children<5 years old who had malaria in the past month had received ACTs. There was equity in ownership of nets for the range 1-5 nets per household. No significant SES difference was found in use of ACTs for treatment of malaria in children under five years old and in pregnant women. The free distribution of LLINs and ACTs increased household coverage of both malaria control interventions and bridged the equity gap in access to them among the most vulnerable groups.

Evaluation of a universal long-lasting insecticidal net (LLIN) distribution campaign in Ghana: cost effectiveness of distribution and hang-up activities

PubMed Central

2014-01-01

Background Between May 2010 and October 2012, approximately 12.5 million long-lasting insecticidal nets (LLINs) were distributed through a national universal mass distribution campaign in Ghana. The campaign included pre-registration of persons and sleeping places, door-to-door distribution of LLINs with ‘hang-up’ activities by volunteers and post-distribution ‘keep-up’ behaviour change communication activities. Hang-up activities were included to encourage high and sustained use. Methods The cost and cost-effectiveness of the LLIN Campaign were evaluated using a before-after design in three regions: Brong Ahafo, Central and Western. The incremental cost effectiveness of the ‘hang-up’ component was estimated using reported variation in the implementation of hang-up activities and LLIN use. Economic costs were estimated from a societal perspective assuming LLINs would be replaced after three years, and included the time of unpaid volunteers and household contributions given to volunteers. Results Across the three regions, 3.6 million campaign LLINs were distributed, and 45.5% of households reported the LLINs received were hung-up by a volunteer. The financial cost of the campaign was USD 6.51 per LLIN delivered. The average annual economic cost was USD 2.90 per LLIN delivered and USD 6,619 per additional child death averted by the campaign. The cost-effectiveness of the campaign was sensitive to the price, lifespan and protective efficacy of LLINs. Hang-up activities constituted 7% of the annual economic cost, though the additional financial cost was modest given the use of volunteers. LLIN use was greater in households in which one or more campaign LLINs were hung by a volunteer (OR = 1.57; 95% CI = 1.09, 2.27; p = 0.02). The additional economic cost of the hang-up activities was USD 0.23 per LLIN delivered, and achieved a net saving per LLIN used and per death averted. Conclusion In this campaign, hang-up activities were estimated to be net

Pilot study on the combination of an organophosphate-based insecticide paint and pyrethroid-treated long lasting nets against pyrethroid resistant malaria vectors in Burkina Faso.

PubMed

Mosqueira, Beatriz; Soma, Dieudonné D; Namountougou, Moussa; Poda, Serge; Diabaté, Abdoulaye; Ali, Ouari; Fournet, Florence; Baldet, Thierry; Carnevale, Pierre; Dabiré, Roch K; Mas-Coma, Santiago

2015-08-01

A pilot study to test the efficacy of combining an organophosphate-based insecticide paint and pyrethroid-treated Long Lasting Insecticide Treated Nets (LLINs) against pyrethroid-resistant malaria vector mosquitoes was performed in a real village setting in Burkina Faso. Paint Inesfly 5A IGR™, comprised of two organophosphates (OPs) and an Insect Growth Regulator (IGR), was tested in combination with pyrethroid-treated LLINs. Efficacy was assessed in terms of mortality for 12 months using Early Morning Collections of malaria vectors and 30-minute WHO bioassays. Resistance to pyrethroids and OPs was assessed by detecting the frequency of L1014F and L1014S kdr mutations and Ace-1(R)G119S mutation, respectively. Blood meal origin was identified using a direct enzyme-linked immunosorbent assay (ELISA). The combination of Inesfly 5A IGR™ and LLINs was effective in killing 99.9-100% of malaria vector populations for 6 months regardless of the dose and volume treated. After 12 months, mortality rates decreased to 69.5-82.2%. The highest mortality rates observed in houses treated with 2 layers of insecticide paint and a larger volume. WHO bioassays supported these results: mortalities were 98.8-100% for 6 months and decreased after 12 months to 81.7-97.0%. Mortality rates in control houses with LLINs were low. Collected malaria vectors consisted exclusively of Anopheles coluzzii and were resistant to pyrethroids, with a L1014 kdr mutation frequency ranging from 60 to 98% through the study. About 58% of An. coluzzii collected inside houses had bloodfed on non-human animals. Combining Inesfly 5A IGR™ and LLINs yielded a one year killing efficacy against An. coluzzii highly resistant to pyrethroids but susceptible to OPs that exhibited an anthropo-zoophilic behaviour in the study area. The results obtained in a real setting supported previous work performed in experimental huts and underscore the need to study the impact that this novel strategy may have on clinical

Comparative field evaluation of combinations of long-lasting insecticide treated nets and indoor residual spraying, relative to either method alone, for malaria prevention in an area where the main vector is Anopheles arabiensis

PubMed Central

2013-01-01

Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly used together in the same households to improve malaria control despite inconsistent evidence on whether such combinations actually offer better protection than nets alone or IRS alone. Methods Comparative tests were conducted using experimental huts fitted with LLINs, untreated nets, IRS plus untreated nets, or combinations of LLINs and IRS, in an area where Anopheles arabiensis is the predominant malaria vector species. Three LLIN types, Olyset®, PermaNet 2.0® and Icon Life® nets and three IRS treatments, pirimiphos-methyl, DDT, and lambda cyhalothrin, were used singly or in combinations. We compared, number of mosquitoes entering huts, proportion and number killed, proportions prevented from blood-feeding, time when mosquitoes exited the huts, and proportions caught exiting. The tests were done for four months in dry season and another six months in wet season, each time using new intact nets. Results All the net types, used with or without IRS, prevented >99% of indoor mosquito bites. Adding PermaNet 2.0® and Icon Life®, but not Olyset® nets into huts with any IRS increased mortality of malaria vectors relative to IRS alone. However, of all IRS treatments, only pirimiphos-methyl significantly increased vector mortality relative to LLINs alone, though this increase was modest. Overall, median mortality of An. arabiensis caught in huts with any of the treatments did not exceed 29%. No treatment reduced entry of the vectors into huts, except for marginal reductions due to PermaNet 2.0® nets and DDT. More than 95% of all mosquitoes were caught in exit traps rather than inside huts. Conclusions Where the main malaria vector is An. arabiensis, adding IRS into houses with intact pyrethroid LLINs does not enhance house-hold level protection except where the IRS employs non-pyrethroid insecticides such as pirimiphos-methyl, which can confer modest enhancements. In

Long-lasting insecticide-treated bed net ownership and use among children under five years of age following a targeted distribution in central Uganda

PubMed Central

2014-01-01

Background Universal coverage of long-lasting insecticide-treated bed nets (LLINs) for prevention of malaria was adopted by the Uganda National Malaria Control Programme in 2007. The first mass distribution of LLINs was implemented in 2010. Initially, a campaign targeted to households with pregnant women and children aged

Costs and effects of two public sector delivery channels for long-lasting insecticidal nets in Uganda.

PubMed

Kolaczinski, Jan H; Kolaczinski, Kate; Kyabayinze, Daniel; Strachan, Daniel; Temperley, Matilda; Wijayanandana, Nayantara; Kilian, Albert

2010-04-20

In Uganda, long-lasting insecticidal nets (LLIN) have been predominantly delivered through two public sector channels: targeted campaigns or routine antenatal care (ANC) services. Their combination in a mixed-model strategy is being advocated to quickly increase LLIN coverage and maintain it over time, but there is little evidence on the efficiency of each system. This study evaluated the two delivery channels regarding LLIN retention and use, and estimated the associated costs, to contribute towards the evidence-base on LLIN delivery channels in Uganda. Household surveys were conducted 5-7 months after LLIN distribution, combining questionnaires with visual verification of LLIN presence. Focus groups and interviews were conducted to further investigate determinants of LLIN retention and use. Campaign distribution was evaluated in Jinja and Adjumani while ANC distribution was evaluated only in the latter district. Costs were calculated from the provider perspective through retrospective analysis of expenditure data, and effects were estimated as cost per LLIN delivered and cost per treated-net-year (TNY). These effects were calculated for the total number of LLINs delivered and for those retained and used. After 5-7 months, over 90% of LLINs were still owned by recipients, and between 74% (Jinja) and 99% (ANC Adjumani) were being used. Costing results showed that delivery was cheapest for the campaign in Jinja and highest for the ANC channel, with economic delivery cost per net retained and used of USD 1.10 and USD 2.31, respectively. Financial delivery costs for the two channels were similar in the same location, USD 1.04 for campaign or USD 1.07 for ANC delivery in Adjumani, but differed between locations (USD 0.67 for campaign delivery in Jinja). Economic cost for ANC distribution were considerably higher (USD 2.27) compared to campaign costs (USD 1.23) in Adjumani. Targeted campaigns and routine ANC services can both achieve high LLIN retention and use among

Effectiveness of a new long-lasting insecticidal nets delivery model in two rural districts of Mozambique: a before-after study.

PubMed

Arroz, Jorge A H; Candrinho, Baltazar; Mendis, Chandana; Varela, Pablo; Pinto, João; Martins, Maria do Rosário O

2018-02-05

In 2015, Mozambique piloted a new model of long-lasting insecticidal nets (LLINs) delivery in a campaign. The new delivery model was used in two rural districts were, and two others were considered as control, maintaining the old delivery model. The aim of this study is to compare the coverage of ownership and use of LLINs in intervention and control districts in Mozambique. A before-after design with control group was carried out 6 months after LLINs distribution. Using systematic probabilistic sampling, 1547 households were surveyed by means of a questionnaire. To find associations between the district categories (intervention and control) and the main outcomes of the study (LLIN ownership, use, and universal coverage achievement), odds ratio (OR) and respective confidence intervals were calculated. Of the 760 households surveyed in the intervention districts, 98.8% had at least one LLIN; of the 787 households surveyed in the control districts, 89.6% had at least one LLIN [OR: 9.7, 95% (CI 4.84-19.46)]. Around 95 and 87% of households owning at least one LLIN reported having slept under the LLIN the previous night in the intervention and control districts, respectively [OR: 3.2; 95% (CI 2.12-4.69)]. Seventy-one percent of the households surveyed achieved universal coverage in the intervention districts against 59.6% in the control districts [OR: 1.6; 95% (CI 1.33-2.03)]. The universal coverage campaign piloted with the new delivery model has increased LLINs ownership, use, and progression for reaching universal coverage targets in the community.

Long-lasting permethrin impregnated uniforms: A randomized-controlled trial for tick bite prevention.

PubMed

Vaughn, Meagan F; Funkhouser, Sheana Whelan; Lin, Feng-Chang; Fine, Jason; Juliano, Jonathan J; Apperson, Charles S; Meshnick, Steven R

2014-05-01

Because of frequent exposure to tick habitats, outdoor workers are at high risk for tick-borne diseases. Adherence to National Institute for Occupational Safety and Health-recommended tick bite prevention methods is poor. A factory-based method for permethrin impregnation of clothing that provides long-lasting insecticidal and repellent activity is commercially available, and studies are needed to assess the long-term effectiveness of this clothing under field conditions. To evaluate the protective effectiveness of long-lasting permethrin impregnated uniforms among a cohort of North Carolina outdoor workers. A double-blind RCT was conducted between March 2011 and September 2012. Subjects included outdoor workers from North Carolina State Divisions of Forestry, Parks and Recreation, and Wildlife who worked in eastern or central North Carolina. A total of 159 volunteer subjects were randomized, and 127 and 101 subjects completed the first and second years of follow-up, respectively. Uniforms of participants in the treatment group were factory-impregnated with long-lasting permethrin whereas control group uniforms received a sham treatment. Participants continued to engage in their usual tick bite prevention activities. Incidence of work-related tick bites reported on weekly tick bite logs. Study subjects reported 1,045 work-related tick bites over 5,251 person-weeks of follow-up. The mean number of reported tick bites in the year prior to enrollment was similar for both the treatment and control groups, but markedly different during the study period. In our analysis conducted in 2013, the effectiveness of long-lasting permethrin impregnated uniforms for the prevention of work-related tick bites was 0.82 (95% CI=0.66, 0.91) and 0.34 (95% CI=-0.67, 0.74) for the first and second years of follow-up. These results indicate that long-lasting permethrin impregnated uniforms are highly effective for at least 1 year in deterring tick bites in the context of typical tick bite

"Before we used to get sick all the time": perceptions of malaria and use of long-lasting insecticide-treated bed nets (LLINs) in a rural Kenyan community

PubMed Central

2010-01-01

Background Malaria is a leading global cause of preventable morbidity and mortality, especially in sub-Saharan Africa, despite recent advances in treatment and prevention technologies. Scale-up and wide distribution of long-lasting insecticide-treated nets (LLINs) could rapidly decrease malarial disease in endemic areas, if used properly and continuously. Studies have shown that effective use of LLINs depends, in part, upon understanding causal factors associated with malaria. This study examined malaria beliefs, attitudes, and practices toward LLINs assessed during a large-scale integrated prevention campaign (IPC) in rural Kenya. Methods Qualitative interviews were conducted with 34 IPC participants who received LLINs as part of a comprehensive prevention package of goods and services. One month after distribution, interviewers asked these individuals about their attitudes and beliefs regarding malaria, and about their use of LLINs. Results Virtually all participants noted that mosquitoes were involved in causing malaria, though a substantial proportion of participants (47 percent) also mentioned an incorrect cause in addition to mosquitoes. For example, participants commonly noted that the weather (rain, cold) or consumption of bad food and water caused malaria. Regardless, most participants used the LLINs they were given and most mentioned positive benefits from their use, namely reductions in malarial illness and in the costs associated with its diagnosis and treatment. Conclusions Attitudes toward LLINs were positive in this rural community in Western Kenya, and respondents noted benefits with LLIN use. With improved understanding and clarification of the direct (mosquitoes) and indirect (e.g., standing water) causes of malaria, it is likely that LLIN use can be sustained, offering effective household-level protection against malaria. PMID:21118550

Impact of a behaviour change intervention on long-lasting insecticidal net care and repair behaviour and net condition in Nasarawa State, Nigeria.

PubMed

Koenker, Hannah; Kilian, Albert; Hunter, Gabrielle; Acosta, Angela; Scandurra, Leah; Fagbemi, Babafunke; Onyefunafoa, Emmanuel O; Fotheringham, Megan; Lynch, Matthew

2015-01-21

While some data on net durability have been accumulating in recent years, including formative qualitative research on attitudes towards net care and repair, no data are available on how the durability of a net is influenced by behaviour of net maintenance, care and repair, and whether behavioural change interventions (BCC) could substantially impact on the average useful life of the net. The study used an intervention-control design with before-after assessment through repeated cross-sectional household surveys with two-stage cluster sampling following Nasarawa State's December 2010 mass campaign. All campaign nets were 100-denier polyester, long-lasting insecticidal nets (LLIN). Baseline, midline, and endline surveys occurred at one-year intervals, in March 2012, March 2013, and April 2014, respectively. Outcome measures were the proportion of confirmed campaign nets with observed repairs, and the proportion in serviceable condition, measured with proportionate hole index (pHI) and according to WHO guidelines. For all respondents, exposure to BCC messages was strongly correlated with increased positive attitude towards care and repair, and increases in attitude were positively correlated with observed net repairs, and with the proportion of nets in serviceable condition. In a multivariate regression model, positive care and repair attitude (OR 6.17 p = 0.001) and level of exposure (1 source: OR 4.00 p = 0.000; 3 sources: OR 9.34 p = 0.000) remained the most significant predictors of net condition, controlling for background and environmental factors. Nets that were tied up had 2.70 higher odds of being in serviceable condition (p = 0.001), while repairs made to nets were not sufficient to improve their pHI category. Estimated median net lifespan was approximately one full year longer for nets in households with a positive compared to a negative attitude. Exposure to multiple channels of a comprehensive BCC intervention was associated with improved

Potential benefits of combining transfluthrin-treated sisal products and long-lasting insecticidal nets for controlling indoor-biting malaria vectors.

PubMed

Masalu, John P; Okumu, Fredros O; Mmbando, Arnold S; Sikulu-Lord, Maggy T; Ogoma, Sheila B

2018-04-10

Transfluthrin vapour prevents mosquito bites by disrupting their host-seeking behaviors. We measured the additional benefits of combining transfluthrin-treated sisal decorations and long-lasting insecticidal nets (LLINs) with an aim of extending protection against early evening, indoor-biting malaria vectors when LLINs are ineffective. We investigated the indoor protective efficacy of locally made sisal decorative baskets (0.28 m 2 ) treated with 2.5 ml and 5.0 ml transfluthrin, in terms of mosquito density, exposure to bites and 24 h mortality. Experiments were conducted in experimental huts, located in Lupiro village, Ulanga District, south-eastern Tanzania. Human landing catches (HLC) were used to measure exposure to bites between 19:00-23:00 h. Each morning, at 06:00 h, mosquitoes were collected inside huts and in exit traps and monitored for 24 h mortality. Sisal decorative baskets (0.28 m 2 ) treated with 2.5 ml and 5.0 ml transfluthrin deterred three-quarters of Anopheles arabiensis mosquitoes from entering huts (relative rate, RR = 0.26, 95% confidence interval, CI: 0.20-0.34, P < 0.001 and RR= 0.29, 95% CI: 0.22-0.37, P < 0.001, respectively). Both treatments induced a 10-fold increase in 24 h mortality of An. arabiensis mosquitoes (odds ratio, OR = 12.26, 95% CI: 7.70-19.51, P < 0.001 and OR = 18.42, 95% CI: 11.36-29.90, P < 0.001, respectively). Sisal decorative items treated with spatial repellents provide additional household and personal protection against indoor biting malaria and nuisance mosquitoes in the early evening, when conventional indoor vector control tools, such as LLINs, are not in use. We recommend future studies to investigate the epidemiological relevance of combining LLINs and transfluthrin decorated baskets in terms of their effect on reduction in malaria prevalence.

Planning long lasting insecticide treated net campaigns: should households' existing nets be taken into account?

PubMed

Yukich, Joshua; Bennett, Adam; Keating, Joseph; Yukich, Rudy K; Lynch, Matt; Eisele, Thomas P; Kolaczinski, Kate

2013-06-14

Mass distribution of long-lasting insecticide treated bed nets (LLINs) has led to large increases in LLIN coverage in many African countries. As LLIN ownership levels increase, planners of future mass distributions face the challenge of deciding whether to ignore the nets already owned by households or to take these into account and attempt to target individuals or households without nets. Taking existing nets into account would reduce commodity costs but require more sophisticated, and potentially more costly, distribution procedures. The decision may also have implications for the average age of nets in use and therefore on the maintenance of universal LLIN coverage over time. A stochastic simulation model based on the NetCALC algorithm was used to determine the scenarios under which it would be cost saving to take existing nets into account, and the potential effects of doing so on the age profile of LLINs owned. The model accounted for variability in timing of distributions, concomitant use of continuous distribution systems, population growth, sampling error in pre-campaign coverage surveys, variable net 'decay' parameters and other factors including the feasibility and accuracy of identifying existing nets in the field. Results indicate that (i) where pre-campaign coverage is around 40% (of households owning at least 1 LLIN), accounting for existing nets in the campaign will have little effect on the mean age of the net population and (ii) even at pre-campaign coverage levels above 40%, an approach that reduces LLIN distribution requirements by taking existing nets into account may have only a small chance of being cost-saving overall, depending largely on the feasibility of identifying nets in the field. Based on existing literature the epidemiological implications of such a strategy is likely to vary by transmission setting, and the risks of leaving older nets in the field when accounting for existing nets must be considered. Where pre-campaign coverage

Insecticide susceptibility of Anopheles stephensi to DDT and current insecticides in an elimination area in Iran.

PubMed

Zare, Mehdi; Soleimani-Ahmadi, Moussa; Davoodi, Sayed Hossein; Sanei-Dehkordi, Alireza

2016-11-04

Iran has recently initiated a malaria elimination program with emphasis on vector control strategies which are heavily reliant on indoor residual spraying and long-lasting insecticidal nets. Insecticide resistance seriously threatens the efficacy of vector control strategies. This study was conducted to determine the insecticide susceptibility of Anopheles stephensi to DDT and current insecticides in Jask county as an active malaria focus in southeastern Iran. In this study, the anopheline larvae were collected from different aquatic habitats in Jask county and transported to insectarium, fed with sugar and then 3-day-old adults were used for susceptibility tests. WHO insecticide susceptibility tests were performed with DDT (4 %), malathion (5 %), lambda-cyhalothrin (0.05 %), deltamethrin (0.05 %) and permethrin (0.75 %). The field strain of An. stephensi was found resistant to DDT and lambda-cyhalothrin. The LT 50 values for DDT and lambda-cyhalothrin in this species were 130.25, and 37.71 min, respectively. Moreover, An. stephensi was completely susceptible to malathion and permethrin and tolerant to deltamethrin. The present study results confirm the resistance of the major malaria vector, An. stephensi, to DDT and lambda-cyhalothrin, and tolerance to deltamethrin, which could gradually increase and spread into other malaria endemic areas. Thus, there is a need for regular monitoring of insecticide resistance in order to select suitable insecticides for vector control interventions towards malaria elimination.

Effect of village-wide use of long-lasting insecticidal nets on visceral Leishmaniasis vectors in India and Nepal: a cluster randomized trial.

PubMed

Picado, Albert; Das, Murari L; Kumar, Vijay; Kesari, Shreekant; Dinesh, Diwakar S; Roy, Lalita; Rijal, Suman; Das, Pradeep; Rowland, Mark; Sundar, Shyam; Coosemans, Marc; Boelaert, Marleen; Davies, Clive R

2010-01-26

Visceral leishmaniasis (VL) control in the Indian subcontinent is currently based on case detection and treatment, and on vector control using indoor residual spraying (IRS). The use of long-lasting insecticidal nets (LN) has been postulated as an alternative or complement to IRS. Here we tested the impact of comprehensive distribution of LN on the density of Phlebotomus argentipes in VL-endemic villages. A cluster-randomized controlled trial with household P. argentipes density as outcome was designed. Twelve clusters from an ongoing LN clinical trial--three intervention and three control clusters in both India and Nepal--were selected on the basis of accessibility and VL incidence. Ten houses per cluster selected on the basis of high pre-intervention P. argentipes density were monitored monthly for 12 months after distribution of LN using CDC light traps (LT) and mouth aspiration methods. Ten cattle sheds per cluster were also monitored by aspiration. A random effect linear regression model showed that the cluster-wide distribution of LNs significantly reduced the P. argentipes density/house by 24.9% (95% CI 1.80%-42.5%) as measured by means of LTs. The ongoing clinical trial, designed to measure the impact of LNs on VL incidence, will confirm whether LNs should be adopted as a control strategy in the regional VL elimination programs. The entomological evidence described here provides some evidence that LNs could be usefully deployed as part of the VL control program. ClinicalTrials.gov CT-2005-015374.

Long-Lasting Insecticide Net Ownership, Access and Use in Southwest Ethiopia: A Community-Based Cross-Sectional Study

PubMed Central

Seyoum, Dinberu; Speybroeck, Niko; Duchateau, Luc; Brandt, Patrick; Rosas-Aguirre, Angel

2017-01-01

Introduction: A large proportion of the Ethiopian population (approximately 68%) lives in malaria risk areas. Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the malaria prevention and control strategy in the country. This study assessed the ownership, access and use of LLNs in the malaria endemic southwest Ethiopia. Methods: A community-based cross-sectional study was conducted in southwest Ethiopia during October–November 2015, including 836 households from sixteen villages around Gilgel-Gibe dam area. Indicators of ownership, access and use of LLINs were derived following the Roll Back Malaria (RBM) guidelines. Factors associated with failure for both LLIN access and use were analysed at household level using a multivariate logistic regression model. Results: The proportion of households with at least one LLIN was 82.7% (95% CI: 80.0, 85.1). However, only 68.9% (95% CI: 65.6, 71.9) had enough LLINs to cover all family members (with ≥one LLIN for every two persons). While 75.3% (95% CI: 68.4, 83.0) of the population was estimated to have accessed to LLINs, only 63.8% (95% CI: 62.3, 65.2) reported to have used a LLIN the previous night. The intra-household gap (i.e., households owning at least one LLIN, but unable to cover all family members) and the behavioral gap (i.e., household members who did not sleep under a LLIN despite having access to one) were 16.8% and 10.5%, respectively. Age, marital status and education of household heads, as well as household size and cooking using firewood were associated with the access to enough LLINs within households. Decreased access to LLINs at households was the main determinant for not achieving ≥80% household members sleeping under a LLIN the previous night. Other associated factors were household size and education level of household head. Conclusions: LLIN coverage levels in study villages remain below national targets of 100% for ownership and 80% for use. The access to

Long-Lasting Insecticide Net Ownership, Access and Use in Southwest Ethiopia: A Community-Based Cross-Sectional Study.

PubMed

Seyoum, Dinberu; Speybroeck, Niko; Duchateau, Luc; Brandt, Patrick; Rosas-Aguirre, Angel

2017-10-27

Introduction : A large proportion of the Ethiopian population (approximately 68%) lives in malaria risk areas. Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the malaria prevention and control strategy in the country. This study assessed the ownership, access and use of LLNs in the malaria endemic southwest Ethiopia. Methods: A community-based cross-sectional study was conducted in southwest Ethiopia during October-November 2015, including 836 households from sixteen villages around Gilgel-Gibe dam area. Indicators of ownership, access and use of LLINs were derived following the Roll Back Malaria (RBM) guidelines. Factors associated with failure for both LLIN access and use were analysed at household level using a multivariate logistic regression model. Results: The proportion of households with at least one LLIN was 82.7% (95% CI: 80.0, 85.1). However, only 68.9% (95% CI: 65.6, 71.9) had enough LLINs to cover all family members (with ≥one LLIN for every two persons). While 75.3% (95% CI: 68.4, 83.0) of the population was estimated to have accessed to LLINs, only 63.8% (95% CI: 62.3, 65.2) reported to have used a LLIN the previous night. The intra-household gap (i.e., households owning at least one LLIN, but unable to cover all family members) and the behavioral gap (i.e., household members who did not sleep under a LLIN despite having access to one) were 16.8% and 10.5%, respectively. Age, marital status and education of household heads, as well as household size and cooking using firewood were associated with the access to enough LLINs within households. Decreased access to LLINs at households was the main determinant for not achieving ≥80% household members sleeping under a LLIN the previous night. Other associated factors were household size and education level of household head. Conclusions: LLIN coverage levels in study villages remain below national targets of 100% for ownership and 80% for use. The access to

Comparison of the Laboratory Standard Washing Using CIPAC Washing Agent and the Domestic Washing on Three Recommended Types of Long-Lasting Insecticidal Mosquito Nets

PubMed Central

Ouattara, Jean Pierre Nabléni; Louwagie, Johanna; Pigeon, Olivier; Spanoghe, Pieter

2013-01-01

Background One of the best ways to prevent malaria is the use of insecticide-treated bed nets. Manufacturers pursue easier, safer and more efficient nets. Hence, many studies on the efficacy and wash resistance using World Health Organization standards have been reported. The commonly used detergent is “Savon de Marseille”, because it closely resembles actually used soaps. At the 54th Collaborative International Pesticides Analytical Council (CIPAC) Technical Meeting in 2010, it was suggested to replace it by a standardized “CIPAC washing agent”. The aim of this study was to investigate the difference between a laboratory hand washing simulation using the CIPAC washing agent (method-1) and a domestic washing (method-2) on different bed nets, as well as the effect of the drying process on the release of active ingredient. Methods Interceptor®, Permanet®2.0 and Netprotect® nets were used in three treatments, each repeated 20 times. The first treatment included method-1 washing and indoor drying. The second treatment included method-2 washing and indoor drying. The third treatment used method-2 washing and UV-drying. The residual insecticide contents were determined using gas chromatography. Results The washing procedure and the number of washes have a significant effect on the release of active ingredient. Statistically, the two washing methods have the same effect on removing the active ingredient from the Interceptor® and Permanet®2.0 net, but a significantly different influence on the Netprotect® nets. The drying process has no significant effect on the insecticide. Conclusion Both washing procedures affected the amount of insecticide remaining on nets independently of the impregnation technology. The active ingredient decreases with the number of washing cycles following an exponential or logarithmic model for coated nets. The laboratory hand washing simulation had more impact on the decrease of active ingredient content of the Netprotect® nets

Impact of changing over of insecticide from synthetic pyrethroids to DDT for indoor residual spray in a malaria endemic area of Orissa, India

PubMed Central

Sharma, Surya K.; Upadhyay, Ashok K.; Haque, Mohammed A.; Tyagi, Prajesh K.; Kindo, Bikrant K.

2012-01-01

Background & objectives: Development of insecticide resistance in malaria vectors has been a major problem for achieving effective vector control. Due to limited availability of insecticides, the only option is management of resistance by judiciously using the insecticides and rotating them to maintain their effectiveness. This study was carried out in a malaria endemic area of Sundergarh district in Orissa where synthetic pyrethroids (SP) were in use for the last couple of years. The change-over from SP to DDT was done in one arm of study, and the other two arms remained on SP and insecticide-treated nets (ITN). Entomological and parasitological monitoring was done to assess the impact. Methods: The study design comprised of three arms (i) two rounds of indoor residual spraying (IRS) with DDT 1g/m2 as a change-over insecticide in areas previously under synthetic pyrethroids; (ii) two rounds of IRS with synthetic pyrethroid (alphacypermethrin, ACM) @ 25 mg/m2; and (iii) an unsprayed area under ITN/long lasting insecticide nets (LNs). Indoor residual spraying was undertaken under strict supervision to maintain quality and coverage. Contact bioassays were conducted to know the persistence of insecticide on sprayed surfaces and adult vector density was monitored in fixed and randomly selected houses. Malaria incidence was measured through fortnightly domiciliary surveillance under primary health care system in all the study villages. Results: The insecticide susceptibility tests showed that An.culicifacies was resistant to DDT but susceptible to malathion and ACM. However, An. fluviatilis was susceptible to all the three insecticides. ACM was effective in killing An. culicifacies on mud and wooden sprayed surfaces and maintained effective bioefficacy ranging from 92 to 100 per cent up to five months, whereas DDT failed to achieve effective mortality in An.culicifacies. However, there was significant decline in the density of An.culicifacies in ACM and DDT areas in

Incremental impact upon malaria transmission of supplementing pyrethroid-impregnated long-lasting insecticidal nets with indoor residual spraying using pyrethroids or the organophosphate, pirimiphos methyl.

PubMed

Hamainza, Busiku; Sikaala, Chadwick H; Moonga, Hawela B; Chanda, Javan; Chinula, Dingani; Mwenda, Mulenga; Kamuliwo, Mulakwa; Bennett, Adam; Seyoum, Aklilu; Killeen, Gerry F

2016-02-18

Long-lasting, insecticidal nets (LLINs) and indoor residual spraying (IRS) are the most widely accepted and applied malaria vector control methods. However, evidence that incremental impact is achieved when they are combined remains limited and inconsistent. Fourteen population clusters of approximately 1000 residents each in Zambia's Luangwa and Nyimba districts, which had high pre-existing usage rates (81.7 %) of pyrethroid-impregnated LLINs were quasi-randomly assigned to receive IRS with either of two pyrethroids, namely deltamethrin [Wetable granules (WG)] and lambdacyhalothrin [capsule suspension (CS)], with an emulsifiable concentrate (EC) or CS formulation of the organophosphate pirimiphos methyl (PM), or with no supplementary vector control measure. Diagnostic positivity of patients tested for malaria by community health workers in these clusters was surveyed longitudinally over pre- and post-treatment periods spanning 29 months, over which the treatments were allocated and re-allocated in advance of three sequential rainy seasons. Supplementation of LLINs with PM CS offered the greatest initial level of protection against malaria in the first 3 months of application (incremental protective efficacy (IPE) [95 % confidence interval (CI)] = 0.63 [CI 0.57, 0.69], P < 0.001), followed by lambdacyhalothrin (IPE [95 % CI] = 0.31 [0.10, 0.47], P = 0.006) and PM EC (IPE, 0.23 [CI 0.15, 0.31], P < 0.001) and then by deltamethrin (IPE [95 % CI] = 0.19 [-0.01, 0.35], P = 0.064). Neither pyrethroid formulation provided protection beyond 3 months after spraying, but the protection provided by both PM formulations persisted undiminished for longer periods: 6 months for CS and 12 months for EC. The CS formulation of PM provided greater protection than the combined pyrethroid IRS formulations throughout its effective life IPE [95 % CI] = 0.79 [0.75, 0.83] over 6 months. The EC formulation of PM provided incremental protection for the first 3 months (IPE [95 % CI] = 0

Insecticide resistance status in Anopheles gambiae in southern Benin

PubMed Central

2010-01-01

Background The emergence of pyrethroid resistance in Anopheles gambiae has become a serious concern to the future success of malaria control. In Benin, the National Malaria Control Programme has recently planned to scaling up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) for malaria prevention. It is, therefore, crucial to monitor the level and type of insecticide resistance in An. gambiae, particularly in southern Benin where reduced efficacy of insecticide-treated nets (ITNs) and IRS has previously been reported. Methods The protocol was based on mosquito collection during both dry and rainy seasons across forty districts selected in southern Benin. Bioassay were performed on adults collected from the field to assess the susceptibility of malaria vectors to insecticide-impregnated papers (permethrin 0.75%, delthamethrin 0.05%, DDT 4%, and bendiocarb 0.1%) following WHOPES guidelines. The species within An. gambiae complex, molecular form and presence of kdr and ace-1 mutations were determined by PCR. Results Strong resistance to permethrin and DDT was found in An. gambiae populations from southern Benin, except in Aglangandan where mosquitoes were fully susceptible (mortality 100%) to all insecticides tested. PCR showed the presence of two sub-species of An. gambiae, namely An. gambiae s.s, and Anopheles melas, with a predominance for An. gambiae s.s (98%). The molecular M form of An. gambiae was predominant in southern Benin (97%). The kdr mutation was detected in all districts at various frequency (1% to 95%) whereas the Ace-1 mutation was found at a very low frequency (≤ 5%). Conclusion This study showed a widespread resistance to permethrin in An. gambiae populations from southern Benin, with a significant increase of kdr frequency compared to what was observed previously in Benin. The low frequency of Ace-1 recorded in all populations is encouraging for the use of bendiocarb as an alternative insecticide to pyrethroids for IRS

Discovery of Rigidified α,β-Unsaturated Imines as New Resistance-breaking Insecticides for Malaria Vector Control.

PubMed

Arlt, Alexander; Böhnke, Niels; Horstmann, Sebastian; Vermeer, Arnoldus W P; Werner, Stefan; Velten, Robert

2016-10-01

During our continuous search for new resistance-breaking insecticides applicable to malaria vector control, a new class of α,β-unsaturated imines was identified by applying the principle of conformational rigidification as a powerful tool for compound optimisation. Herein we describe the successful synthesis of these compounds and their biological test results. Our lead compound 16 from this insecticidal class outperforms market standards, notably for the control of mosquito strains that exhibit either metabolic or target-site resistance to these established insecticides. In our model system for insecticide-treated mosquito nets the compound reveals long-lasting efficacy for up to several months.

A Two-Locus Model of the Evolution of Insecticide Resistance to Inform and Optimise Public Health Insecticide Deployment Strategies

PubMed Central

2017-01-01

We develop a flexible, two-locus model for the spread of insecticide resistance applicable to mosquito species that transmit human diseases such as malaria. The model allows differential exposure of males and females, allows them to encounter high or low concentrations of insecticide, and allows selection pressures and dominance values to differ depending on the concentration of insecticide encountered. We demonstrate its application by investigating the relative merits of sequential use of insecticides versus their deployment as a mixture to minimise the spread of resistance. We recover previously published results as subsets of this model and conduct a sensitivity analysis over an extensive parameter space to identify what circumstances favour mixtures over sequences. Both strategies lasted more than 500 mosquito generations (or about 40 years) in 24% of runs, while in those runs where resistance had spread to high levels by 500 generations, 56% favoured sequential use and 44% favoured mixtures. Mixtures are favoured when insecticide effectiveness (their ability to kill homozygous susceptible mosquitoes) is high and exposure (the proportion of mosquitoes that encounter the insecticide) is low. If insecticides do not reliably kill homozygous sensitive genotypes, it is likely that sequential deployment will be a more robust strategy. Resistance to an insecticide always spreads slower if that insecticide is used in a mixture although this may be insufficient to outperform sequential use: for example, a mixture may last 5 years while the two insecticides deployed individually may last 3 and 4 years giving an overall ‘lifespan’ of 7 years for sequential use. We emphasise that this paper is primarily about designing and implementing a flexible modelling strategy to investigate the spread of insecticide resistance in vector populations and demonstrate how our model can identify vector control strategies most likely to minimise the spread of insecticide resistance

Traditional Nets Interfere with the Uptake of Long-Lasting Insecticidal Nets in the Peruvian Amazon: The Relevance of Net Preference for Achieving High Coverage and Use

PubMed Central

Grietens, Koen Peeters; Muela Ribera, Joan; Soto, Veronica; Tenorio, Alex; Hoibak, Sarah; Aguirre, Angel Rosas; Toomer, Elizabeth; Rodriguez, Hugo; Llanos Cuentas, Alejandro; D'Alessandro, Umberto; Gamboa, Dionicia; Erhart, Annette

2013-01-01

Background While coverage of long-lasting insecticide-treated nets (LLIN) has steadily increased, a growing number of studies report gaps between net ownership and use. We conducted a mixed-methods social science study assessing the importance of net preference and use after Olyset® LLINs were distributed through a mass campaign in rural communities surrounding Iquitos, the capital city of the Amazonian region of Peru. Methods The study was conducted in the catchment area of the Paujil and Cahuide Health Centres (San Juan district) between July 2007 and November 2008. During a first qualitative phase, participant observation and in-depth interviews collected information on key determinants for net preference and use. In a second quantitative phase, a survey among recently confirmed malaria patients evaluated the acceptability and use of both LLINs and traditional nets, and a case control study assessed the association between net preference/use and housing structure (open vs. closed houses). Results A total of 10 communities were selected for the anthropological fieldwork and 228 households participated in the quantitative studies. In the study area, bed nets are considered part of the housing structure and are therefore required to fulfil specific architectural and social functions, such as providing privacy and shelter, which the newly distributed Olyset® LLINs ultimately did not. The LLINs' failure to meet these criteria could mainly be attributed to their large mesh size, transparency and perceived ineffectiveness to protect against mosquitoes and other insects, resulting in 63.3% of households not using any of the distributed LLINs. Notably, LLIN usage was significantly lower in houses with no interior or exterior walls (35.2%) than in those with walls (73.8%) (OR = 5.2, 95CI [2.2; 12.3], p<0.001). Conclusion Net preference can interfere with optimal LLIN use. In order to improve the number of effective days of LLIN protection per dollar spent

Effectiveness and feasibility of long-lasting insecticide-treated curtains and water container covers for dengue vector control in Colombia: a cluster randomised trial.

PubMed

Quintero, Juliana; García-Betancourt, Tatiana; Cortés, Sebastian; García, Diana; Alcalá, Lucas; González-Uribe, Catalina; Brochero, Helena; Carrasquilla, Gabriel

2015-02-01

Long-lasting insecticide-treated net (LLIN) window and door curtains alone or in combination with LLIN water container covers were analysed regarding effectiveness in reducing dengue vector density, and feasibility of the intervention. A cluster randomised trial was conducted in an urban area of Colombia comparing 10 randomly selected control and 10 intervention clusters. In control clusters, routine vector control activities were performed. The intervention delivered first, LLIN curtains (from July to August 2013) and secondly, water container covers (from October to March 2014). Cross-sectional entomological surveys were carried out at baseline (February 2013 to June 2013), 9 weeks after the first intervention (August to October 2013), and 4-6 weeks after the second intervention (March to April 2014). Curtains were installed in 922 households and water container covers in 303 households. The Breteau index (BI) fell from 14 to 6 in the intervention group and from 8 to 5 in the control group. The additional intervention with LLIN covers for water containers showed a significant reduction in pupae per person index (PPI) (p=0.01). In the intervention group, the PPI index showed a clear decline of 71% compared with 25% in the control group. Costs were high but options for cost savings were identified. Short term impact evaluation indicates that the intervention package can reduce dengue vector density but sustained effect will depend on multiple factors. © The author 2015. The World Health Organization has granted Oxford University Press permission for the reproduction of this article.

Cost-effectiveness analysis of vaccinating children in Malawi with RTS,S vaccines in comparison with long-lasting insecticide-treated nets.

PubMed

Seo, Mikyung Kelly; Baker, Peter; Ngo, Karen Ngoc-Lan

2014-02-24

New RTS,S malaria vaccines may soon be licensed, yet its cost-effectiveness is unknown. Before the widespread introduction of RTS,S vaccines, cost-effectiveness studies are needed to help inform governments in resource-poor settings about how best to prioritize between the new vaccine and existing malaria interventions. A Markov model simulated malaria progression in a hypothetical Malawian birth cohort. Parameters were based on published data. Three strategies were compared: no intervention, vaccination at one year, and long-lasting, insecticide-treated nets (LLINs) at birth. Both health service and societal perspectives were explored. Health outcomes were measured in disability-adjusted life years (DALYs) averted and costed in 2012 US$. Incremental cost-effectiveness ratios (ICERs) were calculated and extensive sensitivity analyses were conducted. Three times GDP per capita ($1,095) per DALY averted was used for a cost-effectiveness threshold, whilst one times GDP ($365) was considered 'very cost-effective'. From a societal perspective the vaccine strategy was dominant. It averted 0.11 more DALYs than LLINs and 0.372 more DALYs than the no intervention strategy per person, while costing $10.04 less than LLINs and $59.74 less than no intervention. From a health service perspective the vaccine's ICER was $145.03 per DALY averted, and thus can be considered very cost-effective. The results were robust to changes in all variables except the vaccine and LLINs' duration of efficacy. Vaccines remained cost-effective even at the lowest assumed efficacy levels of 49.6% (mild malaria) and 14.2% (severe malaria), and the highest price of $15. However, from a societal perspective, if the vaccine duration efficacy was set below 2.69 years or the LLIN duration of efficacy was greater than 4.24 years then LLINs became the more cost-effective strategy. The results showed that vaccinating Malawian children with RTS,S vaccines was very cost-effective from both a societal and a

Repeated mass distributions and continuous distribution of long-lasting insecticidal nets: modelling sustainability of health benefits from mosquito nets, depending on case management.

PubMed

Briët, Olivier Jt; Penny, Melissa A

2013-11-07

Stagnating funds for malaria control have spurred interest in the question of how to sustain the gains of recent successes with long-lasting insecticidal nets (LLINs) and improved case management (CM). This simulation study examined the malaria transmission and disease dynamics in scenarios with sustained LLINs and CM interventions and tried to determine optimal LLIN distribution rates. The effects of abruptly halting LLIN distribution were also examined. Dynamic simulations of malaria in humans and mosquitoes were run on the OpenMalaria platform, using stochastic individual-based simulation models. LLINs were distributed in a range of transmission settings, with varying CM coverage levels. In the short-term, LLINs were beneficial over the entire transmission spectrum, reducing both transmission and disease burden. In the long-term, repeated distributions sustainably reduced transmission in all settings. However, because of the resulting reduction in acquired immunity in the population, the malaria disease burden, after initially being reduced, gradually increased and eventually stabilized at a new level. This new level was higher than the pre-intervention level in previously high transmission settings, if there is a maximum disease burden in the relationship between transmission and disease burden at intermediate transmission levels. This result could lead one to conclude that sustained LLIN distribution might not be cost-effective in high transmission settings in the long term. However, improved CM rendered LLINs more cost-effective in higher transmission settings than in those without improved CM and the majority of the African population lives in areas where CM and LLINs are sustainably combined. The effects of changes in LLIN distribution rate on cost-effectiveness were relatively small compared to the effects of changes in transmission setting and CM. Abruptly halting LLIN distribution led to temporary morbidity peaks, which were particularly large in low to

An experimental hut evaluation of Olyset Plus, a long-lasting insecticidal net treated with a mixture of permethrin and piperonyl butoxide, against Anopheles fluviatilis in Odisha State, India.

PubMed

Gunasekaran, Kasinathan; Sahu, Sudhansu Sekhar; Vijayakumar, Tharmalingam; Subramanian, Swaminathan; Yadav, Rajpal Singh; Pigeon, Olivier; Jambulingam, Purushothaman

2016-07-21

Fast development of pyrethroid resistance in malaria vectors prompted the development of new vector control tools including combination of insecticides with different modes of action as part of resistance management strategies. Olyset Plus® is a new long-lasting insecticidal net, in which, permethrin and a synergist, piperonyl butoxide (PBO), are incorporated into filaments. Mixture nets such as this may have application against resistant mosquitoes, particularly those whose resistance is based on oxidative metabolism. There may also be enhanced activity against susceptible mosquitoes since mixed function oxidases are involved in a many metabolic activities including activation to form bioactive compounds. Bio-efficacy of Olyset Plus was evaluated against susceptible malaria vector, Anopheles fluviatilis in experimental huts. Deterrence, blood feeding inhibition, induced exophily and killing effect were measured to assess the bio-efficacy. The results were compared with Olyset Net®, a polyethylene permethrin-incorporated LLIN and a conventionally treated polyester net (with permethrin) washed to just before exhaustion. Results showed significant reduction in entry (treatment: 0.4-0.8; control: 4.2 per trap-night) and increase in exit (56.3-82.9 % and 44.2 %) rates of Anopheles fluviatilis in the treatment arms compared to control (P < 0.05). While blood feeding rates declined in treatment arms (18.8-30.6 %), it increased in control (77.6 %) (P < 0.05). This was further evident from the blood-feeding inhibition rates in treatment arms (60.6-90.6 %). Total mortality was significantly higher in all treatment arms (96.3-100 %) compared to control arm (2 %) (P < 0.05). Chemical analysis for active ingredient (AI) showed retention of 75 and 88 % in Olyset plus and Olyset net respectively after 20 washes. Performance of Olyset Plus washed 20 times was equal to the CTN and Olyset Net against the susceptible malaria vector An. fluviatilis, fulfilling the

The effect of holes in long-lasting insecticidal nets on malaria in Malawi: results from a case-control study.

PubMed

Minta, Anna A; Landman, Keren Z; Mwandama, Dyson A; Shah, Monica P; Eng, Jodi L Vanden; Sutcliffe, James F; Chisaka, Joseph; Lindblade, Kim A; Mathanga, Don P; Steinhardt, Laura C

2017-10-02

Long-lasting insecticidal nets (LLINs) are a cornerstone of malaria prevention. Holes develop in LLINs over time and compromise their physical integrity, but how holes affect malaria transmission risk is not well known. After a nationwide mass LLIN distribution in July 2012, a study was conducted to assess the relationship between LLIN damage and malaria. From March to September 2013, febrile children ages 6-59 months who consistently slept under LLINs (every night for 2 weeks before illness onset) were enrolled in a case-control study at Machinga District Hospital outpatient department. Cases were positive for Plasmodium falciparum asexual parasites by microscopy while controls were negative. Digital photographs of participants' LLINs were analysed using an image-processing programme to measure holes. Total hole area was classified by quartiles and according to the World Health Organization's proportionate hole index (pHI) cut-offs [< 79 cm 2 (good), 80-789 cm 2 (damaged), and > 790 cm 2 (too torn)]. Number of holes by location and size, and total hole area, were compared between case and control LLINs using non-parametric analyses and logistic regression. Of 248 LLINs analysed, 97 (39%) were from cases. Overall, 86% of LLINs had at least one hole. The median number of holes of any size was 9 [interquartile range (IQR) 3, 22], and most holes were located in the lower halves of the nets [median 7 (IQR 2, 16)]. There were no differences in number or location of holes between LLINs used by cases and controls. The median total hole area was 10 cm 2 (IQR 2, 125) for control LLINs and 8 cm 2 (IQR 2, 47) for case LLINs (p = 0.10). Based on pHI, 109 (72%) control LLINs and 83 (86%) case LLINs were in "good" condition. Multivariable modeling showed no association between total hole area and malaria, controlling for child age, caregiver education, and iron versus thatched roof houses. LLIN holes were not associated with increased odds of malaria in this study

Insecticide susceptibility of Anopheles mosquitoes changes in response to variations in the larval environment.

PubMed

Owusu, Henry F; Chitnis, Nakul; Müller, Pie

2017-06-16

Insecticide resistance threatens the success achieved through vector control in reducing the burden of malaria. An understanding of insecticide resistance mechanisms would help to develop novel tools and strategies to restore the efficacy of insecticides. Although we have substantially improved our understanding of the genetic basis of insecticide resistance over the last decade, we still know little of how environmental variations influence the mosquito phenotype. Here, we measured how variations in larval rearing conditions change the insecticide susceptibility phenotype of adult Anopheles mosquitoes. Anopheles gambiae and A. stephensi larvae were bred under different combinations of temperature, population density and nutrition, and the emerging adults were exposed to permethrin. Mosquitoes bred under different conditions showed considerable changes in mortality rates and body weight, with nutrition being the major factor. Weight is a strong predictor of insecticide susceptibility and bigger mosquitoes are more likely to survive insecticide treatment. The changes can be substantial, such that the same mosquito colony may be considered fully susceptible or highly resistant when judged by World Health Organization discriminatory concentrations. The results shown here emphasise the importance of the environmental background in developing insecticide resistance phenotypes, and caution for the interpretation of data generated by insecticide susceptibility assays.

Individual and household factors associated with ownership of long-lasting insecticidal nets and malaria infection in south-central Ethiopia: a case-control study.

PubMed

Deressa, Wakgari

2017-10-06

A recent considerable decline in malaria morbidity and mortality in Ethiopia is likely to be followed by changes in the practice of effective preventive measures and malaria risk factors. This study aimed to identify determinants of long-lasting insecticidal nets (LLINs) ownership and risk of malaria infection. A matched case-control study of 191 case and 377 control households was conducted between October 2014 and November 2015 in Adami Tullu district in south-central Ethiopia. Cases were microscopy or rapid diagnostic test confirmed malaria patients identified at three health centers and nine health posts, and matched on age with two neighbourhood controls. Information was collected on socio-demographic factors, house structure, knowledge on malaria and ownership of LLINs. The logistic regression model was used to determine predictors of LLINs ownership and malaria infection. All cases were infections due to either Plasmodium falciparum (71.2%) or Plasmodium vivax (28.8%). About 31% of the study households had at least one LLINs. Significant determinants of LLINs ownership were household's head malaria knowledge [adjusted odds ratio (AOR) = 2.47, 95% confidence interval (CI) 1.44-4.22], educational status [read and write (AOR = 6.88, 95% CI 2.30-20.55), primary education or higher (AOR = 5.40, 95% CI 1.57-18.55)], farmer respondent (AOR = 0.35, 95% CI 0.17-0.76), having ≥ 3 sleeping areas (AOR = 6.71, 95% CI 2.40-18.77) and corrugated roof type (AOR = 2.49, 95% CI 1.36-4.58). This study was unable to identify important risk factors of malaria infection with regard to sex, household wealth index, house structure, ownership of LLINs, keeping livestock inside house, staying overnight outdoor or having malaria during the last 6 months. Household socio-economic status, educational status and knowledge on malaria were important predictors of LLINs ownership. Households with farmer respondents were less likely to own LLINs. Addressing these factors

Degradation of insecticides used for indoor spraying in malaria control and possible solutions

PubMed Central

2011-01-01

Background The insecticide dichloro-diphenyl-trichloroethane (DDT) is widely used in indoor residual spraying (IRS) for malaria control owing to its longer residual efficacy in the field compared to other World Health Organization (WHO) alternatives. Suitable stabilization to render these alternative insecticides longer lasting could provide a less controversial and more acceptable and effective alternative insecticide formulations than DDT. Methods This study sought to investigate the reasons behind the often reported longer lasting behaviour of DDT by exposing all the WHO approved insecticides to high temperature, high humidity and ultra-violet light. Interactions between the insecticides and some mineral powders in the presence of an aqueous medium were also tested. Simple insecticidal paints were made using slurries of these mineral powders whilst some insecticides were dispersed into a conventional acrylic paint binder. These formulations were then spray painted on neat and manure coated mud plaques, representative of the material typically used in rural mud houses, at twice the upper limit of the WHO recommended dosage range. DDT was applied directly onto mud plaques at four times the WHO recommended concentration and on manure plaques at twice WHO recommended concentration. All plaques were subjected to accelerated ageing conditions of 40°C and a relative humidity of 90%. Results The pyrethroids insecticides outperformed the carbamates and DDT in the accelerated ageing tests. Thus UV exposure, high temperature oxidation and high humidity per se were ruled out as the main causes of failure of the alternative insecticides. Gas chromatography (GC) spectrograms showed that phosphogypsum stabilised the insecticides the most against alkaline degradation (i.e., hydrolysis). Bioassay testing showed that the period of efficacy of some of these formulations was comparable to that of DDT when sprayed on mud surfaces or cattle manure coated surfaces. Conclusions

Netting the malaria menace: Distribution and utilization of long-lasting insecticidal net in a malaria endemic area in Bankura, West Bengal.

PubMed

Mukhopadhyay, D K; Basu, S S; Roy, D; Das, N; Akbar, F; Sarkar, G N

2016-03-01

Long-lasting insecticidal net (LLIN) is considered to be a highly effective intervention against malaria under National Vector Borne Disease Control Programme in India. A cross-sectional study was undertaken to assess the coverage and utilization of LLIN and the factors related thereto. A survey of 1300 households was carried out in Ranibandh block of Bankura district in West Bengal, India, using lot quality assurance sampling (LQAS) method. Coverage/utilization of 80% was considered as minimum acceptable norm. The weighted sample size was calculated from each village of the block. The sociodemographic, economic information of the household along with the availability and use of LLIN was collected through interview and observation. In total, 7320 individuals including 840 children ≤ 5 yr were visited. Overall coverage of adequate LLIN was 65.4% (± 1.5%) and for children ≤ 5 yr, it was 60.5% (± 1.3%). Overall, 66.1% (± 1.4%) people of all ages and 63.7% (± 1.4%) children ≤ 5 yr slept under LLINs in the night before the survey. Out of 26 sub-centres, distribution of LLINs in 10 sub-centres was below the accepted norm, whereas utilization was sub-optimal in 19 sub-centres. In only 18.2% (± 0.5%) households, LLINs remained hanging during daytime. Poverty, caste, education, perception regarding malarial morbidity and preventive action of LLIN were associated significantly with the distribution of LLIN. Similarly, poverty (AOR = 2.14), threat perception regarding malarial morbidity (AOR = 1.51) and mortality (AOR = 2.52) were positively associated with the use of LLIN. Full utilization of bednets by under-fives of the households was higher in villages with sub-centres. Around two-third population of the study area was effectively covered with LLIN. Higher proportion of socially marginalized people received LLIN. Threat perception regarding malaria was directly associated with both receipt and use of LLIN. Behaviour change communication on utilization along

Long-lasting insecticidal net source, ownership and use in the context of universal coverage: a household survey in eastern Rwanda.

PubMed

Kateera, Fredrick; Ingabire, Chantal M; Hakizimana, Emmanuel; Rulisa, Alexis; Karinda, Parfait; Grobusch, Martin P; Mutesa, Leon; van Vugt, Michèle; Mens, Petra F

2015-10-06

Universal long-lasting insecticidal net (LLIN) coverage (ULC) has reduced malaria morbidity and mortality across Africa. Although information is available on bed net use in specific groups, such as pregnant women and children under 5 years, there is paucity of data on their use among the general population. Bed net source, ownership and determinants of use among individuals from households in an eastern Rwanda community 8 months after a ULC were characterized. Using household-based, interviewer-administered questionnaires and interviewer-direct observations, data on bed net source, ownership and key determinants of net use, including demographics, socio-economic status indicators, house structure characteristics, as well as of bed net quantity, type and integrity, were collected from 1400 randomly selected households. Univariate and mixed effects logistic regression modelling was done to assess for determinants of bed net use. A total of 1410 households and 6598 individuals were included in the study. Overall, the proportion of households with at least one net was 92 % while bed net usage was reported among 72 % of household members. Of the households surveyed, a total ownership of 2768 nets was reported, of which about 96 % were reportedly LLINs received from the ULC. By interviewer-physical observation, 88 % of the nets owned were of the LLIN type with the remaining 12 % did not carry any mark to enable type recognition. The odds of bed net use were significantly lower among males and individuals: from households of low socio-economic status, from households with

Implementation strategies to increase access and demand of long-lasting insecticidal nets: a before-and-after study and scale-up process in Mozambique.

PubMed

Arroz, Jorge A H; Mendis, Chandana; Pinto, Liliana; Candrinho, Baltazar; Pinto, João; Martins, Maria do Rosário O

2017-10-25

The universal coverage bed nets campaign is a proven health intervention promoting increased access, ownership, and use of bed nets to reduce malaria burden. This article describes the intervention and implementation strategies that Mozambique carried out recently in order to improve access and increase demand for long-lasting insecticidal nets (LLINs). A before-and-after study with a control group was used during Stage I of the implementation process. The following strategies were tested in Stage I: (1) use of coupons during household registration; (2) use of stickers to identify the registered households; (3) new LLIN ascription formula (one LLIN for every two people). In Stage II, the following additional strategies were implemented: (4) mapping and micro-planning; (5) training; and (6) supervision. Odds ratio (OR) and 95% confidence interval (CI) were used to compare and establish differences between intervened and control districts in Stage I. Main outcomes were: percentage of LLINs distributed, percentage of target households benefited. In Stage I, 87.8% (302,648) of planned LLINs were distributed in the intervention districts compared to 77.1% (219,613) in the control districts [OR: 2.14 (95% CI 2.11-2.16)]. Stage I results also showed that 80.6% (110,453) of households received at least one LLIN in the intervention districts compared to 72.8% (87,636) in the control districts [OR: 1.56 (95% CI 1.53-1.59)]. In Stage II, 98.4% (3,536,839) of the allocated LLINs were delivered, covering 98.6% (1,353,827) of the registered households. Stage I results achieved better LLINs and household coverage in districts with the newly implemented strategies. The results of stage II were also encouraging. Additional strategies adaptation is required for a wide-country LLIN campaign.

The impact of insecticides management linked with resistance expression in Anopheles spp. populations.

PubMed

Silva, Guilherme Liberato da; Pereira, Thiago Nunes; Ferla, Noeli Juarez; Silva, Onilda Santos da

2016-06-01

The resistance of some species of Anopheles to chemical insecticides is spreading quickly throughout the world and has hindered the actions of prevention and control of malaria. The main mechanism responsible for resistance in these insects appears to be the target site known as knock-down resistance (kdr), which causes mutations in the sodium channel. Even so, many countries have made significant progress in the prevention of malaria, focusing largely on vector control through long-lasting insecticide nets (LLINs), indoor residual spraying and (IRS) of insecticides. The objective of this review is to contribute with information on the more applied insecticides for the control of the main vectors of malaria, its effects, and the different mechanisms of resistance. Currently it is necessary to look for others alternatives, e.g. biological control and products derived from plants and fungi, by using other organisms as a possible regulator of the populations of malaria vectors in critical outbreaks.

The development of insecticide-treated durable wall lining for malaria control: insights from rural and urban populations in Angola and Nigeria

PubMed Central

2012-01-01

Background Durable lining (DL) is a deltamethrin-impregnated polyethylene material, which is designed to cover domestic walls that would normally be sprayed with residual insecticide. The operational success of DL as a long-lasting insecticidal substrate will be dependent on a high level of user acceptability as households must maintain correctly installed linings on their walls for several years. Preliminary trials were undertaken to identify a material to develop into a marketable wall lining and to assess its level of acceptability among rural and urban populations. Methods In Angola (n=60), prototype DL and insecticide-treated plastic sheeting (ITPS) were installed on urban house walls and ceilings, respectively, and acceptability was compared to indoor residual spraying (IRS) (n=20) using a knowledge, attitude and practice (KAP) questionnaire. In Nigeria (n=178), three materials (prototype DL, ITPS and insecticide-treated wall netting) were distributed among rural and urban households. User opinions were gathered from focus group discussions, in-depth interviews and KAP questionnaires. Results In Angola, after two weeks, the majority of participants (98%) expressed satisfaction with the products and identified the killing of insects as the materials’ principal benefits (73%). After one year, despite a loss of almost 50% of households to refugee repatriation, all 32 remaining households still asserted that they had liked the DL/ITPS in their homes and given the choice of intervention preferred DL/ITPS to IRS (94%) or insecticide-treated nets (78%). In Nigeria, a dichotomy between rural and urban respondents emerged. Rural participants favoured wall adornments and accepted wall linings because of their perceived decorative value and entomological efficacy. By contrast, urban households preferred minimal wall decoration and rejected the materials based upon objections to their aesthetics and installation feasibility. Conclusions The high level of acceptability

A stitch in time: a cross-sectional survey looking at long lasting insecticide-treated bed net ownership, utilization and attrition in SNNPR, Ethiopia.

PubMed

Batisso, Esey; Habte, Tedila; Tesfaye, Gezahegn; Getachew, Dawit; Tekalegne, Agonafer; Kilian, Albert; Mpeka, Betty; Lynch, Caroline

2012-06-07

Since 2002/03, an estimated 4.7 million nets have been distributed in the Southern Nations, Nationalities and Peoples Region (SNNPR) among an at risk population of approximately 10 million people. Evidence from the region suggests that large-scale net ownership rapidly increased over a relatively short period of time. However, little is known about how coverage is being maintained given that the last mass distribution was in 2006/2007. This study sought to determine the status of current net ownership, utilization and rate of long lasting insecticide-treated nets (LLIN) loss in the previous three years in the context of planning for future net distribution to try to achieve sustainable universal coverage. A total of 750 household respondents were interviewed across malarious, rural kebeles of SNNPR. Households were randomly selected following a two-stage cluster sampling design where kebeles were defined as clusters. Kebeles were chosen using proportional population sampling (PPS), and 25 households within 30 kebeles randomly chosen. Approximately 67.5% (95%CI: 64.1-70.8) of households currently owned at least one net. An estimated 31.0% (95%CI 27.9-34.4) of all nets owned in the previous three years had been discarded by owners, the majority of whom considered the nets too torn, old or dirty (79.9%: 95%CI 75.8-84.0). Households reported that one-third of nets (33.7%) were less than one year old when they were discarded. The majority (58.8%) of currently owned nets had 'good' structural integrity according to a proportionate Hole Index. Nearly two-thirds of households (60.6%) reported using their nets the previous night. The overriding reason for not using nets was that they were too torn (45.7%, 95% CI 39.1-50.7). Yet, few households are making repairs to their nets (3.7%, 95% CI: 2.4-5.1). Results suggest that the life span of nets may be shorter than previously thought, with little maintenance by their owners. With the global move towards malaria elimination it

Insecticide-induced hormesis and arthropod pest management.

PubMed

Guedes, Raul Narciso C; Cutler, G Christopher

2014-05-01

Ecological backlashes such as insecticide resistance, resurgence and secondary pest outbreaks are frequent problems associated with insecticide use against arthropod pest species. The last two have been particularly important in sparking interest in the phenomenon of insecticide-induced hormesis within entomology and acarology. Hormesis describes a biphasic dose-response relationship that is characterized by a reversal of response between low and high doses of a stressor (e.g. insecticides). Although the concept of insecticide-induced hormesis often does not receive sufficient attention, or has been subject to semantic confusion, it has been reported in many arthropod pest species and natural enemies, and has been linked to pest outbreaks and potential problems with insecticide resistance. The study of hormesis remains largely neglected in entomology and acarology. Here, we examined the concept of insecticide-induced hormesis in arthropods, its functional basis and potential fitness consequences, and its importance in arthropod pest management and other areas. © 2013 Society of Chemical Industry.

Electrostatic coating enhances bioavailability of insecticides and breaks pyrethroid resistance in mosquitoes

PubMed Central

Andriessen, Rob; Snetselaar, Janneke; Suer, Remco A.; Osinga, Anne J.; Deschietere, Johan; Lyimo, Issa N.; Mnyone, Ladslaus L.; Brooke, Basil D.; Ranson, Hilary; Knols, Bart G. J.; Farenhorst, Marit

2015-01-01

Insecticide resistance poses a significant and increasing threat to the control of malaria and other mosquito-borne diseases. We present a novel method of insecticide application based on netting treated with an electrostatic coating that binds insecticidal particles through polarity. Electrostatic netting can hold small amounts of insecticides effectively and results in enhanced bioavailability upon contact by the insect. Six pyrethroid-resistant Anopheles mosquito strains from across Africa were exposed to similar concentrations of deltamethrin on electrostatic netting or a standard long-lasting deltamethrin-coated bednet (PermaNet 2.0). Standard WHO exposure bioassays showed that electrostatic netting induced significantly higher mortality rates than the PermaNet, thereby effectively breaking mosquito resistance. Electrostatic netting also induced high mortality in resistant mosquito strains when a 15-fold lower dose of deltamethrin was applied and when the exposure time was reduced to only 5 s. Because different types of particles adhere to electrostatic netting, it is also possible to apply nonpyrethroid insecticides. Three insecticide classes were effective against strains of Aedes and Culex mosquitoes, demonstrating that electrostatic netting can be used to deploy a wide range of active insecticides against all major groups of disease-transmitting mosquitoes. Promising applications include the use of electrostatic coating on walls or eave curtains and in trapping/contamination devices. We conclude that application of electrostatically adhered particles boosts the efficacy of WHO-recommended insecticides even against resistant mosquitoes. This innovative technique has potential to support the use of unconventional insecticide classes or combinations thereof, potentially offering a significant step forward in managing insecticide resistance in vector-control operations. PMID:26324912

Synthetic Sex Pheromone in a Long-Lasting Lure Attracts the Visceral Leishmaniasis Vector, Lutzomyia longipalpis, for up to 12 Weeks in Brazil

PubMed Central

Bray, Daniel P.; Carter, Vicky; Alves, Graziella B.; Brazil, Reginaldo P.; Bandi, Krishna K.; Hamilton, James G. C.

2014-01-01

Current control methodologies have not prevented the spread of visceral leishmaniasis (VL) across Brazil. Here, we describe the development of a new tool for controlling the sand fly vector of the disease: a long-lasting lure, which releases a synthetic male sex pheromone, attractive to both sexes of Lutzomyia longipalpis. This device could be used to improve the effectiveness of residual insecticide spraying as a means of sand fly control, attracting L. longipalpis to insecticide-treated animal houses, where they could be killed in potentially large numbers over a number of weeks. Different lure designs releasing the synthetic pheromone (±)-9-methylgermacrene-B (CAS 183158-38-5) were field-tested in Araçatuba, São Paulo (SP). Experiments compared numbers of sand flies caught overnight in experimental chicken sheds with pheromone lures, to numbers caught in control sheds without pheromone. Prototype lures, designed to last one night, were first used to confirm the attractiveness of the pheromone in SP, and shown to attract significantly more flies to test sheds than controls. Longer-lasting lures were tested when new, and at fortnightly intervals. Lures loaded with 1 mg of pheromone did not attract sand flies for more than two weeks. However, lures loaded with 10 mg of pheromone, with a releasing surface of 15 cm2 or 7.5 cm2, attracted female L. longipalpis for up to ten weeks, and males for up to twelve weeks. Approximately five times more sand flies were caught with 7.5 cm2 10 mg lures when first used than occurred naturally in non-experimental chicken resting sites. These results demonstrate that these lures are suitably long-lasting and attractive for use in sand fly control programmes in SP. To our knowledge, this is the first sex pheromone-based technology targeting an insect vector of a neglected human disease. Further studies should explore the general applicability of this approach for combating other insect-borne diseases. PMID:24651528

Synthetic sex pheromone in a long-lasting lure attracts the visceral leishmaniasis vector, Lutzomyia longipalpis, for up to 12 weeks in Brazil.

PubMed

Bray, Daniel P; Carter, Vicky; Alves, Graziella B; Brazil, Reginaldo P; Bandi, Krishna K; Hamilton, James G C

2014-03-01

Current control methodologies have not prevented the spread of visceral leishmaniasis (VL) across Brazil. Here, we describe the development of a new tool for controlling the sand fly vector of the disease: a long-lasting lure, which releases a synthetic male sex pheromone, attractive to both sexes of Lutzomyia longipalpis. This device could be used to improve the effectiveness of residual insecticide spraying as a means of sand fly control, attracting L. longipalpis to insecticide-treated animal houses, where they could be killed in potentially large numbers over a number of weeks. Different lure designs releasing the synthetic pheromone (±)-9-methylgermacrene-B (CAS 183158-38-5) were field-tested in Araçatuba, São Paulo (SP). Experiments compared numbers of sand flies caught overnight in experimental chicken sheds with pheromone lures, to numbers caught in control sheds without pheromone. Prototype lures, designed to last one night, were first used to confirm the attractiveness of the pheromone in SP, and shown to attract significantly more flies to test sheds than controls. Longer-lasting lures were tested when new, and at fortnightly intervals. Lures loaded with 1 mg of pheromone did not attract sand flies for more than two weeks. However, lures loaded with 10 mg of pheromone, with a releasing surface of 15 cm2 or 7.5 cm2, attracted female L. longipalpis for up to ten weeks, and males for up to twelve weeks. Approximately five times more sand flies were caught with 7.5 cm2 10 mg lures when first used than occurred naturally in non-experimental chicken resting sites. These results demonstrate that these lures are suitably long-lasting and attractive for use in sand fly control programmes in SP. To our knowledge, this is the first sex pheromone-based technology targeting an insect vector of a neglected human disease. Further studies should explore the general applicability of this approach for combating other insect-borne diseases.

Temporo-spatial distribution of insecticide-resistance in Indian malaria vectors in the last quarter-century: Need for regular resistance monitoring and management.

PubMed

Raghavendra, Kamaraju; Velamuri, Poonam Sharma; Verma, Vaishali; Elamathi, Natarajan; Barik, Tapan Kumar; Bhatt, Rajendra Mohan; Dash, Aditya Prasad

2017-01-01

The Indian vector control programme similar to other programmes in the world is still reliant on chemical insecticides. Anopheles culicifacies is the major vector out of six primary malaria vectors in India and alone contributes about 2/3 malaria cases annually; and per se its control is actually control of malaria in India. For effective management of vectors, current information on their susceptibility status to different insecticides is essential. In this review, an attempt was made to compile and present the available data on the susceptibility status of different malaria vector species in India from the last 2.5 decades. Literature search was conducted by different means mainly web and library search; susceptibility data was collated from 62 sources for the nine malaria vector species from 145 districts in 21 states and two union territories between 1991 and 2016. Interpretation of the susceptibility/resistance status was made on basis of the recent WHO criteria. Comprehensive analysis of the data indicated that An. culicifacies, a major vector species was resistant to at least one insecticide in 70% (101/145) of the districts. It was reported mostly resistant to DDT and malathion whereas, its resistant status against deltamethrin varied across the districts. The major threat for the malaria control programmes is multiple-insecticide-resistance in An. culicifacies which needs immediate attention for resistance management in order to sustain the gains achieved so far, as the programmes have targeted malaria elimination by 2030.

Synergistic insecticidal and repellent effects of combined pyrethroid and repellent-impregnated bed nets using a novel long-lasting polymer-coating multi-layer technique.

PubMed

Faulde, Michael K; Nehring, Oliver

2012-08-01

New and improved strategies for malaria control and prevention are urgently needed. As a contribution to an optimized personal protection strategy, a novel long-lasting insecticide and repellent-treated net (LLIRN) has been designed by binding combinations of permethrin plus N,N-diethyl-m-toluamide (DEET), or insect repellent 3535 (IR3535), and etofenprox plus DEET, onto fibres of bed net fabric employing a new multi-layer polymer-coating technique. Protective repellent efficacy, toxicological effectiveness and residual activity of 12 LLIRN types have been evaluated by laboratory testing against adult Aedes aegypti. The novel multi-layer LLIRN design allowed simultaneous embedding at concentrations up to 5,930 mg/m(2) for DEET, 3,408 mg/m(2) for IR3535, 2,296 mg/m(2) for permethrin and 2,349 mg/m(2) for etofenprox, respectively. IR3535 layers prevented co-binding of additional pyrethroid-containing polymer layers, thus making pyrethroids plus DEET LLIRNs an ideal combination. All LLIRNs revealed synergistic insecticidal effects which, when measured against concentration controls of the isolated compounds, were significant in all LLIRN types designed. DEET in DEET plus permethrin LLIRNs significantly (p < 0.0001) reduced the concentration-dependent permethrin 100 % knockdown (KD) time from 55 to 75 %, the corresponding 100 % kill time (p < 0.0001) from 55 to 64 %. DEET in DEET plus etofenprox LLIRNs reduced the dose-specific 100 % knockdown (KD) time of etofenprox from 42 to 50 % (p = 0.004), the 100 % kill time from 25 to 38 % (p < 0.0001). Permethrin or etofenprox did not influence spatial repellency of DEET or IR3535 on LLIRNs. Vice versa, DEET and IR3535 increased spatial and excitatory repellency and reduced landing and probing frequency on LLIRNs resulting in strongly enhanced biting protection, even at low concentrations. One hundred percent biting and probing protection of stored LLIRNs was preserved for 83 weeks with the 5,930 mg/m(2) DEET

Long-lasting insecticide-treated bed net ownership and use among children under five years of age following a targeted distribution in central Uganda.

PubMed

Wanzira, Humphrey; Yeka, Adoke; Kigozi, Ruth; Rubahika, Denis; Nasr, Sussann; Sserwanga, Asadu; Kamya, Moses; Filler, Scott; Dorsey, Grant; Steinhardt, Laura

2014-05-19

Universal coverage of long-lasting insecticide-treated bed nets (LLINs) for prevention of malaria was adopted by the Uganda National Malaria Control Programme in 2007. The first mass distribution of LLINs was implemented in 2010. Initially, a campaign targeted to households with pregnant women and children aged

Measures of Malaria Burden after Long-Lasting Insecticidal Net Distribution and Indoor Residual Spraying at Three Sites in Uganda: A Prospective Observational Study

PubMed Central

Katureebe, Agaba; Zinszer, Kate; Arinaitwe, Emmanuel; Charland, Katia; Kigozi, Ruth; Kilama, Maxwell; Nankabirwa, Joaniter; Yeka, Adoke; Mawejje, Henry; Mpimbaza, Arthur; Donnelly, Martin J.; Rosenthal, Philip J.; Lindsay, Steve W.; Staedke, Sarah G.; Smith, David L.; Kamya, Moses R.; Dorsey, Grant

2016-01-01

Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying of insecticide (IRS) are the primary vector control interventions used to prevent malaria in Africa. Although both interventions are effective in some settings, high-quality evidence is rarely available to evaluate their effectiveness following deployment by a national malaria control program. In Uganda, we measured changes in key malaria indicators following universal LLIN distribution in three sites, with the addition of IRS at one of these sites. Methods and Findings Comprehensive malaria surveillance was conducted from October 1, 2011, to March 31, 2016, in three sub-counties with relatively low (Walukuba), moderate (Kihihi), and high transmission (Nagongera). Between 2013 and 2014, universal LLIN distribution campaigns were conducted in all sites, and in December 2014, IRS with the carbamate bendiocarb was initiated in Nagongera. High-quality surveillance evaluated malaria metrics and mosquito exposure before and after interventions through (a) enhanced health-facility-based surveillance to estimate malaria test positivity rate (TPR), expressed as the number testing positive for malaria/number tested for malaria (number of children tested for malaria: Walukuba = 42,833, Kihihi = 28,790, and Nagongera = 38,690); (b) cohort studies to estimate the incidence of malaria, expressed as the number of episodes per person-year [PPY] at risk (number of children observed: Walukuba = 340, Kihihi = 380, and Nagongera = 361); and (c) entomology surveys to estimate household-level human biting rate (HBR), expressed as the number of female Anopheles mosquitoes collected per house-night of collection (number of households observed: Walukuba = 117, Kihihi = 107, and Nagongera = 107). The LLIN distribution campaign substantially increased LLIN coverage levels at the three sites to between 65.0% and 95.5% of households with at least one LLIN. In Walukuba, over the 28-mo post-intervention period

Impact of long-lasting insecticidal nets on prevalence of subclinical malaria among children in the presence of pyrethroid resistance in Anopheles culicifacies in Central India.

PubMed

Chourasia, Mehul Kumar; Kamaraju, Raghavendra; Kleinschmidt, Immo; Bhatt, Rajendra M; Swain, Dipak Kumar; Knox, Tessa Bellamy; Valecha, Neena

2017-04-01

Subclinical (asymptomatic) cases of malaria could be a major barrier to the success of malaria elimination programs. This study has evaluated the impact of long-lasting insecticidal nets (LLINs) on the prevalence of subclinical malaria in the presence of pyrethroid resistance in the main malaria vector Anopheles culicifacies on malaria transmission among a cohort of children in villages of the Keshkal sub-district in Chhattisgarh state. A cohort of 6582 children ages less than 14 years was enrolled from 80 study clusters. Post monsoon survey was carried out at baseline before LLIN distribution, and 5862 children were followed up in the subsequent year. Study outcomes included assessment of subclinical malarial infections and use of LLINs among the study cohort in the presence of varied levels of pyrethroid resistance. In the baseline survey, the proportion of subclinical malaria was 6·1%. LLIN use during the previous night was 94·8%. Overall, prevalence of subclinical malaria was significantly reduced to 1% (p<0·001) in the second survey. LLIN users were protected from malaria (OR: 0·25, 95% CI=0·12-0·52, p<0.001) and subclinical malaria (OR: 0·25, 95% CI=0·11-0·58, p=0·001) despite the presence of pyrethroid resistance in the study area. In this low transmission area, sleeping under LLINs significantly reduced the burden of malaria among children. In the presence of pyrethroid resistant malaria vector, a high LLIN use of 94·5% was observed to have significantly brought down the proportion of subclinical malaria among the cohort children. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Long-term trends in Anopheles gambiae insecticide resistance in Côte d'Ivoire.

PubMed

Edi, Constant A V; Koudou, Benjamin G; Bellai, Louise; Adja, Akre M; Chouaibou, Mouhamadou; Bonfoh, Bassirou; Barry, Sarah J E; Johnson, Paul C D; Müller, Pie; Dongus, Stefan; N'Goran, Eliezer K; Ranson, Hilary; Weetman, David

2014-11-28

Malaria control is heavily dependent on the use of insecticides that target adult mosquito vectors via insecticide treated nets (ITNs) or indoor residual spraying (IRS). Four classes of insecticide are approved for IRS but only pyrethroids are available for ITNs. The rapid rise in insecticide resistance in African malaria vectors has raised alarms about the sustainability of existing malaria control activities. This problem might be particularly acute in Côte d'Ivoire where resistance to all four insecticide classes has recently been recorded. Here we investigate temporal trends in insecticide resistance across the ecological zones of Côte d'Ivoire to determine whether apparent pan-African patterns of increasing resistance are detectable and consistent across insecticides and areas. We combined data on insecticide resistance from a literature review, and bioassays conducted on field-caught Anopheles gambiae mosquitoes for the four WHO-approved insecticide classes for ITN/IRS. The data were then mapped using Geographical Information Systems (GIS) and the IR mapper tool to provide spatial and temporal distribution data on insecticide resistance in An. gambiae sensu lato from Côte d'Ivoire between 1993 and 2014. Bioassay mortality decreased over time for all insecticide classes, though with significant spatiotemporal variation, such that stronger declines were observed in the southern ecological zone for DDT and pyrethroids than in the central zone, but with an apparently opposite effect for the carbamate and organophosphate. Variation in relative abundance of the molecular forms, coupled with dramatic increase in kdr 1014F frequency in M forms (An. coluzzii) seems likely to be a contributory factor to these patterns. Although records of resistance across insecticide classes have become more common, the number of classes tested in studies has also increased, precluding a conclusion that multiple resistance has also increased. Our analyses attempted synthesis of 22�

Long lasting decontamination foam

DOEpatents

Demmer, Ricky L.; Peterman, Dean R.; Tripp, Julia L.; Cooper, David C.; Wright, Karen E.

2010-12-07

Compositions and methods for decontaminating surfaces are disclosed. More specifically, compositions and methods for decontamination using a composition capable of generating a long lasting foam are disclosed. Compositions may include a surfactant and gelatin and have a pH of less than about 6. Such compositions may further include affinity-shifting chemicals. Methods may include decontaminating a contaminated surface with a composition or a foam that may include a surfactant and gelatin and have a pH of less than about 6.

Multicentre studies of insecticide-treated durable wall lining in Africa and South-East Asia: entomological efficacy and household acceptability during one year of field use

PubMed Central

2012-01-01

Background Indoor residual spraying (IRS) is a primary method of malaria vector control, but its potential impact is constrained by several inherent limitations: spraying must be repeated when insecticide residues decay, householders can tire of the annual imposition and campaign costs are recurrent. Durable lining (DL) can be considered an advanced form of long-lasting IRS where insecticide is gradually released from an aesthetically attractive wall lining material to provide vector control for several years. A multicentre trial was carried out in Equatorial Guinea, Ghana, Mali, South Africa and Vietnam to assess the feasibility, durability, bioefficacy and household acceptability of DL, compared to conventional IRS or insecticide-treated curtains (LLITCs), in a variety of operational settings. Methods This study was conducted in 220 households in traditional rural villages over 12-15 months. In all sites, rolls of DL were cut to fit house dimensions and fixed to interior wall surfaces (usually with nails and caps) by trained teams. Acceptability was assessed using a standardized questionnaire covering such topics as installation, exposure reactions, entomology, indoor environment, aesthetics and durability. Bioefficacy of interventions was evaluated using WHO cone bioassay tests at regular intervals throughout the year. Results The deltamethrin DL demonstrated little to no decline in bioefficacy over 12-15 months, supported by minimal loss of insecticide content. By contrast, IRS displayed a significant decrease in bioactivity by 6 months and full loss after 12 months. The majority of participants in DL households perceived reductions in mosquito density (93%) and biting (82%), but no changes in indoor temperature (83%). Among those households that wanted to retain the DL, 73% cited protective reasons, 20% expressed a desire to keep theirs for decoration and 7% valued both qualities equally. In Equatorial Guinea, when offered a choice of vector control product at

The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control.

PubMed

Oxborough, Richard M; N'Guessan, Raphael; Jones, Rebecca; Kitau, Jovin; Ngufor, Corine; Malone, David; Mosha, Franklin W; Rowland, Mark W

2015-03-24

The rapid selection of pyrethroid resistance throughout sub-Saharan Africa is a serious threat to malaria vector control. Chlorfenapyr is a pyrrole insecticide which shows no cross resistance to insecticide classes normally used for vector control and is effective on mosquito nets under experimental hut conditions. Unlike neurotoxic insecticides, chlorfenapyr owes its toxicity to disruption of metabolic pathways in mitochondria that enable cellular respiration. A series of experiments explored whether standard World Health Organization (WHO) guidelines for evaluation of long-lasting insecticidal nets, developed through testing of pyrethroid insecticides, are suitable for evaluation of non-neurotoxic insecticides. The efficacy of WHO recommended cone, cylinder and tunnel tests was compared for pyrethroids and chlorfenapyr. To establish bioassay exposure times predictive of insecticide-treated net (ITN) efficacy in experimental hut trials, standard three-minute bioassays of pyrethroid and chlorfenapyr ITNs were compared with longer exposures. Mosquito behaviour and response to chlorfenapyr ITN in bioassays conducted at night were compared to day and across a range of temperatures representative of highland and lowland transmission. Standard three-minute bioassay of chlorfenapyr produced extremely low levels of mortality compared to pyrethroids. Thirty-minute day-time bioassay produced mortality closer to hut efficacy of chlorfenapyr ITN but still fell short of the WHO threshold. Overnight tunnel test with chlorfenapyr produced 100% mortality and exceeded the WHO threshold of 80%. The endogenous circadian activity rhythm of anophelines results in inactivity by day and raised metabolism and flight activity by night. A model which explains improved toxicity of chlorfenapyr ITN when tested at night, and during the day at higher ambient temperature, is that activation of chlorfenapyr and disruption of respiratory pathways is enhanced when the insect is more metabolically

Long-lasting response to electrochemotherapy in melanoma patients with cutaneous metastasis

PubMed Central

2013-01-01

Background Treatment of early and multiple cutaneous unresectable recurrences is a major therapeutic problem with around 80% of patients relapsing within 5 years. For lesions refractory to elective treatments, electrochemotherapy (ECT) involving electroporation combined with antineoplastic drug treatment appears to be a new potential option. This study was undertaken to analyze the short- and long-term responses of lesions treated with ECT with intravenous injection of bleomycin in melanoma patients with in-transit disease or distant cutaneous metastases. Methods Between June 2007 and September 2012, 60 patients with relapsed and refractory cutaneous melanoma metastases or in-transit disease underwent 100 courses of ECT with intravenous injection of bleomycin. Response to treatment was evaluated three months after ECT. A long-lasting response was defined as no cutaneous or in-transit relapse after a minimum of six months. Results Three months after ECT, a complete response was observed in 29 patients (48.4%), a partial response in 23 patients (38.3%) and no change or progressive disease in 8 patients (13.3%). The objective response rate of all treated lesions was 86.6%. Thirteen patients (44.8% of complete responders) experienced a long-lasting response after one ECT session and were disease-free after a mean duration of follow-up of 27.5 months. Conclusions The favorable outcome obtained in the present study demonstrates that ECT is a reliable, and effective procedure that provides long-term benefit in terms of curative and palliative treatment for unresectable cutaneous lesions without adversely impacting the quality of life of patients. PMID:24289268

Characterizing the insecticide resistance of Anopheles gambiae in Mali.

PubMed

Cisse, Moussa B M; Keita, Chitan; Dicko, Abdourhamane; Dengela, Dereje; Coleman, Jane; Lucas, Bradford; Mihigo, Jules; Sadou, Aboubacar; Belemvire, Allison; George, Kristen; Fornadel, Christen; Beach, Raymond

2015-08-22

The impact of indoor residual spraying (IRS) and long-lasting insecticide nets (LLINs), key components of the national malaria control strategy of Mali, is threatened by vector insecticide resistance. The objective of this study was to assess the level of insecticide resistance in Anopheles gambiae sensu lato populations from Mali against four classes of insecticide recommended for IRS: organochlorines (OCs), pyrethroids (PYs), carbamates (CAs) and organophosphates (OPs). Characterization of resistance was done in 13 sites across southern Mali and assessed presence and distribution of physiological mechanisms that included target-site modifications: knockdown resistance (kdr) and altered acetycholinesterase (AChE), and/or metabolic mechanisms: elevated esterases, glutathione S-transferases (GSTs), and monooxygenases. The World Health Organization (WHO) tube test was used to determine phenotypic resistance of An. gambiae s.l. to: dichlorodiphenyltrichloroethane (DDT) (OC), deltamethrin (PY), lambda-cyhalothrin (PY), bendiocarb (CA), and fenitrothion (OP). Identification of sibling species and presence of the ace-1 (R) and Leu-Phe kdr, resistance-associated mutations, were determined using polymerase chain reaction (PCR) technology. Biochemical assays were conducted to detect increased activity of GSTs, oxidases and esterases. Populations tested showed high levels of resistance to DDT in all 13 sites, as well as increased resistance to deltamethrin and lambda-cyhalothrin in 12 out of 13 sites. Resistance to fenitrothion and bendiocarb was detected in 1 and 4 out of 13 sites, respectively. Anopheles coluzzii, An. gambiae sensu stricto and Anopheles arabiensis were identified with high allelic frequencies of kdr in all sites where each of the species were found (13, 12 and 10 sites, respectively). Relatively low allelic frequencies of ace-1 (R) were detected in four sites where this assessment was conducted. Evidence of elevated insecticide metabolism, based on oxidase

Evaluation of community-based continuous distribution of long-lasting insecticide-treated nets in Toamasina II District, Madagascar.

PubMed

de Beyl, Celine Zegers; Kilian, Albert; Brown, Andrea; Sy-Ar, Mohamad; Selby, Richmond Ato; Randriamanantenasoa, Felicien; Ranaivosoa, Jocelyn; Zigirumugabe, Sixte; Gerberg, Lilia; Fotheringham, Megan; Lynch, Matthew; Koenker, Hannah

2017-08-10

Continuous distribution of insecticide-treated nets (ITNs) is thought to be an effective mechanism to maintain ITN ownership and access between or in the absence of mass campaigns, but evidence is limited. A community-based ITN distribution pilot was implemented and evaluated in Toamasina II District, Madagascar, to assess this new channel for continuous ITN distribution. Beginning 9 months after the December 2012 mass campaign, a community-based distribution pilot ran for an additional 9 months, from September 2013 to June 2014. Households requested ITN coupons from community agents in their village. After verification by the agents, households exchanged the coupon for an ITN at a distribution point. The evaluation was a two-stage cluster survey with a sample size of 1125 households. Counterfactual ITN ownership and access were calculated by excluding ITNs received through the community pilot. At the end of the pilot, household ownership of any ITN was 96.5%, population access to ITN was 81.5 and 61.5% of households owned at least 1 ITN for every 2 people. Without the ITNs provided through the community channel, household ownership of any ITN was estimated at 74.6%, population access to an ITN at 55.5%, and households that owned at least 1 ITN for 2 people at only 34.7%, 18 months after the 2012 campaign. Ownership of community-distributed ITNs was higher among the poorest wealth quintiles. Over 80% of respondents felt the community scheme was fair and simple to use. Household ITN ownership and population ITN access exceeded RBM targets after the 9-month community distribution pilot. The pilot successfully provided coupons and ITNs to households requesting them, particularly for the least poor wealth quintiles, and the scheme was well-perceived by communities. Further research is needed to determine whether community-based distribution can sustain ITN ownership and access over the long term, how continuous availability of ITNs affects household net replacement

Changes in malaria burden and transmission in sentinel sites after the roll-out of long-lasting insecticidal nets in Papua New Guinea.

PubMed

Hetzel, Manuel W; Reimer, Lisa J; Gideon, Gibson; Koimbu, Gussy; Barnadas, Céline; Makita, Leo; Siba, Peter M; Mueller, Ivo

2016-06-14

Papua New Guinea exhibits a complex malaria epidemiology due to diversity in malaria parasites, mosquito vectors, human hosts, and their natural environment. Heterogeneities in transmission and burden of malaria at various scales are likely to affect the success of malaria control interventions, and vice-versa. This manuscript assesses changes in malaria prevalence, incidence and transmission in sentinel sites following the first national distribution of long-lasting insecticidal nets (LLINs). Before and after the distribution of LLINs, data collection in six purposively selected sentinel sites included clinical surveillance in the local health facility, household surveys and entomological surveys. Not all activities were carried out in all sites. Mosquitoes were collected by human landing catches. Diagnosis of malaria infection in humans was done by rapid diagnostic test, light microscopy and PCR for species confirmation. Following the roll-out of LLINs, the average monthly malaria incidence rate dropped from 13/1,000 population to 2/1,000 (incidence rate ratio = 0.12; 95 % CI: 0.09-0.17; P < 0.001). The average population prevalence of malaria decreased from 15.7 % pre-LLIN to 4.8 % post-LLIN (adjusted odds ratio = 0.26; 95 % CI: 0.20-0.33; P < 0.001). In general, reductions in incidence and prevalence were more pronounced in infections with P. falciparum than with P. vivax. Additional morbidity indicators (anaemia, splenomegaly, self-reported fever) showed a decreasing trend in most sites. Mean Anopheles man biting rates decreased from 83 bites/person/night pre-LLIN to 31 post-LLIN (P = 0.008). Anopheles species composition differed between sites but everywhere diversity was lower post-LLIN. In two sites, post-LLIN P. vivax infections in anophelines had decreased but P. falciparum infections had increased despite the opposite observation in humans. LLIN distribution had distinct effects on P. falciparum and P. vivax. Higher resilience of

Status of insecticide resistance in high-risk malaria provinces in Afghanistan.

PubMed

Ahmad, Mushtaq; Buhler, Cyril; Pignatelli, Patricia; Ranson, Hilary; Nahzat, Sami Mohammad; Naseem, Mohammad; Sabawoon, Muhammad Farooq; Siddiqi, Abdul Majeed; Vink, Martijn

2016-02-18

Insecticide resistance seriously threatens the efficacy of vector control interventions in malaria endemic countries. In Afghanistan, the status of insecticide resistance is largely unknown while distribution of long-lasting insecticidal nets has intensified in recent years. The main objective of this study was thus to measure the level of resistance to four classes of insecticides in provinces with medium to high risk of malaria transmission. Adult female mosquitoes were reared from larvae successively collected in the provinces of Nangarhar, Kunar, Badakhshan, Ghazni and Laghman from August to October 2014. WHO insecticide susceptibility tests were performed with DDT (4 %), malathion (5 %), bendiocarb (0.1 %), permethrin (0.75 %) and deltamethrin (0.05 %). In addition, the presence of kdr mutations was investigated in deltamethrin resistant and susceptible Anopheles stephensi mosquitoes collected in the eastern provinces of Nangarhar and Kunar. Analyses of mortality rates revealed emerging resistance against all four classes of insecticides in the provinces located east and south of the Hindu Kush mountain range. Resistance is observed in both An. stephensi and Anopheles culicifacies, the two dominant malaria vectors in these provinces. Anopheles superpictus in the northern province of Badakhshan shows a different pattern of susceptibility with suspected resistance observed only for deltamethrin and bendiocarb. Genotype analysis of knock down resistance (kdr) mutations at the voltage-gated channel gene from An. stephensi mosquitoes shows the presence of the known resistant alleles L1014S and L1014F. However, a significant fraction of deltamethrin-resistant mosquitoes were homozygous for the 1014L wild type allele indicating that other mechanisms must be considered to account for the observed pyrethroid resistance. This study confirms the importance of monitoring insecticide resistance for the development of an integrated vector management in Afghanistan. The

House screening with insecticide-treated netting provides sustained reductions in domestic populations of Aedes aegypti in Merida, Mexico

PubMed Central

Che-Mendoza, Azael; Medina-Barreiro, Anuar; Koyoc-Cardeña, Edgar; Uc-Puc, Valentín; Contreras-Perera, Yamili; Herrera-Bojórquez, Josué; Dzul-Manzanilla, Felipe; Correa-Morales, Fabian; Ranson, Hilary; Lenhart, Audrey; McCall, Philip J.; Kroeger, Axel; Vazquez-Prokopec, Gonzalo

2018-01-01

Background There is a need for effective methods to control Aedes aegypti and prevent the transmission of dengue, chikungunya, yellow fever and Zika viruses. Insecticide treated screening (ITS) is a promising approach, particularly as it targets adult mosquitoes to reduce human-mosquito contact. Methodology/Principal findings A cluster-randomised controlled trial evaluated the entomological efficacy of ITS based intervention, which consisted of the installation of pyrethroid-impregnated long-lasting insecticide-treated netting material fixed as framed screens on external doors and windows. A total of 10 treatment and 10 control clusters (100 houses/cluster) were distributed throughout the city of Merida, Mexico. Cross-sectional entomological surveys quantified indoor adult mosquito infestation at baseline (pre-intervention) and throughout four post-intervention (PI) surveys spaced at 6-month intervals corresponding to dry/rainy seasons over two years (2012–2014). A total of 844 households from intervention clusters (86% coverage) were protected with ITS at the start of the trial. Significant reductions in the indoor presence and abundance of Ae. aegypti adults (OR = 0.48 and IRR = 0.45, P<0.05 respectively) and the indoor presence and abundance of Ae. aegypti female mosquitoes (OR = 0.47 and IRR = 0.44, P<0.05 respectively) were detected in intervention clusters compared to controls. This high level of protective effect was sustained for up to 24 months PI. Insecticidal activity of the ITS material declined with time, with ~70% mortality being demonstrated in susceptible mosquito cohorts up to 24 months after installation. Conclusions/Significance The strong and sustained entomological impact observed in this study demonstrates the potential of house screening as a feasible, alternative approach to a sustained long-term impact on household infestations of Ae. aegypti. Larger trials quantifying the effectiveness of ITS on epidemiological endpoints are warranted

20 CFR 416.909 - How long the impairment must last.

Code of Federal Regulations, 2010 CFR

2010-04-01

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20 CFR 220.28 - How long the impairment must last.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 1 2010-04-01 2010-04-01 false How long the impairment must last. 220.28 Section 220.28 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT... long the impairment must last. Unless the claimant's impairment is expected to result in death, it must...

Evidence of multiple/cross resistance to Bt and Organophosphate insecticides in Puerto Rico population of the fall armyworm, Spodoptera frugiperda

USDA-ARS?s Scientific Manuscript database

BACKGROUND: Fall armyworm (FAW) is a damaging pest of many economic crops. Long-term use of chemical control prompted resistance development to many insecticide classes. Many populations were found to be significantly less susceptible to major Bt toxins expressed in transgenic crops. In this study, ...

Long-Lasting Sound-Evoked Afterdischarge in the Auditory Midbrain.

PubMed

Ono, Munenori; Bishop, Deborah C; Oliver, Douglas L

2016-02-12

Different forms of plasticity are known to play a critical role in the processing of information about sound. Here, we report a novel neural plastic response in the inferior colliculus, an auditory center in the midbrain of the auditory pathway. A vigorous, long-lasting sound-evoked afterdischarge (LSA) is seen in a subpopulation of both glutamatergic and GABAergic neurons in the central nucleus of the inferior colliculus of normal hearing mice. These neurons were identified with single unit recordings and optogenetics in vivo. The LSA can continue for up to several minutes after the offset of the sound. LSA is induced by long-lasting, or repetitive short-duration, innocuous sounds. Neurons with LSA showed less adaptation than the neurons without LSA. The mechanisms that cause this neural behavior are unknown but may be a function of intrinsic mechanisms or the microcircuitry of the inferior colliculus. Since LSA produces long-lasting firing in the absence of sound, it may be relevant to temporary or chronic tinnitus or to some other aftereffect of long-duration sound.

Long-Lasting Sound-Evoked Afterdischarge in the Auditory Midbrain

PubMed Central

Ono, Munenori; Bishop, Deborah C.; Oliver, Douglas L.

2016-01-01

Different forms of plasticity are known to play a critical role in the processing of information about sound. Here, we report a novel neural plastic response in the inferior colliculus, an auditory center in the midbrain of the auditory pathway. A vigorous, long-lasting sound-evoked afterdischarge (LSA) is seen in a subpopulation of both glutamatergic and GABAergic neurons in the central nucleus of the inferior colliculus of normal hearing mice. These neurons were identified with single unit recordings and optogenetics in vivo. The LSA can continue for up to several minutes after the offset of the sound. LSA is induced by long-lasting, or repetitive short-duration, innocuous sounds. Neurons with LSA showed less adaptation than the neurons without LSA. The mechanisms that cause this neural behavior are unknown but may be a function of intrinsic mechanisms or the microcircuitry of the inferior colliculus. Since LSA produces long-lasting firing in the absence of sound, it may be relevant to temporary or chronic tinnitus or to some other aftereffect of long-duration sound. PMID:26867811

The paradigm of eave tubes: scaling up house improvement and optimizing insecticide delivery against disease-transmitting mosquitoes.

PubMed

Okumu, Fredros

2017-05-19

Control of mosquito-borne diseases is greatly compromised by spread of insecticide resistance, high implementation costs and sub-optimal compliance among users. Improved housing has potential to reduce malaria transmission nearly as much as long-lasting insecticide-treated nets (LLINs), while also preventing other arthropod-borne diseases and improving overall well-being. Yet, it is hardly promoted as mainstream intervention, partly because of high costs, minimal communal benefits to people in non-improved houses, and low scalability. By exploiting biological observations of mosquito behaviours around dwellings, scientists have developed a new approach that integrates effective vector control into housing developments. The technique involves blocking eave spaces in local houses, leaving a few cylindrical holes into which plastic tubes with insecticide-laden electrostatic nettings are inserted. Where houses already have blocked eaves, these cylindrical holes are drilled and the tubes inserted. The eave tube technology, as it is called, is an innovative new approach for implementing housing improvements, by creating a new scalable product that can be integrated in houses during or after construction. It takes away insecticides from proximity of users, and instead puts them where mosquitoes are most likely to enter houses, thereby reducing insecticidal exposure among household occupants, while maximizing exposure of mosquitoes. This way, lower quantities of insecticides are used, better house ventilation achieved, intervention costs reduced, and mass communal benefits achieved even were vectors are resistant to similar insecticides when delivered conventionally. There are however still some critical pieces missing, notably epidemiological, social and economic evidence that the above assertions are true and sustainable. Besides, there also some technical limitations to be considered, namely: (1) need for extensive house modifications before eave tubes are inserted, (2

Traditional nets interfere with the uptake of long-lasting insecticidal nets in the Peruvian Amazon: the relevance of net preference for achieving high coverage and use.

PubMed

Grietens, Koen Peeters; Muela Ribera, Joan; Soto, Veronica; Tenorio, Alex; Hoibak, Sarah; Aguirre, Angel Rosas; Toomer, Elizabeth; Rodriguez, Hugo; Llanos Cuentas, Alejandro; D'Alessandro, Umberto; Gamboa, Dionicia; Erhart, Annette

2013-01-01

While coverage of long-lasting insecticide-treated nets (LLIN) has steadily increased, a growing number of studies report gaps between net ownership and use. We conducted a mixed-methods social science study assessing the importance of net preference and use after Olyset® LLINs were distributed through a mass campaign in rural communities surrounding Iquitos, the capital city of the Amazonian region of Peru. The study was conducted in the catchment area of the Paujil and Cahuide Health Centres (San Juan district) between July 2007 and November 2008. During a first qualitative phase, participant observation and in-depth interviews collected information on key determinants for net preference and use. In a second quantitative phase, a survey among recently confirmed malaria patients evaluated the acceptability and use of both LLINs and traditional nets, and a case control study assessed the association between net preference/use and housing structure (open vs. closed houses). A total of 10 communities were selected for the anthropological fieldwork and 228 households participated in the quantitative studies. In the study area, bed nets are considered part of the housing structure and are therefore required to fulfil specific architectural and social functions, such as providing privacy and shelter, which the newly distributed Olyset® LLINs ultimately did not. The LLINs' failure to meet these criteria could mainly be attributed to their large mesh size, transparency and perceived ineffectiveness to protect against mosquitoes and other insects, resulting in 63.3% of households not using any of the distributed LLINs. Notably, LLIN usage was significantly lower in houses with no interior or exterior walls (35.2%) than in those with walls (73.8%) (OR = 5.2, 95CI [2.2; 12.3], p<0.001). Net preference can interfere with optimal LLIN use. In order to improve the number of effective days of LLIN protection per dollar spent, appropriate quantitative and qualitative methods

Combining long-lasting insecticidal nets and indoor residual spraying for malaria prevention in Ethiopia: study protocol for a cluster randomized controlled trial.

PubMed

Deressa, Wakgari; Loha, Eskindir; Balkew, Meshesha; Hailu, Alemayehu; Gari, Taye; Kenea, Oljira; Overgaard, Hans J; Gebremichael, Teshome; Robberstad, Bjarne; Lindtjørn, Bernt

2016-01-12

Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the main malaria prevention interventions in Ethiopia. There is conflicting evidence that the combined application of both interventions is better than either LLINs or IRS used alone. This trial aims to investigate whether the combination of LLINs (PermaNet 2.0, Vestergaard Frandsen, Lausanne, Switzerland) with IRS using propoxur will enhance the protective benefits and cost-effectiveness of the interventions against malaria and its effect on mosquito behavior, as compared to each intervention alone. This 2 x 2 factorial cluster randomized controlled trial is being carried out in the Adami Tullu district in south-central Ethiopia for about 116 weeks from September 2014 to December 2016. The trial is based on four arms: LLINs + IRS, LLINs alone, IRS alone and control. Villages (or clusters) will be the unit of randomization. The sample size includes 44 clusters per arm, with each cluster comprised of approximately 35 households (about 175 people). Prior to intervention, all households in the LLINs + IRS and LLINs alone arms will be provided with LLINs free of charge. Households in the LLINs + IRS and IRS alone arms will be sprayed with carbamate propoxur once a year just before the main malaria transmission season throughout the investigation. The primary outcome of this trial will be a malaria incidence based on the results of the rapid diagnostic tests in patients with a fever or history of fever attending health posts by passive case detection. Community-based surveys will be conducted each year to assess anemia among children 5-59 months old. In addition, community-based malaria prevalence surveys will be conducted each year on a representative sample of households during the main transmission season. The cost-effectiveness of the interventions and entomological studies will be simultaneously conducted. Analysis will be based on an intention-to-treat principle. This trial aims to

Determinants of long-lasting insecticidal net use in Burkina Faso after a mass distribution in the Diébougou health district.

PubMed

Tinoaga Ouédraogo, L; Ouédraogo, I; Yaméogo, A; Ouédraogo, V

2013-04-01

In 2009, a mass distribution of long-lasting insecticidal nets (LLINs) was conducted in an experimental site of the Diébougou health district. Carried out 1year after the distribution, this study aimed to determine the presence of LLINs in households, to determine the LLIN use rate, and thirdly, to identify key factors associated with LLIN use in households. We conducted a cross-sectional descriptive and analytical study, which covered the entire Diébougou health district. The study population consisted of households in the district. The statistical unit was the household head, or if absent his designated representative. For the selection of households to be studied, we considered the health centers and their geographic accessibility. We thus defined three zones: an area within 5 km of health centers, the area between 5 and 10 km away, and the area beyond 10 km. In each area, we randomly selected 20 households, totaling 60 households in the area of each health center, giving a sample of 840 households to be surveyed. We selected 60 households per health center in accordance with the time and financial resources allocated to data collection. The data were analyzed using the Epi Info 3.5.1 software package. The Chi square test was used to investigate the association between the dependent and independent variables with statistical significance set at P<0.05. When an association was demonstrated, the relative risk (RR) was calculated with the 95% confidence interval. A total of 822 households (97.8%) were surveyed, households inhabited by 6379 people including 1175 (11.4%) children under 5 years of age and 158 (2.5%) pregnant women. The overall use of LLINs was 76.5%. This rate was 81.7% in children under 5 years and 57.6% among pregnant women. Factors influencing the use of LLINs were the implementation of a communication plan by health actors (RR=2.42 [2.03-2.83]), the social position of the household head (RR=1.62 [1.43-1.83]), the marital status of the household

Long-lasting insecticidal net (LLIN) ownership, use and cost of implementation after a mass distribution campaign in Kasaï Occidental Province, Democratic Republic of Congo.

PubMed

Ntuku, Henry Maggi; Ruckstuhl, Laura; Julo-Réminiac, Jean-Emmanuel; Umesumbu, Solange E; Bokota, Alain; Tshefu, Antoinette Kitoto; Lengeler, Christian

2017-01-09

Long-lasting insecticidal nets (LLIN) are a highly effective means for preventing malaria infection and reducing associated morbidity and mortality. Mass free distribution campaigns have been shown to rapidly increase LLIN ownership and use. Around 3.5 million LLINs were distributed free of charge in the Kasaï Occidental Province in the Democratic Republic of Congo (DRC) in September-October 2014, using two different approaches, a fixed delivery strategy and a door-to-door strategy including hang-up activities. Repeated community-based cross-sectional surveys were conducted 2 months before and six months after the mass distribution. Descriptive statistics were used to measure changes in key malaria household indicators. LLIN ownership and use were compared between delivery strategies. Univariate and multivariate logistic regression analyses were used to identify factors associated with LLIN use before and after the mass distribution. A comparative financial cost analysis between the fixed delivery and door-to-door distribution strategies was carried out from the provider's perspective. Household ownership of at least one LLIN increased from 39.4% pre-campaign to 91.4% post-campaign and LLIN universal coverage, measured as the proportion of households with at least one LLIN for every two people increased from 4.1 to 41.1%. Population access to LLIN within the household increased from 22.2 to 80.7%, while overall LLIN use increased from 18.0 to 68.3%. Higher LLIN ownership was achieved with the fixed delivery strategy compared with the door-to-door (92.5% [95% CI 90.2-94.4%] versus 85.2% [95% CI 78.5-90.0%]), while distribution strategy did not have a significant impact on LLIN use (69.6% [95% CI 63.1-75.5%] versus 65.7% [95% CI 52.7-76.7%]). Malaria prevalence among children aged 6-59 months was 44.8% post-campaign. Living in a household with sufficient numbers of LLIN to cover all members was the strongest determinant of LLIN use. The total financial cost per

Efficacy of permethrin treated long-lasting insecticidal nets on malaria transmission and observations on the perceived side effects, collateral benefits and human safety in a hyperendemic tribal area of Orissa, India.

PubMed

Sharma, Surya K; Tyagi, Prajesh K; Upadhyay, Ashok K; Haque, Mohammed A; Mohanty, Suman S; Raghavendra, Kamaraju; Dash, Aditya P

2009-11-01

Studies were conducted on the efficacy of Olyset nets-a long-lasting insecticidal net (LLIN) factory treated with 2% (w/w) permethrin on malaria transmission in an area under the influence of pyrethroid susceptible vector species Anopheles culicifacies and A. fluviatilis in Sundargarh District, Orissa, India. The study area comprised 22 villages that were randomized into three clusters and designated as Olyset net, untreated net, and no net area. Malaria incidence in the study population was measured through longitudinal active surveillance at fortnightly intervals. There was a reduction of 65-70% in malaria incidence in Olyset net area as compared to the control areas. The attack rate of Plasmodium falciparum or number of episodes per person per year in different age groups also showed significant reduction in Olyset net area as compared to untreated net and no net areas. Cross-sectional point prevalence surveys showed 45.7% reduction of malaria prevalence in Olyset net users, whereas there was an increase of 33.3% and 51% in untreated net and no net villages respectively. The compliance rate of Olyset net usage in the study population was 80-98% during different months, whereas it was between 70% and 90% for untreated nets. There were minimal complains of skin irritation (4%), itching (8%) and eye irritation (1.2%). However, these effects were only transitory in nature lasting for few hours of the first usage. Olyset nets also provided collateral benefits in terms of relief not only from mosquitoes and malaria but also from other household pests such as head lice, bed bugs, cockroaches, ants and houseflies. The Olyset nets were found to be safe to humans as no adverse event was recorded in the net users that can be attributed to the use of net. The study showed that Olyset nets are effective personal protection tool that can be used in a community based intervention programme.

Lethal and Sub-lethal Effects of Four Insecticides on the Aphidophagous Coccinellid Adalia bipunctata (Coleoptera: Coccinellidae).

PubMed

Depalo, Laura; Lanzoni, Alberto; Masetti, Antonio; Pasqualini, Edison; Burgio, Giovanni

2017-12-05

Conventional insecticide assays, which measure the effects of insecticide exposure on short-term mortality, overlook important traits, including persistence of toxicity or sub-lethal effects. Therefore, such approaches are especially inadequate for prediction of the overall impact of insecticides on beneficial arthropods. In this study, the side effects of four modern insecticides (chlorantraniliprole, emamectin benzoate, spinosad, and spirotetramat) on Adalia bipunctata (L.) (Coleoptera: Coccinellidae) were evaluated under laboratory conditions by exposition on treated potted plants. In addition to investigation of acute toxicity and persistence of harmful activity in both larvae and adults of A. bipunctata, demographic parameters were evaluated, to provide a comprehensive picture of the nontarget effects of these products. Field doses of the four insecticides caused detrimental effects to A. bipunctata; but in different ways. Overall, spinosad showed the best toxicological profile among the products tested. Emamectin benzoate could be considered a low-risk insecticide, but had high persistence. Chlorantraniliprole exhibited lethal effects on early instar larvae and adults, along with a long-lasting activity, instead spirotetramat showed a low impact on larval and adult mortality and can be considered a short-lived insecticide. However, demographic analysis demonstrated that chlorantraniliprole and spirotetramat caused sub-lethal effects. Our findings highlight that sole assessment of mortality can lead to underestimation of the full impact of pesticides on nontarget insects. Demographic analysis was demonstrated to be a sensitive method for detection of the sub-lethal effects of insecticides on A. bipunctata, and this approach should be considered for evaluation of insecticide selectivity. © 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.

Performance of honey bee colonies under a long-lasting dietary exposure to sublethal concentrations of the neonicotinoid insecticide thiacloprid.

PubMed

Siede, Reinhold; Faust, Lena; Meixner, Marina D; Maus, Christian; Grünewald, Bernd; Büchler, Ralph

2017-07-01

Substantial honey bee colony losses have occurred periodically in the last decades. The drivers for these losses are not fully understood. The influence of pests and pathogens are beyond dispute, but in addition, chronic exposure to sublethal concentrations of pesticides has been suggested to affect the performance of honey bee colonies. This study aims to elucidate the potential effects of a chronic exposure to sublethal concentrations (one realistic worst-case concentration) of the neonicotinoid thiacloprid to honey bee colonies in a three year replicated colony feeding study. Thiacloprid did not significantly affect the colony strength. No differences between treatment and control were observed for the mortality of bees, the infestation with the parasitic mite Varroa destructor and the infection levels of viruses. No colony losses occurred during the overwintering seasons. Furthermore, thiacloprid did not influence the constitutive expression of the immunity-related hymenoptaecin gene. However, upregulation of hymenoptaecin expression as a response to bacterial challenge was less pronounced in exposed bees than in control bees. Under field conditions, bee colonies are not adversely affected by a long-lasting exposure to sublethal concentrations of thiacloprid. No indications were found that field-realistic and higher doses exerted a biologically significant effect on colony performance. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Evaluating the efficacy of biological and conventional insecticides with the new 'MCD bottle' bioassay.

PubMed

Sternberg, Eleanore D; Waite, Jessica L; Thomas, Matthew B

2014-12-16

Control of mosquitoes requires the ability to evaluate new insecticides and to monitor resistance to existing insecticides. Monitoring tools should be flexible and low cost so that they can be deployed in remote, resource poor areas. Ideally, a bioassay should be able to simulate transient contact between mosquitoes and insecticides, and it should allow for excito-repellency and avoidance behaviour in mosquitoes. Presented here is a new bioassay, which has been designed to meet these criteria. This bioassay was developed as part of the Mosquito Contamination Device (MCD) project and, therefore, is referred to as the MCD bottle bioassay. Presented here are two experiments that serve as a proof-of-concept for the MCD bottle bioassay. The experiments used four insecticide products, ranging from fast-acting, permethrin-treated, long-lasting insecticide nets (LLINs) that are already widely used for malaria vector control, to the slower acting entomopathogenic fungus, Beauveria bassiana, that is currently being evaluated as a prospective biological insecticide. The first experiment used the MCD bottle to test the effect of four different insecticides on Anopheles stephensi with a range of exposure times (1 minute, 3 minutes, 1 hour). The second experiment is a direct comparison of the MCD bottle and World Health Organization (WHO) cone bioassay that tests a subset of the insecticides (a piece of LLIN and a piece of netting coated with B. bassiana spores) and a further reduced exposure time (5 seconds) against both An. stephensi and Anopheles gambiae. Immediate knockdown and mortality after 24 hours were assessed using logistic regression and daily survival was assessed using Cox proportional hazards models. Across both experiments, fungus performed much more consistently than the chemical insecticides but measuring the effect of fungus required monitoring of mosquito mortality over several days to a week. Qualitatively, the MCD bottle and WHO cone performed comparably

Field durability of the same type of long-lasting insecticidal net varies between regions in Nigeria due to differences in household behaviour and living conditions.

PubMed

Kilian, Albert; Koenker, Hannah; Obi, Emmanuel; Selby, Richmond A; Fotheringham, Megan; Lynch, Matthew

2015-03-24

With the recent publication of WHO-recommended methods to estimate net survival, comparative analyses from different areas have now become possible. With this in mind, a study was undertaken in Nigeria to compare the performance of a specific long-lasting insecticidal net (LLIN) product in three socio-ecologically different areas. In addition, the objective was to assess the feasibility of a retrospective study design for durability. In three states, Zamfara in the north, Nasarawa in the centre and Cross River in the south, four local government areas were selected one year after mass distribution of 100-denier polyester LLINs. From a representative sample of 300 households per site that had received campaign nets, an assessment of net survival was made based on rate of loss of nets and the physical condition of surviving nets measured by the proportionate hole index (pHI). Surveys were repeated after two and three years. Over the three-year period 98% of the targeted sample size of 3,720 households was obtained and 94% of the 5,669 campaign nets found were assessed for damage. With increasing time since distribution, recall of having received campaign nets dropped by 11-22% and only 31-87% of nets actually lost were reported. Using a recall bias adjustment, attrition rates were fairly similar in all three sites. The proportion of surviving nets in serviceable condition differed dramatically, however, resulting in an estimated median net survival of 3.0 years in Nasarawa, 4.5 years in Cross River and 4.7 years in Zamfara. Although repairs on damaged nets increased from around 10% at baseline to 21-38% after three years, the average pHI value for each of the four hole size categories did not differ between repaired and unrepaired nets. First, the differences observed in net survival are driven by living conditions and household behaviours and not the LLIN material. Second, recall bias in a retrospective durability study can be significant and while adjustments can

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.

Long-lasting desynchronization in rat hippocampal slice induced by coordinated reset stimulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tass, P. A.; Barnikol, U. B.; Department of Stereotaxic and Functional Neurosurgery, University of Cologne, D-50931 Cologne

2009-07-15

In computational models it has been shown that appropriate stimulation protocols may reshape the connectivity pattern of neural or oscillator networks with synaptic plasticity in a way that the network learns or unlearns strong synchronization. The underlying mechanism is that a network is shifted from one attractor to another, so that long-lasting stimulation effects are caused which persist after the cessation of stimulation. Here we study long-lasting effects of multisite electrical stimulation in a rat hippocampal slice rendered epileptic by magnesium withdrawal. We show that desynchronizing coordinated reset stimulation causes a long-lasting desynchronization between hippocampal neuronal populations together with amore » widespread decrease in the amplitude of the epileptiform activity. In contrast, periodic stimulation induces a long-lasting increase in both synchronization and amplitude.« less

42 CFR 63a.8 - How long does grant support last?

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false How long does grant support last? 63a.8 Section 63a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.8 How long does grant support last...

42 CFR 63a.8 - How long does grant support last?

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false How long does grant support last? 63a.8 Section 63a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.8 How long does grant support last...

42 CFR 63a.8 - How long does grant support last?

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false How long does grant support last? 63a.8 Section 63a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.8 How long does grant support last...

42 CFR 63a.8 - How long does grant support last?

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false How long does grant support last? 63a.8 Section 63a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.8 How long does grant support last...

42 CFR 63a.8 - How long does grant support last?

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false How long does grant support last? 63a.8 Section 63a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTES OF HEALTH TRAINING GRANTS § 63a.8 How long does grant support last...

Mechanisms of Translation Control Underlying Long-lasting Synaptic Plasticity and the Consolidation of Long-term Memory

PubMed Central

Santini, Emanuela; Huynh, Thu N.; Klann, Eric

2018-01-01

The complexity of memory formation and its persistence is a phenomenon that has been studied intensely for centuries. Memory exists in many forms and is stored in various brain regions. Generally speaking, memories are reorganized into broadly distributed cortical networks over time through systems level consolidation. At the cellular level, storage of information is believed to initially occur via altered synaptic strength by processes such as long-term potentiation (LTP). New protein synthesis is required for long-lasting synaptic plasticity as well as for the formation of long-term memory. The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of cap-dependent protein synthesis and is required for numerous forms of long-lasting synaptic plasticity and long-term memory. As such, the study of mTORC1 and protein factors that control translation initiation and elongation have enhanced our understanding of how the process of protein synthesis is regulated during memory formation. Herein we will discuss the molecular mechanisms that regulate protein synthesis as well as pharmacological and genetic manipulations that demonstrate the requirement for proper translational control in long-lasting synaptic plasticity and long-term memory formation. PMID:24484700

Insecticide discovery: an evaluation and analysis.

PubMed

Sparks, Thomas C

2013-09-01

There is an on-going need for the discovery and development of new insecticides due to the loss of existing products through the development of resistance, the desire for products with more favorable environmental and toxicological profiles, shifting pest spectrums, and changing agricultural practices. Since 1960, the number of research-based companies in the US and Europe involved in the discovery of new insecticidal chemistries has been declining. In part this is a reflection of the increasing costs of the discovery and development of new pesticides. Likewise, the number of compounds that need to be screened for every product developed has, until recently, been climbing. In the past two decades the agrochemical industry has been able to develop a range of new products that have more favorable mammalian vs. insect selectivity. This review provides an analysis of the time required for the discovery, or more correctly the building process, for a wide range of insecticides developed during the last 60 years. An examination of the data around the time requirements for the discovery of products based on external patents, prior internal products, or entirely new chemistry provides some unexpected observations. In light of the increasing costs of discovery and development, coupled with fewer companies willing or able to make the investment, insecticide resistance management takes on greater importance as a means to preserve existing and new insecticides. Copyright © 2013 Elsevier Inc. All rights reserved.

Rapid and long-lasting learning of feature binding

PubMed Central

Yashar, Amit; Carrasco, Marisa

2016-01-01

How are features integrated (bound) into objects and how can this process be facilitated? Here we investigated the role of rapid perceptual learning in feature binding and its long-lasting effects. By isolating the contributions of individual features from their conjunctions between training and test displays, we demonstrate for the first time that training can rapidly and substantially improve feature binding. Observers trained on a conjunction search task consisting of a rapid display with one target-conjunction, then tested with a new target-conjunction. Features were the same between training and test displays. Learning transferred to the new target when its conjunction was presented as a distractor, but not when only its component features were presented in different conjunction distractors during training. Training improvement lasted for up to 16 months, but, in all conditions, it was specific to the trained target. Our findings suggest that with short training observers’ ability to bind two specific features into an object is improved, and that this learning effect can last for over a year. Moreover, our findings show that while the short-term learning effect reflects activation of presented items and their binding, long-term consolidation is task specific. PMID:27289484

Colorful Demos with a Long-Lasting Soap Bubble.

ERIC Educational Resources Information Center

Behroozi, F.; Olson, D. W.

1994-01-01

Describes several demonstrations that feature interaction of light with soap bubbles. Includes directions about how to produce a long-lasting stationary soap bubble with an easily changeable size and describes the interaction of white light with the bubble. (DDR)

Insecticide solvents: interference with insecticidal action.

PubMed

Brattsten, L B; Wilkinson, C F

1977-06-10

Several commercial solvent mixtures commonly used as insecticide carriers in spray formulations increase by more than threefold the microsomal N-demethylation of p-chloro N-methylaniline in midgut preparations of southern army-worm (Spodoptera eridania) larvae exposed orally to the test solvents. Under laboratory conditions, the same solvent mixtures exhibit a protective action against the in vivo toxicity of the insecticide carbaryl to the larvae. The data are discussed with respect to possible solvent-insecticide interactions occurring under field conditions and, more broadly, to potential toxicological hazards of these solvents to humans.

Long-lasting transition toward sustainable elimination of desert malaria under irrigation development

PubMed Central

Baeza, Andres; Bouma, Menno J.; Dhiman, Ramesh C.; Baskerville, Edward B.; Ceccato, Pietro; Yadav, Rajpal Singh; Pascual, Mercedes

2013-01-01

In arid areas, people living in the proximity of irrigation infrastructure are potentially exposed to a higher risk of malaria due to changes in ecohydrological conditions that lead to increased vector abundance. However, irrigation provides a pathway to economic prosperity that over longer time scales is expected to counteract these negative effects. A better understanding of this transition between increased malaria risk and regional elimination, in particular whether it is slow or abrupt, is relevant to sustainable development and disease management. By relying on space as a surrogate for stages of time, we investigate this transition in a semidesert region of India where a megairrigation project is underway and expected to cover more than 1,900 million hectares and benefit around 1 million farmers. Based on spatio-temporal epidemiological cases of Plasmodium vivax malaria and land-use irrigation from remote sensing sources, we show that this transition is characterized by an enhanced risk in areas adjacent to the trunk of the irrigation network, despite a forceful and costly insecticide-based control. Moreover, this transition between climate-driven epidemics and sustained low risk has already lasted a decade. Given the magnitude of these projects, these results suggest that increased health costs have to be planned for over a long time horizon. They further highlight the need to integrate assessments of both health and environmental impacts to guide adaptive mitigation strategies. Our results should help to define and track these transitions in other arid parts of the world subjected to similar tradeoffs. PMID:23942131

Field efficacy of a new mosaic long-lasting mosquito net (PermaNet® 3.0) against pyrethroid-resistant malaria vectors: a multi centre study in Western and Central Africa

PubMed Central

2010-01-01

Background Due to the spread of pyrethroid-resistance in malaria vectors in Africa, new strategies and tools are urgently needed to better control malaria transmission. The aim of this study was to evaluate the performances of a new mosaic long-lasting insecticidal net (LLIN), i.e. PermaNet® 3.0, against wild pyrethroid-resistant Anopheles gambiae s.l. in West and Central Africa. Methods A multi centre experimental hut trial was conducted in Malanville (Benin), Vallée du Kou (Burkina Faso) and Pitoa (Cameroon) to investigate the exophily, blood feeding inhibition and mortality induced by PermaNet® 3.0 (i.e. a mosaic net containing piperonyl butoxide and deltamethrin on the roof) comparatively to the WHO recommended PermaNet® 2.0 (unwashed and washed 20-times) and a conventionally deltamethrin-treated net (CTN). Results The personal protection and insecticidal activity of PermaNet 3.0 and PermaNet® 2.0 were excellent (>80%) in the "pyrethroid-tolerant" area of Malanville. In the pyrethroid-resistance areas of Pitoa (metabolic resistance) and Vallée du Kou (presence of the L1014F kdr mutation), PermaNet® 3.0 showed equal or better performances than PermaNet® 2.0. It should be noted however that the deltamethrin content on PermaNet® 3.0 was up to twice higher than that of PermaNet® 2.0. Significant reduction of efficacy of both LLIN was noted after 20 washes although PermaNet® 3.0 still fulfilled the WHO requirement for LLIN. Conclusion The use of combination nets for malaria control offers promising prospects. However, further investigations are needed to demonstrate the benefits of using PermaNet® 3.0 for the control of pyrethroid resistant mosquito populations in Africa. PMID:20423479

Navy Entomologists Assist CDC’s Fight Against Malaria

DTIC Science & Technology

2013-01-01

long - lasting insec- ticide treated bed nets (LLINs): 2) indoor residual spraying (IRS) of living quarters using long - lasting residual ... insecticide susceptible malaria mosquitoes for residual insecticide testing of IRS sprayed walls and long lasting insecticide -treated bed nets . which is...the Navy Entomology Center of Excellence sprays panels, made of materials

Insecticide-treated durable wall lining (ITWL): future prospects for control of malaria and other vector-borne diseases.

PubMed

Messenger, Louisa A; Rowland, Mark

2017-05-22

While long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control throughout sub-Saharan Africa, there is an urgent need for the development of novel insecticide delivery mechanisms to sustain and consolidate gains in disease reduction and to transition towards malaria elimination and eradication. Insecticide-treated durable wall lining (ITWL) may represent a new paradigm for malaria control as a potential complementary or alternate longer-lasting intervention to IRS. ITWL can be attached to inner house walls, remain efficacious over multiple years and overcome some of the operational constraints of first-line control strategies, specifically nightly behavioural compliance required of LLINs and re-current costs and user fatigue associated with IRS campaigns. Initial experimental hut trials of insecticide-treated plastic sheeting reported promising results, achieving high levels of vector mortality, deterrence and blood-feeding inhibition, particularly when combined with LLINs. Two generations of commercial ITWL have been manufactured to date containing either pyrethroid or non-pyrethroid formulations. While some Phase III trials of these products have demonstrated reductions in malaria incidence, further large-scale evidence is still required before operational implementation of ITWL can be considered either in a programmatic or more targeted community context. Qualitative studies of ITWL have identified aesthetic value and observable entomological efficacy as key determinants of household acceptability. However, concerns have been raised regarding installation feasibility and anticipated cost-effectiveness. This paper critically reviews ITWL as both a putative mechanism of house improvement or more conventional intervention and discusses its future prospects as a method for controlling malaria and other vector-borne diseases.

Environmentally friendly tool to control mosquito populations without risk of insecticide resistance: the Lehmann’s funnel entry trap

PubMed Central

2013-01-01

Background Current malaria control strategies have cut down the malaria burden in many endemic areas, however the emergence and rapid spread of insecticide and drug resistance undermine the success of these efforts. There is growing concern that malaria eradication will not be achieved without the introduction of novel control tools. One approach that has been developed in the last few years is based on house screening to reduce indoor mosquito vector densities and consequently decrease malaria transmission. Here screening and trapping were combined in one tool to control mosquito populations. The trap does not require an insecticide or even an attractant, yet it effectively collects incoming resistant and susceptible mosquitoes and kills them. Results Performance of the funnel entry trap was tested in low and high malaria vector density areas. An overall reduction of 70 to 80% of mosquito density was seen in both. Species and molecular forms of Anopheles gambiae identification indicated no variation in the number of Anopheles arabiensis and the molecular forms of An. gambiae between houses and traps. Mosquitoes collected in the traps and in houses were highly resistant to pyrethroids (0.9 kdr-based mechanism). Conclusion There is a global consensus that new intervention tools are needed to cross the last miles in malaria elimination/eradication. The funnel entry trap showed excellent promise in suppressing mosquito densities even in area of high insecticide resistance. It requires no chemicals and is self-operated. PMID:23758904

Spastic long-lasting reflexes in the awake rat after sacral spinal cord injury.

PubMed

Bennett, D J; Sanelli, L; Cooke, C L; Harvey, P J; Gorassini, M A

2004-05-01

Following chronic sacral spinal cord transection in rats the affected tail muscles exhibit marked spasticity, with characteristic long-lasting tail spasms evoked by mild stimulation. The purpose of the present paper was to characterize the long-lasting reflex seen in tail muscles in response to electrical stimulation of the tail nerves in the awake spastic rat, including its development with time and relation to spasticity. Before and after sacral spinal transection, surface electrodes were placed on the tail for electrical stimulation of the caudal nerve trunk (mixed nerve) and for recording EMG from segmental tail muscles. In normal and acute spinal rats caudal nerve trunk stimulation evoked little or no EMG reflex. By 2 wk after injury, the same stimulation evoked long-lasting reflexes that were 1) very low threshold, 2) evoked from rest without prior EMG activity, 3) of polysynaptic latency with >6 ms central delay, 4) about 2 s long, and 5) enhanced by repeated stimulation (windup). These reflexes produced powerful whole tail contractions (spasms) and developed gradually over the weeks after the injury (< or =52 wk tested), in close parallel to the development of spasticity. Pure low-threshold cutaneous stimulation, from electrical stimulation of the tip of the tail, also evoked long-lasting spastic reflexes, not seen in acute spinal or normal rats. In acute spinal rats a strong C-fiber stimulation of the tip of the tail (20 x T) could evoke a weak EMG response lasting about 1 s. Interestingly, when this C-fiber stimulation was used as a conditioning stimulation to depolarize the motoneuron pool in acute spinal rats, a subsequent low-threshold stimulation of the caudal nerve trunk evoked a 300-500 ms long reflex, similar to the onset of the long-lasting reflex in chronic spinal rats. A similar conditioned reflex was not seen in normal rats. Thus there is an unusually long low-threshold polysynaptic input to the motoneurons (pEPSP) that is normally inhibited by

Insecticide exposure impacts vector-parasite interactions in insecticide-resistant malaria vectors.

PubMed

Alout, Haoues; Djègbè, Innocent; Chandre, Fabrice; Djogbénou, Luc Salako; Dabiré, Roch Kounbobr; Corbel, Vincent; Cohuet, Anna

2014-07-07

Currently, there is a strong trend towards increasing insecticide-based vector control coverage in malaria endemic countries. The ecological consequence of insecticide applications has been mainly studied regarding the selection of resistance mechanisms; however, little is known about their impact on vector competence in mosquitoes responsible for malaria transmission. As they have limited toxicity to mosquitoes owing to the selection of resistance mechanisms, insecticides may also interact with pathogens developing in mosquitoes. In this study, we explored the impact of insecticide exposure on Plasmodium falciparum development in insecticide-resistant colonies of Anopheles gambiae s.s., homozygous for the ace-1 G119S mutation (Acerkis) or the kdr L1014F mutation (Kdrkis). Exposure to bendiocarb insecticide reduced the prevalence and intensity of P. falciparum oocysts developing in the infected midgut of the Acerkis strain, whereas exposure to dichlorodiphenyltrichloroethane reduced only the prevalence of P. falciparum infection in the Kdrkis strain. Thus, insecticide resistance leads to a selective pressure of insecticides on Plasmodium parasites, providing, to our knowledge, the first evidence of genotype by environment interactions on vector competence in a natural Anopheles-Plasmodium combination. Insecticide applications would affect the transmission of malaria in spite of resistance and would reduce to some degree the impact of insecticide resistance on malaria control interventions. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

[Survey of the use of long-lasting expanding gases in ophthalmology in Japan].

PubMed

Sakamoto, Taiji; Hida, Tetsuo; Tano, Yasuo; Negi, Akira; Takeuchi, Shinobu; Ishibashi, Tatsuro; Inoue, Yoshitsugu; Ohguro, Nobuyuki; Okada, Annabelle Ayame

2008-01-01

To survey the use of long-lasting expanding gases in ophthalmology in Japan. A questionnaire was sent to 1,236 teaching hospitals approved by the Japanese Ophthalmological Society requesting information regarding indications, methods, efficacy and complications related to the use of long-lasting expanding gases administered from January through December 2005. Four-hundred and fifty-nine hospitals responded to the survey (response rate 37.1%). A total of 174,221 ophthalmic surgeries were performed during the survey period, with long-lasting expanding gases used in 19,816 of cases (11.4%). The surgical procedure was vitrectomy in 89.6% of cases in which gas was administered. The most frequent indication for gas use was rhegmatogenous retinal detachment, for which SF6 was the preferred gas. Industrial use gas was utilized in 76.1% of cases, while 22.4% of cases received medical use gas. Increase in intraocular pressure was the most common complication of intraocular gas tamponade (3121 cases, 15.7%), followed by cataract formation. Ninety-eight percent of ophthalmologists responding supported the use of long-lasting expanding gases with vitrectomy, 85% with scleral buckling procedures, and 84% with surgery to remove subretinal hemorrhage. The consensus was that substantial deterioration of surgical results would occur if long-lasting expanding gases could not be used. Long-lasting expanding gases are being widely administered in ophthalmology in Japan, and appear to have good efficacy for a variety of indications. Several complications related to the use of these gases were reported, however the rates of complications were low.

Large-scale implementation of disease control programmes: a cost-effectiveness analysis of long-lasting insecticide-treated bed net distribution channels in a malaria-endemic area of western Kenya-a study protocol.

PubMed

Gama, Elvis; Were, Vincent; Ouma, Peter; Desai, Meghna; Niessen, Louis; Buff, Ann M; Kariuki, Simon

2016-11-21

Historically, Kenya has used various distribution models for long-lasting insecticide-treated bed nets (LLINs) with variable results in population coverage. The models presently vary widely in scale, target population and strategy. There is limited information to determine the best combination of distribution models, which will lead to sustained high coverage and are operationally efficient and cost-effective. Standardised cost information is needed in combination with programme effectiveness estimates to judge the efficiency of LLIN distribution models and options for improvement in implementing malaria control programmes. The study aims to address the information gap, estimating distribution cost and the effectiveness of different LLIN distribution models, and comparing them in an economic evaluation. Evaluation of cost and coverage will be determined for 5 different distribution models in Busia County, an area of perennial malaria transmission in western Kenya. Cost data will be collected retrospectively from health facilities, the Ministry of Health, donors and distributors. Programme-effectiveness data, defined as the number of people with access to an LLIN per 1000 population, will be collected through triangulation of data from a nationally representative, cross-sectional malaria survey, a cross-sectional survey administered to a subsample of beneficiaries in Busia County and LLIN distributors' records. Descriptive statistics and regression analysis will be used for the evaluation. A cost-effectiveness analysis will be performed from a health-systems perspective, and cost-effectiveness ratios will be calculated using bootstrapping techniques. The study has been evaluated and approved by Kenya Medical Research Institute, Scientific and Ethical Review Unit (SERU number 2997). All participants will provide written informed consent. The findings of this economic evaluation will be disseminated through peer-reviewed publications. Published by the BMJ Publishing

Development of Diagnostic Insecticide Concentrations and Assessment of Insecticide Susceptibility in German Cockroach (Dictyoptera: Blattellidae) Field Strains Collected From Public Housing

PubMed Central

Fardisi, Mahsa; Gondhalekar, Ameya D.

2017-01-01

Abstract Insecticide resistance in German cockroaches (Blattella germanica (L.)) has been a barrier to effective control since its first documentation in the 1950s. A necessary first step toward managing resistance is to understand insecticide susceptibility profiles in field-collected strains so that active ingredients (AIs) with lowest resistance levels can be identified. As a first step in this study, diagnostic concentrations (DCs) were determined for 14 insecticide AIs based on lethal concentrations that killed 99% or 90% of the individuals from a susceptible lab strain (JWax-S). Next, cockroaches were collected from two low-income multifamily housing complexes in Danville, IL, and Indianapolis, IN, and used to establish laboratory strains. These strains were screened against the 14 AI-DCs in vial bioassays, and susceptibility profiles were determined by comparing percent mortalities between the field strains relative to the JWax-S strain. Results revealed lowest resistance of field strains to boric acid, abamectin, dinotefuran, clothianidin, thiamethoxam, and chlorfenapyr. For the AIs hydramethylnon and imidacloprid, field strains did not display survivorship different than the lab strain, but >90% mortality was never achieved. Lastly, both field strains displayed resistance to indoxacarb, fipronil, acetamiprid, beta-cyfluthrin, bifenthrin, and lambda-cyhalothrin, but at varying levels. These results satisfy two objectives. First, baseline monitoring DCs were established for 14 insecticides presently registered for use against cockroaches, which represents a useful resource. Second, our findings reveal insecticide AIs with lowest resistance levels for use in forthcoming field studies that will investigate impacts of different insecticide deployment strategies on resistance management and evolution in cockroach field populations. PMID:28334270

Bioengineering of a cellulosic fabric for insecticide delivery via grafted cyclodextrin.

PubMed

Romi, Roberto; Lo Nostro, Pierandrea; Bocci, Eugenio; Ridi, Francesca; Baglioni, Piero

2005-01-01

beta-Cyclodextrin (beta-CD) can be easily grafted onto cellulosic textiles through covalent bonds. In such a way beta-CD empty cavities provide an efficient tool for entrapping different kinds of hydrophobic molecules on the surface of the fabric and releasing them slowly in time. The capability of cyclodextrins to include hydrophobic molecules such as fragrances, antimicrobial agents, and other chemicals can be then exploited to produce new grafted textiles with peculiar and useful performances. In this work we report the inclusion of two different products, the pyrethroid insecticide permethrin (PERM) and the insect repellent N,N-diethyl-m-toluamide (DEET), into beta-CD molecules grafted on cotton fabric. UV-vis spectrophotometry and thermal analysis confirmed the presence of the guest molecules on the fabric surface. Bioassays were carried out on two mosquito species of medical importance, Aedes aegypti and Anopheles stephensi; knock down effect and mortality were measured using standard World Health Organization (WHO) cone tests. Repellency and irritancy (blood feeding inhibition) were also measured using cage tests and a baited tunnel device. PERM-treated fabrics kept the insecticidal/irritant efficacy even for a long time after the treatment, whereas DEET activity lasted more shortly.

Impact of insecticide resistance in Anopheles arabiensis on malaria incidence and prevalence in Sudan and the costs of mitigation

PubMed Central

Kafy, Hmooda Toto; Ismail, Bashir Adam; Mnzava, Abraham Peter; Lines, Jonathan; Abdin, Mogahid Shiekh Eldin; Eltaher, Jihad Sulieman; Banaga, Anuar Osman; West, Philippa; Bradley, John; Cook, Jackie; Thomas, Brent; Subramaniam, Krishanthi; Hemingway, Janet; Knox, Tessa Bellamy; Malik, Elfatih M.; Yukich, Joshua O.; Donnelly, Martin James; Kleinschmidt, Immo

2017-01-01

Insecticide-based interventions have contributed to ∼78% of the reduction in the malaria burden in sub-Saharan Africa since 2000. Insecticide resistance in malaria vectors could presage a catastrophic rebound in disease incidence and mortality. A major impediment to the implementation of insecticide resistance management strategies is that evidence of the impact of resistance on malaria disease burden is limited. A cluster randomized trial was conducted in Sudan with pyrethroid-resistant and carbamate-susceptible malaria vectors. Clusters were randomly allocated to receive either long-lasting insecticidal nets (LLINs) alone or LLINs in combination with indoor residual spraying (IRS) with a pyrethroid (deltamethrin) insecticide in the first year and a carbamate (bendiocarb) insecticide in the two subsequent years. Malaria incidence was monitored for 3 y through active case detection in cohorts of children aged 1 to <10 y. When deltamethrin was used for IRS, incidence rates in the LLIN + IRS arm and the LLIN-only arm were similar, with the IRS providing no additional protection [incidence rate ratio (IRR) = 1.0 (95% confidence interval [CI]: 0.36–3.0; P = 0.96)]. When bendiocarb was used for IRS, there was some evidence of additional protection [interaction IRR = 0.55 (95% CI: 0.40–0.76; P < 0.001)]. In conclusion, pyrethroid resistance may have had an impact on pyrethroid-based IRS. The study was not designed to assess whether resistance had an impact on LLINs. These data alone should not be used as the basis for any policy change in vector control interventions. PMID:29229808

Toxicity of Insecticides on Various Life Stages of Two Tortricid Pests of Cranberries and on a Non-Target Predator

PubMed Central

Rodriguez-Saona, Cesar; Wanumen, Andrea Carolina; Salamanca, Jordano; Holdcraft, Robert; Kyryczenko-Roth, Vera

2016-01-01

Laboratory and extended laboratory bioassays were conducted to determine the residual toxicities of various insecticides against two key pests of cranberries, Sparganothis sulfureana and Choristoneura parallela (Lepidoptera: Tortricidae), and their non-target effects on the predatory Orius insidiosus (Hemiptera: Anthocoridae). The effects of nine insecticides with different modes of action on S. sulfureana and Ch. parallela eggs, larvae, and adults were tested in the laboratory, while the efficacy of a post-bloom application on larval mortality and mass of these pests and on adult O. insidiosus was evaluated in extended laboratory experiments. The organophosphate chlorpyrifos and the spinosyn spinetoram provided long-lasting (seven-day) control against all stages of both pests. The growth regulator methoxyfenozide and the diamides chlorantraniliprole and cyantraniliprole had strong (1–7 days) larvicidal, particularly on young larvae, and growth inhibitory activity, but only the diamides were adulticidal. Among neonicotinoids, acetamiprid had stronger ovicidal and adulticidal activity than thiamethoxam, showing within-insecticide class differences in toxicities; however, both were weak on larvae. Lethality of novaluron and indoxacarb was inconsistent, varying depending on species and stage. Chlorpyrifos was most toxic to O. insidiosus. These results show species- and stage-specific toxicities, and greater compatibility with biological control, of the newer reduced-risk classes of insecticides than older chemistries. PMID:27092527

Toxicity of Insecticides on Various Life Stages of Two Tortricid Pests of Cranberries and on a Non-Target Predator.

PubMed

Rodriguez-Saona, Cesar; Wanumen, Andrea Carolina; Salamanca, Jordano; Holdcraft, Robert; Kyryczenko-Roth, Vera

2016-04-15

Laboratory and extended laboratory bioassays were conducted to determine the residual toxicities of various insecticides against two key pests of cranberries, Sparganothis sulfureana and Choristoneura parallela (Lepidoptera: Tortricidae), and their non-target effects on the predatory Orius insidiosus (Hemiptera: Anthocoridae). The effects of nine insecticides with different modes of action on S. sulfureana and Ch. parallela eggs, larvae, and adults were tested in the laboratory, while the efficacy of a post-bloom application on larval mortality and mass of these pests and on adult O. insidiosus was evaluated in extended laboratory experiments. The organophosphate chlorpyrifos and the spinosyn spinetoram provided long-lasting (seven-day) control against all stages of both pests. The growth regulator methoxyfenozide and the diamides chlorantraniliprole and cyantraniliprole had strong (1-7 days) larvicidal, particularly on young larvae, and growth inhibitory activity, but only the diamides were adulticidal. Among neonicotinoids, acetamiprid had stronger ovicidal and adulticidal activity than thiamethoxam, showing within-insecticide class differences in toxicities; however, both were weak on larvae. Lethality of novaluron and indoxacarb was inconsistent, varying depending on species and stage. Chlorpyrifos was most toxic to O. insidiosus. These results show species- and stage-specific toxicities, and greater compatibility with biological control, of the newer reduced-risk classes of insecticides than older chemistries.

Genetics, Synergists, and Age Affect Insecticide Sensitivity of the Honey Bee, Apis mellifera

PubMed Central

Rinkevich, Frank D.; Margotta, Joseph W.; Pittman, Jean M.; Danka, Robert G.; Tarver, Matthew R.; Ottea, James A.; Healy, Kristen B.

2015-01-01

The number of honey bee colonies in the United States has declined to half of its peak level in the 1940s, and colonies lost over the winter have reached levels that are becoming economically unstable. While the causes of these losses are numerous and the interaction between them is very complex, the role of insecticides has garnered much attention. As a result, there is a need to better understand the risk of insecticides to bees, leading to more studies on both toxicity and exposure. While much research has been conducted on insecticides and bees, there have been very limited studies to elucidate the role that bee genotype and age has on the toxicity of these insecticides. The goal of this study was to determine if there are differences in insecticide sensitivity between honey bees of different genetic backgrounds (Carniolan, Italian, and Russian stocks) and assess if insecticide sensitivity varies with age. We found that Italian bees were the most sensitive of these stocks to insecticides, but variation was largely dependent on the class of insecticide tested. There were almost no differences in organophosphate bioassays between honey bee stocks (<1-fold), moderate differences in pyrethroid bioassays (1.5 to 3-fold), and dramatic differences in neonicotinoid bioassays (3.4 to 33.3-fold). Synergism bioassays with piperonyl butoxide, amitraz, and coumaphos showed increased phenothrin sensitivity in all stocks and also demonstrated further physiological differences between stocks. In addition, as bees aged, the sensitivity to phenothrin significantly decreased, but the sensitivity to naled significantly increased. These results demonstrate the variation arising from the genetic background and physiological transitions in honey bees as they age. This information can be used to determine risk assessment, as well as establishing baseline data for future comparisons to explain the variation in toxicity differences for honey bees reported in the literature. PMID

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

Mitochondrial impacts of insecticidal formate esters in insecticide-resistant and insecticide-susceptible Drosophila melanogaster.

PubMed

Song, Cheol; Scharf, Michael E

2009-06-01

Previous research on insecticidal formate esters in flies and mosquitoes has documented toxicity profiles, metabolism characteristics and neurological impacts. The research presented here investigated mitochondrial impacts of insecticidal formate esters and their hydrolyzed metabolite formic acid in the model dipteran insect Drosophila melanogaster Meig. These studies compared two Drosophila strains: an insecticide-susceptible strain (Canton-S) and a strain resistant by cytochrome P450 overexpression (Hikone-R). In initial studies investigating inhibition of mitochondrial cytochrome c oxidase, two proven insecticidal materials (hydramethylnon and sodium cyanide) caused significant inhibition. However, for insecticidal formate esters and formic acid, no significant inhibition was identified in either fly strain. Mitochondrial impacts of formate esters were then investigated further by tracking toxicant-induced cytochrome c release from mitochondria into the cytoplasm, a biomarker of apoptosis and neurological dysfunction. Formic acid and three positive control treatments (rotenone, antimycin A and sodium cyanide) induced cytochrome c release, verifying that formic acid is capable of causing mitochondrial disruption. However, when comparing formate ester hydrolysis and cytochrome c release between Drosophila strains, formic acid liberation was only weakly correlated with cytochrome c release in the susceptible Canton-S strain (r(2) = 0.70). The resistant Hikone-R strain showed no correlation (r(2) < 0.0001) between formate ester hydrolysis and cytochrome c release. The findings of this study provide confirmation of mitochondrial impacts by insecticidal formate esters and suggest links between mitochondrial disruption, respiratory inhibition, apoptosis and formate-ester-induced neurotoxicity.

Wash-resistance of pirimiphos-methyl insecticide treatments of window screens and eave baffles for killing indoor-feeding malaria vector mosquitoes: an experimental hut trial, South East of Zambia.

PubMed

Chinula, Dingani; Sikaala, Chadwick H; Chanda-Kapata, Pascalina; Hamainza, Busiku; Zulu, Reuben; Reimer, Lisa; Chizema, Elizabeth; Kiware, Samson; Okumu, Fredros O; Killeen, Gerry

2018-04-13

The effectiveness of long-lasting insecticidal-treated nets (LLINs) and indoor residual spraying (IRS) for malaria control is threatened by resistance to commonly used pyrethroid insecticides. Rotations, mosaics, combinations, or mixtures of insecticides from different complementary classes are recommended by the World Health Organization (WHO) for mitigating against resistance, but many of the alternatives to pyrethroids are prohibitively expensive to apply in large national IRS campaigns. Recent evaluations of window screens and eave baffles (WSEBs) treated with pirimiphos-methyl (PM), to selectively target insecticides inside houses, demonstrated malaria vector mortality rates equivalent or superior to IRS. However, the durability of efficacy when co-applied with polyacrylate-binding agents (BA) remains to be established. This study evaluated whether WSEBs, co-treated with PM and BA have comparable wash resistance to LLINs and might therefore remain insecticidal for years rather than months. WHO-recommended wire ball assays of insecticidal efficacy were applied to polyester netting treated with or without BA plus 1 or 2 g/sq m PM. They were then tested for insecticidal efficacy using fully susceptible insectary-reared Anopheles gambiae mosquitoes, following 0, 5, 10, 15, then 20 washes as per WHO-recommended protocols for accelerated ageing of LLINs. This was followed by a small-scale field trial in experimental huts to measure malaria vector mortality achieved by polyester netting WSEBs treated with BA and 2 g/sq m PM after 0, 10 and then 20 standardized washes, alongside recently applied IRS using PM. Co-treatment with BA and either dosage of PM remained insecticidal over 20 washes in the laboratory. In experimental huts, WSEBs treated with PM plus BA consistently killed similar proportions of Anopheles arabiensis mosquitoes to PM-IRS (both consistently ≥ 94%), even after 20 washes. Co-treating WSEBs with both PM and BA results in wash

Development of Diagnostic Insecticide Concentrations and Assessment of Insecticide Susceptibility in German Cockroach (Dictyoptera: Blattellidae) Field Strains Collected From Public Housing.

PubMed

Fardisi, Mahsa; Gondhalekar, Ameya D; Scharf, Michael E

2017-06-01

Insecticide resistance in German cockroaches (Blattella germanica (L.)) has been a barrier to effective control since its first documentation in the 1950s. A necessary first step toward managing resistance is to understand insecticide susceptibility profiles in field-collected strains so that active ingredients (AIs) with lowest resistance levels can be identified. As a first step in this study, diagnostic concentrations (DCs) were determined for 14 insecticide AIs based on lethal concentrations that killed 99% or 90% of the individuals from a susceptible lab strain (JWax-S). Next, cockroaches were collected from two low-income multifamily housing complexes in Danville, IL, and Indianapolis, IN, and used to establish laboratory strains. These strains were screened against the 14 AI-DCs in vial bioassays, and susceptibility profiles were determined by comparing percent mortalities between the field strains relative to the JWax-S strain. Results revealed lowest resistance of field strains to boric acid, abamectin, dinotefuran, clothianidin, thiamethoxam, and chlorfenapyr. For the AIs hydramethylnon and imidacloprid, field strains did not display survivorship different than the lab strain, but >90% mortality was never achieved. Lastly, both field strains displayed resistance to indoxacarb, fipronil, acetamiprid, beta-cyfluthrin, bifenthrin, and lambda-cyhalothrin, but at varying levels. These results satisfy two objectives. First, baseline monitoring DCs were established for 14 insecticides presently registered for use against cockroaches, which represents a useful resource. Second, our findings reveal insecticide AIs with lowest resistance levels for use in forthcoming field studies that will investigate impacts of different insecticide deployment strategies on resistance management and evolution in cockroach field populations. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.

Transposable elements and insecticide resistance.

PubMed

Rostant, Wayne G; Wedell, Nina; Hosken, David J

2012-01-01

Transposable elements (TEs) are mobile DNA sequences that are able to copy themselves within a host genome. They were initially characterized as selfish genes because of documented or presumed costs to host fitness, but it has become increasingly clear that not all TEs reduce host fitness. A good example of TEs benefiting hosts is seen with insecticide resistance, where in a number of cases, TE insertions near specific genes confer resistance to these man-made products. This is particularly true of Accord and associated TEs in Drosophila melanogaster and Doc insertions in Drosophila simulans. The first of these insertions also has sexually antagonistic fitness effects in the absence of insecticides, and although the magnitude of this effect depends on the genetic background in which Accord finds itself, this represents an excellent example of intralocus sexual conflict where the precise allele involved is well characterized. We discuss this finding and the role of TEs in insecticide resistance. We also highlight areas for further research, including the need for surveys of the prevalence and fitness consequences of the Doc insertion and how Drosophila can be used as models to investigate resistance in pest species. Copyright © 2012 Elsevier Inc. All rights reserved.

Toxicity of selected insecticides applied to western spruce budworm

Treesearch

Jacqueline L. Robertson; Nancy L. Gillette; Melvin Look; Barbara A. Lucas; Robert L. Lyon

1975-01-01

The contact toxicity of 100 insecticides to last stage larvae of Choristoneura occidentalis Freeman was tested by topical application in a 10-yr series of screening experiments. Pyrethroids were generally the most toxic group of chemicals tested. Compounds more toxic than the standard, mexacarbate, at Ld50 were:...

Toxicity of selected insecticides applied to western spruce budworm

Treesearch

Jacqueline E. Robertson; Nancy L. Gillette; Barbara A. Lucas; Robert L. Lyon

1976-01-01

The contact toxlaty of 100 insecticides to last stage larvae of Choristoneura occidentalis Freeman was tested by topical application in a 10-yr series of screening experiments. Pyrethroids were generally the most toxic group of chemicals tested. Compounds more toxic than the standard, mexacarbate, at LD90 were:...

Investigating mosquito net durability for malaria control in Tanzania - attrition, bioefficacy, chemistry, degradation and insecticide resistance (ABCDR): study protocol.

PubMed

Lorenz, Lena M; Overgaard, Hans J; Massue, Dennis J; Mageni, Zawadi D; Bradley, John; Moore, Jason D; Mandike, Renata; Kramer, Karen; Kisinza, William; Moore, Sarah J

2014-12-13

Long-Lasting Insecticidal Nets (LLINs) are one of the major malaria vector control tools, with most countries adopting free or subsidised universal coverage campaigns of populations at-risk from malaria. It is essential to understand LLIN durability so that public health policy makers can select the most cost effective nets that last for the longest time, and estimate the optimal timing of repeated distribution campaigns. However, there is limited knowledge from few countries of the durability of LLINs under user conditions. This study investigates LLIN durability in eight districts of Tanzania, selected for their demographic, geographic and ecological representativeness of the country as a whole. We use a two-stage approach: First, LLINs from recent national net campaigns will be evaluated retrospectively in 3,420 households. Those households will receive one of three leading LLIN products at random (Olyset®, PermaNet®2.0 or Netprotect®) and will be followed up for three years in a prospective study to compare their performance under user conditions. LLIN durability will be evaluated by measuring Attrition (the rate at which nets are discarded by households), Bioefficacy (the insecticidal efficacy of the nets measured by knock-down and mortality of mosquitoes), Chemical content (g/kg of insecticide available in net fibres) and physical Degradation (size and location of holes). In addition, we will extend the current national mosquito insecticide Resistance monitoring program to additional districts and use these data sets to provide GIS maps for use in health surveillance and decision making by the National Malaria Control Program (NMCP). The data will be of importance to policy makers and vector control specialists both in Tanzania and the SSA region to inform best practice for the maintenance of high and cost-effective coverage and to maximise current health gains in malaria control.

Adolescent ethanol exposure: does it produce long-lasting electrophysiological effects?

PubMed

Ehlers, Cindy L; Criado, José R

2010-02-01

This review discusses evidence for long-lasting neurophysiological changes that may occur following exposure to ethanol during adolescent development in animal models. Adolescence is the time that most individuals first experience ethanol exposure, and binge drinking is not uncommon during adolescence. If alcohol exposure is neurotoxic to the developing brain during adolescence, not unlike it is during fetal development, then understanding how ethanol affects the developing adolescent brain becomes a major public health issue. Adolescence is a critical time period when cognitive, emotional, and social maturation occurs and it is likely that ethanol exposure may affect these complex processes. To study the effects of ethanol on adolescent brain, animal models where the dose and time of exposure can be carefully controlled that closely mimic the human condition are needed. The studies reviewed provide evidence that demonstrates that relatively brief exposure to high levels of ethanol, via ethanol vapors, during a period corresponding to parts of adolescence in the rat is sufficient to cause long-lasting changes in functional brain activity. Disturbances in waking electroencephalogram and a reduction in the P3 component of the event-related potential (ERP) have been demonstrated in adult rats that were exposed to ethanol vapor during adolescence. Adolescent ethanol exposure was also found to produce long-lasting reductions in the mean duration of slow-wave sleep (SWS) episodes and the total amount of time spent in SWS, a finding consistent with a premature aging of sleep. Further studies are necessary to confirm these findings, in a range of strains, and to link those findings to the neuroanatomical and neurochemical mechanisms potentially underlying the lasting effects of adolescent ethanol exposure. 2010 Elsevier Inc. All rights reserved.

13 CFR 124.1005 - How long does an SDB certification last?

Code of Federal Regulations, 2012 CFR

2012-01-01

... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false How long does an SDB certification... Protests Relating to Federal Small Disadvantaged Business Programs § 124.1005 How long does an SDB certification last? (a) A firm that is certified to be an SDB will generally be certified for a period of three...

13 CFR 124.1005 - How long does an SDB certification last?

Code of Federal Regulations, 2010 CFR

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false How long does an SDB certification... Protests Relating to Federal Small Disadvantaged Business Programs § 124.1005 How long does an SDB certification last? (a) A firm that is certified to be an SDB will generally be certified for a period of three...

13 CFR 124.1005 - How long does an SDB certification last?

Code of Federal Regulations, 2011 CFR

2011-01-01

... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false How long does an SDB certification... Protests Relating to Federal Small Disadvantaged Business Programs § 124.1005 How long does an SDB certification last? (a) A firm that is certified to be an SDB will generally be certified for a period of three...

13 CFR 124.1005 - How long does an SDB certification last?

Code of Federal Regulations, 2014 CFR

2014-01-01

... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false How long does an SDB certification... Protests Relating to Federal Small Disadvantaged Business Programs § 124.1005 How long does an SDB certification last? (a) A firm that is certified to be an SDB will generally be certified for a period of three...

13 CFR 124.1005 - How long does an SDB certification last?

Code of Federal Regulations, 2013 CFR

2013-01-01

... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false How long does an SDB certification... Protests Relating to Federal Small Disadvantaged Business Programs § 124.1005 How long does an SDB certification last? (a) A firm that is certified to be an SDB will generally be certified for a period of three...

Optimal Cotton Insecticide Application Termination Timing: A Meta-Analysis.

PubMed

Griffin, T W; Zapata, S D

2016-08-01

The concept of insecticide termination timing is generally accepted among cotton (Gossypium hirsutum) researchers; however, exact timings are often disputed. Specifically, there is uncertainty regarding the last economic insecticide application to control fruit-feeding pests including tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)), boll weevil (Anthonomus grandis), bollworm (Helicoverpa zea), tobacco budworm (Heliothis virescens), and cotton fleahopper (Pseudatomoscelis seriatus). A systematic review of prior studies was conducted within a meta-analytic framework. Nine publicly available articles were amalgamated to develop an optimal timing principle. These prior studies reported 53 independent multiple means comparison field experiments for a total of 247 trial observations. Stochastic plateau theory integrated with econometric meta-analysis methodology was applied to the meta-database to determine the shape of the functional form of both the agronomic optimal insecticide termination timing and corresponding yield potential. Results indicated that current university insecticide termination timing recommendations are later than overall estimated timing suggested. The estimated 159 heat units (HU) after the fifth position above white flower (NAWF5) was found to be statistically different than the 194 HU termination used as the status quo recommended termination timing. Insecticides applied after 159 HU may have been applied in excess, resulting in unnecessary economic and environmental costs. Empirical results also suggested that extending the insecticide termination time by one unit resulted in a cotton lint yield increase of 0.27 kilograms per hectare up to the timing where the plateau began. Based on economic analyses, profit-maximizing producers may cease application as soon as 124 HU after NAWF5. These results provided insights useful to improve production systems by applying inputs only when benefits were expected to be in excess of the

Getting Over It: Long-Lasting Effects of Emotion Regulation on Amygdala Response.

PubMed

Denny, Bryan T; Inhoff, Marika C; Zerubavel, Noam; Davachi, Lila; Ochsner, Kevin N

2015-09-01

Little is known about whether emotion regulation can have lasting effects on the ability of a stimulus to continue eliciting affective responses in the future. We addressed this issue in this study. Participants cognitively reappraised negative images once or four times, and then 1 week later, they passively viewed old and new images, so that we could identify lasting effects of prior reappraisal. As in prior work, active reappraisal increased prefrontal responses but decreased amygdala responses and self-reported emotion. At 1 week, amygdala responses remained attenuated for images that had been repeatedly reappraised compared with images that had been reappraised once, new control images, and control images that had been seen as many times as reappraised images but had never been reappraised. Prefrontal activation was not selectively elevated for repeatedly reappraised images and was not related to long-term attenuation of amygdala responses. These results suggest that reappraisal can exert long-lasting "dose-dependent" effects on amygdala response that may cause lasting changes in the neural representation of an unpleasant event's emotional value. © The Author(s) 2015.

miR-191 and miR-135 are required for long-lasting spine remodelling associated with synaptic long-term depression

NASA Astrophysics Data System (ADS)

Hu, Zhonghua; Yu, Danni; Gu, Qin-Hua; Yang, Yanqin; Tu, Kang; Zhu, Jun; Li, Zheng

2014-02-01

Activity-dependent modification of dendritic spines, subcellular compartments accommodating postsynaptic specializations in the brain, is an important cellular mechanism for brain development, cognition and synaptic pathology of brain disorders. NMDA receptor-dependent long-term depression (NMDAR-LTD), a prototypic form of synaptic plasticity, is accompanied by prolonged remodelling of spines. The mechanisms underlying long-lasting spine remodelling in NMDAR-LTD, however, are largely unclear. Here we show that LTD induction causes global changes in miRNA transcriptomes affecting many cellular activities. Specifically, we show that expression changes of miR-191 and miR-135 are required for maintenance but not induction of spine restructuring. Moreover, we find that actin depolymerization and AMPA receptor exocytosis are regulated for extended periods of time by miRNAs to support long-lasting spine plasticity. These findings reveal a miRNA-mediated mechanism and a role for AMPA receptor exocytosis in long-lasting spine plasticity, and identify a number of candidate miRNAs involved in LTD.

20 CFR 404.1509 - How long the impairment must last.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How long the impairment must last. 404.1509 Section 404.1509 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Definition of Disability § 404.1509 How...

Genome-wide identification of long non-coding RNA genes and their association with insecticide resistance and metamorphosis in diamondback moth, Plutella xylostella.

PubMed

Liu, Feiling; Guo, Dianhao; Yuan, Zhuting; Chen, Chen; Xiao, Huamei

2017-11-20

Long non-coding RNA (lncRNA) is a class of noncoding RNA >200 bp in length that has essential roles in regulating a variety of biological processes. Here, we constructed a computational pipeline to identify lncRNA genes in the diamondback moth (Plutella xylostella), a major insect pest of cruciferous vegetables. In total, 3,324 lncRNAs corresponding to 2,475 loci were identified from 13 RNA-Seq datasets, including samples from parasitized, insecticide-resistant strains and different developmental stages. The identified P. xylostella lncRNAs had shorter transcripts and fewer exons than protein-coding genes. Seven out of nine randomly selected lncRNAs were validated by strand-specific RT-PCR. In total, 54-172 lncRNAs were specifically expressed in the insecticide resistant strains, among which one lncRNA was located adjacent to the sodium channel gene. In addition, 63-135 lncRNAs were specifically expressed in different developmental stages, among which three lncRNAs overlapped or were located adjacent to the metamorphosis-associated genes. These lncRNAs were either strongly or weakly co-expressed with their overlapping or neighboring mRNA genes. In summary, we identified thousands of lncRNAs and presented evidence that lncRNAs might have key roles in conferring insecticide resistance and regulating the metamorphosis development in P. xylostella.

Decrease of insecticide resistance over generations without exposure to insecticides in Nilaparvata lugens (Hemipteran: Delphacidae).

PubMed

Yang, Yajun; Dong, Biqin; Xu, Hongxing; Zheng, Xusong; Tian, Junce; Heong, Kongleun; Lu, Zhongxian

2014-08-01

The brown planthopper, Nilaparvata lugens (Stål), is one of the most important insect pests on paddy rice in tropical and temperate Asia. Overuse and misuse of insecticides have resulted in the development of high resistance to many different insecticides in this pest. Studies were conducted to evaluate the change of resistance level to four insecticides over 15 generations without any exposure to insecticides in brown planthopper. After 15 generations' rearing without exposure to insecticide, brown planthopper could reverse the resistance to imidacloprid, chlorpyrifos, fipronil, and fenobucarb. The range and style of resistance reversal of brown planthopper differed when treated with four different insecticides. To monitor potential changes in insect physiological responses, we measured the activity of each of the three selected enzymes, including acetylcholinesterases (AChE), general esterases (EST), and glutathione S-transferases. After multiple generations' rearing without exposure to insecticide, AChE and EST activities of brown planthopper declined with the increased generations, suggesting that the brown planthopper population adjusted activities of EST and AChE to adapt to the non-insecticide environment. These findings suggest that the reducing, temporary stop, or rotation of insecticide application could be incorporated into the brown planthopper management.

30 CFR 250.170 - How long does a suspension last?

Code of Federal Regulations, 2010 CFR

2010-07-01

... Section 250.170 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF General Suspensions § 250.170 How long does a suspension last? (a) MMS may issue suspensions for up to 5 years per suspension. The Regional...

20 CFR 220.28 - How long the impairment must last.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 20 Employees' Benefits 1 2013-04-01 2012-04-01 true How long the impairment must last. 220.28 Section 220.28 Employees' Benefits RAILROAD RETIREMENT BOARD REGULATIONS UNDER THE RAILROAD RETIREMENT ACT DETERMINING DISABILITY Disability Under the Railroad Retirement Act for Any Regular Employment § 220.28 How...

The impact of insecticide applications on the dynamics of resistance: The case of four Aedes aegypti populations from different Brazilian regions

PubMed Central

Martins, Ademir de Jesus; Maciel-de-Freitas, Rafael; Linss, Jutta Gerlinde Birggitt; Araújo, Simone Costa; Lima, José Bento Pereira; Valle, Denise

2018-01-01

Background In the tropics, the utilization of insecticides is still an important strategy for controlling Aedes aegypti, the principle vector of dengue, chikungunya and Zika viruses. However, increasing insecticide resistance in Ae. aegypti populations might hinder insecticide efficacy on a long-term basis. It will be important to understand the dynamics and evolution of insecticide resistance by assessing its frequency and the mechanisms by which it occurs. Methodology/Principal findings The insecticide resistance status of four Brazilian Ae. aegypti populations was monitored. Quantitative bioassays with the major insecticides employed in the country was performed: the adulticide deltamethrin (a pyrethroid—PY) and the larvicides, temephos (an organophosphate) and diflubenzuron (a chitin synthesis inhibitor). Temephos resistance was detected in all populations although exhibiting a slight decrease over time probably due to the interruption of field use. All vector populations were susceptible to diflubenzuron, recently introduced in the country to control Ae. aegypti. Resistance against deltamethrin was extremely high in three populations. Molecular assays investigated substitutions in the voltage gated sodium channel (NaV), the PY target site, at positions 1011, 1016 and 1534. Elevated frequencies of substitutions Val1016Ile and Phe1534Cys related to high PY resistance levels were identified. Biochemical assays detected alterations in the activities of two detoxifying enzyme classes related to metabolic resistance, glutathion-S-transferases and esterases. The results obtained were evaluated in the context of both recent insecticide use and the records of dengue incidence in each locality. Conclusions/Significance The four Ae. aegypti populations evaluated were resistant to the neurotoxic insecticides, temephos and deltamethrin. However, they were still susceptible to diflubenzuron. A probable correlation between adult insect resistance to PY and the domestic

Organophosphorus Insecticide Pharmacokinetics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timchalk, Charles

2010-01-01

This chapter highlights a number of current and future applications of pharmacokinetics to assess organophosphate (OP) insecticide dosimetry, biological response and risk in humans exposed to these agents. Organophosphates represent a large family of pesticides where insecticidal as well as toxicological mode of action is associated with their ability to target and inhibit acetylcholinesterase (AChE). Pharmacokinetics entails the quantitative integration of physiological and metabolic processes associated with the absorption, distribution, metabolism and excretion (ADME) of drugs and xenobiotics. Pharmacokinetic studies provide important data on the amount of toxicant delivered to a target site as well as species-, age-, gender-specific andmore » dose-dependent differences in biological response. These studies have been conducted with organophosphorus insecticides in multiple species, at various dose levels, and across different routes of exposure to understand their in vivo pharmacokinetics and how they contribute to the observed toxicological response. To access human exposure to organophosphorus insecticides, human pharmacokinetic studies have been conducted and used to develop biological monitoring strategies based on the quantitation of key metabolites in biological fluids. Pharmacokinetic studies with these insecticides are also useful to facilitate extrapolation of dosimetry and biological response from animals to humans and for the assessment of human health risk. In this regard, physiologically based pharmacokinetic and pharmacodynamic (PBPK/PD) models are being utilized to assess risk and understand the toxicological implications of known or suspected exposures to various insecticides. In this chapter a number of examples are presented that illustrate the utility and limitation of pharmacokinetic studies to address human health concerns associated with organophosphorus insecticides.« less

Long-lasting upper D-region ionospheric modifications caused by intense +/- CG lightning discharges

NASA Astrophysics Data System (ADS)

Haldoupis, Christos

2013-04-01

In a recent Geophysical Research Letter we have presented observations from a single maritime storm showing that intense positive cloud-to-ground (+CG) lightning discharges during nighttime, which trigger both an elve and a sprite, are associated with long-lasting conductivity modifications in the upper D-region ionosphere. The ionospheric disturbances can be observed as perturbations in the amplitude and phase of VLF (very low frequency) signals propagating through or near the disturbed region. They are manifested as LOng Recovery early VLF Events (LOREs) which can last up to 20 - 30 minutes. The same ionospheric modifications may also produce abrupt step-like changes in VLF transmissions which offset signal levels for longer times (>30-60 min). Here we discuss these observations supplementing them with new evidence and some statistics. Among other things, the unpublished results show that very intense (currents > 250-300 kA) CG lightning discharges of either positive or negative polarity are always accompanied mainly by step-like LOREs. The evidence suggests that the electromagnetic pulse (EMP) of a very high peak current CG lightning stroke, which is likely able to produce an elve, produces by electron impact long lasting and spatially extended elevations in electron density at VLF ionospheric reflection heights in the upper D region ionosphere. The results identify a mechanism for the LORE VLF signatures and confirm predictions and postulations that elves may be accompanied by significant and long-lasting electron density perturbations in the upper D- lower E- region ionosphere.

42 CFR 65.6 - How long does grant support last?

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false How long does grant support last? 65.6 Section 65.6 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS WASTE WORKER TRAINING § 65.6 How...

42 CFR 65.6 - How long does grant support last?

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false How long does grant support last? 65.6 Section 65.6 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS WASTE WORKER TRAINING § 65.6 How...

42 CFR 65.6 - How long does grant support last?

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false How long does grant support last? 65.6 Section 65.6 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS WASTE WORKER TRAINING § 65.6 How...

Compilation and analysis of global surface water concentrations for individual insecticide compounds.

PubMed

Stehle, Sebastian; Bub, Sascha; Schulz, Ralf

2018-10-15

The decades-long agricultural use of insecticides resulted in frequent contamination of surface waters globally regularly posing high risks for the aquatic biodiversity. However, the concentration levels of individual insecticide compounds have by now not been compiled and reported using global scale data, hampering our knowledge on the insecticide exposure of aquatic ecosystems. Here, we specify measured insecticide concentrations (MICs, comprising in total 11,300 water and sediment concentrations taken from a previous publication) for 28 important insecticide compounds covering four major insecticide classes. Results show that organochlorine and organophosphate insecticides, which dominated the global insecticide market for decades, have been detected most often and at highest concentration levels in surface waters globally. In comparison, MICs of the more recent pyrethroids and neonicotinoids were less often reported and generally at lower concentrations as a result of their later market introduction and lower application rates. An online insecticide classification calculator (ICC; available at: https://static.magic.eco/icc/v1) is provided in order to enable the comparison and classification of prospective MICs with available global insecticide concentrations. Spatial analyses of existing data show that most MICs were reported for surface waters in North America, Asia and Europe, whereas highest concentration levels were detected in Africa, Asia and South America. An evaluation of water and sediment MICs showed that theoretical organic carbon-water partition coefficients (K OC ) determined in the laboratory overestimated K OC values based on actual field concentrations by up to a factor of more than 20, with highest deviations found for highly sorptive pyrethroids. Overall, the comprehensive compilation of insecticide field concentrations presented here is a valuable tool for the classification of future surface water monitoring results and serves as important

Respiratory Complications of Organophosphorus Nerve Agent and Insecticide Poisoning. Implications for Respiratory and Critical Care

PubMed Central

Hulse, Elspeth J.; Davies, James O. J.; Simpson, A. John; Sciuto, Alfred M.

2014-01-01

Organophosphorus (OP) compound poisoning is a major global public health problem. Acute OP insecticide self-poisoning kills over 200,000 people every year, the majority from self-harm in rural Asia. Highly toxic OP nerve agents (e.g., sarin) are a significant current terrorist threat, as shown by attacks in Damascus during 2013. These anticholinesterase compounds are classically considered to cause an acute cholinergic syndrome with decreased consciousness, respiratory failure, and, in the case of insecticides, a delayed intermediate syndrome that requires prolonged ventilation. Acute respiratory failure, by central and peripheral mechanisms, is the primary cause of death in most cases. However, preclinical and clinical research over the last two decades has indicated a more complex picture of respiratory complications after OP insecticide poisoning, including onset of delayed neuromuscular junction dysfunction during the cholinergic syndrome, aspiration causing pneumonia and acute respiratory distress syndrome, and the involvement of solvents in OP toxicity. The treatment of OP poisoning has not changed over the last 50 years. However, a better understanding of the multiple respiratory complications of OP poisoning offers additional therapeutic opportunities. PMID:25419614

Teppeki, selective insecticide about Bombus terrestris.

PubMed

Fanigliulo, Angela; Filì, Vittorio; Pacella, Rosa; Comes, Soccorsa; Crescenzi, Aniello

2009-01-01

At a time when a highly controversial debate about the causes of the widespread deaths of bees is taking place all over Europe, which accused the agriculture and its practices with particular reference to the harmful effects of some insecticides, it seems important to point out as another insecticide, the Teppeki, can be selective about bumble and have a good compatibility with the activity of the apiaries. This insecticide has the active ingredient flonicamid (500 g/kg) belonging to a new chemical class, called pyridinecarboxamides: the product works systemic and is known as having a long lasting efficacy against all important aphid species. Bioagritest test facility of Pignola (PZ, Italy) has conducted in two successive production cycles an experimental trial on a tomato hydroponic cultivation within the Agricola Bonsai farm in Sibari (CS, Italy), whose objective was to measure the selectivity of flonicamid on Bombus terrestris, insects playing an important role in the pollination of certain species grown in greenhouse such as Tomato, Eggplant, Pepper and Cucumber. On the pollinated flower B. terrestris leaves some trace of its visit, a typical dark trademark: on the detection of the marking of flowers was based the testing program conducted by Bioagritest. Two thesis were compared: A, standard) treatment with a foliar insecticide, the neonicotinoide acetamiprid, normally used for control of aphids and whiteflies (unlike other neonicotinoides--imidacloprid and thiametoxam--quite selective about B. terrestris) and B, Teppeki) foliar treatment with Teppeki, to the maximum dose indicated on the label. The experimental design included the use of randomized blocks with 4 repetitions (4 plots/thesis with 100 plants each). In every thesis six B. terrestris hives were placed 2 days before treatment: the respective holes remained closed during the treatment and the 12 following hours. In order to verify the pollination, by the detection of the flower marking, 2 flowers

31 CFR 19.865 - How long may my debarment last?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 31 Money and Finance: Treasury 1 2011-07-01 2011-07-01 false How long may my debarment last? 19.865 Section 19.865 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE...) If the debarment is for a violation of the provisions of the Drug-Free Workplace Act of 1988, your...

31 CFR 19.865 - How long may my debarment last?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 31 Money and Finance: Treasury 1 2014-07-01 2014-07-01 false How long may my debarment last? 19.865 Section 19.865 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE...) If the debarment is for a violation of the provisions of the Drug-Free Workplace Act of 1988, your...

31 CFR 19.865 - How long may my debarment last?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false How long may my debarment last? 19.865 Section 19.865 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE...) If the debarment is for a violation of the provisions of the Drug-Free Workplace Act of 1988, your...

31 CFR 19.865 - How long may my debarment last?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 31 Money and Finance: Treasury 1 2013-07-01 2013-07-01 false How long may my debarment last? 19.865 Section 19.865 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE...) If the debarment is for a violation of the provisions of the Drug-Free Workplace Act of 1988, your...

31 CFR 19.865 - How long may my debarment last?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 31 Money and Finance: Treasury 1 2012-07-01 2012-07-01 false How long may my debarment last? 19.865 Section 19.865 Money and Finance: Treasury Office of the Secretary of the Treasury GOVERNMENTWIDE...) If the debarment is for a violation of the provisions of the Drug-Free Workplace Act of 1988, your...

Long-range correlation in cosmic microwave background radiation.

PubMed

Movahed, M Sadegh; Ghasemi, F; Rahvar, Sohrab; Tabar, M Reza Rahimi

2011-08-01

We investigate the statistical anisotropy and gaussianity of temperature fluctuations of Cosmic Microwave Background (CMB) radiation data from the Wilkinson Microwave Anisotropy Probe survey, using the Multifractal Detrended Fluctuation Analysis, Rescaled Range, and Scaled Windowed Variance methods. Multifractal Detrended Fluctuation Analysis shows that CMB fluctuations has a long-range correlation function with a multifractal behavior. By comparing the shuffled and surrogate series of CMB data, we conclude that the multifractality nature of the temperature fluctuation of CMB radiation is mainly due to the long-range correlations, and the map is consistent with a gaussian distribution.

Insecticide resistance in vector Chagas disease: evolution, mechanisms and management.

PubMed

Mougabure-Cueto, Gastón; Picollo, María Inés

2015-09-01

Chagas disease is a chronic parasitic infection restricted to America. The disease is caused by the protozoa Trypanosoma cruzi, which is transmitted to human through the feces of infected triatomine insects. Because no treatment is available for the chronic forms of the disease, vector chemical control represents the best way to reduce the incidence of the disease. Chemical control has been based principally on spraying dwellings with insecticide formulations and led to the reduction of triatomine distribution and consequent interruption of disease transmission in several areas from endemic region. However, in the last decade it has been repeatedly reported the presence triatomnes, mainly Triatoma infestans, after spraying with pyrethroid insecticides, which was associated to evolution to insecticide resistance. In this paper the evolution of insecticide resistance in triatomines is reviewed. The insecticide resistance was detected in 1970s in Rhodnius prolixus and 1990s in R. prolixus and T. infestans, but not until the 2000s resistance to pyrthroids in T. infestans associated to control failures was described in Argentina and Bolivia. The main resistance mechanisms (i.e. enhanced metabolism, altered site of action and reduced penetration) were described in the T. infestans resistant to pyrethrods. Different resistant profiles were demonstrated suggesting independent origin of the different resistant foci of Argentina and Bolivia. The deltamethrin resistance in T. infestans was showed to be controlled by semi-dominant, autosomally inherited factors. Reproductive and developmental costs were also demonstrated for the resistant T. infestans. A discussion about resistance and tolerance concepts and the persistence of T. infestans in Gran Chaco region are presented. In addition, theoretical concepts related to toxicological, evolutionary and ecological aspects of insecticide resistance are discussed in order to understand the particular scenario of pyrethroid

Ecohealth Interventions Limit Triatomine Reinfestation following Insecticide Spraying in La Brea, Guatemala

PubMed Central

Lucero, David E.; Morrissey, Leslie A.; Rizzo, Donna M.; Rodas, Antonieta; Garnica, Roberto; Stevens, Lori; Bustamante, Dulce M.; Monroy, Maria Carlota

2013-01-01

In this study, we evaluate the effect of participatory Ecohealth interventions on domestic reinfestation of the Chagas disease vector Triatoma dimidiata after village-wide suppression of the vector population using a residual insecticide. The study was conducted in the rural community of La Brea, Guatemala between 2002 and 2009 where vector infestation was analyzed within a spatial data framework based on entomological and socio-economic surveys of homesteads within the village. Participatory interventions focused on community awareness and low-cost home improvements using local materials to limit areas of refuge and alternative blood meals for the vector within the home, and potential shelter for the vector outside the home. As a result, domestic infestation was maintained at ≤ 3% and peridomestic infestation at ≤ 2% for 5 years beyond the last insecticide spraying, in sharp contrast to the rapid reinfestation experienced in earlier insecticide only interventions. PMID:23382173

Status of Insecticide Resistance in Papua New Guinea: An Update from Nation-Wide Monitoring of Anopheles Mosquitoes.

PubMed

Koimbu, Gussy; Czeher, Cyrille; Katusele, Michelle; Sakur, Muker; Kilepak, Lemen; Tandrapah, Anthony; Hetzel, Manuel W; Pulford, Justin; Robinson, Leanne; Karl, Stephan

2018-01-01

Insecticide resistance (IR) monitoring is an important component of vector-borne disease control. The last assessment of IR in Papua New Guinea (PNG) was conducted in 2010. Since then, vector populations have been exposed to higher levels of pyrethroids with the continued nation-wide distribution of insecticide-treated nets. Here, we provide an update on phenotypic IR in four highly malaria-endemic areas of PNG. IR against deltamethrin, lambda-cyhalothrin, and dichlorodiphenyltrichloroethane was assessed using World Health Organization bioassays. A total of 108 bioassays for each insecticide were conducted screening 2,290 adult female anopheline mosquitoes. No phenotypic resistance was observed. Bioassay parameters agreed well with those observed in other studies that used the same assays and insecticides. These results indicate that the three tested insecticides are still universally effective in PNG. Continued IR monitoring (every 1-2 years) in PNG is recommended to detect reduced susceptibility early and adjust guidelines to prevent widespread resistance.

Chlorinated hydrocarbon insecticides

USGS Publications Warehouse

Friend, M.; Franson, J.C.

1999-01-01

Chlorinated hydrocarbon insecticides (OCs) are diverse synthetic chemicals that belong to several groups, based on chemical structure. DDT is the best known of these insecticides. First synthesized in 1874, DDT remained obscure until its insecticidal properties became known in 1939, a discovery that earned a Nobel Prize in 1948. The means of synthesizing the cyclodiene group, the most toxic of the OCs, was discovered in 1928 and resulted in a Nobel Prize in 1950. The insecticidal properties of cyclodienes, which include aldrin, dieldrin, and endrin (Table 40.1), were discovered about 1945. OCs became widely used in the United States following World War II. Their primary uses included broad spectrum applications for agricultural crops and forestry and, to a lesser extent, human health protection by spraying to destroy mosquitoes and other potential disease carriers. These compounds also became widely used to combat insect carriers of domestic animal diseases.

Long-Lasting Neural and Behavioral Effects of Iron Deficiency in Infancy

PubMed Central

Lozoff, Betsy; Beard, John; Connor, James; Felt, Barbara; Georgieff, Michael; Schallert, Timothy

2006-01-01

Infants are at high risk for iron deficiency and iron-deficiency anemia. This review summarizes evidence of long-term effects of iron deficiency in infancy. Follow-up studies from preschool age to adolescence report poorer cognitive, motor, and social-emotional function, as well as persisting neurophysiologic differences. Research in animal models points to mechanisms for such long-lasting effects. Potential mechanisms relate to effects of iron deficiency during brain development on neurometabolism, myelination, and neurotransmitter function. PMID:16770951

The substrate for long-lasting memory: if not protein synthesis, then what?

PubMed Central

Routtenberg, Aryeh

2011-01-01

The prevailing textbook view that de novo protein synthesis is required for memory (e.g., Bear, 2006) is seriously flawed and the alternative hypothesis has been proposed in which post-translational modification (PTM) of proteins already synthesized and already present within the synapse is ‘the’ substrate for long-lasting memory (Routtenberg and Rekart, 2005). Protein synthesis serves a replenishment role. The first part of this review discusses how long-lasting memory can be achieved with ‘only’ PTM of existing synaptic proteins. The second part critically reviews a recent report published in Neuron 2007 that exemplifies the current view of protein synthesis and memory while also illustrating how these results can be understood within this new PTM framework. A necessary yet unexpected conclusion to emerge from consideration of the consequences of a PTM mechanism as the necessary, sufficient and exclusive substrate for long-lasting memory (Routtenberg and Rekart, 2005), is that the central Hebbian dogma that cells that ‘fire together, wire together’ is an unlikely mechanism for long-lasting memory. Thus, a unique feature of the PTM model is that longevity of information storage is achieved not by stability of the synaptic mechanism, but by impermanent pseudoredundant circuits. This is so because PTM is a reversible process and thus any permanent connection, any ‘lasting effect’ cannot be in the form of stable synapse formation. We have therefore proposed a solution in which network level processes regulate cellular mechanisms, even as such mechanisms regulate the network. Thus, synapses are ‘meta-stabilized’ by regulated feedback mediated by the circuit in which the synapse is embedded. For example, spontaneous activity is proposed to be a substrate feedback mechanism we term ‘cryptic rehearsal’ to sustain for some period of time after learning an approximation to the state initially created by input. Additionally, because the duplication

Pink light emitting long-lasting phosphorescence in Sm 3+-doped CdSiO 3

NASA Astrophysics Data System (ADS)

Lei, Bingfu; Liu, Yingliang; Liu, Jie; Ye, Zeren; Shi, Chunshan

2004-04-01

Novel pink light emitting long-lasting afterglow CdSiO 3:Sm 3+ phosphors are prepared by the conventional high-temperature solid-state method and their luminescent properties are investigated. XRD and photoluminescence (PL) spectra are used to characterize the synthesized phosphors. The phosphors are well crystallized by calcinations at 1050°C for 5 h. These phosphors emit pink light and show long-lasting phosphorescence after they are excited with 254 nm ultraviolet light. The phosphorescence lasts for nearly 5 h in the light perception of the dark-adapted human eye (0.32 mcd/m 2). The phosphorescence mechanism is also investigated. All the results indicate that these phosphors have promising potential practical applications.

Genome wide discovery of long intergenic non-coding RNAs in Diamondback moth (Plutella xylostella) and their expression in insecticide resistant strains

PubMed Central

Etebari, Kayvan; Furlong, Michael J.; Asgari, Sassan

2015-01-01

Long non-coding RNAs (lncRNAs) play important roles in genomic imprinting, cancer, differentiation and regulation of gene expression. Here, we identified 3844 long intergenic ncRNAs (lincRNA) in Plutella xylostella, which is a notorious pest of cruciferous plants that has developed field resistance to all classes of insecticides, including Bacillus thuringiensis (Bt) endotoxins. Further, we found that some of those lincRNAs may potentially serve as precursors for the production of small ncRNAs. We found 280 and 350 lincRNAs that are differentially expressed in Chlorpyrifos and Fipronil resistant larvae. A survey on P. xylostella midgut transcriptome data from Bt-resistant populations revealed 59 altered lincRNA in two resistant strains compared with the susceptible population. We validated the transcript levels of a number of putative lincRNAs in deltamethrin-resistant larvae that were exposed to deltamethrin, which indicated that this group of lincRNAs might be involved in the response to xenobiotics in this insect. To functionally characterize DBM lincRNAs, gene ontology (GO) enrichment of their associated protein-coding genes was extracted and showed over representation of protein, DNA and RNA binding GO terms. The data presented here will facilitate future studies to unravel the function of lincRNAs in insecticide resistance or the response to xenobiotics of eukaryotic cells. PMID:26411386

Modelling the impact of the long-term use of insecticide-treated bed nets on Anopheles mosquito biting time.

PubMed

Ferreira, Claudia P; Lyra, Silas P; Azevedo, Franciane; Greenhalgh, David; Massad, Eduardo

2017-09-15

Evidence of changing in biting and resting behaviour of the main malaria vectors has been mounting up in recent years as a result of selective pressure by the widespread and long-term use of insecticide-treated bed nets (ITNs), and indoor residual spraying. The impact of resistance behaviour on malaria intervention efficacy has important implications for the epidemiology and malaria control programmes. In this context, a theoretical framework is presented to understand the mechanisms determining the evolution of feeding behaviour under the pressure of use of ITNs. An agent-based stochastic model simulates the impact of insecticide-treated bed nets on mosquito fitness by reducing the biting rates, as well as increasing mortality rates. The model also incorporates a heritability function that provides the necessary genetic plasticity upon which natural selection would act to maximize the fitness under the pressure of the control strategy. The asymptotic equilibrium distribution of mosquito population versus biting time is shown for several daily uses of ITNs, and the expected disruptive selection on this mosquito trait is observed in the simulations. The relative fitness of strains that bite at much earlier time with respect to the wild strains, when a threshold of about 50% of ITNs coverage highlights the hypothesis of a behaviour selection. A sensitivity analysis has shown that the top three parameters that play a dominant role on the mosquito fitness are the proportion of individuals using bed nets and its effectiveness, the impact of bed nets on mosquito oviposition, and the mosquito genetic plasticity related to changing in biting time. By taking the evolutionary aspect into account, the model was able to show that the long-term use of ITNs, although representing an undisputed success in reducing malaria incidence and mortality in many affected areas, is not free of undesirable side effects. From the evolutionary point of view of the parasite virulence, it

An enigmatic long-lasting gamma-ray burst not accompanied by a bright supernova.

PubMed

Della Valle, M; Chincarini, G; Panagia, N; Tagliaferri, G; Malesani, D; Testa, V; Fugazza, D; Campana, S; Covino, S; Mangano, V; Antonelli, L A; D'Avanzo, P; Hurley, K; Mirabel, I F; Pellizza, L J; Piranomonte, S; Stella, L

2006-12-21

Gamma-ray bursts (GRBs) are short, intense flashes of soft gamma-rays coming from the distant Universe. Long-duration GRBs (those lasting more than approximately 2 s) are believed to originate from the deaths of massive stars, mainly on the basis of a handful of solid associations between GRBs and supernovae. GRB 060614, one of the closest GRBs discovered, consisted of a 5-s hard spike followed by softer, brighter emission that lasted for approximately 100 s (refs 8, 9). Here we report deep optical observations of GRB 060614 showing no emerging supernova with absolute visual magnitude brighter than M(V) = -13.7. Any supernova associated with GRB 060614 was therefore at least 100 times fainter, at optical wavelengths, than the other supernovae associated with GRBs. This demonstrates that some long-lasting GRBs can either be associated with a very faint supernova or produced by different phenomena.

Long-Lasting Permethrin-Impregnated Clothing Protects against Mosquito Bites in Outdoor Workers

PubMed Central

Londono-Renteria, Berlin; Patel, Jaymin C.; Vaughn, Meagan; Funkhauser, Sheana; Ponnusamy, Loganathan; Grippin, Crystal; Jameson, Sam B.; Apperson, Charles; Mores, Christopher N.; Wesson, Dawn M.; Colpitts, Tonya M.; Meshnick, Steven R.

2015-01-01

Outdoor exposure to mosquitoes is a risk factor for many diseases, including malaria and dengue. We have previously shown that long-lasting permethrin-impregnated clothing protects against tick and chigger bites in a double-blind randomized controlled trial in North Carolina outdoor workers. Here, we evaluated whether this clothing is protective against mosquito bites by measuring changes in antibody titers to mosquito salivary gland extracts. On average, there was a 10-fold increase in titer during the spring and summer when mosquito exposure was likely to be the highest. During the first year of the study, the increase in titer in subjects wearing treated uniforms was 2- to 2.5-fold lower than that of control subjects. This finding suggests that long-lasting permethrin-impregnated clothing provided protection against mosquito bites. PMID:26195460

Long-lasting ibogaine protection against NMDA-induced convulsions in mice.

PubMed

Leal, M B; de Souza, D O; Elisabetsky, E

2000-08-01

Ibogaine, a putative antiaddictive drug, is remarkable in its apparent ability to downgrade withdrawal symptoms and drug craving for extended periods of time after a single dose. Ibogaine acts as a non-competitive NMDA receptor antagonist, while NMDA has been implicated in long lasting changes in neuronal function and in the physiological basis of drug addiction. The purpose of this study was to verify if persistent changes in NMDA receptors could be shown in vivo and in vitro after a single administration of ibogaine. The time course of ibogaine effects were examined on NMDA-induced seizures and [3H] MK-801 binding to cortical membranes in mice 30 min, 24, 48, and 72 h post treatment. Ibogaine (80 mg/kg, ip) was effective in inhibiting convulsions induced by NMDA at 24 and 72 hours post administration. Likewise, [3H] MK-801 binding was significantly decreased at 24 and 72 h post ibogaine. No significant differences from controls were found at 30 min or 48 h post ibogaine. This long lasting and complex pattern of modulation of NMDA receptors prompted by a single dose of ibogaine may be associated to its antiaddictive properties.

42 CFR 65a.8 - How long does grant support last?

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false How long does grant support last? 65a.8 Section 65a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS SUBSTANCES BASIC RESEARCH...

42 CFR 65a.8 - How long does grant support last?

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false How long does grant support last? 65a.8 Section 65a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS SUBSTANCES BASIC RESEARCH...

42 CFR 65a.8 - How long does grant support last?

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false How long does grant support last? 65a.8 Section 65a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS SUBSTANCES BASIC RESEARCH...

42 CFR 65a.8 - How long does grant support last?

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false How long does grant support last? 65a.8 Section 65a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS SUBSTANCES BASIC RESEARCH...

42 CFR 65a.8 - How long does grant support last?

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false How long does grant support last? 65a.8 Section 65a.8 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES FELLOWSHIPS, INTERNSHIPS, TRAINING NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES HAZARDOUS SUBSTANCES BASIC RESEARCH...

Effects of persistent insecticides on beneficial soil arthropod in conventional fields compared to organic fields, puducherry.

PubMed

Anbarashan, Padmavathy; Gopalswamy, Poyyamoli

2013-07-15

The usage of synthetic fertilizers/insecticides in conventional farming has dramatically increased over the past decades. The aim of the study was to compare the effects of bio-pesticides and insecticides/pesticides on selected beneficial non targeted arthropods. Orders Collembola, Arachinida/Opiliones, Oribatida and Coleoptera were the main groups of arthropods found in the organic fields and Coleoptera, Oribatida, Gamasida and Collembola in conventional fields. Pesticides/insecticides had a significant effect on non-targeted arthropods order- Collembola, Arachinida/Opiliones, Hymenoptera and Thysonoptera were suppressed after pesticides/insecticides spraying. Bio-insecticides in organic fields had a non-significant effect on non targeted species and they started to increase in abundance after 7 days of spraying, whereas insecticide treatment in conventional fields had a significant long-term effect on non targeted arthropods and short term effect on pests/insects, it started to increase after 21 days of the spraying. These results indicate that insecticide treatment kept non targeted arthropods at low abundance. In conclusion, organic farming does not significantly affected the beneficial-non targeted arthropods biodiversity, whereas preventive insecticide application in conventional fields had significant negative effects on beneficial non targeted arthropods. Therefore, conventional farmers should restrict insecticide applications, unless pest densities reach the thresholds and more desirably can switch to organic farming practices.

COMPARISON OF ACUTE NEUROBEHAVIORAL EFFECTS OF N-METHYL CARBAMATE INSECTICIDES.

EPA Science Inventory

The acute neurobehavioral and cholinesterase (ChE)-inhibiting effects of N-methyl carbamate insecticides have not been systematically compared. We evaluated five carbamates - carbaryl (CB), propoxur (PP), oxamyl (OM), methomyl (MM), and methiocarb (MC). Adult male Long-Evans ra...

[Preliminary evaluation of the insecticide susceptibility in Anopheles gambiae and Culex quinquefasciatus from Lobito (Angola), using WHO standard assay].

PubMed

Toto, J C; Besnard, P; Le Mire, J; Almeida, D S I; Dos Santos, M A; Fortes, F; Foumane, V; Simard, F; Awono-Ambene, H P; Carnevale, P

2011-10-01

Field collections of the most common urban mosquito vectors Anopheles gambiae and Culex quinquefasciatus were carried out in June 2003, March 2004 and November 2005 to gather preliminary data on the insecticide susceptibility in mosquitoes from Lobito (Angola) using the WHO standard bioassays. Bioassays were performed on F0 adults emerging from the field larval collections and on unfed adults from landing catches on volunteers. Batches of mosquitoes from three selected locations (Alto Liro, San Jao and Bela Vista) were exposed for 1 hour to several insecticides such as DDT 4%, carbosulfan 0.4%, permethrin 1%, deltamethrin 0.05% and cyfluthrin 0.15%, in order to estimate the immediate knockdown times (kdT50 and kdT95) and the mortality rate after exposure. The results revealed that mosquito susceptibility to insecticides varied depending on the insecticide, the site and the period of collection. The main local malaria vector A. gambiae (both M and S forms) was basically resistant to DDT and susceptible to all pyrethoids, regardless of the period and the site of collections. The overall mortality rate due to DDT was 73% in Alto Liro, 89% in San Jao and varied depending on the period in Bela Vista between 95% in March 2004 and 100% in November 2005. The mortality due to pyrethoids was 100% at all locations, with the kdT50 and KdT95 times ranging between 9 and 16 minutes and between 18 and 29 minutes, respectively. Concerning the C. quinquefasciatus, populations from Yard and Caponte were resistant to all insecticides tested; the mortality rate was 40% with deltamethrin and 70% with permethrin, while no lethal effect was observed with DDT or carbosulfan. In conclusion, despite its probable high resistance to DDT, the main local malaria vector A. gambiae remained fully susceptible to pyrethroids. This could forecast a good biological efficacy of the scheduled vector control interventions in Angola, based on a large-scale distribution of long-lasting, insecticide

CADDIS Volume 2. Sources, Stressors and Responses: Insecticides

EPA Pesticide Factsheets

Introduction to the insecticides module, when to list insecticides as a candidate cause, ways to measure insecticides, simple and detailed conceptual diagrams for insecticides, insecticides module references and literature reviews.

How long do the short-term violent video game effects last?

PubMed

Barlett, Christopher; Branch, Omar; Rodeheffer, Christopher; Harris, Richard

2009-01-01

How long do the effects of the initial short-term increase in aggression and physiological arousal last after violent video game play? Study 1 (N=91) had participants complete pre- and postvideo game measures of aggressive thoughts, aggressive feelings, and heart rate. Then, participants completed Time 3 measures after 4 min or 9 min of delay. Study 2 employed a similar procedure, but had participants (N=91) complete the hot sauce paradigm to assess aggressive behavior after a 0, 5, or 10 min delay. First, results indicated that aggressive feelings, aggressive thoughts, aggressive behavior, and heart rate initially increased after violent video game play. Second, results of the delay condition revealed that the increase in aggressive feelings and aggressive thoughts lasted less than 4 min, whereas heart rate and aggressive behavior lasted 4-9 min. Copyright 2009 Wiley-Liss, Inc.

THE INTERACTION OF AN ANTICHOLINESTERASE INSECTICIDE, DIAZINON, WITH A PYRETHROID INSECTICIDE, DELTAMETHRIN.

EPA Science Inventory

This present study explores the interaction of the toxicity induced by an organophosphorus insecticide, diazinon (diethyl 2-isopropyl-6methyl-4-pyrimidal phosphorothionate), with a pyrethroid insecticide, deltamethrin ((S)-a-cyano-3-phenoxybenzyl (1R,3R)-3-(2,2-dibromovinyl)-2,...

Long-Lasting Permethrin-Impregnated Clothing Protects Against Mosquito Bites in Outdoor Workers.

PubMed

Londono-Renteria, Berlin; Patel, Jaymin C; Vaughn, Meagan; Funkhauser, Sheana; Ponnusamy, Loganathan; Grippin, Crystal; Jameson, Sam B; Apperson, Charles; Mores, Christopher N; Wesson, Dawn M; Colpitts, Tonya M; Meshnick, Steven R

2015-10-01

Outdoor exposure to mosquitoes is a risk factor for many diseases, including malaria and dengue. We have previously shown that long-lasting permethrin-impregnated clothing protects against tick and chigger bites in a double-blind randomized controlled trial in North Carolina outdoor workers. Here, we evaluated whether this clothing is protective against mosquito bites by measuring changes in antibody titers to mosquito salivary gland extracts. On average, there was a 10-fold increase in titer during the spring and summer when mosquito exposure was likely to be the highest. During the first year of the study, the increase in titer in subjects wearing treated uniforms was 2- to 2.5-fold lower than that of control subjects. This finding suggests that long-lasting permethrin-impregnated clothing provided protection against mosquito bites. © The American Society of Tropical Medicine and Hygiene.

Long-lasting D-region ionospheric modifications, caused by intense lightning in association with elve and sprite pairs

NASA Astrophysics Data System (ADS)

Haldoupis, Christos; Cohen, Morris; Cotts, Benjamin; Arnone, Enrico; Inan, Umran

2012-08-01

Observations show that intense +CG lightning discharges which trigger both an elve and a sprite are associated with long-lasting conductivity modifications in the upper D-region ionosphere. They are observed as strong perturbations in VLF signals propagating through the disturbed region, manifested as LOng Recovery Early VLF events (LORE), which can last up to 30 minutes. These same ionospheric modifications are also responsible for step-like changes, seen mostly in off-storm VLF transmissions, which offset signal levels even for longer times. The evidence suggests that when a very intense positive cloud to ground lightning stroke leads to an elve and a high altitude sprite, and possibly a sprite halo as well, there is production of long lasting elevations in electron density at VLF reflection heights that cause LOREs and severe effects on VLF propagation. The present results confirm past predictions and postulations that elves may be accompanied by long-lasting electron density perturbations in the lower ionosphere.

Flupyradifurone: a brief profile of a new butenolide insecticide

PubMed Central

Nauen, Ralf; Jeschke, Peter; Velten, Robert; Beck, Michael E; Ebbinghaus-Kintscher, Ulrich; Thielert, Wolfgang; Wölfel, Katharina; Haas, Matthias; Kunz, Klaus; Raupach, Georg

2015-01-01

BACKGROUND The development and commercialisation of new chemical classes of insecticides for efficient crop protection measures against destructive invertebrate pests is of utmost importance to overcome resistance issues and to secure sustainable crop yields. Flupyradifurone introduced here is the first representative of the novel butenolide class of insecticides active against various sucking pests and showing an excellent safety profile. RESULTS The discovery of flupyradifurone was inspired by the butenolide scaffold in naturally occurring stemofoline. Flupyradifurone acts reversibly as an agonist on insect nicotinic acetylcholine receptors but is structurally different from known agonists, as shown by chemical similarity analysis. It shows a fast action on a broad range of sucking pests, as demonstrated in laboratory bioassays, and exhibits excellent field efficacy on a number of crops with different application methods, including foliar, soil, seed treatment and drip irrigation. It is readily taken up by plants and translocated in the xylem, as demonstrated by phosphor imaging analysis. Flupyradifurone is active on resistant pests, including cotton whiteflies, and is not metabolised by recombinantly expressed CYP6CM1, a cytochrome P450 conferring metabolic resistance to neonicotinoids and pymetrozine. CONCLUSION The novel butenolide insecticide flupyradifurone shows unique properties and will become a new tool for integrated pest management around the globe, as demonstrated by its insecticidal, ecotoxicological and safety profile. © 2014 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:25351824

Exploration of Novel Botanical Insecticide Leads: Synthesis and Insecticidal Activity of β-Dihydroagarofuran Derivatives.

PubMed

Zhao, Ximei; Xi, Xin; Hu, Zhan; Wu, Wenjun; Zhang, Jiwen

2016-02-24

The discovery of novel leads and new mechanisms of action is of vital significance to the development of pesticides. To explore lead compounds for botanical insecticides, 77 β-dihydroagarofuran derivatives were designed and synthesized. Their structures were mainly confirmed by (1)H NMR, (13)C NMR, DEPT-135°, IR, MS, and HRMS. Their insecticidal activity was evaluated against the third-instar larvae of Mythimna separata Walker, and the results indicated that, of these derivatives, eight exhibited more promising insecticidal activity than the positive control, celangulin-V. Particularly, compounds 5.7, 6.6, and 6.7 showed LD50 values of 37.9, 85.1, and 21.1 μg/g, respectively, which were much lower than that of celangulin-V (327.6 μg/g). These results illustrated that β-dihydroagarofuran ketal derivatives can be promising lead compounds for developing novel mechanism-based and highly effective botanical insecticides. Moreover, some newly discovered structure-activity relationships are discussed, which may provide some important guidance for insecticide development.

A pre-intervention study of malaria vector abundance in Rio Muni, Equatorial Guinea: Their role in malaria transmission and the incidence of insecticide resistance alleles

PubMed Central

Ridl, Frances C; Bass, Chris; Torrez, Miguel; Govender, Dayanandan; Ramdeen, Varsha; Yellot, Lee; Edu, Amado Edjang; Schwabe, Christopher; Mohloai, Peter; Maharaj, Rajendra; Kleinschmidt, Immo

2008-01-01

Background Following the success of the malaria control intervention on the island of Bioko, malaria control by the use of indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLITN) was extended to Rio Muni, on the mainland part of Equatorial Guinea. This manuscript reports on the malaria vectors present and the incidence of insecticide resistant alleles prior to the onset of the programme. Methods Anopheles mosquitoes were captured daily using window traps at 30 sentinel sites in Rio Muni, from December 2006 to July 2007. The mosquitoes were identified to species and their sporozoite rates, knockdown resistance (kdr) and acetylcholinesterase (AChE) sensitivity measured, to define the role of vector species in malaria transmission and their potential susceptibility to insecticides. Results A total of 6,162 Anopheles mosquitoes were collected of which 4,808 were morphologically identified as Anopheles gambiae s.l., 120 Anopheles funestus, 1,069 Anopheles moucheti, and 165 Anopheles nili s.l.. Both M and S molecular forms of Anopheles gambiae s.s. and Anopheles melas were identified. Anopheles ovengensis and Anopheles carnevalei were the only two members of the An. nili group to be identified. Using the species-specific sporozoite rates and the average number of mosquitoes per night, the number of infective mosquitoes per trap per 100 nights for each species complex was calculated as a measure of transmission risk. Both kdr-w and kdr-e alleles were present in the S-form of An. gambiae s.s. (59% and 19% respectively) and at much lower frequencies in the M-form (9.7% and 1.8% respectively). The kdr-w and kdr-e alleles co-occurred in 103 S-form and 1 M-form specimens. No insensitive AChE was detected. Conclusion Anopheles gambiae s.s, a member of the Anopheles gambiae complex was shown to be the major vector in Rio Muni with the other three groups playing a relatively minor role in transmission. The demonstration of a high frequency of kdr alleles

ANABOLIC STEROIDS HAVE LONG-LASTING EFFECTS ON MALE SOCIAL BEHAVIORS

PubMed Central

Salas-Ramirez, Kaliris Y.; Montalto, Pamela R.; Sisk, Cheryl L.

2010-01-01

Anabolic androgenic steroids (AAS) use by adolescents is steadily increasing. Adolescence involves remodeling of steroid-sensitive neural circuits that mediate social behaviors, and previous studies using animal models document effects of AAS on male social behaviors. The present experiments tested whether AAS have persistent and more pronounced behavioral consequences when drug exposure occurs during adolescence as compared to exposure in adulthood. Male Syrian hamsters were injected daily for 14 days with either vehicle or an AAS cocktail containing testosterone cypionate (2 mg/kg), nandrolone decanoate (2 mg/kg), and boldenone undecylenate (1 mg/kg), either during adolescence (27-41 days of age) or adulthood (63-77 days of age). As adults, subjects were tested two or four weeks after the last injection for either sexual behavior with a receptive female or male-male agonistic behavior in a resident-intruder test. Compared with vehicle-treated males, AAS-treated males, regardless of age of treatment, displayed fewer long intromissions and a significant increase in latency to the first long intromission, indicative of reduced potential to reach sexual satiety. Increased aggression was observed in males exposed to AAS compared with males treated with vehicle, independently of age of AAS treatment. However, unlike hamsters exposed to AAS in adulthood, hamsters exposed to AAS during adolescence did not display any submissive or risk-assessment behaviors up to 4 weeks after discontinuation of AAS treatment. Thus, AAS have long-lasting effects on male sexual and agonistic behaviors, with AAS exposure during adolescence resulting in a more pronounced reduction in submissive behavior compared to AAS exposure in adulthood. PMID:20036695

FXR1P Limits Long-Term Memory, Long-Lasting Synaptic Potentiation, and de novo GluA2 Translation

PubMed Central

Jones, Emma V.; Altimimi, Haider F.; Farmer, W. Todd; Gandin, Valentina; Hanna, Edith; Zong, Ruiting; Barbon, Alessandro; Nelson, David L.; Topisirovic, Ivan; Rochford, Joseph; Stellwagen, David; Béïque, Jean-Claude; Murai, Keith K.

2014-01-01

SUMMARY Translational control of mRNAs allows for rapid and selective changes in synaptic protein expression, changes that are required for long-lasting plasticity and memory formation in the brain. Fragile X Related Protein 1 (FXR1P) is an RNA-binding protein that controls mRNA translation in non-neuronal cells and co-localizes with translational machinery in neurons. However, its neuronal mRNA targets and role in the brain are unknown. Here, we demonstrate that removal of FXR1P from the forebrain of postnatal mice selectively enhances long-term storage of spatial memories, hippocampal late-phase LTP (L-LTP) and de novo GluA2 synthesis. Furthermore, FXR1P binds specifically to the 5’UTR of GluA2 mRNA to repress translation and limit the amount of GluA2 incorporated at potentiated synapses. This study uncovers a new mechanism for regulating long-lasting synaptic plasticity and spatial memory formation and reveals an unexpected divergent role of FXR1P among Fragile X proteins in brain plasticity. PMID:25456134

Soluto-inertial phenomena: Designing long-range, long-lasting, surface-specific interactions in suspensions

PubMed Central

Banerjee, Anirudha; Williams, Ian; Azevedo, Rodrigo Nery; Squires, Todd M.

2016-01-01

Equilibrium interactions between particles in aqueous suspensions are limited to distances less than 1 μm. Here, we describe a versatile concept to design and engineer nonequilibrium interactions whose magnitude and direction depends on the surface chemistry of the suspended particles, and whose range may extend over hundreds of microns and last thousands of seconds. The mechanism described here relies on diffusiophoresis, in which suspended particles migrate in response to gradients in solution. Three ingredients are involved: a soluto-inertial “beacon” designed to emit a steady flux of solute over long time scales; suspended particles that migrate in response to the solute flux; and the solute itself, which mediates the interaction. We demonstrate soluto-inertial interactions that extend for nearly half a millimeter and last for tens of minutes, and which are attractive or repulsive, depending on the surface chemistry of the suspended particles. Experiments agree quantitatively with scaling arguments and numerical computations, confirming the basic phenomenon, revealing design strategies, and suggesting a broad set of new possibilities for the manipulation and control of suspended particles. PMID:27410044

Long-lasting response to electrochemotherapy in melanoma patients with cutaneous metastasis.

PubMed

Caracò, Corrado; Mozzillo, Nicola; Marone, Ugo; Simeone, Ester; Benedetto, Lucia; Di Monta, Gianluca; Di Cecilia, Maria Luisa; Botti, Gerardo; Ascierto, Paolo Antonio

2013-12-01

Treatment of early and multiple cutaneous unresectable recurrences is a major therapeutic problem with around 80% of patients relapsing within 5 years. For lesions refractory to elective treatments, electrochemotherapy (ECT) involving electroporation combined with antineoplastic drug treatment appears to be a new potential option. This study was undertaken to analyze the short- and long-term responses of lesions treated with ECT with intravenous injection of bleomycin in melanoma patients with in-transit disease or distant cutaneous metastases. Between June 2007 and September 2012, 60 patients with relapsed and refractory cutaneous melanoma metastases or in-transit disease underwent 100 courses of ECT with intravenous injection of bleomycin. Response to treatment was evaluated three months after ECT. A long-lasting response was defined as no cutaneous or in-transit relapse after a minimum of six months. Three months after ECT, a complete response was observed in 29 patients (48.4%), a partial response in 23 patients (38.3%) and no change or progressive disease in 8 patients (13.3%). The objective response rate of all treated lesions was 86.6%. Thirteen patients (44.8% of complete responders) experienced a long-lasting response after one ECT session and were disease-free after a mean duration of follow-up of 27.5 months. The favorable outcome obtained in the present study demonstrates that ECT is a reliable, and effective procedure that provides long-term benefit in terms of curative and palliative treatment for unresectable cutaneous lesions without adversely impacting the quality of life of patients.

Exterior view of LongTerm Oxidizer Silo (T28D) in left background ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Exterior view of Long-Term Oxidizer Silo (T-28D) in left background (taller structure) and adjacent Oxidizer Conditioning Structure (T-28B) at extreme left background, looking south. At far right in foreground is a nitrogen tank in a concrete truck well - Air Force Plant PJKS, Systems Integration Laboratory, Long-Term Oxidizer Silo, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

Long-term variations in the gamma-ray background on SMM

NASA Technical Reports Server (NTRS)

Kurfess, J. D.; Share, G. H.; Kinzer, R. L.; Johnson, W. N.; Adams, J. H., Jr.

1989-01-01

Long-term temporal variations in the various components of the background radiation detected by the gamma-ray spectrometer on the Solar Maximum Mission are presented. The SMM gamma-ray spectrometer was launched in February, 1980 and continues to operate normally. The extended period of mission operations has provided a large data base in which it is possible to investigate a variety of environmental and instrumental background effects. In particular, several effects associated with orbital precession are introduced and discussed.

Developmental neurotoxicity of succeeding generations of insecticides

PubMed Central

Abreu-Villaça, Yael; Levin, Edward D.

2016-01-01

Insecticides are by design toxic. They must be toxic to effectively kill target species of insects. Unfortunately, they also have off-target toxic effects that can harm other species, including humans. Developmental neurotoxicity is one of the most prominent off-target toxic risks of insecticides. Over the past seven decades several classes of insecticides have been developed, each with their own mechanisms of effect and toxic side effects. This review covers the developmental neurotoxicity of the succeeding generations of insecticides including organochlorines, organophosphates, pyrethroids, carbamates and neonicotinoids. The goal of new insecticide development is to more effectively kill target species with fewer toxic side effects on non-target species. From the experience with the developmental neurotoxicity caused by the generations of insecticides developed in the past advice is offered how to proceed with future insecticide development to decrease neurotoxic risk. PMID:27908457

Long-Lasting Orthostatic Hypotension and Constipation After Celiac Plexus Block; A Case Report.

PubMed

Yousefshahi, Fardin; Tahmasebi, Mamak

2018-02-01

This case report presents a 55 years old man, presented with abdominal pain and diagnosed with a metastatic pancreatic tumor, who developed long lasting orthostatic hypotension and constipation following a celiac plexus block.

Characteristics of long-lasting haze episodes observed in Seoul, South Korea, for 2009-2014

NASA Astrophysics Data System (ADS)

Lee, Hae-Jung; Kim, Jeong Eun; Cha, Joo Wan; Song, Seungjoo; Ryoo, Sang-Boom; Kim, Yong Pyo

2018-03-01

The meteorological, physical, chemical, and optical characteristics of long-lasting haze in Seoul were studied. Four episodes were observed between 2009 and 2014, all in winter. PM10 mass concentration (PM10), chemical species, and aerosol optical depth (AOD) were analyzed along with the synoptic meteorological conditions. During the episodes, the temporal variations of the PM10 generally proceeded from the west along the Yellow Sea. The ground-based AOD was also high in Seoul and other sites. High AOD (MODIS) distributions were observed to move from China to Korea. The high sulfate concentration, along with the high sulfur oxidation ratio value of the third and fourth episodes (Eps. 3 and 4), respectively, corroborated the possible long-range transport of air pollutants. Stagnant meteorological conditions were a reason for the occurrence of long-lasting hazes. An anticyclone system had a dominant influence on the Korean peninsula during all episodes. The air mass over China was able to rise, and that over Korea was more stagnant in terms of climatology except Ep. 2. In addition to transport from outside, locally emitted air pollutants contributed to the PM10 partly due to the stagnant conditions, during which diurnal variations in NO2 and nitrates showed similar peak times during Eps. 3 and 4. Analysis of the episodes consistently showed that the long-lasting haze episodes were influenced by both the long-range transport of air pollutants from outside Seoul, mostly from China, and the accumulation of air pollutants that were locally emitted and transformed.

Insecticide Resistance Mechanisms in the Green Peach Aphid Myzus persicae (Hemiptera: Aphididae) I: A Transcriptomic Survey

PubMed Central

Silva, Andrea X.; Jander, Georg; Samaniego, Horacio; Ramsey, John S; Figueroa, Christian C.

2012-01-01

Background Insecticide resistance is one of the best examples of rapid micro-evolution found in nature. Since the development of the first synthetic insecticide in 1939, humans have invested considerable effort to stay ahead of resistance phenotypes that repeatedly develop in insects. Aphids are a group of insects that have become global pests in agriculture and frequently exhibit insecticide resistance. The green peach aphid, Myzus persicae, has developed resistance to at least seventy different synthetic compounds, and different insecticide resistance mechanisms have been reported worldwide. Methodology/Principal Findings To further characterize this resistance, we analyzed genome-wide transcriptional responses in three genotypes of M. persicae, each exhibiting different resistance mechanisms, in response to an anti-cholinesterase insecticide. The sensitive genotype (exhibiting no resistance mechanism) responded to the insecticide by up-regulating 183 genes primarily ones related to energy metabolism, detoxifying enzymes, proteins of extracellular transport, peptidases and cuticular proteins. The second genotype (resistant through a kdr sodium channel mutation), up-regulated 17 genes coding for detoxifying enzymes, peptidase and cuticular proteins. Finally, a multiply resistant genotype (carrying kdr and a modified acetylcholinesterase), up-regulated only 7 genes, appears not to require induced insecticide detoxification, and instead down-regulated many genes. Conclusions/Significance This study suggests strongly that insecticide resistance in M. persicae is more complex that has been described, with the participation of a broad array of resistance mechanisms. The sensitive genotype exhibited the highest transcriptional plasticity, accounting for the wide range of potential adaptations to insecticides that this species can evolve. In contrast, the multiply resistant genotype exhibited a low transcriptional plasticity, even for the expression of genes encoding

Long-Lasting Orthostatic Hypotension and Constipation After Celiac Plexus Block; A Case Report

PubMed Central

Yousefshahi, Fardin; Tahmasebi, Mamak

2018-01-01

This case report presents a 55 years old man, presented with abdominal pain and diagnosed with a metastatic pancreatic tumor, who developed long lasting orthostatic hypotension and constipation following a celiac plexus block. PMID:29868459

Mesoionic insecticides: a novel class of insecticides that modulate nicotinic acetylcholine receptors.

PubMed

Holyoke, Caleb W; Cordova, Daniel; Zhang, Wenming; Barry, James D; Leighty, Robert M; Dietrich, Robert F; Rauh, James J; Pahutski, Thomas F; Lahm, George P; Tong, My-Hanh Thi; Benner, Eric A; Andreassi, John L; Smith, Rejane M; Vincent, Daniel R; Christianson, Laurie A; Teixeira, Luis A; Singh, Vineet; Hughes, Kenneth A

2017-04-01

As the world population grows towards 9 billion by 2050, it is projected that food production will need to increase by 60%. A critical part of this growth includes the safe and effective use of insecticides to reduce the estimated 20-49% loss of global crop yields owing to pests. The development of new insecticides will help to sustain this protection and overcome insecticide resistance. A novel class of mesoionic compounds has been discovered, with exceptional insecticidal activity on a range of Hemiptera and Lepidoptera. These compounds bind to the orthosteric site of the nicotinic acetylcholine receptor and result in a highly potent inhibitory action at the receptor with minimal agonism. The synthesis, biological activity, optimization and mode of action will be discussed. Triflumezopyrim insect control will provide a powerful tool for control of hopper species in rice throughout Asia. Dicloromezotiaz can provide a useful control tool for lepidopteran pests, with an underexploited mode of action among these pests. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Impact of long-lasting, insecticidal nets on anaemia and prevalence of Plasmodium falciparum among children under five years in areas with highly resistant malaria vectors.

PubMed

Tokponnon, Filémon T; Ogouyémi, Aurore Hounto; Sissinto, Yolande; Sovi, Arthur; Gnanguenon, Virgile; Cornélie, Sylvie; Adéothy, Adicath Adéola; Ossè, Razaki; Wakpo, Abel; Gbénou, Dina; Oke, Mariam; Kinde-Gazard, Dorothée; Kleinschmidt, Immo; Akogbeto, Martin C; Massougbodji, Achille

2014-03-01

The widespread use of insecticide-treated nets (LLINs) leads to the development of vector resistance to insecticide. This resistance can reduce the effectiveness of LLIN-based interventions and perhaps reverse progress in reducing malaria morbidity. To prevent such difficulty, it is important to know the real impact of resistance in the effectiveness of mosquito nets. Therefore, an assessment of LLIN efficacy was conducted in malaria prevention among children in high and low resistance areas. The study was conducted in four rural districts and included 32 villages categorized as low or high resistance areas in Plateau Department, south-western Benin. Larvae collection was conducted to measure vector susceptibility to deltamethrin and knockdown resistance (kdr) frequency. In each resistance area, around 500 children were selected to measure the prevalence of malaria infection as well as the prevalence of anaemia associated with the use of LLINs. Observed mortalities of Anopheles gambiae s.s population exposed to deltamethrin ranged from 19 to 96%. Knockdown resistance frequency was between 38 and 84%. The prevalence of malaria infection in children under five years was 22.4% (19.9-25.1). This prevalence was 17.3% (14.2-20.9) in areas of high resistance and 27.1% (23.5-31.1) in areas of low resistance (p=0.04). Eight on ten children that were aged six - 30 months against seven on ten of those aged 31-59 months were anaemic. The anaemia observed in the six to 30-month old children was significantly higher than in the 31-59 month old children (p=0.00) but no difference associated with resistance areas was observed (p=0.35). The net use rate was 71%. The risk of having malaria was significantly reduced (p<0.05) with LLIN use in both low and high resistance areas. The preventive effect of LLINs in high resistance areas was 60% (95% CI: 40-70), and was significantly higher than that observed in low resistance areas (p<0.05). The results of this study showed that the

A decision-support tool to predict spray deposition of insecticides in commercial potato fields and its implications for their performance

USDA-ARS?s Scientific Manuscript database

In conventional and most IPM programs, application of insecticides continues to be the most important responsive pest control tactic. For both immediate and long-term optimization and sustainability of insecticide applications, it is paramount to study the factors affecting the performance of insect...

Neonicotinoid Insecticides Alter Induced Defenses and Increase Susceptibility to Spider Mites in Distantly Related Crop Plants

PubMed Central

Szczepaniec, Adrianna; Raupp, Michael J.; Parker, Roy D.; Kerns, David; Eubanks, Micky D.

2013-01-01

Background Chemical suppression of arthropod herbivores is the most common approach to plant protection. Insecticides, however, can cause unintended, adverse consequences for non-target organisms. Previous studies focused on the effects of pesticides on target and non-target pests, predatory arthropods, and concomitant ecological disruptions. Little research, however, has focused on the direct effects of insecticides on plants. Here we demonstrate that applications of neonicotinoid insecticides, one of the most important insecticide classes worldwide, suppress expression of important plant defense genes, alter levels of phytohormones involved in plant defense, and decrease plant resistance to unsusceptible herbivores, spider mites Tetranychus urticae (Acari: Tetranychidae), in multiple, distantly related crop plants. Methodology/Principal Findings Using cotton (Gossypium hirsutum), corn (Zea mays) and tomato (Solanum lycopersicum) plants, we show that transcription of phenylalanine amonia lyase, coenzyme A ligase, trypsin protease inhibitor and chitinase are suppressed and concentrations of the phytohormone OPDA and salicylic acid were altered by neonicotinoid insecticides. Consequently, the population growth of spider mites increased from 30% to over 100% on neonicotinoid-treated plants in the greenhouse and by nearly 200% in the field experiment. Conclusions/Significance Our findings are important because applications of neonicotinoid insecticides have been associated with outbreaks of spider mites in several unrelated plant species. More importantly, this is the first study to document insecticide-mediated disruption of plant defenses and link it to increased population growth of a non-target herbivore. This study adds to growing evidence that bioactive agrochemicals can have unanticipated ecological effects and suggests that the direct effects of insecticides on plant defenses should be considered when the ecological costs of insecticides are evaluated. PMID

Anopheles coluzzii larval habitat and insecticide resistance in the island area of Manoka, Cameroon.

PubMed

Etang, Josiane; Mbida Mbida, Arthur; Ntonga Akono, Patrick; Binyang, Jerome; Eboumbou Moukoko, Carole Else; Lehman, Leopold Gustave; Awono-Ambene, Parfait; Talipouo, Abdou; Ekoko Eyisab, Wolfgang; Tagne, Darus; Tchoffo, Romeo; Manga, Lucien; Mimpfoundi, Remy

2016-05-20

The effectiveness of Long-Lasting Insecticidal Nets and Indoor Residual Spraying in malaria vector control is threatened by vector resistance to insecticides. Knowledge of mosquito habitats and patterns of insecticide resistance would facilitate the development of appropriate vector control strategies. Therefore, we investigated An. coluzzii larval habitats and resistance to insecticides in the Manoka rural island area compared with the Youpwe suburban inland area, in Douala VI and II districts respectively. Anopheline larvae and pupae were collected from open water bodies in December 2013 and April 2014 and reared until adult emergence. Two to four day old emerging females were morphologically identified as belonging to the An. gambiae complex and used for WHO susceptibility tests with 4 % DDT, 0.75 % permethrin, and 0.05 % deltamethrin, with or without piperonyl butoxide (PBO) synergist. Control and surviving specimens were identified down to the species using a PCR-RFLP method. Survivors were genotyped for kdr L1014 mutations using Hot Oligonucleotide Ligation Assay. In both study sites, ponds, residual puddles, boats, and drains were identified as the major An. gambiae s.l. larval habitats. A total of 1397 females, including 784 specimens from Manoka and 613 from Youpwe, were used for resistance testing. The two mosquito populations displayed resistance to DDT, permethrin and deltamethrin, with variable mortality rates from 1 % to 90 %. The knock-down times were also significantly increased (at least 2.8 fold). Pre-exposure of mosquitoes to PBO did not impact on their mortality to DDT, conversely the mortality rates to permethrin and deltamethrin were significantly increased (7.56 ≤ X(2) ≤ 48.63, df = 1, p < 0.01), suggesting involvement of P450 oxidases in pyrethroid resistance. A subsample of 400 An. gambiae s.l. specimens including 280 control and 120 survivors from bioassays were all found to be An. coluzzii species. Only the kdr

Vector-control personnel’s knowledge, perceptions and practices towards insecticides used for indoor residual spraying in Limpopo Province, South Africa

PubMed Central

2013-01-01

Background Contradictory arguments regarding the benefits and harm of insecticides, especially DDT, have caused concerns in different societal circles, threatening to undermine the achievements of the indoor residual spraying (IRS) programme in South Africa. These concerns were exacerbated by the screening of a documentary on South African Broadcasting Corporation (SABC) Television with anti-DDT sentiments. Consequently, Limpopo Malaria Control Programme (LMCP) Management advocated for an investigation to determine the potential effect of such campaigns on vector-control personnel’s knowledge and perceived effects of insecticides on human health, with a view to improving the educational materials designed for use in training vector-control personnel. Methods The study was a cross-sectional descriptive survey using a structured field-piloted questionnaire, administered to 233 randomly selected vector-control personnel. Ethical clearance was granted by the University of KwaZulu-Natal. Approval for the study was granted by the Department of Health, Limpopo. Participation in the study was voluntary and all respondents signed informed consent. Descriptive statistics were used to analyse the collected data. Results Most respondents (96.6%) had a positive perception of IRS as a method to control malaria. Despite their positive perception, 93.6% viewed IRS insecticides to be potentially harmful to the users. DDT was perceived to cause long-term reproductive and respiratory effects, whereas alpha-cypermethrin and deltamethrin were largely associated with skin irritation/itchiness and skin burn. Study participants were more worried about DDT’s potential effects on their reproductive system, including poor sexual performance, decline in libido, miscarriage and bearing children with genetic defects. However, none reported personal experience of bearing a child with genetic defects or miscarriage. Most anti-insecticide messages, especially relating to DDT, emanated from

Development of an insecticidal nanoemulsion with Manilkara subsericea (Sapotaceae) extract

PubMed Central

2014-01-01

Background Plants have been recognized as a good source of insecticidal agents, since they are able to produce their own defensives to insect attack. Moreover, there is a growing concern worldwide to develop pesticides with low impact to environment and non-target organisms. Hexane-soluble fraction from ethanolic crude extract from fruits of Manilkara subsericea and its triterpenes were considered active against a cotton pest (Dysdercus peruvianus). Several natural products with insecticidal activity have poor water solubility, including triterpenes, and nanotechnology has emerged as a good alternative to solve this main problem. On this context, the aim of the present study was to develop an insecticidal nanoemulsion containing apolar fraction from fruits of Manilkara subsericea. Results It was obtained a formulation constituted by 5% of oil (octyldodecyl myristate), 5% of surfactants (sorbitan monooleate/polysorbate 80), 5% of apolar fraction from M. subsericea and 85% of water. Analysis of mean droplet diameter (155.2 ± 3.8 nm) confirmed this formulation as a nanoemulsion. It was able to induce mortality in D. peruvianus. It was observed no effect against acetylcholinesterase or mortality in mice induced by the formulation, suggesting the safety of this nanoemulsion for non-target organisms. Conclusions The present study suggests that the obtained O/A nanoemulsion may be useful to enhance water solubility of poor water soluble natural products with insecticidal activity, including the hexane-soluble fraction from ethanolic crude extract from fruits of Manilkara subsericea. PMID:24886215

Long-lasting effects of subliminal affective priming from facial expressions.

PubMed

Sweeny, Timothy D; Grabowecky, Marcia; Suzuki, Satoru; Paller, Ken A

2009-12-01

Unconscious processing of stimuli with emotional content can bias affective judgments. Is this subliminal affective priming merely a transient phenomenon manifested in fleeting perceptual changes, or are long-lasting effects also induced? To address this question, we investigated memory for surprise faces 24 h after they had been shown with 30-ms fearful, happy, or neutral faces. Surprise faces subliminally primed by happy faces were initially rated as more positive, and were later remembered better, than those primed by fearful or neutral faces. Participants likely to have processed primes supraliminally did not respond differentially as a function of expression. These results converge with findings showing memory advantages with happy expressions, though here the expressions were displayed on the face of a different person, perceived subliminally, and not present at test. We conclude that behavioral biases induced by masked emotional expressions are not ephemeral, but rather can last at least 24 h.

Pharmacological treatment of organophosphorus insecticide poisoning: the old and the (possible) new.

PubMed

Eddleston, Michael; Chowdhury, Fazle Rabbi

2016-03-01

Despite being a major clinical and public health problem across the developing world, responsible for at least 5 million deaths over the last three decades, the clinical care of patients with organophosphorus (OP) insecticide poisoning has little improved over the last six decades. We are still using the same two antidotes - atropine and oximes - that first came into clinical use in the late 1950s. Clinical research in South Asia has shown how improved regimens of atropine can prevent deaths. However, we are still unsure about which patients are most likely to benefit from the use of oximes. Supplemental antidotes, such as magnesium, clonidine and sodium bicarbonate, have all been proposed and studied in small trials without production of definitive answers. Novel antidotes such as nicotinic receptor antagonists, beta-adrenergic agonists and lipid emulsions are being studied in large animal models and in pilot clinical trials. Hopefully, one or more of these affordable and already licensed antidotes will find their place in routine clinical care. However, the large number of chemically diverse OP insecticides, the varied poisoning they produce and their varied response to treatment might ultimately make it difficult to determine definitively whether these antidotes are truly effective. In addition, the toxicity of the varied solvents and surfactants formulated with the OP active ingredients complicates both treatment and studies. It is possible that the only effective way to reduce deaths from OP insecticide poisoning will be a steady reduction in their agricultural use worldwide. © 2015 The British Pharmacological Society.

The role of ependymin in the development of long lasting synaptic changes.

PubMed

Shashoua, V E

1.) Three types of training experiments (a complex motor task, avoidance conditioning and classical conditioning) in the goldfish and one in the mouse (T-maze learning) indicate that the brain extracellular glycoprotein (ependymin) has a role in the consolidation process of long-term memory formation. 2.) Direct ELISA measures of the concentration of ependymin in the brain extracellular fluid (ECF) indicate that its level decreases after goldfish learn to associate a light stimulus (cs) with the subsequent arrival of a shock (US): paired CS-US gave changes whereas an unpaired presentation of CS-US gave no changes in comparison to unstimulated controls. 3.) Ependymin is released into ECF and CSF as mixtures of three types of disulfide-linked dimers of two acidic polypeptide chains (M. W. 37 kDa and 31 kDa). It contains 10% carbohydrate as an N-linked glycan. 4.) Ependymin has the capacity to polymerize in response to events that deplete Ca2+ from the brain extracellular environment. A molecular hypothesis relating polymerization properties to the process of formation of long-lasting synaptic changes is proposed. 5.) Investigations of the pattern of regeneration of goldfish optic nerve and the mechanisms of long-term potentiation (LTP) of rat brain hippocampal slices suggest that ependymin has a role in the formation of long-lasting synaptic changes. The E.M. data show that polymerized products which stain with anti-ependymin sera accumulate at synapses and in new spines after LTP.

Weevil x Insecticide: Does 'Personality' Matter?

PubMed

Morales, Juliana A; Cardoso, Danúbia G; Della Lucia, Terezinha Maria C; Guedes, Raul Narciso C

2013-01-01

An insect's behavior is the expression of its integrated physiology in response to external and internal stimuli, turning insect behavior into a potential determinant of insecticide exposure. Behavioral traits may therefore influence insecticide efficacy against insects, compromising the validity of standard bioassays of insecticide activity, which are fundamentally based on lethality alone. By extension, insect 'personality' (i.e., an individual's integrated set of behavioral tendencies that is inferred from multiple empirical measures) may also be an important determinant of insecticide exposure and activity. This has yet to be considered because the behavioral studies involving insects and insecticides focus on populations rather than on individuals. Even among studies of animal 'personality', the relative contributions of individual and population variation are usually neglected. Here, we assessed behavioral traits (within the categories: activity, boldness/shyness, and exploration/avoidance) of individuals from 15 populations of the maize weevil (Sitophilus zeamais), an important stored-grain pest with serious problems of insecticide resistance, and correlated the behavioral responses with the activity of the insecticide deltamethrin. This analysis was performed at both the population and individual levels. There was significant variation in weevil 'personality' among individuals and populations, but variation among individuals within populations accounted for most of the observed variation (92.57%). This result emphasizes the importance of individual variation in behavioral and 'personality' studies. When the behavioral traits assessed were correlated with median lethal time (LT50) at the population level and with the survival time under insecticide exposure, activity traits, particularly the distance walked, significantly increased survival time. Therefore, behavioral traits are important components of insecticide efficacy, and individual variation should be

Prenatal exposure to cannabinoids evokes long-lasting functional alterations by targeting CB1 receptors on developing cortical neurons.

PubMed

de Salas-Quiroga, Adán; Díaz-Alonso, Javier; García-Rincón, Daniel; Remmers, Floortje; Vega, David; Gómez-Cañas, María; Lutz, Beat; Guzmán, Manuel; Galve-Roperh, Ismael

2015-11-03

The CB1 cannabinoid receptor, the main target of Δ(9)-tetrahydrocannabinol (THC), the most prominent psychoactive compound of marijuana, plays a crucial regulatory role in brain development as evidenced by the neurodevelopmental consequences of its manipulation in animal models. Likewise, recreational cannabis use during pregnancy affects brain structure and function of the progeny. However, the precise neurobiological substrates underlying the consequences of prenatal THC exposure remain unknown. As CB1 signaling is known to modulate long-range corticofugal connectivity, we analyzed the impact of THC exposure on cortical projection neuron development. THC administration to pregnant mice in a restricted time window interfered with subcerebral projection neuron generation, thereby altering corticospinal connectivity, and produced long-lasting alterations in the fine motor performance of the adult offspring. Consequences of THC exposure were reminiscent of those elicited by CB1 receptor genetic ablation, and CB1-null mice were resistant to THC-induced alterations. The identity of embryonic THC neuronal targets was determined by a Cre-mediated, lineage-specific, CB1 expression-rescue strategy in a CB1-null background. Early and selective CB1 reexpression in dorsal telencephalic glutamatergic neurons but not forebrain GABAergic neurons rescued the deficits in corticospinal motor neuron development of CB1-null mice and restored susceptibility to THC-induced motor alterations. In addition, THC administration induced an increase in seizure susceptibility that was mediated by its interference with CB1-dependent regulation of both glutamatergic and GABAergic neuron development. These findings demonstrate that prenatal exposure to THC has long-lasting deleterious consequences in the adult offspring solely mediated by its ability to disrupt the neurodevelopmental role of CB1 signaling.

Acute Ethanol Has Biphasic Effects on Short- and Long-Term Memory in Both Foreground and Background Contextual Fear Conditioning in C57BL/6 Mice

PubMed Central

Gulick, Danielle; Gould, Thomas J.

2009-01-01

Background Ethanol is a frequently abused, addictive drug that impairs cognitive function. Ethanol may disrupt cognitive processes by altering attention, short-term memory, and/ or long-term memory. Interestingly, some research suggests that ethanol may enhance cognitive processes at lower doses. The current research examined the dose-dependent effects of ethanol on contextual and cued fear conditioning. In addition, the present studies assessed the importance of stimulus salience in the effects of ethanol and directly compared the effects of ethanol on short-term and long-term memory. Methods This study employed both foreground and background fear conditioning, which differ in the salience of contextual stimuli, and tested conditioning at 4 hours, 24 hours, and 1 week in order to assess the effects of ethanol on short-term and long-term memory. Foreground conditioning consisted of 2 presentations of a foot shock unconditioned stimulus (US) (2 seconds, 0.57 mA). Background conditioning consisted of 2 auditory conditioned stimulus (30 seconds, 85 dB white noise)–foot shock (US; 2 seconds, 0.57 mA) pairings. Results For both foreground and background conditioning, ethanol enhanced short-term and long-term memory for contextual and cued conditioning at a low dose (0.25 g/kg) and impaired short-term and long-term memory for contextual and cued conditioning at a high dose (1.0 g/kg). Conclusions These results suggest that ethanol has long-lasting, biphasic effects on short-term and long-term memory for contextual and cued conditioning. Furthermore, the effects of ethanol on contextual fear conditioning are independent of the salience of the context. PMID:17760787

Evaluation of Polyethylene-Based Long Lasting Treated Bed Net Netprotect on Anopheles Mosquitoes, Malaria Incidence, and Net Longivity in Western Kenya

PubMed Central

Odhiambo, M. T. O.; Skovmand, O.; Vulule, J. M.; Kokwaro, E. D.

2013-01-01

We studied the effect on malaria incidence, mosquito abundance, net efficacy, net use rate, chemical analysis, and holes of a long lasting insecticide treated bed net (Netprotect) in western Kenya, 2007–2010. Nets were hung in 150 households 6 months before they were hung in a second, 2 km away. Indoor resting densities were monitored by pyrethrum spray catch and malaria cases by passive detection using clinical manifestations and rapid diagnostic test. The probability of finding An. arabiensis in the control area was 2.6 times higher than that in intervention area during the first 6 months. Human blood feeding index of Anopheles funestus declined 17%. After bed nets were hung in the second area, malaria incidence declined 25% down to the level in the first area. Incidence remained at this low level for 2 years. 90% of collected nets were efficacious after 3-year use. Deltamethrin dosage declined from 1.9 to 0.5 g/kg over 3 years. Attrition rate after 3 years was 21%. WHO hole index changed from 333 to 114 to 381 over the three years. This index summarizes the numbers of holes in size categories and multiplies with the mean hole area per category. It is very sensitive to the impact of big holes in a few nets. PMID:24194770

[Risk of long-lasting negative cognitive consequences after electroconvulsive therapy].

PubMed

Svendsen, Anne Marie; Miskowiak, Kamilla; Vinberg, Maj

2013-10-28

This case study describes a patient who had a unipolar depression and experienced long-lasting cognitive problems after electroconvulsive therapy (ECT). Neuropsychological testing revealed lower scores on measures of learning, memory and sustained attention. These results stress the importance of informing patients who have ECT of the potential cognitive consequences of this treatment as it may influence the patients' functional capabilities. Prospective studies are needed since we do not have sufficient knowledge regarding the 3-5% of these patients who experience sustained cognitive problems.

Insecticide Use and Breast Cancer Risk among Farmers’ Wives in the Agricultural Health Study

PubMed Central

Werder, Emily; Satagopan, Jaya; Blair, Aaron; Hoppin, Jane A.; Koutros, Stella; Lerro, Catherine C.; Sandler, Dale P.; Alavanja, Michael C.; Beane Freeman, Laura E.

2017-01-01

Background: Some epidemiologic and laboratory studies suggest that insecticides are related to increased breast cancer risk, but the evidence is inconsistent. Women engaged in agricultural work or who reside in agricultural areas may experience appreciable exposures to a wide range of insecticides. Objective: We examined associations between insecticide use and breast cancer incidence among wives of pesticide applicators (farmers) in the prospective Agricultural Health Study. Methods: Farmers and their wives provided information on insecticide use, demographics, and reproductive history at enrollment in 1993–1997 and in 5-y follow-up interviews. Cancer incidence was determined via cancer registries. Among 30,594 wives with no history of breast cancer before enrollment, we examined breast cancer risk in relation to the women’s and their husbands’ insecticide use using Cox proportional hazards regression to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Results: During an average 14.7-y follow-up, 39% of the women reported ever using insecticides, and 1,081 were diagnosed with breast cancer. Although ever use of insecticides overall was not associated with breast cancer risk, risk was elevated among women who had ever used the organophosphates chlorpyrifos [HR=1.4 (95% CI: 1.0, 2.0)] or terbufos [HR=1.5 (95% CI: 1.0, 2.1)], with nonsignificantly increased risks for coumaphos [HR=1.5 (95% CI: 0.9, 2.5)] and heptachlor [HR=1.5 (95% CI: 0.7, 2.9)]. Risk in relation to the wives’ use was associated primarily with premenopausal breast cancer. We found little evidence of differential risk by tumor estrogen receptor status. Among women who did not apply pesticides, the husband’s use of fonofos was associated with elevated risk, although no exposure–response trend was observed. Conclusion: Use of several organophosphate insecticides was associated with elevated breast cancer risk. However, associations for the women’s and husbands�

Long-Lasting Effects of Subliminal Affective Priming from Facial Expressions

PubMed Central

Sweeny, Timothy D.; Grabowecky, Marcia; Suzuki, Satoru; Paller, Ken A.

2009-01-01

Unconscious processing of stimuli with emotional content can bias affective judgments. Is this subliminal affective priming merely a transient phenomenon manifested in fleeting perceptual changes, or are long-lasting effects also induced? To address this question, we investigated memory for surprise faces 24 hours after they had been shown with 30-ms fearful, happy, or neutral faces. Surprise faces subliminally primed by happy faces were initially rated as more positive, and were later remembered better, than those primed by fearful or neutral faces. Participants likely to have processed primes supraliminally did not respond differentially as a function of expression. These results converge with findings showing memory advantages with happy expressions, though here the expressions were displayed on the face of a different person, perceived subliminally, and not present at test. We conclude that behavioral biases induced by masked emotional expressions are not ephemeral, but rather can last at least 24 hours. PMID:19695907

Developmental neurotoxicity of the organophosphorus insecticide chlorpyrifos: from clinical findings to preclinical models and potential mechanisms

PubMed Central

Burke, Richard D.; Todd, Spencer W.; Lumsden, Eric; Mullins, Roger J.; Mamczarz, Jacek; Fawcett, William P.; Gullapalli, Rao P.; Randall, William R.; Pereira, Edna F. R.; Albuquerque, Edson X.

2017-01-01

Organophosphorus (OP) insecticides are pest-control agents heavily used worldwide. Unfortunately, they are also well known for the toxic effects that they can trigger in humans. Clinical manifestations of an acute exposure of humans to OP insecticides include a well-defined cholinergic crisis that develops as a result of the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that hydrolyzes the neurotransmitter acetylcholine (ACh). Prolonged exposures to levels of OP insecticides that are insufficient to trigger signs of acute intoxication, which are hereafter referred to as subacute exposures, have also been associated with neurological deficits. In particular, epidemiological studies have reported statistically significant correlations between prenatal subacute exposures to OP insecticides, including chlorpyrifos, and neurological deficits that range from cognitive impairments to tremors in childhood. The primary objectives of this article are: (i) to address the short- and long-term neurological issues that have been associated with acute and subacute exposures of humans to OP insecticides, especially early in life (ii) to discuss the translational relevance of animal models of developmental exposure to OP insecticides, and (iii) to review mechanisms that are likely to contribute to the developmental neurotoxicity of OP insecticides. Most of the discussion will be focused on chlorpyrifos, the top-selling OP insecticide in the United States and throughout the world. These points are critical for the identification and development of safe and effective interventions to counter and/or prevent the neurotoxic effects of these chemicals in the developing brain. PMID:28791702

Bacterial Urease and its Role in Long-Lasting Human Diseases

PubMed Central

Konieczna, Iwona; Żarnowiec, Paulina; Kwinkowski, Marek; Kolesińska, Beata; Frączyk, Justyna; Kamiński, Zbigniew; Kaca, Wiesław

2012-01-01

Urease is a virulence factor found in various pathogenic bacteria. It is essential in colonization of a host organism and in maintenance of bacterial cells in tissues. Due to its enzymatic activity, urease has a toxic effect on human cells. The presence of ureolytic activity is an important marker of a number of bacterial infections. Urease is also an immunogenic protein and is recognized by antibodies present in human sera. The presence of such antibodies is connected with progress of several long-lasting diseases, like rheumatoid arthritis, atherosclerosis or urinary tract infections. In bacterial ureases, motives with a sequence and/or structure similar to human proteins may occur. This phenomenon, known as molecular mimicry, leads to the appearance of autoantibodies, which take part in host molecules destruction. Detection of antibodies-binding motives (epitopes) in bacterial proteins is a complex process. However, organic chemistry tools, such as synthetic peptide libraries, are helpful in both, epitope mapping as well as in serologic investigations. In this review, we present a synthetic report on a molecular organization of bacterial ureases - genetic as well as structural. We characterize methods used in detecting urease and ureolytic activity, including techniques applied in disease diagnostic processes and in chemical synthesis of urease epitopes. The review also provides a summary of knowledge about a toxic effect of bacterial ureases on human body and about occurrence of anti-urease antibodies in long-lasting diseases. PMID:23305365

Malaria Vector Control Still Matters despite Insecticide Resistance.

PubMed

Alout, Haoues; Labbé, Pierrick; Chandre, Fabrice; Cohuet, Anna

2017-08-01

Mosquito vectors' resistance to insecticides is usually considered a major threat to the recent progresses in malaria control. However, studies measuring the impact of interventions and insecticide resistance reveal inconsistencies when using entomological versus epidemiological indices. First, evaluation tests that do not reflect the susceptibility of mosquitoes when they are infectious may underestimate insecticide efficacy. Moreover, interactions between insecticide resistance and vectorial capacity reveal nonintuitive outcomes of interventions. Therefore, considering ecological interactions between vector, parasite, and environment highlights that the impact of insecticide resistance on the malaria burden is not straightforward and we suggest that vector control still matters despite insecticide resistance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Insecticide Exposures on Commercial Aircraft: A Literature Review and Screening Level Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddalena, Randy I.; McKone, Thomas E.

2008-10-01

sampler, based on a thin-film polymer-coated glass design, was developed specifically for deployment in the airliner ventilation system for long-term unattended monitoring of insecticide loading in the aircraft. Because access was not available for either treated aircraft or treatment records during the course of this study, the development and calibration of the passive samplers was halted prior to completion. Continued development of a field ready passive sampler for insecticides in aircraft would require collaboration with the airline industry to finalize the method for deployment and calibration conditions for the sampler. The Task 3 screening level modeling assessment used a dynamic two-box mass balance model that includes treated surfaces and air to explore the time-concentration history of insecticides in the cabin. The model was parameterized using information gathered during the literature review and run for several different insecticide use scenarios. Chemical degradation or sequestration in the surface compartment and mass transfer from the surface to the air limit the rate at which insecticides are removed from the system. This rate limiting process can result in an accumulation of insecticide in the airliner cabin following repeated applications. The extent of accumulation is a function of the overall persistence of the chemical in the system and the amount of chemical applied during each treatment.« less

Activity of Selected Formulated Biorational and Synthetic Insecticides Against Larvae of Helicoverpa armigera (Lepidoptera: Noctuidae).

PubMed

Vivan, L M; Torres, J B; Fernandes, P L S

2017-02-01

This work studied 17 insecticides belonging to nucleopolyhedrovirus (NPV), Bacillus thuringiensis (Bt kurstaki and Bt aizawai), benzoylureas (insect growth regulators [IGRs]), carbamates, organophosphates, spinosyns, and diamides against larvae of Helicoverpa armigera (Hübner), invasive species in the South American continent. Larvae of different instars were fed for 7 d with untreated or insecticide-treated diets. Mortality was recorded daily for 7 d, and surviving larvae were individually weighed on the seventh day. The NPV and Bt insecticides caused 100% mortality of first-instar larvae and first-instar and second-instar larvae, respectively. However, both NPV and Bt-based products caused low mortality of third-instar larvae and did not kill older larvae. The IGR lufenuron was highly effective against all three ages of larvae tested, whereas teflubenzuron and triflumuron produced maximum 60% mortality of second-instar larvae and lower than 50% to older larvae. Thiodicarb, chlorantraniliprole, indoxacarb, chlorpyrifos, and chlorfenapyr, irrespective of tested age, caused 100% mortality of larvae, with the last two insecticides reaching 100% mortality within 2 d of feeding on the treated diet. Flubendiamide caused lower mortality but significantly affected the weight of surviving larvae, whereas neither spinosad nor methomyl produced significant mortality or affected the weight of larvae. Based on the results, the age of H. armigera larvae plays an important role in the recommendation of NPV and Bt insecticides. Furthermore, there are potential options between biological and synthetic insecticides tested against H. armigera, and recording larval size during monitoring, in addition to the infestation level, should be considered when recommending biological-based insecticides to control this pest. © 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.

Double Neutron Star Mergers and Short Gamma-ray Bursts: Long-lasting High-energy Signatures and Remnant Dichotomy

NASA Astrophysics Data System (ADS)

Murase, Kohta; Toomey, Michael W.; Fang, Ke; Oikonomou, Foteini; Kimura, Shigeo S.; Hotokezaka, Kenta; Kashiyama, Kazumi; Ioka, Kunihito; Mészáros, Peter

2018-02-01

The recent detection of gravitational waves and electromagnetic counterparts from the double neutron star merger event GW+EM170817 supports the standard paradigm of short gamma-ray bursts (SGRBs) and kilonovae/macronovae. It is important to reveal the nature of the compact remnant left after the merger, either a black hole or neutron star, and their physical link to the origin of the long-lasting emission observed in SGRBs. The diversity of the merger remnants may also lead to different kinds of transients that can be detected in future. Here we study the high-energy emission from the long-lasting central engine left after the coalescence, under certain assumptions. In particular, we consider the X-ray emission from a remnant disk and the nonthermal nebular emission from disk-driven outflows or pulsar winds. We demonstrate that late-time X-ray and high-frequency radio emission can provide useful constraints on properties of the hidden compact remnants and their connections to long-lasting SGRB emission, and we discuss the detectability of nearby merger events through late-time observations at ∼30–100 days after the coalescence. We also investigate the GeV–TeV gamma-ray emission that occurs in the presence of long-lasting central engines and show the importance of external inverse Compton radiation due to upscattering of X-ray photons by relativistic electrons in the jet. We also search for high-energy gamma rays from GW170817 in the Fermi-LAT data and report upper limits on such long-lasting emission. Finally, we consider the implications of GW+EM170817 and discuss the constraints placed by X-ray and high-frequency radio observations.

Toxicity of selected insecticides and insecticide mixtures to adult brown stink bug (Heteroptera: Pentatomidae)

USDA-ARS?s Scientific Manuscript database

Glass vial bioassay were conducted to evaluate the toxicity of selected insecticides and insecticide mixtures to the brown stink bug (BSB), Euschistus servus (Say) collected from blacklight traps, cotton plants and weeds in farming areas in the Brazos Valley of Texas. Dicrotophos was 5- and 18-fold...

INSECTICIDE-TREATED BED NETS IN RONDÔNIA, BRAZIL: EVALUATION OF THEIR IMPACT ON MALARIA CONTROL

PubMed Central

Vieira, Gabriel de Deus; Basano, Sergio de Almeida; Katsuragawa, Tony Hiroshi; Camargo, Luís Marcelo Aranha

2014-01-01

Mosquito nets treated with long-lasting insecticide (LLINs), when used in compliance with guidelines of the World Health Organization, may be effective for malaria vector control. In 2012, approximately 150,000 LLINs were installed in nine municipalities in the state of Rondônia. However, no studies have assessed their impact on the reduction of malaria incidence. This study analyzed secondary data of malaria incidence, in order to assess the impact of LLINs on the annual parasite incidence (API). The results showed no statistically significant differences in API one year after LLIN installation when compared to municipalities without LLINs. The adoption of measures for malaria vector control should be associated with epidemiological studies and evaluations of their use and efficiency, with the aim of offering convincing advantages that justify their implementation and limit malaria infection in the Amazon Region. PMID:25351543

Rapid Scale-Up of Long-Lasting Insecticide-Treated Bed Nets through Integration into the National Immunization Program during Child Health Week in Togo, 2004

PubMed Central

Wolkon, Adam; Vanden Eng, Jodi L.; Morgah, Kodjo; Eliades, M. James; Thwing, Julie; Terlouw, Dianne J.; Takpa, Vincent; Dare, Aboudou; Sodahlon, Yao K.; Doumanou, Yao; Hightower, Allen W.; Lama, Marcel; Thawani, Neeta; Slutsker, Laurence; Hawley, William A.

2010-01-01

In December 2004, Togo was the first country to conduct a nationwide free insecticide-treated net (ITN) distribution as part of its National Integrated Child Health Campaign. Community-based cross-sectional surveys were conducted one and nine months post-campaign as part of a multidisciplinary evaluation of the nationwide distribution of ITNs to children 9–59 months of age to evaluate ITN ownership, equity, and use. Our results demonstrated that at one month post-campaign, 93.1% of all eligible children received an ITN. Household ITN ownership and equity increased significantly post-campaign. Nine months post-campaign, 78.6% of households with a child eligible to participate in the campaign retained at least one campaign net. Use by eligible children was 43.5% at one month post-campaign (during the dry season) and 52.9% at nine months post-campaign (during the rainy season). Household ownership of at least one ITN increased from 8.0% pre-campaign to 62.5% one month post-campaign. Together, these findings demonstrate that in this setting, increased household ITN ownership, equity, and retention can be achieved on a national scale through free ITN distribution during an integrated campaign. PMID:21036829

Describing the role of Drosophila melanogaster ABC transporters in insecticide biology using CRISPR-Cas9 knockouts.

PubMed

Denecke, Shane; Fusetto, Roberto; Batterham, Philip

2017-12-01

ABC transporters have a well-established role in drug resistance, effluxing xenobiotics from cells and tissues within the organism. More recently, research has been dedicated to understanding the role insect ABC transporters play in insecticide toxicity, but progress in understanding the contribution of specific transporters has been hampered by the lack of functional genetic tools. Here, we report knockouts of three Drosophila melanogaster ABC transporter genes, Mdr49, Mdr50, and Mdr65, that are homologous to the well-studied mammalian ABCB1 (P-glycoprotein). Each knockout mutant was created in the same wild type background and tested against a panel of insecticides representing different chemical classes. Mdr65 knockouts were more susceptible to all neuroactive insecticides tested, but Mdr49 and Mdr50 knockouts showed increased susceptibility or resistance depending on the insecticide used. Mdr65 was chosen for further analysis. Calculation of LC 50 values for the Mdr65 knockout allowed the substrate specificity of this transporter to be examined. No obvious distinguishing structural features were shared among MDR65 substrates. A role for Mdr65 in insecticide transport was confirmed by testing the capacity of the knockout to synergize with the ABC inhibitor verapamil and by measuring the levels of insecticide retained in the body of knockout flies. These data unambiguously establish the influence of ABC transporters on the capacity of wild type D. melanogaster to tolerate insecticide exposure and suggest that both tissue and substrate specificity underpin this capacity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chlorfenapyr (A Pyrrole Insecticide) Applied Alone or as a Mixture with Alpha-Cypermethrin for Indoor Residual Spraying against Pyrethroid Resistant Anopheles gambiae sl: An Experimental Hut Study in Cove, Benin

PubMed Central

Ngufor, Corine; Critchley, Jessica; Fagbohoun, Josias; N’Guessan, Raphael; Todjinou, Damien; Rowland, Mark

2016-01-01

Background Indoor spraying of walls and ceilings with residual insecticide remains a primary method of malaria control. Insecticide resistance in malaria vectors is a growing problem. Novel insecticides for indoor residual spraying (IRS) which can improve the control of pyrethroid resistant malaria vectors are urgently needed. Insecticide mixtures have the potential to improve efficacy or even to manage resistance in some situations but this possibility remains underexplored experimentally. Chlorfenapyr is a novel pyrrole insecticide which has shown potential to improve the control of mosquitoes which are resistant to current WHO-approved insecticides. Method The efficacy of IRS with chlorfenapyr applied alone or as a mixture with alpha-cypermeththrin (a pyrethroid) was evaluated in experimental huts in Cove, Southern Benin against wild free flying pyrethroid resistant Anopheles gambiae sl. Comparison was made with IRS with alpha-cypermethrin alone. Fortnightly 30-minute in situ cone bioassays were performed to assess the residual efficacy of the insecticides on the treated hut walls. Results Survival rates of wild An gambiae from the Cove hut site in WHO resistance bioassays performed during the trial were >90% with permethrin and deltamethrin treated papers. Mortality of free-flying mosquitoes entering the experimental huts was 4% in the control hut. Mortality with alpha-cypermethrin IRS did not differ from the control (5%, P>0.656). The highest mortality was achieved with chlorfenapyr alone (63%). The alpha-cypermethrin + chlorfenapyr mixture killed fewer mosquitoes than chlorfenapyr alone (43% vs. 63%, P<0.001). While the cone bioassays showed a more rapid decline in residual mortality with chlorfenapyr IRS to <30% after only 2 weeks, fortnightly mortality rates of wild free-flying An gambiae entering the chlorfenapyr IRS huts were consistently high (50–70%) and prolonged, lasting over 4 months. Conclusion IRS with chlorfenapyr shows potential to

Tissue time course and bioavailability of the pyrethroid insecticide bifenthrin in the Long-Evans rat

EPA Science Inventory

Bifenthrin is a pyrethroid insecticide and human exposure to it can occur by oral, pulmonary and dermal routes. Pyrethroids are neurotoxic agents and it is generally believed that the parent pyrethroid is the toxic entity. This study evaluated the oral disposition and bioavaila...

Comparing insecticide-treated bed net use to Plasmodium falciparum infection among schoolchildren living near Lake Victoria, Kenya.

PubMed

Okoyo, Collins; Mwandawiro, Charles; Kihara, Jimmy; Simiyu, Elses; Gitonga, Caroline W; Noor, Abdisalan M; Njenga, Sammy M; Snow, Robert W

2015-12-22

Under trial conditions insecticide-treated nets have been shown to provide significant clinical and mortality protection under a range of malaria transmission intensity conditions. There are, however, few operational impact data, notably in very intense transmission conditions. This study, reports on malaria infection among Kenyan schoolchildren living in areas of intense malaria transmission and their reported use of insecticide-treated bed nets. 5188 children in 54 schools were randomly sampled from seven counties surrounding Lake Victoria between May and June 2014. A questionnaire was administered to schoolchildren in classes 2-6 on the use of a long-lasting, insecticide-treated net (LLIN) the night before the survey and provided a single blood sample for a rapid diagnostic test for malaria infection. Analysis of the impact of insecticide-treated net use on malaria prevalence was undertaken using a multivariable, mixed effects, logistic regression at 95% confidence interval (CI), taking into account hierarchical nature of the data and results adjusted for school clusters. The overall prevalence of malaria infection was 48.7%, two-thirds (67.9%) of the children reported using LLIN, 91.3% of the children reported that their households own at least one LLIN and the household LLIN coverage was 2.5 persons per one LLIN. The prevalence of infection showed variation across the counties, with prevalence being highest in Busia (66.9%) and Homabay (51.8%) counties, and lowest in Migori County (29.6%). Generally, malaria parasite prevalence differed between age groups and gender with the highest prevalence occurring in children below 7 years (50.6%) and males (52.2%). Adjusting for county and school, there was a significant reduction in odds of malaria infection among the schoolchildren who reported LLIN use the previous night by 14 % (aOR 0.86, 95% CI 0.74-0.98, P < 0.027). Malaria transmission continues to be high around Lake Victoria. Despite evidence of increasing

A Longitudinal Hepatitis B Vaccine Cohort Demonstrates Long-lasting Hepatitis B Virus (HBV) Cellular Immunity Despite Loss of Antibody Against HBV Surface Antigen

PubMed Central

Simons, Brenna C.; Spradling, Philip R.; Bruden, Dana J. T.; Zanis, Carolyn; Case, Samantha; Choromanski, Tammy L.; Apodaca, Minjun; Brogdon, Hazel D.; Dwyer, Gaelen; Snowball, Mary; Negus, Susan; Bruce, Michael G.; Morishima, Chihiro; Knall, Cindy; McMahon, Brian J.

2016-01-01

Background. Long-lasting protection resulting from hepatitis B vaccine, despite loss of antibody against hepatitis B virus (HBV) surface antigen (anti-HBs), is undetermined. Methods. We recruited persons from a cohort vaccinated with plasma-derived hepatitis B vaccine in 1981 who have been followed periodically since. We performed serological testing for anti-HBs and microRNA-155 and assessed HBV-specific T-cell responses by enzyme-linked immunospot and cytometric bead array. Study subgroups were defined 32 years after vaccination as having an anti-HBs level of either ≥10 mIU/mL (group 1; n = 13) or <10 mIU/mL (group 2; n = 31). Results. All 44 participants, regardless of anti-HBs level, tested positive for tumor necrosis factor α, interleukin 10, or interleukin 6 production by HBV surface antigen–specific T cells. The frequency of natural killer T cells correlated with the level of anti-HBs (P = .008). The proportion of participants who demonstrated T-cell responses to HBV core antigen varied among the cytokines measured, suggesting some natural exposure to HBV in the study group. No participant had evidence of breakthrough HBV infection. Conclusions. Evidence of long-lasting cellular immunity, regardless of anti-HBs level, suggests that protection afforded by primary immunization with plasma-derived hepatitis B vaccine during childhood and adulthood lasts at least 32 years. PMID:27056956

Long lasting effects of chronic heavy cannabis abuse.

PubMed

Nestoros, Joannis N; Vakonaki, Elena; Tzatzarakis, Manolis N; Alegakis, Athanasios; Skondras, Markos D; Tsatsakis, Aristidis M

2017-06-01

The purpose of this study was to evaluate the extent of short-term memory impairment and schizophrenia-like symptoms in heavy and systematic cannabis users and the association between the severity of abuse and the longevity of its persistent symptoms after refraining from such use. A complete psychiatric examination and a psychometric evaluation were performed in 48 solely cannabis users. Additionally, head hair samples were analyzed and the detected cannabinoids levels were correlated with the psychometric findings. A total of 33.3% (n = 16) of the total examined cannabis users were currently imprisoned. The years of abuse ranged from 1 to 35 years and the median daily dose was 5.84.4 gr and 4.84.0 gr for prisoners (n = 16) and non prisoners (n = 32), respectively. A total of 39.6% of the users experienced hallucinations (mostly auditory), 54.2% experienced delusions (mostly ideas of reference and persecution), 85.4% had organic brain dysfunction in a test addressing visual-motor functioning and visual perception skills, and all users (100%) were found to have organic brain dysfunction in a test of visual memory immediate recall. The cannabinoid metabolite levels in the hair samples were consistent with the reported history of substance abuse and total grams of consumption for the participants below 35 years old (p < .001). Statistically elevated cannabinoids levels were observed in users with auditory hallucinations compared to users without any hallucinations (p = .019). The existence of hallucinations, delusions, and organic brain dysfunction in heavy cannabis users seems to be associated with cannabinoid levels in hair. The continuation of persistent symptoms 3 months after the discontinuation of cannabis abuse, was a remarkable finding. We provide evidence that chronic and heavy cannabis abuse results in long-lasting brain dysfunction in all users and in long-lasting schizophrenia-like psychotic symptoms in more than half of all users

Bacterial insecticides and inert materials

USDA-ARS?s Scientific Manuscript database

The term “novel insecticides” can be regarded as a category that includes the insecticides with novel mode of action, but also insecticides that are novel in terms of their low mammalian toxicity and environmental-friendly profiles. Under this context, it is difficult to identify active ingredients ...

Insecticide Resistance in Fleas.

PubMed

Rust, Michael K

2016-03-17

Fleas are the major ectoparasite of cats, dogs, and rodents worldwide and potential vectors of animal diseases. In the past two decades the majority of new control treatments have been either topically applied or orally administered to the host. Most reports concerning the development of insecticide resistance deal with the cat flea, Ctenocephalides felis felis. Historically, insecticide resistance has developed to many of the insecticides used to control fleas in the environment including carbamates, organophosphates, and pyrethroids. Product failures have been reported with some of the new topical treatments, but actual resistance has not yet been demonstrated. Failures have often been attributed to operational factors such as failure to adequately treat the pet and follow label directions. With the addition of so many new chemistries additional monitoring of flea populations is needed.

The gut microbiota of insecticide-resistant insects houses insecticide-degrading bacteria: A potential source for biotechnological exploitation.

PubMed

Almeida, Luis Gustavo de; Moraes, Luiz Alberto Beraldo de; Trigo, José Roberto; Omoto, Celso; Cônsoli, Fernando Luis

2017-01-01

The exploration of new niches for microorganisms capable of degrading recalcitrant molecules is still required. We hypothesized the gut microbiota associated with insect-resistant lines carry pesticide degrading bacteria, and predicted they carry bacteria selected to degrade pesticides they were resistant to. We isolated and accessed the pesticide-degrading capacity of gut bacteria from the gut of fifth instars of Spodoptera frugiperda strains resistant to lambda-cyhalothrin, deltamethrin, chlorpyrifos ethyl, spinosad and lufenuron, using insecticide-selective media. Sixteen isolates belonging to 10 phylotypes were obtained, from which four were also associated with the susceptible strain. However, growth of gut bacteria associated with larvae from the susceptible strain was not obtained in any of the insecticide-based selective media tested. Growth of isolates was affected by the concentration of insecticides in the media, and all grew well up to 40 μg/ml. The insecticide-degrading capacity of selected isolates was assessed by GC or LC-MS/MS analyses. In conclusion, resistant strains of S. frugiperda are an excellent reservoir of insecticide-degrading bacteria with bioremediation potential. Moreover, gut-associated bacteria are subjected to the selection pressure imposed by insecticides on their hosts and may influence the metabolization of pesticides in insects.

The gut microbiota of insecticide-resistant insects houses insecticide-degrading bacteria: A potential source for biotechnological exploitation

PubMed Central

de Almeida, Luis Gustavo; de Moraes, Luiz Alberto Beraldo; Trigo, José Roberto; Omoto, Celso

2017-01-01

The exploration of new niches for microorganisms capable of degrading recalcitrant molecules is still required. We hypothesized the gut microbiota associated with insect-resistant lines carry pesticide degrading bacteria, and predicted they carry bacteria selected to degrade pesticides they were resistant to. We isolated and accessed the pesticide-degrading capacity of gut bacteria from the gut of fifth instars of Spodoptera frugiperda strains resistant to lambda-cyhalothrin, deltamethrin, chlorpyrifos ethyl, spinosad and lufenuron, using insecticide-selective media. Sixteen isolates belonging to 10 phylotypes were obtained, from which four were also associated with the susceptible strain. However, growth of gut bacteria associated with larvae from the susceptible strain was not obtained in any of the insecticide-based selective media tested. Growth of isolates was affected by the concentration of insecticides in the media, and all grew well up to 40 μg/ml. The insecticide-degrading capacity of selected isolates was assessed by GC or LC-MS/MS analyses. In conclusion, resistant strains of S. frugiperda are an excellent reservoir of insecticide-degrading bacteria with bioremediation potential. Moreover, gut-associated bacteria are subjected to the selection pressure imposed by insecticides on their hosts and may influence the metabolization of pesticides in insects. PMID:28358907

Lantos-Hyde United States Government Malaria Strategy, 2009-2014

DTIC Science & Technology

2010-04-25

Long lasting insecticide -treated nets (LLINs); • Indoor residual spraying (IRS) with insecticides ; • Intermittent preventive treatment of...measures: insecticide -treated mosquito nets (ITNs); indoor residual spraying (IRS) of insecticides ; artemisinin-based combination therapy (ACTs); and...is national policy. Indoor residual spraying : Between 2005 and 2009, PMI supported the introduction or

Insecticides against headlice in Glasgow.

PubMed

Lindsay, S W; Peock, S

1993-08-01

A postal questionnaire for describing current practices of insecticide usage for the prevention and treatment of pediculosis was sent to 53 pharmacists in Glasgow. 91% returned completed questionnaires. Between 19,000 to 36,000 bottles of insecticide against headlice were bought by the public in Glasgow in 1991. Most of these were sold in small volumes (less than 100 ml) and sales were highest during the autumn. Although pharmacists sold a range of different classes of insecticide, the most popular were those that contained malathion, the treatment for pediculosis recommended by the Health Board. Choice of treatment was probably influenced by advice given to the public by pharmacists and general practitioners. Clients preferred shampoo formulations. There was evidence that treatments were used prophylactically against headlice. However, there was little indication of large scale resistance to insecticides in the louse population. The results indicate that headlice remain a persistent problem in Glasgow, despite the public adhering to the advice of health professionals.

ANTICHOLINESTERASE INSECTICIDE RETROSPECTIVE

PubMed Central

Casida, John E.; Durkin, Kathleen A.

2012-01-01

The anticholinesterase (antiChE) organophosphorus (OP) and methylcarbamate (MC) insecticides have been used very effectively as contact and systemic plant protectants for seven decades. About 90 of these compounds are still in use – the largest number for any insecticide chemotype or mode of action. In both insects and mammals, AChE inhibition and acetylcholine accumulation leads to excitation and death. The cholinergic system of insects is located centrally (where it is protected from ionized OPs and MCs) but not at the neuromuscular junction. Structural differences between insect and mammalian AChE are also evident in their genomics, amino acid sequences and active site conformations. Species selectivity is determined in part by inhibitor and target site specificity. Pest population selection with OPs and MCs has resulted in a multitude of modified AChEs of altered inhibitor specificity some conferring insecticide resistance and others enhancing sensitivity. Much of the success of antiChE insecticides results from a suitable balance of bioactivation and detoxification by families of CYP450 oxidases, hydrolases, glutathione S-transferases and others. Known inhibitors for these enzymes block detoxification and enhance potency which is particularly important in resistant strains. The current market for OPs and MCs of 19% of worldwide insecticide sales is only half of that of 10 years ago for several reasons: there have been no major new compounds for 30 years; resistance has eroded their effectiveness; human toxicity problems are still encountered; the patents have expired reducing the incentive to update registration packages; alternative chemotypes or control methods have been developed. Despite this decline, they still play a major role in pest control and the increasing knowledge on their target sites and metabolism may make it possible to redesign the inhibitors for insensitive AChEs and to target new sites in the cholinergic system. The OPs and MCs are down

Anticholinesterase insecticide retrospective.

PubMed

Casida, John E; Durkin, Kathleen A

2013-03-25

The anticholinesterase (antiChE) organophosphorus (OP) and methylcarbamate (MC) insecticides have been used very effectively as contact and systemic plant protectants for seven decades. About 90 of these compounds are still in use - the largest number for any insecticide chemotype or mode of action. In both insects and mammals, AChE inhibition and acetylcholine accumulation leads to excitation and death. The cholinergic system of insects is located centrally (where it is protected from ionized OPs and MCs) but not at the neuromuscular junction. Structural differences between insect and mammalian AChE are also evident in their genomics, amino acid sequences and active site conformations. Species selectivity is determined in part by inhibitor and target site specificity. Pest population selection with OPs and MCs has resulted in a multitude of modified AChEs of altered inhibitor specificity some conferring insecticide resistance and others enhancing sensitivity. Much of the success of antiChE insecticides results from a suitable balance of bioactivation and detoxification by families of CYP450 oxidases, hydrolases, glutathione S-transferases and others. Known inhibitors for these enzymes block detoxification and enhance potency which is particularly important in resistant strains. The current market for OPs and MCs of 19% of worldwide insecticide sales is only half of that of 10 years ago for several reasons: there have been no major new compounds for 30 years; resistance has eroded their effectiveness; human toxicity problems are still encountered; the patents have expired reducing the incentive to update registration packages; alternative chemotypes or control methods have been developed. Despite this decline, they still play a major role in pest control and the increasing knowledge on their target sites and metabolism may make it possible to redesign the inhibitors for insensitive AChEs and to target new sites in the cholinergic system. The OPs and MCs are down

Insecticide resistance in disease vectors from Mayotte: an opportunity for integrated vector management

PubMed Central

2014-01-01

Background Mayotte, a small island in the Indian Ocean, has been affected for many years by vector-borne diseases. Malaria, Bancroftian filariasis, dengue, chikungunya and Rift Valley fever have circulated or still circulate on the island. They are all transmitted by Culicidae mosquitoes. To limit the impact of these diseases on human health, vector control has been implemented for more than 60 years on Mayotte. In this study, we assessed the resistance levels of four major vector species (Anopheles gambiae, Culex pipiens quinquefasciatus, Aedes aegypti and Aedes albopictus) to two types of insecticides: i) the locally currently-used insecticides (organophosphates, pyrethroids) and ii) alternative molecules that are promising for vector control and come from different insecticide families (bacterial toxins or insect growth regulators). When some resistance was found to one of these insecticides, we characterized the mechanisms involved. Methods Larval and adult bioassays were used to evaluate the level of resistance. When resistance was found, we tested for the presence of metabolic resistance through detoxifying enzyme activity assays, or for target-site mutations through molecular identification of known resistance alleles. Results Resistance to currently-used insecticides varied greatly between the four vector species. While no resistance to any insecticides was found in the two Aedes species, bioassays confirmed multiple resistance in Cx. p. quinquefasciatus (temephos: ~ 20 fold and deltamethrin: only 10% mortality after 24 hours). In An. gambiae, resistance was scarce: only a moderate resistance to temephos was found (~5 fold). This resistance appears to be due only to carboxyl-esterase overexpression and not to target modification. Finally, and comfortingly, none of the four species showed resistance to any of the new insecticides. Conclusions The low resistance observed in Mayotte’s main disease vectors is particularly interesting, because it leaves a

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

Diagnostic Doses of Insecticides for Adult Aedes aegypti to Assess Insecticide Resistance in Cuba.

PubMed

Rodríguez, María Magdalena; Crespo, Ariel; Hurtado, Daymi; Fuentes, Ilario; Rey, Jorge; Bisset, Juan Andrés

2017-06-01

The objective of this study was to determine diagnostic doses (DDs) of 5 insecticides for the Rockefeller susceptible strain of Aedes aegypti , using the Centers for Disease Control and Prevention (CDC) bottle bioassay as a tool for monitoring insecticide resistance in the Cuban vector control program. The 30-min DD values determined in this study were 13.5 μg/ml, 6.5 μg/ml, 6 μg/ml, 90.0 μg/ml, and 15.0 μg/ml for cypermethrin, deltamethrin, lambda-cyhalothrin, chlorpyrifos, and propoxur, respectively. To compare the reliability of CDC bottle bioassay with the World Health Organization susceptible test, 3 insecticide-resistant strains were evaluated for deltamethrin and lambda-cyhalothrin. Results showed that the bottles can be used effectively from 21 to 25 days after treatment and reused up to 4 times, depending on the storage time. The CDC bottle bioassay is an effective tool to assess insecticide resistance in field populations of Ae. aegypti in Cuba and can be incorporated into vector management programs using the diagnostic doses determined in this study.

Insecticide resistance in the sand fly, Phlebotomus papatasi from Khartoum State, Sudan

PubMed Central

2012-01-01

Background Phlebotomus papatasi the vector of cutaneous leishmaniasis (CL) is the most widely spread sand fly in Sudan. No data has previously been collected on insecticide susceptibility and/or resistance of this vector, and a first study to establish a baseline data is reported here. Methods Sand flies were collected from Surogia village, (Khartoum State), Rahad Game Reserve (eastern Sudan) and White Nile area (Central Sudan) using light traps. Sand flies were reared in the Tropical Medicine Research Institute laboratory. The insecticide susceptibility status of first progeny (F1) of P. papatasi of each population was tested using WHO insecticide kits. Also, P. papatasi specimens from Surogia village and Rahad Game Reserve were assayed for activities of enzyme systems involved in insecticide resistance (acetylcholinesterase (AChE), non-specific carboxylesterases (EST), glutathione-S-transferases (GSTs) and cytochrome p450 monooxygenases (Cyt p450). Results Populations of P. papatasi from White Nile and Rahad Game Reserve were sensitive to dichlorodiphenyltrichloroethane (DDT), permethrin, malathion, and propoxur. However, the P. papatasi population from Surogia village was sensitive to DDT and permethrin but highly resistant to malathion and propoxur. Furthermore, P. papatasi of Surogia village had significantly higher insecticide detoxification enzyme activity than of those of Rahad Game Reserve. The sand fly population in Surogia displayed high AChE activity and only three specimens had elevated levels for EST and GST. Conclusions The study provided evidence for malathion and propoxur resistance in the sand fly population of Surogia village, which probably resulted from anti-malarial control activities carried out in the area during the past 50 years. PMID:22397726

Insecticide poisoning

MedlinePlus

Cannon RD, Ruha A-M. Insecticides, herbicides, and rodenticides. In: Adams JG, ed. Emergency Medicine . 2nd ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 146. Welker K, Thompson TM. Pesticides. ...

An Intervention to Reduce Residential Insecticide Exposure during Pregnancy among an Inner-City Cohort

PubMed Central

Williams, Megan K.; Barr, Dana B.; Camann, David E.; Cruz, Linda A.; Carlton, Elizabeth J.; Borjas, Mejico; Reyes, Andria; Evans, Dave; Kinney, Patrick L.; Whitehead, Ralph D.; Perera, Frederica P.; Matsoanne, Stephen; Whyatt, Robin M.

2006-01-01

Background We previously reported widespread insecticide exposure during pregnancy among inner-city women from New York City. Here we report on a pilot intervention using integrated pest management (IPM) to reduce pest infestations and residential insecticide exposures among pregnant New York City African-American and Latina women (25 intervention and 27 control homes). Methods The IPM consisted of professional cleaning, sealing of pest entry points, application of low-toxicity pesticides, and education. Cockroach infestation levels and 2-week integrated indoor air samples were collected at baseline and one month postintervention. The insecticides detected in the indoor air samples were also measured in maternal and umbilical cord blood collected at delivery. Results Cockroach infestations decreased significantly (p = 0.016) after the intervention among intervention cases but not control households. Among the intervention group, levels of piperonyl butoxide (a pyrethroid synergist) were significantly lower in indoor air samples after the intervention (p = 0.016). Insecticides were detected in maternal blood samples collected at delivery from controls but not from the intervention group. The difference was significant for trans-permethrin (p = 0.008) and of borderline significance (p = 0.1) for cis-permethrin and 2-isopropoxyphenol (a propoxur metabolite). Conclusion To our knowledge, this is the first study to use biologic dosimeters of prenatal pesticide exposure for assessing effectiveness of IPM. These pilot data suggest that IPM is an effective strategy for reducing pest infestation levels and the internal dose of insecticides during pregnancy. PMID:17107853

Conventional Prompt Global Strike and Long Range Ballistic Missiles: Background and Issues

DTIC Science & Technology

2017-02-03

Conventional Prompt Global Strike and Long-Range Ballistic Missiles: Background and Issues Amy F. Woolf Specialist in Nuclear Weapons Policy...February 3, 2017 Congressional Research Service 7-5700 www.crs.gov R41464 Conventional Prompt Global Strike and Long-Range Ballistic Missiles...Congressional Research Service Summary Conventional prompt global strike (CPGS) weapons would allow the United States to strike targets anywhere

Long-lasting ovulation inhibition with a new injectable progestagen ORG-2154.

PubMed

Coutinho, E M; De Souza, J C; Barbosa, I C; Dourado Silva, V

1982-06-01

A new long-acting injectable progestagen was tested in 15 women who volunteered for the study. The occurrence of ovulation was assumed by the elevation of progesterone levels above 2ng/ml following a pre-ovulatory estradiol peak. Following a 200mg injection, ovulation was inhibited in all 15 women for five to ten months. In four subjects the interval between the injection and the first progesterone peak was five months. For eight, the interval was six to eight months. In the other three women, ovulation occurred more than eight months following injection. Bleeding episodes, similar to menstruation, occurred in most patients. Bleeding intervals lasting longer than 45 days occurred in nine subjects but more prolonged amenorrhea lasting longer than 60 days was reported by only five subjects. Blood chemistry which included blood cell counts, cholesterol, glucose, alkaline phosphatase, transaminases, urea nitrogen and creatinine remained within normal limits throughout the treatment.

Biting deterrence and insecticidal activity of hydrazide–hydrazones and their corresponding 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazoles against Aedes aegypti

USDA-ARS?s Scientific Manuscript database

BACKGROUND: Hydrazones are important compounds for drug design and they have also good insecticidal activity. In this study, A series of hydrazide–hydrazones (1-10) and 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazoles (11-20) were investigated for their biting deterrent and insecticidal act...

Insecticide Resistance and Management Strategies in Urban Ecosystems

PubMed Central

Zhu, Fang; Lavine, Laura; O’Neal, Sally; Lavine, Mark; Foss, Carrie; Walsh, Douglas

2016-01-01

The increased urbanization of a growing global population makes imperative the development of sustainable integrated pest management (IPM) strategies for urban pest control. This emphasizes pests that are closely associated with the health and wellbeing of humans and domesticated animals. Concurrently there are regulatory requirements enforced to minimize inadvertent exposures to insecticides in the urban environment. Development of insecticide resistance management (IRM) strategies in urban ecosystems involves understanding the status and mechanisms of insecticide resistance and reducing insecticide selection pressure by combining multiple chemical and non-chemical approaches. In this review, we will focus on the commonly used insecticides and molecular and physiological mechanisms underlying insecticide resistance in six major urban insect pests: house fly, German cockroach, mosquitoes, red flour beetle, bed bugs and head louse. We will also discuss several strategies that may prove promising for future urban IPM programs. PMID:26751480

Discovery of Species-selective and Resistance-breaking Anticholinesterase Insecticides for the Malaria Mosquito

PubMed Central

Carlier, Paul R.; Bloomquist, Jeffrey R.; Totrov, Max; Li, Jianyong

2017-01-01

Great reductions in malaria mortality have been accomplished in the last 15 years, in part due to the widespread roll-out of insecticide-treated bednets across sub-Saharan Africa. To date, these nets only employ pyrethroids, insecticides that target the voltage-gated sodium ion channel of the malaria vector, Anopheles gambiae. Due to the growing emergence of An. gambiae strains that are resistant to pyrethroids, there is an urgent need to develop new public health insecticides that engage a different target and possess low mammalian toxicity. In this review, we will describe efforts to develop highly species-specific and resistance-breaking inhibitors of An. gambiae acetylcholinesterase (AgAChE). These efforts have been greatly aided by advances in knowledge of the structure of the enzyme, and two major inhibitor design strategies have been explored. Since AgAChE possesses an unpaired Cys residue not present in mammalian AChE, a logical strategy to achieve selective inhibition involves design of compounds that could ligate that Cys. A second strategy involves the design of new molecules to target the catalytic serine of the enzyme. Here the challenge is not only to achieve high inhibition selectivity vs human AChE, but also to demonstrate toxicity to An. gambiae that carry the G119S resistance mutation of AgAChE. The advances made and challenges remaining will be presented. This review is part of the special issue “Insecticide Mode of Action: From Insect to Mammalian Toxicity. PMID:28176636

Insecticide-treated nets provide protection against malaria to children in an area of insecticide resistance in Southern Benin.

PubMed

Bradley, John; Ogouyèmi-Hounto, Aurore; Cornélie, Sylvie; Fassinou, Jacob; de Tove, Yolande Sissinto Savi; Adéothy, Adicath Adéola; Tokponnon, Filémon T; Makoutode, Patrick; Adechoubou, Alioun; Legba, Thibaut; Houansou, Telesphore; Kinde-Gazard, Dorothée; Akogbeto, Martin C; Massougbodji, Achille; Knox, Tessa Bellamy; Donnelly, Martin; Kleinschmidt, Immo

2017-05-26

Malaria control is heavily reliant on insecticides, especially pyrethroids. Resistance of mosquitoes to insecticides may threaten the effectiveness of insecticide-based vector control and lead to a resurgence of malaria in Africa. In 21 villages in Southern Benin with high levels of insecticide resistance, the resistance status of local vectors was measured at the same time as the prevalence of malaria infection in resident children. Children who used LLINs had lower levels of malaria infection [odds ratio = 0.76 (95% CI 0.59, 0.98, p = 0.033)]. There was no evidence that the effectiveness of nets was different in high and low resistance locations (p = 0.513). There was no association between village level resistance and village level malaria prevalence (p = 0.999). LLINs continue to offer individual protection against malaria infection in an area of high resistance. Insecticide resistance is not a reason to stop efforts to increase coverage of LLINs in Africa.

Identification and validation of a gene causing cross-resistance between insecticide classes in Anopheles gambiae from Ghana.

PubMed

Mitchell, Sara N; Stevenson, Bradley J; Müller, Pie; Wilding, Craig S; Egyir-Yawson, Alexander; Field, Stuart G; Hemingway, Janet; Paine, Mark J I; Ranson, Hilary; Donnelly, Martin James

2012-04-17

In the last decade there have been marked reductions in malaria incidence in sub-Saharan Africa. Sustaining these reductions will rely upon insecticides to control the mosquito malaria vectors. We report that in the primary African malaria vector, Anopheles gambiae sensu stricto, a single enzyme, CYP6M2, confers resistance to two classes of insecticide. This is unique evidence in a disease vector of cross-resistance associated with a single metabolic gene that simultaneously reduces the efficacy of two of the four classes of insecticide routinely used for malaria control. The gene-expression profile of a highly DDT-resistant population of A. gambiae s.s. from Ghana was characterized using a unique whole-genome microarray. A number of genes were significantly overexpressed compared with two susceptible West African colonies, including genes from metabolic families previously linked to insecticide resistance. One of the most significantly overexpressed probe groups (false-discovery rate-adjusted P < 0.0001) belonged to the cytochrome P450 gene CYP6M2. This gene is associated with pyrethroid resistance in wild A. gambiae s.s. populations) and can metabolize both type I and type II pyrethroids in recombinant protein assays. Using in vitro assays we show that recombinant CYP6M2 is also capable of metabolizing the organochlorine insecticide DDT in the presence of solubilizing factor sodium cholate.

Identification and validation of a gene causing cross-resistance between insecticide classes in Anopheles gambiae from Ghana

PubMed Central

Mitchell, Sara N.; Stevenson, Bradley J.; Müller, Pie; Wilding, Craig S.; Egyir-Yawson, Alexander; Field, Stuart G.; Hemingway, Janet; Paine, Mark J. I.; Ranson, Hilary; Donnelly, Martin James

2012-01-01

In the last decade there have been marked reductions in malaria incidence in sub-Saharan Africa. Sustaining these reductions will rely upon insecticides to control the mosquito malaria vectors. We report that in the primary African malaria vector, Anopheles gambiae sensu stricto, a single enzyme, CYP6M2, confers resistance to two classes of insecticide. This is unique evidence in a disease vector of cross-resistance associated with a single metabolic gene that simultaneously reduces the efficacy of two of the four classes of insecticide routinely used for malaria control. The gene-expression profile of a highly DDT-resistant population of A. gambiae s.s. from Ghana was characterized using a unique whole-genome microarray. A number of genes were significantly overexpressed compared with two susceptible West African colonies, including genes from metabolic families previously linked to insecticide resistance. One of the most significantly overexpressed probe groups (false-discovery rate-adjusted P < 0.0001) belonged to the cytochrome P450 gene CYP6M2. This gene is associated with pyrethroid resistance in wild A. gambiae s.s. populations) and can metabolize both type I and type II pyrethroids in recombinant protein assays. Using in vitro assays we show that recombinant CYP6M2 is also capable of metabolizing the organochlorine insecticide DDT in the presence of solubilizing factor sodium cholate. PMID:22460795

Comparative analysis of response to selection with three insecticides in the dengue mosquito Aedes aegypti using mRNA sequencing

PubMed Central

2014-01-01

Background Mosquito control programmes using chemical insecticides are increasingly threatened by the development of resistance. Such resistance can be the consequence of changes in proteins targeted by insecticides (target site mediated resistance), increased insecticide biodegradation (metabolic resistance), altered transport, sequestration or other mechanisms. As opposed to target site resistance, other mechanisms are far from being fully understood. Indeed, insecticide selection often affects a large number of genes and various biological processes can hypothetically confer resistance. In this context, the aim of the present study was to use RNA sequencing (RNA-seq) for comparing transcription level and polymorphism variations associated with adaptation to chemical insecticides in the mosquito Aedes aegypti. Biological materials consisted of a parental susceptible strain together with three child strains selected across multiple generations with three insecticides from different classes: the pyrethroid permethrin, the neonicotinoid imidacloprid and the carbamate propoxur. Results After ten generations, insecticide-selected strains showed elevated resistance levels to the insecticides used for selection. RNA-seq data allowed detecting over 13,000 transcripts, of which 413 were differentially transcribed in insecticide-selected strains as compared to the susceptible strain. Among them, a significant enrichment of transcripts encoding cuticle proteins, transporters and enzymes was observed. Polymorphism analysis revealed over 2500 SNPs showing > 50% allele frequency variations in insecticide-selected strains as compared to the susceptible strain, affecting over 1000 transcripts. Comparing gene transcription and polymorphism patterns revealed marked differences among strains. While imidacloprid selection was linked to the over transcription of many genes, permethrin selection was rather linked to polymorphism variations. Focusing on detoxification enzymes

THE ANTICHOLINESTERASE INSECTICIDE, DIAZINON, MAY POTENTIATE THE TOXICITY OF THE PYRETHROID INSECTICIDE DELTAMETHRIN AT LOW DOSAGES.

EPA Science Inventory

This present study explores the interaction of the toxicity induced by an organophosphorus insecticide, diazinon (diethyl 2-isopropyl-6methyl-4-pyrimidal phosphorothionate), with a pyrethroid insecticide, deltamethrin ((S)-a-cyano-3-phenoxybenzyl (1R,3R)-3-(2,2-dibromovinyl)-2,...

CADDIS Volume 2. Sources, Stressors and Responses: Insecticides - Simple Conceptual Diagram

EPA Pesticide Factsheets

Introduction to the insecticides module, when to list insecticides as a candidate cause, ways to measure insecticides, simple and detailed conceptual diagrams for insecticides, insecticides module references and literature reviews.

CADDIS Volume 2. Sources, Stressors and Responses: Insecticides - Detailed Conceptual Diagram

EPA Pesticide Factsheets

Introduction to the insecticides module, when to list insecticides as a candidate cause, ways to measure insecticides, simple and detailed conceptual diagrams for insecticides, insecticides module references and literature reviews.

Developmental neurotoxicity of the organophosphorus insecticide chlorpyrifos: from clinical findings to preclinical models and potential mechanisms.

PubMed

Burke, Richard D; Todd, Spencer W; Lumsden, Eric; Mullins, Roger J; Mamczarz, Jacek; Fawcett, William P; Gullapalli, Rao P; Randall, William R; Pereira, Edna F R; Albuquerque, Edson X

2017-08-01

Organophosphorus (OP) insecticides are pest-control agents heavily used worldwide. Unfortunately, they are also well known for the toxic effects that they can trigger in humans. Clinical manifestations of an acute exposure of humans to OP insecticides include a well-defined cholinergic crisis that develops as a result of the irreversible inhibition of acetylcholinesterase (AChE), the enzyme that hydrolyzes the neurotransmitter acetylcholine (ACh). Prolonged exposures to levels of OP insecticides that are insufficient to trigger signs of acute intoxication, which are hereafter referred to as subacute exposures, have also been associated with neurological deficits. In particular, epidemiological studies have reported statistically significant correlations between prenatal subacute exposures to OP insecticides, including chlorpyrifos, and neurological deficits that range from cognitive impairments to tremors in childhood. The primary objectives of this article are: (i) to address the short- and long-term neurological issues that have been associated with acute and subacute exposures of humans to OP insecticides, especially early in life (ii) to discuss the translational relevance of animal models of developmental exposure to OP insecticides, and (iii) to review mechanisms that are likely to contribute to the developmental neurotoxicity of OP insecticides. Most of the discussion will be focused on chlorpyrifos, the top-selling OP insecticide in the United States and throughout the world. These points are critical for the identification and development of safe and effective interventions to counter and/or prevent the neurotoxic effects of these chemicals in the developing brain. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms. © 2017 International Society for Neurochemistry.

Multi-country assessment of residual bio-efficacy of insecticides used for indoor residual spraying in malaria control on different surface types: results from program monitoring in 17 PMI/USAID-supported IRS countries.

PubMed

Dengela, Dereje; Seyoum, Aklilu; Lucas, Bradford; Johns, Benjamin; George, Kristen; Belemvire, Allison; Caranci, Angela; Norris, Laura C; Fornadel, Christen M

2018-01-30

comparisons of mosquito mortality rates were then made to determine any significant differences when comparing insecticide formulation, country, year, surface type, and the source of the mosquitoes used in testing. The residual efficacy of alpha-cypermethrin ranged from 4 to 10 months (average = 6.4 months), with no reported incidents of underperformance when compared to the efficacy range provided in WHO guidelines. Deltamethrin residual efficacy results reported a range of 1 to 10 months (average = 4.9 months), with two instances of underperformance. The residual efficacy of bendiocarb ranged from 2 weeks to 7 months (average = 2.8 months) and failed to achieve proposed minimum efficacy on 14 occasions. Lastly, long-lasting pirimiphos-methyl efficacy ranged from 2 months to 9 months (average = 5.3 months), but reported 13 incidents of underperformance. Much of the data used to determine application rate and expected efficacy of insecticides approved for use in IRS programs are collected in controlled laboratory or pilot field studies. However, the generalizability of the results obtained under controlled conditions are limited and unlikely to account for variation in locally sourced housing materials, climate, and the myriad other factors that may influence the bio-efficacy of insecticides. Here, data are presented that confirm the variation in residual efficacy observed when monitoring household surfaces sprayed during PMI/USAID-supported IRS campaigns. All insecticides except alpha-cypermethrin showed evidence of failing to meet the minimum range of residual efficacy proposed in WHO criteria at least once. However, this initial effort in characterizing program-wide insecticide bio-efficacy indicates that some insecticides, such as bendiocarb and pirimiphos-methyl, may be vulnerable to variations in the local environment. Additionally, the comparative analysis performed in this study provides evidence that mosquito mortality rates differ with

Selective Maintenance of Motor Performance in Older Adults from Long-Lasting Sport Practice

ERIC Educational Resources Information Center

Dascal, Juliana Bayeux; Teixeira, Luis Augusto

2016-01-01

Purpose: Decline of motor performance in older individuals affects their quality of life. Understanding the contribution of sport-related training in advanced ages might help to attenuate motor performance decay as one gets older. The purpose of our study was to evaluate the extent to which long-lasting training in running or sport-specific skills…

Insecticide treated curtains and residual insecticide treatment to control Aedes aegypti: An acceptability study in Santiago de Cuba

PubMed Central

Van der Stuyft, Patrick; Toledo, María Eugenia; Ceballos, Enrique; Fabré, Francisco; Lefèvre, Pierre

2018-01-01

Background Within the context of a field trial conducted by the Cuban vector control program (AaCP), we assessed acceptability of insecticide-treated curtains (ITCs) and residual insecticide treatment (RIT) with deltamethrin by the community. We also assessed the potential influence of interviewees’ risk perceptions for getting dengue and disease severity. Methodology/principal findings We embedded a qualitative study using in-depth interviews in a cluster randomized trial (CRT) testing the effectiveness of ITCs and RIT in Santiago de Cuba. In-depth interviews (N = 38) were conducted four and twelve months after deployment of the tools with people who accepted the tools, who stopped using them and who did not accept the tools. Data analysis was deductive. Main reasons for accepting ITCs at the start of the trial were perceived efficacy and not being harmful to health. Constraints linked to manufacturer instructions were the main reason for not using ITCs. People stopped using the ITCs due to perceived allergy, toxicity and low efficacy. Few heads of households refused RIT despite the noting reasons for rejection, such as allergy, health hazard and toxicity. Positive opinions of the vector control program influenced acceptability of both tools. However, frequent insecticide fogging as part of routine AaCP vector control actions diminished perceived efficacy of both tools and, therefore, acceptability. Fifty percent of interviewees did feel at risk for getting dengue and considered dengue a severe disease. However, this did not appear to influence acceptability of ITCs or RIT. Conclusion/significance Acceptability of ITCs and RIT was linked to acceptability of AaCP routine vector control activities. However, uptake and use were not always an indication of acceptability. Factors leading to acceptability may be best identified using qualitative methods, but more research is needed on the concept of acceptability and its measurement. PMID:29293501

Integrated Pest Management Practices Reduce Insecticide Applications, Preserve Beneficial Insects, and Decrease Pesticide Residues in Flue-Cured Tobacco Production.

PubMed

Slone, Jeremy D; Burrack, Hannah J

2016-12-01

Integrated pest management (IPM) recommendations, including scouting and economic thresholds (ETs), are available for North Carolina flue-cured tobacco growers, although ETs for key pests have not been updated in several decades. Moreover, reported IPM adoption rates by flue-cured tobacco growers remain low, at < 40%, according to NC cooperative extension surveys conducted during the last four years. Previous research has suggested that timing insecticide treatments using currently available ETs can reduce the average number of applications to two or fewer per season. We conducted field-scale trials at nine commercial tobacco farms, three in 2104 and six in 2015, to quantify inputs associated with current scouting recommendations, to determine if current ETs were able to reduce insecticide applications as compared to grower standard practices, and to assess the impacts of reduced insecticide applications on end of season yield and pesticide residues. Two fields were identified at each farm and were scouted weekly for insects. One field was only treated with insecticides if pests reached ET (IPM), while the other field was managed per grower discretion (Grower Standard). IPM fields received an average of two fewer insecticide applications without compromising yield. More insecticide applications resulted in higher pesticide residues in cured leaf samples from Grower Standard fields than those from IPM fields. Reductions in insecticides and management intensity also resulted in larger beneficial insect populations in IPM fields. © 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.

An Operational Framework for Insecticide Resistance Management Planning

PubMed Central

Chanda, Emmanuel; Thomsen, Edward K.; Musapa, Mulenga; Kamuliwo, Mulakwa; Brogdon, William G.; Norris, Douglas E.; Masaninga, Freddie; Wirtz, Robert; Sikaala, Chadwick H.; Muleba, Mbanga; Craig, Allen; Govere, John M.; Ranson, Hilary; Hemingway, Janet; Seyoum, Aklilu; Macdonald, Michael B.

2016-01-01

Arthropod vectors transmit organisms that cause many emerging and reemerging diseases, and their control is reliant mainly on the use of chemical insecticides. Only a few classes of insecticides are available for public health use, and the increased spread of insecticide resistance is a major threat to sustainable disease control. The primary strategy for mitigating the detrimental effects of insecticide resistance is the development of an insecticide resistance management plan. However, few examples exist to show how to implement such plans programmatically. We describe the formulation and implementation of a resistance management plan for mosquito vectors of human disease in Zambia. We also discuss challenges, steps taken to address the challenges, and directions for the future. PMID:27089119

An Operational Framework for Insecticide Resistance Management Planning.

PubMed

Chanda, Emmanuel; Thomsen, Edward K; Musapa, Mulenga; Kamuliwo, Mulakwa; Brogdon, William G; Norris, Douglas E; Masaninga, Freddie; Wirtz, Robert; Sikaala, Chadwick H; Muleba, Mbanga; Craig, Allen; Govere, John M; Ranson, Hilary; Hemingway, Janet; Seyoum, Aklilu; Macdonald, Michael B; Coleman, Michael

2016-05-01

Arthropod vectors transmit organisms that cause many emerging and reemerging diseases, and their control is reliant mainly on the use of chemical insecticides. Only a few classes of insecticides are available for public health use, and the increased spread of insecticide resistance is a major threat to sustainable disease control. The primary strategy for mitigating the detrimental effects of insecticide resistance is the development of an insecticide resistance management plan. However, few examples exist to show how to implement such plans programmatically. We describe the formulation and implementation of a resistance management plan for mosquito vectors of human disease in Zambia. We also discuss challenges, steps taken to address the challenges, and directions for the future.

Insecticide Resistance: Challenge to Pest Management and Basic Research

NASA Astrophysics Data System (ADS)

Brattsten, L. B.; Holyoke, C. W.; Leeper, J. R.; Raffa, K. F.

1986-03-01

The agricultural use of synthetic insecticides usually protects crops but imposes strong selection pressures that can result in the development of resistance. The most important resistance mechanisms are enhancement of the capacity to metabolically detoxify insecticides and alterations in target sites that prevent insecticides from binding to them. Insect control methods must incorporate strategies to minimize resistance development and preserve the utility of the insecticides. The most promising approach, integrated pest management, includes the use of chemical insecticides in combination with improved cultural and biologically based techniques.

Readout circuit with novel background suppression for long wavelength infrared focal plane arrays

NASA Astrophysics Data System (ADS)

Xie, L.; Xia, X. J.; Zhou, Y. F.; Wen, Y.; Sun, W. F.; Shi, L. X.

2011-02-01

In this article, a novel pixel readout circuit using a switched-capacitor integrator mode background suppression technique is presented for long wavelength infrared focal plane arrays. This circuit can improve dynamic range and signal-to-noise ratio by suppressing the large background current during integration. Compared with other background suppression techniques, the new background suppression technique is less sensitive to the process mismatch and has no additional shot noise. The proposed circuit is theoretically analysed and simulated while taking into account the non-ideal characteristics. The result shows that the background suppression non-uniformity is ultra-low even for a large process mismatch. The background suppression non-uniformity of the proposed circuit can also remain very small with technology scaling.

Insecticide Resistance and Metabolic Mechanisms Involved in Larval and Adult Stages of Aedes aegypti Insecticide-Resistant Reference Strains from Cuba.

PubMed

Bisset, Juan Andrés; Rodríguez, María Magdalena; French, Leydis; Severson, David W; Gutiérrez, Gladys; Hurtado, Daymi; Fuentes, Ilario

2014-12-01

Studies were conducted to compare levels of insecticide resistance and to determine the metabolic resistance mechanisms in larval and adult stages of Aedes aegypti from Cuba. Three insecticide-resistant reference strains of Ae. aegypti from Cuba were examined. These strains were derived from a Santiago de Cuba strain isolated in 1997; it was previously subjected to a strong selection for resistance to temephos (SAN-F6), deltamethrin (SAN-F12), and propoxur (SAN-F13) and routinely maintained in the laboratory under selection pressure up to the present time, when the study was carried out. In addition, an insecticide-susceptible strain was used for comparison. The insecticide resistance in larvae and adults was determined using standard World Health Organization methodologies. Insecticide resistance mechanisms were determined by biochemical assays. The esterases (α EST and β EST) and mixed function oxidase (MFO) activities were significantly higher in adults than in the larvae of the three resistant strains studied. The association of resistance level with the biochemical mechanism for each insecticide was established for each stage. The observed differences between larval and adult stages of Ae. aegypti in their levels of insecticide resistance and the biochemical mechanisms involved should be included as part of monitoring and surveillance activities in Ae. aegypti vector control programs.

Insecticide-driven patterns of genetic variation in the dengue vector Aedes aegypti in Martinique Island.

PubMed

Marcombe, Sébastien; Paris, Margot; Paupy, Christophe; Bringuier, Charline; Yebakima, André; Chandre, Fabrice; David, Jean-Philippe; Corbel, Vincent; Despres, Laurence

2013-01-01

Effective vector control is currently challenged worldwide by the evolution of resistance to all classes of chemical insecticides in mosquitoes. In Martinique, populations of the dengue vector Aedes aegypti have been intensively treated with temephos and deltamethrin insecticides over the last fifty years, resulting in heterogeneous levels of resistance across the island. Resistance spreading depends on standing genetic variation, selection intensity and gene flow among populations. To determine gene flow intensity, we first investigated neutral patterns of genetic variability in sixteen populations representative of the many environments found in Martinique and experiencing various levels of insecticide pressure, using 6 microsatellites. Allelic richness was lower in populations resistant to deltamethrin, and consanguinity was higher in populations resistant to temephos, consistent with a negative effect of insecticide pressure on neutral genetic diversity. The global genetic differentiation was low, suggesting high gene flow among populations, but significant structure was found, with a pattern of isolation-by-distance at the global scale. Then, we investigated adaptive patterns of divergence in six out of the 16 populations using 319 single nucleotide polymorphisms (SNPs). Five SNP outliers displaying levels of genetic differentiation out of neutral expectations were detected, including the kdr-V1016I mutation in the voltage-gated sodium channel gene. Association tests revealed a total of seven SNPs associated with deltamethrin resistance. Six other SNPs were associated with temephos resistance, including two non-synonymous substitutions in an alkaline phosphatase and in a sulfotransferase respectively. Altogether, both neutral and adaptive patterns of genetic variation in mosquito populations appear to be largely driven by insecticide pressure in Martinique.

Insecticide Mixtures Could Enhance the Toxicity of Insecticides in a Resistant Dairy Population of Musca domestica L

PubMed Central

Khan, Hafiz Azhar Ali; Akram, Waseem; Shad, Sarfraz Ali; Lee, Jong-Jin

2013-01-01

House flies, Musca domestica L., are important pests of dairy operations worldwide, with the ability to adapt wide range of environmental conditions. There are a number of insecticides used for their management, but development of resistance is a serious problem. Insecticide mixtures could enhance the toxicity of insecticides in resistant insect pests, thus resulting as a potential resistance management tool. The toxicity of bifenthrin, cypermethrin, deltamethrin, chlorpyrifos, profenofos, emamectin benzoate and fipronil were assessed separately, and in mixtures against house flies. A field-collected population was significantly resistant to all the insecticides under investigation when compared with a laboratory susceptible strain. Most of the insecticide mixtures like one pyrethroid with other compounds evaluated under two conditions (1∶1-“A” and LC50: LC50-“B”) significantly increased the toxicity of pyrethroids in the field population. Under both conditions, the combination indices of pyrethroids with other compounds, in most of the cases, were significantly below 1, suggesting synergism. The enzyme inhibitors, PBO and DEF, when used in combination with insecticides against the resistant population, toxicities of bifenthrin, cypermethrin, deltamethrin and emamectin were significantly increased, suggesting esterase and monooxygenase based resistance mechanism. The toxicities of bifenthrin, cypermethrin and deltamethrin in the resistant population of house flies could be enhanced by the combination with chlorpyrifos, profenofos, emamectin and fipronil. The findings of the present study might have practical significance for resistance management in house flies. PMID:23613758

Involvement of TrkB- and p75NTR-signaling pathways in two contrasting forms of long-lasting synaptic plasticity

NASA Astrophysics Data System (ADS)

Sakuragi, Shigeo; Tominaga-Yoshino, Keiko; Ogura, Akihiko

2013-11-01

The repetition of experience is often necessary to establish long-lasting memory. However, the cellular mechanisms underlying this repetition-dependent consolidation of memory remain unclear. We previously observed in organotypic slice cultures of the rodent hippocampus that repeated inductions of long-term potentiation (LTP) led to a slowly developing long-lasting synaptic enhancement coupled with synaptogenesis. We also reported that repeated inductions of long-term depression (LTD) produced a long-lasting synaptic suppression coupled with synapse elimination. We proposed these phenomena as useful in vitro models for analyzing repetition-dependent consolidation. Here, we hypothesized that the enhancement and suppression are mediated by the brain-derived neurotrophic factor (BDNF)-TrkB signaling pathway and the proBDNF-p75NTR pathway, respectively. When we masked the respective pathways, reversals of the enhancement and suppression resulted. These results suggest the alternative activation of the p75NTR pathway by BDNF under TrkB-masking conditions and of the TrkB pathway by proBDNF under p75NTR-masking conditions, thus supporting the aforementioned hypothesis.

Use of a Box Model to Estimate the Airborne Concentration of Volatilized DDT in an Experimental Hut in a Tropical Climate

DTIC Science & Technology

2012-06-19

long -­‐ lasting   insecticidal   netting  (LLIN)  have  been  an   effective  tandem  in  vector  control...1.  Introduction     1.1   Background                  The  use  of   indoor   residual   spraying  (IRS...ingestion  or  skin  contact.  9,10    However,  the  widespread

Tennessee and Florida: Continuity and Change in Long-Lasting State Performance Funding Systems for Higher Education. CCRC Brief. Number 43

ERIC Educational Resources Information Center

Dougherty, Kevin J.; Natow, Rebecca S.

2010-01-01

This study analyzes changes over time in long-lasting state performance funding systems for higher education. It addresses two research questions: First, in what ways have long-lasting systems changed over time in funding levels, indicators used to allocate funds, and measures used for those indicators? Second, what political actors, actions, and…

Comparative performance of three experimental hut designs for measuring malaria vector responses to insecticides in Tanzania.

PubMed

Massue, Dennis J; Kisinza, William N; Malongo, Bernard B; Mgaya, Charles S; Bradley, John; Moore, Jason D; Tenu, Filemoni F; Moore, Sarah J

2016-03-15

Experimental huts are simplified, standardized representations of human habitations that provide model systems to evaluate insecticides used in indoor residual spray (IRS) and long-lasting insecticidal nets (LLINs) to kill disease vectors. Hut volume, construction materials and size of entry points impact mosquito entry and exposure to insecticides. The performance of three standard experimental hut designs was compared to evaluate insecticide used in LLINs. Field studies were conducted at the World Health Organization Pesticide Evaluation Scheme (WHOPES) testing site in Muheza, Tanzania. Three East African huts, three West African huts, and three Ifakara huts were compared using Olyset(®) and Permanet 2.0(®) versus untreated nets as a control. Outcomes measured were mortality, induced exophily (exit rate), blood feeding inhibition and deterrence (entry rate). Data were analysed using linear mixed effect regression and Bland-Altman comparison of paired differences. A total of 613 mosquitoes were collected in 36 nights, of which 13.5% were Anopheles gambiae sensu lato, 21% Anopheles funestus sensu stricto, 38% Mansonia species and 28% Culex species. Ifakara huts caught three times more mosquitoes than the East African and West African huts, while the West African huts caught significantly fewer mosquitoes than the other hut types. Mosquito densities were low, very little mosquito exit was measured in any of the huts with no measurable exophily caused by the use of either Olyset or Permanet. When the huts were directly compared, the West African huts measured greater exophily than other huts. As unholed nets were used in the experiments and few mosquitoes were captured, it was not possible to measure difference in feeding success either between treatments or hut types. In each of the hut types there was increased mortality when Permanet or Olyset were present inside the huts compared to the control, however this did not vary between the hut types. Both East African

Insecticide resistance in bedbugs in Thailand and laboratory evaluation of insecticides for the control of Cimex hemipterus and Cimex lectularius (Hemiptera: Cimicidae).

PubMed

Tawatsin, Apiwat; Thavara, Usavadee; Chompoosri, Jakkrawarn; Phusup, Yutthana; Jonjang, Nisarat; Khumsawads, Chayada; Bhakdeenuan, Payu; Sawanpanyalert, Pathom; Asavadachanukorn, Preecha; Mulla, Mir S; Siriyasatien, Padet; Debboun, Mustapha

2011-09-01

Bedbugs are found in many countries around the world, and in some regions they are resistant to numerous insecticides. This study surveyed bedbugs in Thailand and determined their resistance to insecticides. The surveys were carried out in six provinces that attract large numbers of foreign tourists: Bangkok, Chonburi, Chiang Mai, Ubon Ratchathani, Phuket, and Krabi. Bedbugs were collected from hotels and colonized in the laboratory to evaluate their resistance to insecticides. Cimex hemipterus (F.) was found in some hotels in Bangkok, Chonburi, Phuket, and Krabi, whereas Cimex lectularius L. was found only in hotels in Chiang Mai. No bedbugs were found in Ubon Ratchathani. The colonized bedbugs showed resistance to groups of insecticides, including organochlorines (dichlorodiphenyl trichloroethane, dieldrin), carbamates (bendiocarb, propoxur), organophosphates (malathion, fenitrothion), and pyrethroids (cyfluthrin, deltamethrin, permethrin, lambda-cyhalothrin, etofenprox) in tests using World Health Organization insecticide-impregnated papers. The new insecticides imidacloprid (neonicotinoid group), chlorfenapyr (pyrrole group), and fipronil (phenylpyrazole group) were effective against the bedbugs; however, organophosphate (diazinon), carbamates (fenobucarb, propoxur), and pyrethroids (bifenthrin, cypermethrin, esfenvalerate, etofenprox) were ineffective. Aerosols containing various pyrethroid insecticides with two to four different active ingredients were effective against the bedbugs. The results obtained from this study suggested that both species of bedbugs in Thailand have developed marked resistance to various groups of insecticides, especially those in the pyrethroid group, which are the most common insecticides used for pest control. Therefore, an integrated pest management should be implemented for managing bedbugs in Thailand.

Conifer flavonoid compounds inhibit detoxification enzymes and synergize insecticides.

PubMed

Wang, Zhiling; Zhao, Zhong; Cheng, Xiaofei; Liu, Suqi; Wei, Qin; Scott, Ian M

2016-02-01

Detoxification by glutathione S-transferases (GSTs) and esterases are important mechanisms associated with insecticide resistance. Discovery of novel GST and esterase inhibitors from phytochemicals could provide potential new insecticide synergists. Conifer tree species contain flavonoids, such as taxifolin, that inhibit in vitro GST activity. The objectives were to test the relative effectiveness of taxifolin as an enzyme inhibitor and as an insecticide synergist in combination with the organophosphorous insecticide, Guthion (50% azinphos-methyl), and the botanical insecticide, pyrethrum, using an insecticide-resistant Colorado potato beetle (CPB) Leptinotarsa decemlineata (Say) strain. Both taxifolin and its isomer, quercetin, increased the mortality of 1(st) instar CPB larvae after 48h when combined with Guthion, but not pyrethrum. Taxifolin had greater in vitro esterase inhibition compared with the commonly used esterase inhibitor, S, S, S-tributyl phosphorotrithioate (DEF). An in vivo esterase and GST inhibition effect after ingestion of taxifolin was measured, however DEF caused a greater suppression of esterase activity. This study demonstrated that flavonoid compounds have both in vitro and in vivo esterase inhibition, which is likely responsible for the insecticide synergism observed in insecticide-resistant CPB. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Neuropeptide y gates a stress-induced, long-lasting plasticity in the sympathetic nervous system.

PubMed

Wang, Qian; Wang, Manqi; Whim, Matthew D

2013-07-31

Acute stress evokes the fight-or-flight reflex, which via release of the catecholamine hormones affects the function of every major organ. Although the reflex is transient, it has lasting consequences that produce an exaggerated response when stress is reexperienced. How this change is encoded is not known. We investigated whether the reflex affects the adrenal component of the sympathetic nervous system, a major branch of the stress response. Mice were briefly exposed to the cold-water forced swim test (FST) which evoked an increase in circulating catecholamines. Although this hormonal response was transient, the FST led to a long-lasting increase in the catecholamine secretory capacity measured amperometrically from chromaffin cells and in the expression of tyrosine hydroxylase. A variety of approaches indicate that these changes are regulated postsynaptically by neuropeptide Y (NPY), an adrenal cotransmitter. Using immunohistochemistry, RT-PCR, and NPY(GFP) BAC mice, we find that NPY is synthesized by all chromaffin cells. Stress failed to increase secretory capacity in NPY knock-out mice. Genetic or pharmacological interference with NPY and Y1 (but not Y2 or Y5) receptor signaling attenuated the stress-induced change in tyrosine hydroxylase expression. These results indicate that, under basal conditions, adrenal signaling is tonically inhibited by NPY, but stress overrides this autocrine negative feedback loop. Because acute stress leads to a lasting increase in secretory capacity in vivo but does not alter sympathetic tone, these postsynaptic changes appear to be an adaptive response. We conclude that the sympathetic limb of the stress response exhibits an activity-dependent form of long-lasting plasticity.

Long-lasting injection of solar energetic electrons into the heliosphere

NASA Astrophysics Data System (ADS)

Dresing, N.; Gómez-Herrero, R.; Heber, B.; Klassen, A.; Temmer, M.; Veronig, A.

2018-05-01

Context. The main sources of solar energetic particle (SEP) events are solar flares and shocks driven by coronal mass ejections (CMEs). While it is generally accepted that energetic protons can be accelerated by shocks, whether or not these shocks can also efficiently accelerate solar energetic electrons is still debated. In this study we present observations of the extremely widespread SEP event of 26 Dec 2013 To the knowledge of the authors, this is the widest longitudinal SEP distribution ever observed together with unusually long-lasting energetic electron anisotropies at all observer positions. Further striking features of the event are long-lasting SEP intensity increases, two distinct SEP components with the second component mainly consisting of high-energy particles, a complex associated coronal activity including a pronounced signature of a shock in radio type-II observations, and the interaction of two CMEs early in the event. Aims: The observations require a prolonged injection scenario not only for protons but also for electrons. We therefore analyze the data comprehensively to characterize the possible role of the shock for the electron event. Methods: Remote-sensing observations of the complex solar activity are combined with in situ measurements of the particle event. We also apply a graduated cylindrical shell (GCS) model to the coronagraph observations of the two associated CMEs to analyze their interaction. Results: We find that the shock alone is likely not responsible for this extremely wide SEP event. Therefore we propose a scenario of trapped energetic particles inside the CME-CME interaction region which undergo further acceleration due to the shock propagating through this region, stochastic acceleration, or ongoing reconnection processes inside the interaction region. The origin of the second component of the SEP event is likely caused by a sudden opening of the particle trap.

Insecticide resistance and diminished secondary kill performance of bait formulations against German cockroaches (Dictyoptera: Blattellidae)

PubMed Central

Ko, Alexander E.; Bieman, Donald N.; Schal, Coby; Silverman, Jules

2015-01-01

BACKGROUND Bait formulations are considered the most effective method for reducing German cockroach infestations. An important property of some bait formulations is secondary kill, whereby active ingredient is translocated in insect-produced residues throughout the cockroach population, especially affecting relatively sedentary early instar nymphs. RESULTS Blattella germanica was collected from a location where baits containing hydramethylnon, fipronil, or indoxacarb became ineffective, and these AIs were topically applied to adult males. Results revealed the first evidence for hydramethylnon resistance, moderate resistance to fipronil and extremely high resistance to indoxacarb. Insecticide residues excreted by field-collected males that ingested commercial baits effectively killed nymphs of an insecticide-susceptible laboratory strain of B. germanica but failed to kill most nymphs of the field-collected strain. CONCLUSIONS We report three novel findings: 1) The first evidence for hydramethylnon resistance in any insect; 2) extremely high levels of indoxacarb resistance in a field population; and 3) reduced secondary mortality in an insecticide-resistant field-collected strain of B. germanica. We suggest that while secondary mortality is considered to be advantageous in cockroach interventions, the ingestion of sublethal doses of AI by nymphs may select for high insecticide resistance by increasing the frequency of AI resistance alleles within the population. PMID:26689433

Radioligand Recognition of Insecticide Targets.

PubMed

Casida, John E

2018-04-04

Insecticide radioligands allow the direct recognition and analysis of the targets and mechanisms of toxic action critical to effective and safe pest control. These radioligands are either the insecticides themselves or analogs that bind at the same or coupled sites. Preferred radioligands and their targets, often in both insects and mammals, are trioxabicyclooctanes for the γ-aminobutyric acid (GABA) receptor, avermectin for the glutamate receptor, imidacloprid for the nicotinic receptor, ryanodine and chlorantraniliprole for the ryanodine receptor, and rotenone or pyridaben for NADH + ubiquinone oxidoreductase. Pyrethroids and other Na + channel modulator insecticides are generally poor radioligands due to lipophilicity and high nonspecific binding. For target site validation, the structure-activity relationships competing with the radioligand in the binding assays should be the same as that for insecticidal activity or toxicity except for rapidly detoxified or proinsecticide analogs. Once the radioligand assay is validated for relevance, it will often help define target site modifications on selection of resistant pest strains, selectivity between insects and mammals, and interaction with antidotes and other chemicals at modulator sites. Binding assays also serve for receptor isolation and photoaffinity labeling to characterize the interactions involved.

Insecticidal and repellent activities of insecticide-sucrose solutions to Culex pipiens molestus (Diptera: Culicidae) under laboratory and field conditions.

PubMed

Shin, Ehyun; Park, Chan; Ahn, Young-Joon; Lee, Dong-Kyu; Chang, Kyu-Sik

2011-06-01

Culex pipiens molestus Forskal has been reported as a dominant species in underground structures of urban areas in the Republic of Korea (ROK) during all seasons and becomes bothersome to humans in late autumn and winter. Most Cx. pipiens molestus in septic tanks are controlled in the ROK using larvicides such as Bt and IGR. However, there are a number of problems associated with larvicides, such as high cost and requirement for frequent use. In the present work, a new control method for Cx. pipiens molestus in septic tanks by using mixtures of sucrose solution with insecticides was investigated. The insecticidal and repellent activities of ten insecticides were evaluated for best control of Cx. pipiens molestus in septic tanks. Firstly, differences in susceptibilities to insecticides were evaluated in topical assays by forced direct contact bioassay and in a screened wire cage by free direct contact bioassay. The difference in insecticide susceptibility in the mosquitoes was the result of repellency by the insecticides. In three septic tanks, the density of Culex mosquitoes was sharply reduced by a deltamethrin-sucrose solution kit. The results demonstrated the potential for mosquito control by deltamethrin-sucrose solution, and the study offers basic information related to mosquito control in septic tanks. Copyright © 2011 Society of Chemical Industry.

Infrared video tracking of Anopheles gambiae at insecticide-treated bed nets reveals rapid decisive impact after brief localised net contact

PubMed Central

Parker, Josephine E.A.; Angarita-Jaimes, Natalia; Abe, Mayumi; Towers, Catherine E.; Towers, David; McCall, Philip J.

2015-01-01

Long-lasting insecticidal bed nets (LLINs) protect humans from malaria transmission and are fundamental to malaria control worldwide, but little is known of how mosquitoes interact with nets. Elucidating LLIN mode of action is essential to maintain or improve efficacy, an urgent need as emerging insecticide resistance threatens their future. Tracking multiple free-flying Anopheles gambiae responding to human-occupied bed nets in a novel large-scale system, we characterised key behaviours and events. Four behavioural modes with different levels of net contact were defined: swooping, visiting, bouncing and resting. Approximately 75% of all activity occurred at the bed net roof where multiple brief contacts were focussed above the occupant’s torso. Total flight and net contact times were lower at LLINs than untreated nets but the essential character of the response was unaltered. LLINs did not repel mosquitoes but impacted rapidly: LLIN contact of less than 1 minute per mosquito during the first ten minutes reduced subsequent activity; after thirty minutes, activity at LLINs was negligible. Velocity measurements showed that mosquitoes detected nets, including unbaited untreated nets, prior to contact. This is the most complete characterisation of mosquito-LLIN interactions to date, and reveals many aspects of LLIN mode of action, important for developing the next generation of LLINs. PMID:26323965

Identification of a novel cytochrome P450 CYP321B1 gene from tobacco cutworm moth (Spodoptera litura) and RNA interference to evaluate its role in commonly used insecticides

USDA-ARS?s Scientific Manuscript database

BACKGROUND: Insect cytochrome P450 monooxygenases (CYPs or P450s) play an important role in detoxifying insecticides leading to resistance in insect populations. A polyphagous pest, Spodoptera litura (Lepidoptera, Noctuidae) has been shown to be resistant to a wide range of insecticides. In this stu...

Sucrose Improves Insecticide Activity Against Drosophila suzukii (Diptera: Drosophilidae).

PubMed

Cowles, Richard S; Rodriguez-Saona, Cesar; Holdcraft, Robert; Loeb, Gregory M; Elsensohn, Johanna E; Hesler, Steven P

2015-04-01

The addition of sucrose to insecticides targeting spotted wing drosophila, Drosophila suzukii (Matsumura), enhanced lethality in laboratory, semifield, and field tests. In the laboratory, 0.1% sucrose added to a spray solution enhanced spotted wing drosophila feeding. Flies died 120 min earlier when exposed to spinosad residues at label rates enhanced with sucrose. Added sucrose reduced the LC50 for dried acetamiprid residues from 82 to 41 ppm in the spray solution. Laboratory bioassays of spotted wing drosophila mortality followed exposure to grape and blueberry foliage and/or fruit sprayed and aged in the field. On grape foliage, the addition of 2.4 g/liter of sugar with insecticide sprays resulted in an 11 and 6% increase of spotted wing drosophila mortality at 1 and 2 d exposures to residues, respectively, averaged over seven insecticides with three concentrations. In a separate experiment, spinetoram and cyantraniliprole reduced by 95-100% the larval infestation of blueberries, relative to the untreated control, 7 d after application at labeled rates when applied with 1.2 g/liter sucrose in a spray mixture, irrespective of rainfall; without sucrose infestation was reduced by 46-91%. Adding sugar to the organically acceptable spinosyn, Entrust, reduced larval infestation of strawberries by >50% relative to without sugar for five of the six sample dates during a season-long field trial. In a small-plot field test with blueberries, weekly applications in alternating sprays of sucrose plus reduced-risk insecticides, spinetoram or acetamiprid, reduced larval infestation relative to the untreated control by 76%; alternating bifenthrin and phosmet (without sucrose) reduced infestation by 65%. © 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.

Degradation of Insecticides in Poultry Manure: Determining the Insecticidal Treatment Interval for Managing House Fly (Diptera: Muscidae) Populations in Poultry Farms.

PubMed

Ong, Song-Quan; Ab Majid, Abdul Hafiz; Ahmad, Hamdan

2016-04-01

It is crucial to understand the degradation pattern of insecticides when designing a sustainable control program for the house fly, Musca domestica (L.), on poultry farms. The aim of this study was to determine the half-life and degradation rates of cyromazine, chlorpyrifos, and cypermethrin by spiking these insecticides into poultry manure, and then quantitatively analyzing the insecticide residue using ultra-performance liquid chromatography. The insecticides were later tested in the field in order to study the appropriate insecticidal treatment intervals. Bio-assays on manure samples were later tested at 3, 7, 10, and 15 d for bio-efficacy on susceptible house fly larvae. Degradation analysis demonstrated that cyromazine has the shortest half-life (3.01 d) compared with chlorpyrifos (4.36 d) and cypermethrin (3.75 d). Cyromazine also had a significantly greater degradation rate compared with chlorpyrifos and cypermethrin. For the field insecticidal treatment interval study, 10 d was the interval that had been determined for cyromazine due to its significantly lower residue; for ChCy (a mixture of chlorpyrifos and cypermethrin), the suggested interval was 7 d. Future work should focus on the effects of insecticide metabolites on targeted pests and the poultry manure environment.

Leishmaniasis sand fly vector density reduction is less marked in destitute housing after insecticide thermal fogging

PubMed Central

2013-01-01

Background Insecticide thermal fogging (ITF) is a tool to control vector borne diseases. Insecticide application success for vector control has been associated with housing materials and architecture. Vector abundance is correlated with weather changes. Nevertheless, housing quality and weather impacts on vector abundance have been unaccounted for in most New World insecticide control trials for leishmaniasis vectors. Methods We conducted a 15 month insecticide control trial that included two deltamethrin [6 mg a.i.m-2] based ITF interventions in 12 of 24 monitored houses at Trinidad de Las Minas, a hyperendemic cutaneous leishmaniasis transmission village in western Panamá. During the study we followed sand fly (SF) abundance, keeping track of rainfall and quantified housing quality using an index based on architecture and construction materials. Results We found a 50 to 80% reduction in SF density in the fogged houses when compared with control houses, while controlling for seasonal changes in SF abundance associated with rainfall. We found heterogeneities in the reductions, as abundance changed according to SF species: Lutzomyia gomezi, Lu. panamensis, Lu. dysponeta and Lu. triramula reduced in density between 40% and 90% after ITF. In contrast, Lu. trapidoi density increased 5% after ITF. Differences in the impact of ITF were associated with housing quality, the most destitute houses, i.e., those with features that ease insect entrance, had a disproportionally larger SF abundance, in some cases with increased domiciliary SF density following the ITF. Conclusion Our results suggest the potential of insecticide application to control SF density and leishmaniasis transmission could depend on housing quality beyond insecticide efficiency. PMID:23742709

Potential exposure of pollinators to neonicotinoid insecticides from the use of insecticide seed treatments in the mid-southern United States.

PubMed

Stewart, Scott D; Lorenz, Gus M; Catchot, Angus L; Gore, Jeff; Cook, Don; Skinner, John; Mueller, Thomas C; Johnson, Donald R; Zawislak, Jon; Barber, Jonathan

2014-08-19

Research was done during 2012 to evaluate the potential exposure of pollinators to neonicotinoid insecticides used as seed treatments on corn, cotton, and soybean. Samples were collected from small plot evaluations of seed treatments and from commercial fields in agricultural production areas in Arkansas, Mississippi, and Tennessee. In total, 560 samples were analyzed for concentrations of clothianidin, imidacloprid, thiamethoxam, and their metabolites. These included pollen from corn and cotton, nectar from cotton, flowers from soybean, honey bees, Apis mellifera L., and pollen carried by foragers returning to hives, preplanting and in-season soil samples, and wild flowers adjacent to recently planted fields. Neonicotinoid insecticides were detected at a level of 1 ng/g or above in 23% of wild flower samples around recently planted fields, with an average detection level of about 10 ng/g. We detected neonicotinoid insecticides in the soil of production fields prior to planting at an average concentration of about 10 ng/g, and over 80% of the samples having some insecticide present. Only 5% of foraging honey bees tested positive for the presence of neonicotinoid insecticides, and there was only one trace detection (< 1 ng/g) in pollen being carried by those bees. Soybean flowers, cotton pollen, and cotton nectar contained little or no neonicotinoids resulting from insecticide seed treatments. Average levels of neonicotinoid insecticides in corn pollen ranged from less than 1 to 6 ng/g. The highest neonicotinoid concentrations were found in soil collected during early flowering from insecticide seed treatment trials. However, these levels were generally not well correlated with neonicotinoid concentrations in flowers, pollen, or nectar. Concentrations in flowering structures were well below defined levels of concern thought to cause acute mortality in honey bees. The potential implications of our findings are discussed.

Characterizing Interplanetary Structures of Long-Lasting Ionospheric Storm Events

NASA Astrophysics Data System (ADS)

Tandoi, C.; Dong, Y.; Ngwira, C. M.; Damas, M. C.

2015-12-01

Geomagnetic storms can result in periods of heightened TEC (Total Electron Content) in Earth's ionosphere. These periods of change in TEC (dTEC) can have adverse impacts on a technological society, such as scintillation of radio signals used by communication and navigation satellites. However, it is unknown which exact properties of a given storm cause dTEC. We are comparing different solar wind properties that result in a significant long-lasting dTEC to see if there are any patterns that remain constant in these storms. These properties, among others, include the interplanetary magnetic field By and Bz components, the proton density, and the flow speed. As a preliminary investigation, we have studied 15 solar storms. Preliminary results will be presented. In the future, we hope to increase our sample size and analyze over 80 different solar storms, which result in significant dTEC.

Insecticide Recommendations for Arkansas. MP 144.

ERIC Educational Resources Information Center

Jones, Bill F.; Barnes, Gordon

This publication gives, in chart form, insecticides for use on animals, field crops, fruits, flowers, trees and shrubs, household pests, recreation areas, lawn and turf grass, pecans, stored grain, and vegetables. Included in the charts are the insecticides recommended for each insect, formulation to be used, amount, time to apply, and other…

Mechanistic modeling of insecticide risks to breeding birds in ...

EPA Pesticide Factsheets

Insecticide usage in the United States is ubiquitous in urban, suburban, and rural environments. In evaluating data for an insecticide registration application and for registration review, scientists at the United States Environmental Protection Agency (USEPA) assess the fate of the insecticide and the risk the insecticide poses to the environment and non-target wildlife. At the present time, current USEPA risk assessments do not include population-level endpoints. In this paper, we present a new mechanistic model, which allows risk assessors to estimate the effects of insecticide exposure on the survival and seasonal productivity of birds known to use agricultural fields during their breeding season. The new model was created from two existing USEPA avian risk assessment models, the Terrestrial Investigation Model (TIM v.3.0) and the Markov Chain Nest Productivity model (MCnest). The integrated TIM/MCnest model has been applied to assess the relative risk of 12 insecticides used to control corn pests on a suite of 31 avian species known to use cornfields in midwestern agroecosystems. The 12 insecticides that were assessed in this study are all used to treat major pests of corn (corn root worm borer, cutworm, and armyworm). After running the integrated TIM/MCnest model, we found extensive differences in risk to birds among insecticides, with chlorpyrifos and malathion (organophosphates) generally posing the greatest risk, and bifenthrin and ë-cyhalothrin (

Newer insecticides for plant virus disease management.

PubMed

Castle, Steven; Palumbo, John; Prabhaker, Nilima

2009-05-01

Effective management of insect and mite vectors of plant pathogens is of crucial importance to minimize vector-borne diseases in crops. Pesticides play an important role in managing vector populations by reducing the number of individuals that can acquire and transmit a virus, thereby potentially lowering disease incidence. Certain insecticides exhibit properties other than lethal toxicity that affect feeding behaviours or otherwise interfere with virus transmission. To evaluate the potential of various treatments against the Bemisia tabaci-transmitted Cucurbit yellow stunting disorder virus (CYSDV), insecticide field trials were conducted in Yuma, AZ, USA, during spring and autumn growing seasons. Differences in vector-intensity each season led to mixed results, but at least five insecticide treatments showed promise in limiting virus spread during spring 2008. Increasing concern among growers in this region regarding recent epidemics of CYSDV is leading to more intensive use of insecticides that threatens to erupt into unmanageable resistance. Sustainability of insecticides is an important goal of pest management and more specifically resistance management, especially for some of the most notorious vector species such as B. tabaci and Myzus persiscae that are likely to develop resistance.

5 CFR 894.703 - How long does my coverage as an annuitant or compensationer last?

Code of Federal Regulations, 2010 CFR

2010-01-01

... 5 Administrative Personnel 2 2010-01-01 2010-01-01 false How long does my coverage as an annuitant or compensationer last? 894.703 Section 894.703 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES DENTAL AND VISION INSURANCE...

5 CFR 894.703 - How long does my coverage as an annuitant or compensationer last?

Code of Federal Regulations, 2011 CFR

2011-01-01

... 5 Administrative Personnel 2 2011-01-01 2011-01-01 false How long does my coverage as an annuitant or compensationer last? 894.703 Section 894.703 Administrative Personnel OFFICE OF PERSONNEL MANAGEMENT (CONTINUED) CIVIL SERVICE REGULATIONS (CONTINUED) FEDERAL EMPLOYEES DENTAL AND VISION INSURANCE...

Toxicity of nine insecticides on four natural enemies of Spodoptera exigua

PubMed Central

Liu, Yongqiang; Li, Xiangying; Zhou, Chao; Liu, Feng; Mu, Wei

2016-01-01

Spodoptera exigua, which feeds on various crops worldwide, has natural enemies that are susceptible to the insecticides used against S. exigua. We investigate the toxicity and residue risk of 9 insecticides on the development of H. axyridis, C. sinica, S. manilae and T. remus. S. manilae and T. remus adults were sensitive to all 9 insecticides (LC50 less than 2.75 mg a.i. liter−1), while H. axyridis and C. sinica adults were less sensitive (LC50 between 6 × 10−5 mg a.i. liter−1 and 78.95 mg a.i. liter−1). Emamectin benzoate, spinosad, indoxacarb, alpha-cypermethrin, chlorfenapyr and chlorantraniliprole showed no toxicity on H. axyridis, C. sinica, S. manilae and T. remus pupae with the recommended field concentrations. The risk analysis indicated that chlorantraniliprole is harmless to larvae of four natural enemies and adult of H. axyridis, C. sinica and S. manilae. Emamectin benzoate and spinosad had higher safety to the development of H. axyridis, C. sinica, S. manilae and T. remus with the risk duration less than 4d. Indoxacarb, tebufenozide, chlorfenapyr, methomyl, alpha-cypermethrin and chlorpyrifos showed dangerously toxic and long risk duration on S. manilae and T. remus adults. PMID:27958333

Role of cytochrome P450s in insecticide resistance: impact on the control of mosquito-borne diseases and use of insecticides on Earth.

PubMed

David, Jean-Philippe; Ismail, Hanafy Mahmoud; Chandor-Proust, Alexia; Paine, Mark John Ingraham

2013-02-19

The fight against diseases spread by mosquitoes and other insects has enormous environmental, economic and social consequences. Chemical insecticides remain the first line of defence but the control of diseases, especially malaria and dengue fever, is being increasingly undermined by insecticide resistance. Mosquitoes have a large repertoire of P450s (over 100 genes). By pinpointing the key enzymes associated with insecticide resistance we can begin to develop new tools to aid the implementation of control interventions and reduce their environmental impact on Earth. Recent technological advances are helping us to build a functional profile of the P450 determinants of insecticide metabolic resistance in mosquitoes. Alongside, the cross-responses of mosquito P450s to insecticides and pollutants are also being investigated. Such research will provide the means to produce diagnostic tools for early detection of P450s linked to resistance. It will also enable the design of new insecticides with optimized efficacy in different environments.

Role of cytochrome P450s in insecticide resistance: impact on the control of mosquito-borne diseases and use of insecticides on Earth

PubMed Central

David, Jean-Philippe; Ismail, Hanafy Mahmoud; Chandor-Proust, Alexia; Paine, Mark John Ingraham

2013-01-01

The fight against diseases spread by mosquitoes and other insects has enormous environmental, economic and social consequences. Chemical insecticides remain the first line of defence but the control of diseases, especially malaria and dengue fever, is being increasingly undermined by insecticide resistance. Mosquitoes have a large repertoire of P450s (over 100 genes). By pinpointing the key enzymes associated with insecticide resistance we can begin to develop new tools to aid the implementation of control interventions and reduce their environmental impact on Earth. Recent technological advances are helping us to build a functional profile of the P450 determinants of insecticide metabolic resistance in mosquitoes. Alongside, the cross-responses of mosquito P450s to insecticides and pollutants are also being investigated. Such research will provide the means to produce diagnostic tools for early detection of P450s linked to resistance. It will also enable the design of new insecticides with optimized efficacy in different environments. PMID:23297352

Survival and swimming behavior of insecticide-exposed larvae and pupae of the yellow fever mosquito Aedes aegypti

PubMed Central

2014-01-01

Background The yellow fever mosquito Aedes aegypti is essentially a container-inhabiting species that is closely associated with urban areas. This species is a vector of human pathogens, including dengue and yellow fever viruses, and its control is of paramount importance for disease prevention. Insecticide use against mosquito juvenile stages (i.e. larvae and pupae) is growing in importance, particularly due to the ever-growing problems of resistance to adult-targeted insecticides and human safety concerns regarding such use in human dwellings. However, insecticide effects on insects in general and mosquitoes in particular primarily focus on their lethal effects. Thus, sublethal effects of such compounds in mosquito juveniles may have important effects on their environmental prevalence. In this study, we assessed the survival and swimming behavior of A. aegypti 4th instar larvae (L4) and pupae exposed to increasing concentrations of insecticides. We also assessed cell death in the neuromuscular system of juveniles. Methods Third instar larvae of A. aegypti were exposed to different concentrations of azadirachtin, deltamethrin, imidacloprid and spinosad. Insect survival was assessed for 10 days. The distance swam, the resting time and the time spent in slow swimming were assessed in 4th instar larvae (L4) and pupae. Muscular and nervous cells of L4 and pupae exposed to insecticides were marked with the TUNEL reaction. The results from the survival bioassays were subjected to survival analysis while the swimming behavioral data were subjected to analyses of covariance, complemented with a regression analysis. Results All insecticides exhibited concentration-dependent effects on survival of larvae and pupae of the yellow fever mosquito. The pyrethroid deltamethrin was the most toxic insecticide followed by spinosad, imidacloprid, and azadirachtin, which exhibited low potency against the juveniles. All insecticides except azadirachtin reduced L4 swimming speed and

The benefits of cholinergic enhancement during perceptual learning are long-lasting

PubMed Central

Rokem, Ariel; Silver, Michael A.

2013-01-01

The neurotransmitter acetylcholine (ACh) regulates many aspects of cognition, including attention and memory. Previous research in animal models has shown that plasticity in sensory systems often depends on the behavioral relevance of a stimulus and/or task. However, experimentally increasing ACh release in the cortex can result in experience-dependent plasticity, even in the absence of behavioral relevance. In humans, the pharmacological enhancement of ACh transmission by administration of the cholinesterase inhibitor donepezil during performance of a perceptual task increases the magnitude of perceptual learning (PL) and its specificity to physical parameters of the stimuli used for training. Behavioral effects of PL have previously been shown to persist for many months. In the present study, we tested whether enhancement of PL by donepezil is also long-lasting. Healthy human subjects were trained on a motion direction discrimination task during cholinergic enhancement, and follow-up testing was performed 5–15 months after the end of training and without additional drug administration. Increases in performance associated with training under donepezil were evident in follow-up retesting, indicating that cholinergic enhancement has beneficial long-term effects on PL. These findings suggest that cholinergic enhancement of training procedures used to treat clinical disorders should improve long-term outcomes of these procedures. PMID:23755006

A multi-year field study to evaluate the environmental fate and agronomic effects of insecticide mixtures.

PubMed

Whiting, Sara A; Strain, Katherine E; Campbell, Laura A; Young, Bryan G; Lydy, Michael J

2014-11-01

A mixture of insecticides used in corn production was monitored over a three-year period in a field study to determine how long each persists in the environment, where each insecticide travels within the corn field, and the efficacy of using soil-applied insecticides with genetically modified corn. The genetically modified corn contained the insecticidal Cry1Ab and Cry3Bb1 proteins (Bt corn) and the Cry1Ab protein was found to persist only during the corn growing season in soil, runoff water, and runoff sediment with highest concentrations measured during pollination. Very low concentrations of Cry1Ab proteins were measured in soil collected in the non-Bt corn field, and no Cry1Ab proteins were detected in shallow groundwater or soil pore water. Clothianidin, a neonicotinoid insecticide used as a seed coating, was detected in all matrices and remained persistent throughout the year in soil pore water. Tefluthrin, a pyrethroid insecticide applied at planting to control corn rootworm larvae (Diabrotica spp., Coleoptera: Chrysomelidae) populations, was consistently detected in soil, runoff water, and runoff sediment during the corn growing season, but was not detected in groundwater or soil pore water. Tefluthrin did not have an effect on root damage from corn rootworm larvae feeding to Bt corn, but did prevent damage to non-Bt corn. A slight reduction in grain yield was observed in the non-Bt, no tefluthrin treatment when compared to all other treatments, but no significant difference in grain yield was observed among Bt corn treatments regardless of soil insecticide application. In the current study, the use of tefluthrin on Bt corn did not significantly affect crop damage or yield, and tefluthrin may travel off-site in runoff water and sediment. Copyright © 2014 Elsevier B.V. All rights reserved.

An Early Sensitive Period Induces Long-Lasting Plasticity in the Honeybee Nervous System

PubMed Central

Grosso, Juan P.; Barneto, Jesica A.; Velarde, Rodrigo A.; Pagano, Eduardo A.; Zavala, Jorge A.; Farina, Walter M.

2018-01-01

The effect of early experiences on the brain during a sensitive period exerts a long-lasting influence on the mature individual. Despite behavioral and neural plasticity caused by early experiences having been reported in the honeybee Apis mellifera, the presence of a sensitive period in which associative experiences lead to pronounced modifications in the adult nervous system is still unclear. Laboratory-reared bees were fed with scented food within specific temporal windows and were assessed for memory retention, in the regulation of gene expression related to the synaptic formation and in the olfactory perception of their antennae at 17 days of age. Bees were able to retain a food-odor association acquired 5–8 days after emergence, but not before, and showed better retention than those exposed to an odor at 9–12 days. In the brain, the odor-rewarded experiences that occurred at 5–8 days of age boosted the expression levels of the cell adhesion proteins neurexin 1 (Nrx1) and neuroligin 2 (Nlg2) involved in synaptic strength. At the antennae, the experiences increased the electrical response to a novel odor but not to the one experienced. Therefore, a sensitive period that induces long-lasting behavioral, functional and structural changes is found in adult honeybees. PMID:29449804

An Early Sensitive Period Induces Long-Lasting Plasticity in the Honeybee Nervous System.

PubMed

Grosso, Juan P; Barneto, Jesica A; Velarde, Rodrigo A; Pagano, Eduardo A; Zavala, Jorge A; Farina, Walter M

2018-01-01

The effect of early experiences on the brain during a sensitive period exerts a long-lasting influence on the mature individual. Despite behavioral and neural plasticity caused by early experiences having been reported in the honeybee Apis mellifera , the presence of a sensitive period in which associative experiences lead to pronounced modifications in the adult nervous system is still unclear. Laboratory-reared bees were fed with scented food within specific temporal windows and were assessed for memory retention, in the regulation of gene expression related to the synaptic formation and in the olfactory perception of their antennae at 17 days of age. Bees were able to retain a food-odor association acquired 5-8 days after emergence, but not before, and showed better retention than those exposed to an odor at 9-12 days. In the brain, the odor-rewarded experiences that occurred at 5-8 days of age boosted the expression levels of the cell adhesion proteins neurexin 1 ( Nrx1 ) and neuroligin 2 ( Nlg2 ) involved in synaptic strength. At the antennae, the experiences increased the electrical response to a novel odor but not to the one experienced. Therefore, a sensitive period that induces long-lasting behavioral, functional and structural changes is found in adult honeybees.

Susceptibility of Culicidae Mosquitoes to Some Insecticides Recommended by WHO in a Malaria Endemic Area of Southeastern Iran

PubMed Central

Fathian, Mousa; Vatandoost, Hassan; Moosa-Kazemi, Seyed Hassan; Raeisi, Ahmad; Yaghoobi-Ershadi, Mohammad Reza; Oshaghi, Mohammad Ali; Sedaghat, Mohammad Mehdi

2015-01-01

Background: According to the national strategy plan on monitoring of insecticides resistance, this study was carried out to determine the base line susceptibility of the Culicidae mosquitoes to the WHO-recommended insecticides in an endemic focus of malaria in southeastern Iran. Methods: Larval collection was carried out by dipping method and adult collection occurred by suction tube from January to December 2010. The susceptibility test was assessed to DDT 4 %, malathion 5 %, propoxur 0.1 %, deltamethrin 0.05 %, lambda-cyhalothrin 0.05 %, and cyfluthrin 0.15 % at different interval times (discriminative dose) followed by 24 h recovery period. The LT50 and LT90 values were calculated for plotting the regression line using Microsoft office Excel software ver. 2007. Results: Anopheles stephensi was quite resistant to DDT and showed susceptible or tolerant to other insecticides. The LT50 and LT90 values to DDT in this species were 29.07, and 98.26 minutes, respectively. Anopheles culicifacies and Anopheles dthali were found susceptible or tolerant to insecticides. Culex pipiens was found resistance to DDT, propoxur, lambda-cyhalothrin and cyfluthrin whereas observed susceptible to malathion and tolerant to deltamethrin. Ochlerotatus caspius sl. was resistant to DDT, whereas found susceptible to other insecticides. Culisita longiareolata was susceptible to deltamethrin, whereas tolerant to other insecticides. The LT50 and LT90 values of Cs. longiareolata to DDT were 17.82, and 51.26 minutes. Conclusion: We suggested the same study in different parts of the country for monitoring and evaluation of control measures. PMID:26114141

20 CFR 404.1560 - When we will consider your vocational background.

Code of Federal Regulations, 2011 CFR

2011-04-01

... background. 404.1560 Section 404.1560 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE... benefits based on disability which began before age 22, or widow's or widower's benefits based on... activity, and that lasted long enough for you to learn to do it. (See § 404.1565(a).) (2) Determining...

Possession and Usage of Insecticidal Bed Nets among the People of Uganda: Is BRAC Uganda Health Programme Pursuing a Pro-Poor Path?

PubMed Central

Ahmed, Syed Masud; Zerihun, Abebual

2010-01-01

Background The use of insecticidal bed nets is found to be an effective public health tool for control of malaria, especially for under-five children and pregnant women. BRAC, an indigenous Bangladeshi non-governmental development organization, started working in the East African state of Uganda in June 2006. As part of its efforts to improve the health and well-being of its participants, BRAC Uganda has been distributing long lasting insecticide-treated bed nets (LLIN) at a subsidized price through health volunteers since February 2008. This study was conducted in March-April 2009 to examine how equitable the programme had been in consistence with BRAC Uganda's pro-poor policy. Methodology/Principal Findings Information on possession of LLINs and relevant knowledge on its proper use and maintenance was collected from households either with an under-five child and/or a pregnant woman. The sample included three villages from each of the 10 branch offices where BRAC Uganda's community-based health programme was operating. Data were collected by trained enumerators through face-to-face interviews using a hand-held personal digital assistant (PDA). Findings reveal that the study population had superficial knowledge on malaria and its transmission, including the use and maintenance of LLINs. The households' rate of possession of bed nets (41–59%), and the proportion of under-five children (17–19%) and pregnant women (25–27%) who reported sleeping under an LLIN were not encouraging. Inequity was observed in the number of LLINs possessed by the households, in the knowledge on its use and maintenance, and between the two programme areas. Conclusions/Significance The BRAC Uganda's LLINs distribution at a subsidized price appeared to be inadequate and inequitable, and BRAC's knowledge dissemination is insufficient for initiating preventive actions such as proper use of LLINs to interrupt malaria transmission. Findings contribute to the on-going debate on LLINs

Long-lasting, experience-dependent alcohol preference in Drosophila

PubMed Central

Peru y Colón de Portugal, Raniero L.; Ojelade, Shamsideen A.; Penninti, Pranav S.; Dove, Rachel J.; Nye, Matthew J.; Acevedo, Summer F.; Lopez, Antonio; Rodan, Aylin R.; Rothenfluh, Adrian

2013-01-01

To understand the molecular and neural mechanisms underlying alcohol addiction, many models ranging from vertebrates to invertebrates have been developed. In Drosophila melanogaster, behavioral paradigms from assaying acute responses to alcohol, to behaviors more closely modeling addiction, have emerged in recent years. However, both the CAFÉ assay, similar to a 2-bottle choice consumption assay, as well as conditioned odor preference, where ethanol is used as the reinforcer, are labor intensive and have low throughput. To address this limitation, we have established a novel ethanol consumption preference assay, called FRAPPÉ, which allows for fast, high throughput measurement of consumption in individual flies, using a fluorescence plate reader. We show that naïve flies do not prefer to consume ethanol, but various pre-exposures, such as ethanol vapor or voluntary ethanol consumption, induce ethanol preference. This ethanol-primed preference is long lasting and is not driven by calories contained in ethanol during the consumption choice. Our novel experience-dependent model of ethanol preference in Drosophila – a highly genetically tractable organism – therefore recapitulates salient features of human alcohol abuse and will facilitate the molecular understanding of the development of alcohol preference. PMID:24164972

Evaluating the feasibility of using insecticide quantification kits (IQK) for estimating cyanopyrethroid levels for indoor residual spraying in Vanuatu

PubMed Central

2014-01-01

Background The quality of routine indoor residual spraying (IRS) operations is rarely assessed because of the limited choice of methods available for quantifying insecticide content in the field. This study, therefore, evaluated a user-friendly, rapid colorimetric assay for detecting insecticide content after routine IRS operations were conducted. Methods This study was conducted in Tafea Province, Vanuatu. Routine IRS was conducted with lambda cyhalothrin. Two methods were used to quantify the IRS activities: 1) pre-spray application of small felt pads and 2) post-spray removal of insecticide with adhesive. The insecticide content was quantified using a colorimetric assay (Insecticide Quantification Kit [IQK]), which involved exposing each sample to the test reagents for 15 mins. The concentration of insecticide was indicated by the depth of red colour. Results The IQK proved simple to perform in the field and results could be immediately interpreted by the programme staff. The insecticide content was successfully sampled by attaching felt pads to the house walls prior to spraying. The IRS operation was well conducted, with 83% of houses being sprayed at the target dose (20 – 30 mg AI/m2). The average reading across all houses was 24.4 ± 1.5 mg AI/m2. The results from the felt pads applied pre-spray were used as a base to compare methods for sampling insecticide from walls post-spray. The adhesive of Sellotape did not collect adequate samples. However, the adhesive of the felt pads provided accurate samples of the insecticide content on walls. Conclusion The IQK colorimetric assay proved to be a useful tool that was simple to use under realistic field conditions. The assay provided rapid information on IRS spray dynamics and spray team performance, facilitating timely decision making and reporting for programme managers. The IQK colorimetric assay will have direct applications for routine quality control in malaria control programmes globally and has the

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.

Effects of onboard insecticide use on airline flight attendants.

PubMed

Kilburn, Kaye H

2004-06-01

Flight attendants (FAs) exposed to insecticide spray in an aircraft were compared with unexposed subjects for neurobehavioral function, pulmonary function, mood states, and symptoms. The 33 symptomatic FAs were self-selected, and 5 had retired for disability. Testing procedures included balance, reaction time, color discrimination, visual fields, grip strength, verbal recall, problem solving, attention and discrimination functions, and long-term memory functions. Measurements were expressed as a percentage of their predicted values (derived from unexposed controls), and the author compared the means of the percentage predicted values by analysis of variance. Symptom frequencies and Profile of Mood States (POMS) scores were assessed. FAs were significantly more impaired than controls with respect to balance with eyes closed, grip strength, and color discrimination. Nearly half had 3 or more abnormal neurobehavioral functions, after adjustment was made for age, sex, and education level. Neither elevated POMS scores nor frequencies of average symptoms correlated with their numbers of abnormal measurements. Occupational exposure to synthetic pyrethrin insecticides on airliners was associated with neurobehavioral impairment and disability retirement.

Trifluoromethylphenyl amides as novel insecticides and fungicides

USDA-ARS?s Scientific Manuscript database

Because of increased resistance to insecticides in arthropods, it is necessary to identify new chemicals that may have novel modes of action. Following an extensive literature search for compounds with insecticidal and mosquito repellent activity, we have designed and synthesized a set of 20 trif...

Trifluoromethylphenyl amides as novel insecticides and fungicides

USDA-ARS?s Scientific Manuscript database

Because of increased resistance to insecticides in arthropods, it is necessary to identify new chemicals that may have novel modes of action. Following an extensive literature search for compounds with insecticidal and mosquito repellent activity, we have designed and synthesized a set of 20 trifluo...

Trifluoromethylphenyl amides as novel insecticides and fungicides

USDA-ARS?s Scientific Manuscript database

Because of increased resistance to insecticides in arthropods, it is necessary to identify new chemicals that may have novel modes of action. Following an extensive literature search for compounds with insecticidal and mosquito repellent activity, we have designed and synthesized a set of 20 triflu...

Modeling radon daughter deposition rates for low background detectors

NASA Astrophysics Data System (ADS)

Westerdale, S.; Guiseppe, V. E.; Rielage, K.; Elliot, S. R.; Hime, A.

2009-10-01

Detectors such as those looking for dark matter and those working to detect neutrinoless double-beta decay require record low levels of background radiation. One major source of background radiation is from radon daughters that decay from airborne radon. In particular, ^222Rn decay products may be deposited on any detector materials that are exposed to environmental radon. Long-lasting daughters, especially ^210Pb, can pose a long-term background radiation source that can interfere with the detectors' measurements by emitting alpha particles into sensitive parts of the detectors. A better understanding of this radon daughter deposition will allow for preventative actions to be taken to minimize the amount of noise from this source. A test stand has therefore been set up to study the impact of various environmental factors on the rate of radon daughter deposition so that a model can be constructed. Results from the test stand and a model of radon daughter deposition will be presented.

[Household insecticides: pattern of use according to per capita income].

PubMed

Diel, Cristiane; Facchini, Luiz Augusto; Dall'Agnol, Marinel Mór

2003-02-01

Although insecticides are widely used in many countries, few studies of their use in households have been conducted. This study was carried out to describe the household use of insecticides according to per capita income. From October 1999 to January 2000, questionnaires on the use of household insecticides were applied to 2,039 households in the urban area of Pelotas, Brazil. Data was collected on income, use of insecticides in the 12 months prior to the interview, product type and chemical group of the insecticides found in the households and, mechanical protection used for insect control. Chi-square test for trends was used to assess relationships, prevalence rates and confidence intervals. Household insecticides were used in 89% of the households visited at least in one occasion in the 12 months prior to the interview. In 79% one or more units of insecticides were found in the household at the time of the interview. The most common types were aerosols and tablet refills for electric devices of the pyrethroid chemical group. Mechanical protection against insects was not widely used. Higher income households most frequently had insecticides in the form of pyrethroid aerosols while organophosphate sprays were more frequently found in lower income households.

First evidence of resistance to pyrethroid insecticides in Italian Aedes albopictus populations 26 years after invasion.

PubMed

Pichler, Verena; Bellini, Romeo; Veronesi, Rodolfo; Arnoldi, Daniele; Rizzoli, Annapaola; Lia, Riccardo Paolo; Otranto, Domenico; Montarsi, Fabrizio; Carlin, Sara; Ballardini, Marco; Antognini, Elisa; Salvemini, Marco; Brianti, Emanuele; Gaglio, Gabriella; Manica, Mattia; Cobre, Pietro; Serini, Paola; Velo, Enkelejda; Vontas, John; Kioulos, Ilias; Pinto, Joao; Della Torre, Alessandra; Caputo, Beniamino

2018-06-01

Aedes albopictus has spread during the last few decades all over the world. This has increased significantly the risk of exotic arbovirus transmission (e.g. chikungunya, dengue, and Zika) also in temperate areas, as demonstrated by the Chikungunya 2007 and 2017 outbreaks in northeastern and central Italy. Insecticides are an important tool for limiting the circulation of these mosquito-borne viruses. The aim of the present study was to address the gap in current knowledge of pyrethroid insecticide resistance of European Ae. albopictus populations, focusing on populations from Italy, Albania and Greece. Bioassays for resistance to permethrin (0.75%), α-cypermethrin (0.05%) or deltamethrin (0.05%) were performed according to World Health Organization (WHO) protocols and showed reduced susceptibility (<90% mortality) of some Italian populations to permethrin and α-cypermethrin, but not to deltamethrin. This study reports the first evidence of resistance to pyrethroids in adult Italian Ae. albopictus populations. Results refer to the season preceding the Chikungunya 2017 outbreak in central Italy and highlight the need to increase efforts to monitor the spread of insecticide resistance and the need to develop strategies to limit the spread of insecticide resistance, particularly in areas where extensive treatments have been carried out to contain disease outbreaks. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Insecticide resistance is mediated by multiple mechanisms in recently introduced Aedes aegypti from Madeira Island (Portugal)

PubMed Central

Seixas, Gonçalo; Grigoraki, Linda; Weetman, David; Vicente, José Luís; Silva, Ana Clara; Pinto, João; Vontas, John

2017-01-01

Background Aedes aegypti is a major mosquito vector of arboviruses, including dengue, chikungunya and Zika. In 2005, Ae. aegypti was identified for the first time in Madeira Island. Despite an initial insecticide-based vector control program, the species expanded throughout the Southern coast of the island, suggesting the presence of insecticide resistance. Here, we characterized the insecticide resistance status and the underlying mechanisms of two populations of Ae. aegypti from Madeira Island, Funchal and Paúl do Mar. Methodology/Principal findings WHO susceptibility bioassays indicated resistance to cyfluthrin, permethrin, fenitrothion and bendiocarb. Use of synergists significantly increased mortality rates, and biochemical assays indicated elevated activities of detoxification enzymes, suggesting the importance of metabolic resistance. Microarray-based transcriptome analysis detected significant upregulation in both populations of nine cytochrome P450 oxidase genes (including four known pyrethroid metabolizing enzymes), the organophosphate metabolizer CCEae3a, Glutathione-S-transferases, and multiple putative cuticle proteins. Genotyping of knockdown resistance loci linked to pyrethroid resistance revealed fixation of the 1534C mutation, and presence with moderate frequencies of the V1016I mutation in each population. Conclusions/Significance Significant resistance to three major insecticide classes (pyrethroid, carbamate and organophosphate) is present in Ae. aegypti from Madeira Island, and appears to be mediated by multiple mechanisms. Implementation of appropriate resistance management strategies including rotation of insecticides with alternative modes of action, and methods other than chemical-based vector control are strongly advised to delay or reverse the spread of resistance and achieve efficient control. PMID:28742096

Theoretical impact of insecticide-impregnated school uniforms on dengue incidence in Thai children

PubMed Central

Massad, Eduardo; Amaku, Marcos; Coutinho, Francisco Antonio Bezerra; Kittayapong, Pattamaporn; Wilder-Smith, Annelies

2013-01-01

Background Children carry the main burden of morbidity and mortality caused by dengue. Children spend a considerable amount of their day at school; hence strategies that reduce human–mosquito contact to protect against the day-biting habits of Aedes mosquitoes at schools, such as insecticide-impregnated uniforms, could be an effective prevention strategy. Methodology We used mathematical models to calculate the risk of dengue infection based on force of infection taking into account the estimated proportion of mosquito bites that occur in school and the proportion of school time that children wear the impregnated uniforms. Principal findings The use of insecticide-impregnated uniforms has efficacy varying from around 6% in the most pessimistic estimations, to 55% in the most optimistic scenarios simulated. Conclusions Reducing contact between mosquito bites and human hosts via insecticide-treated uniforms during school time is theoretically effective in reducing dengue incidence and may be a valuable additional tool for dengue control in school-aged children. The efficacy of this strategy, however, is dependent on the compliance of the target population in terms of proper and consistent wearing of uniforms and, perhaps more importantly, the proportion of bites inflicted by the Aedes population during school time. PMID:23541045

Pyrethroid insecticides maintain repellent effect on knock-down resistant populations of Aedes aegypti mosquitoes.

PubMed

Bowman, Natalie M; Akialis, Kristin; Cave, Grayson; Barrera, Roberto; Apperson, Charles S; Meshnick, Steven R

2018-01-01

Pyrethroid-treated clothing is commonly worn for protection against mosquitoes; pyrethroids are both insecticides and repellents. Pyrethroid resistance has become increasingly common in Aedes aegypti, the vector of dengue, Zika, and other arboviruses, but it is not clear whether resistance is associated with reductions in repellency. In order to determine whether long-lasting permethrin impregnated (LLPI) clothing is protective, we used Aedes aegypti from New Orleans, LA (pyrethroid-sensitive) and San Juan, PR (resistant) to measure both lethality and repellency. PCR and Sanger sequencing were used to confirm resistance status by detecting mutations in the kdr gene at positions 1016 and 1534. Arm-in-cage trials of 100 Aedes aegypti females from both populations were performed for 10 minutes to bare arm or an arm clothed in untreated military camouflage or military camouflage impregnated with deltamethrin, permethrin, or etofenprox. Trials were repeated 4-5 times on different days. Number of landings, number of blood meals, and immediate and 24-hour mortality were recorded. Mortality was extremely low in all trials. Compared to untreated cloth, mosquitoes demonstrated a trend towards a 2%-63% reduction in landings and a statistically significant 78-100% reduction in blood feeding on pyrethroid-treated cloth for most insecticides. Effects were observed in both pyrethroid-sensitive and pyrethroid-resistant mosquito populations. Our data show that kdr mutations are associated with pyrethroid resistance but are likely not the only contributors. Pyrethroids appear to maintain repellent effect against resistant mosquitoes. This finding suggests that even in places where pyrethroid resistance is widespread, permethrin still has a role for use as a repellent on clothing to protect against mosquito bites.

An insecticidal toxin from Nephila clavata spider venom.

PubMed

Jin, Lin; Fang, Mingqian; Chen, Mengrou; Zhou, Chunling; Ombati, Rose; Hakim, Md Abdul; Mo, Guoxiang; Lai, Ren; Yan, Xiuwen; Wang, Yumin; Yang, Shilong

2017-07-01

Spiders are the most successful insect predators given that they use their venom containing insecticidal peptides as biochemical weapons for preying. Due to the high specificity and potency of peptidic toxins, discoveries of insecticidal toxins from spider venom have provided an opportunity to obtain natural compounds for agricultural applications without affecting human health. In this study, a novel insecticidal toxin (μ-NPTX-Nc1a) was identified and characterized from the venom of Nephila clavata. Its primary sequence is GCNPDCTGIQCGWPRCPGGQNPVMDKCVSCCPFCPPKSAQG which was determined by automated Edman degradation, cDNA cloning, and MS/MS analysis. BLAST search indicated that Nc1a shows no similarity with known peptides or proteins, indicating that Nc1a belongs to a novel family of insecticidal peptide. Nc1a displayed inhibitory effects on Na V and K V channels in cockroach dorsal unpaired median neurons. The median lethal dose (LD50) of Nc1a on cockroach was 573 ng/g. Herein, a study that identifies a novel insecticidal toxin, which can be a potential candidate and/or template for the development of bioinsecticides, is presented.

Long-lasting attentional influence of negative and taboo words in an auditory variant of the emotional Stroop task.

PubMed

Bertels, Julie; Kolinsky, Régine; Pietrons, Elise; Morais, José

2011-02-01

Using an auditory adaptation of the emotional and taboo Stroop tasks, the authors compared the effects of negative and taboo spoken words in mixed and blocked designs. Both types of words elicited carryover effects with mixed presentations and interference with blocked presentations, suggesting similar long-lasting attentional effects. Both were also relatively resilient to the long-lasting influence of the preceding emotional word. Hence, contrary to what has been assumed (Schmidt & Saari, 2007), negative and taboo words do not seem to differ in terms of the temporal dynamics of the interdimensional shifting, at least in the auditory modality. PsycINFO Database Record (c) 2011 APA, all rights reserved.

Sensitivity of Bemisia Tabaci (Hemiptera: Aleyrodidae) to Several New Insecticides in China: Effects of Insecticide Type and Whitefly Species, Strain, and Stage

PubMed Central

Xie, Wen; Liu, Yang; Wang, Shaoli; Wu, Qingjun; Pan, Huipeng; Yang, Xin; Guo, Litao; Zhang, Youjun

2014-01-01

Abstract Whitefly biotypes B and Q are the two most damaging members of the Bemisia tabaci (Hemiptera: Aleyrodidae) species complex. Control of B. tabaci (and especially of Q) has been impaired by resistance to commonly used insecticides. To find new insecticides for B. tabaci management in China, we investigated the sensitivity of eggs, larvae, and adults of laboratory strains of B and Q (named Lab-B and Lab-Q) and field strains of Q to several insecticides. For eggs, larvae, and adults of B. tabaci and for six insecticides (cyantraniliprole, chlorantraniliprole, pyriproxyfen, buprofezin, acetamiprid, and thiamethoxam), LC 50 values were higher for Lab-Q than for Lab-B; avermectin LC 50 values, however, were low for adults of both Lab-Q and Lab-B. Based on the laboratory results, insecticides were selected to test against eggs, larvae, and adults of four field strains of B. tabaci Q. Although the field strains differed in their sensitivity to the insecticides, the eggs and larvae of all strains were highly sensitive to cyantraniliprole, and the adults of all strains were highly sensitive to avermectin. The eggs, larvae, and adults of B. tabaci Q were generally more resistant than those of B. tabaci B to the tested insecticides. B. tabaci Q eggs and larvae were sensitive to cyantraniliprole and pyriproxyfen, whereas B. tabaci Q adults were sensitive to avermectin. Field trials should be conducted with cyantraniliprole, pyriproxyfen, and avermectin for control of B. tabaci Q and B in China. PMID:25434040

Laboratory assays of select candidate insecticides for control of Dendroctonus ponderosae Hopkins Pesticide Management Science 67: 548−555

Treesearch

C.J. Fettig; C.J. Hayes; S.R. McKelvey; S.R. Mori

2011-01-01

BACKGROUND: The mountain pine beetle, Dendroctonus ponderosaeHopkins (Coleoptera: Curculionidae, Scolytinae), is the most destructive bark beetle in western North America. Dendroctonus ponderosae can be prevented from successfully colonizing and killing individual trees by ground-based sprays of insecticides applied directly to...

Insecticide resistance mechanisms associated with different environments in the malaria vector Anopheles gambiae: a case study in Tanzania

PubMed Central

2014-01-01

Background Resistance of mosquitoes to insecticides is a growing concern in Africa. Since only a few insecticides are used for public health and limited development of new molecules is expected in the next decade, maintaining the efficacy of control programmes mostly relies on resistance management strategies. Developing such strategies requires a deep understanding of factors influencing resistance together with characterizing the mechanisms involved. Among factors likely to influence insecticide resistance in mosquitoes, agriculture and urbanization have been implicated but rarely studied in detail. The present study aimed at comparing insecticide resistance levels and associated mechanisms across multiple Anopheles gambiae sensu lato populations from different environments. Methods Nine populations were sampled in three areas of Tanzania showing contrasting agriculture activity, urbanization and usage of insecticides for vector control. Insecticide resistance levels were measured in larvae and adults through bioassays with deltamethrin, DDT and bendiocarb. The distribution of An. gambiae sub-species and pyrethroid target-site mutations (kdr) were investigated using molecular assays. A microarray approach was used for identifying transcription level variations associated to different environments and insecticide resistance. Results Elevated resistance levels to deltamethrin and DDT were identified in agriculture and urban areas as compared to the susceptible strain Kisumu. A significant correlation was found between adult deltamethrin resistance and agriculture activity. The subspecies Anopheles arabiensis was predominant with only few An. gambiae sensu stricto identified in the urban area of Dar es Salaam. The L1014S kdr mutation was detected at elevated frequency in An gambiae s.s. in the urban area but remains sporadic in An. arabiensis specimens. Microarrays identified 416 transcripts differentially expressed in any area versus the susceptible reference

Blood meal origins and insecticide susceptibility of Anopheles arabiensis from Chano in South-West Ethiopia

PubMed Central

2013-01-01

Background Anopheles arabiensis, the main malaria vector in Ethiopia, shows both anthropophilic and zoophilic behaviours. Insecticide resistance is increasing, and alternative methods of vector control are needed. The objectives of this study were to determine the blood meal origins and the susceptibility to insecticides of An. arabiensis from Chano village near Arba Minch in South-West Ethiopia. Methods Blood meal sources of anopheline mosquitoes collected using Centers for Disease Control and Prevention (CDC) light traps and pyrethrum spray catches (PSC) from human dwellings, and hand-held mouth aspirators from outdoor pit shelters were analysed using a direct enzyme-linked-immunosorbent assay (ELISA). The susceptibility of An. arabiensis to pyrethroid insecticides (alphacypermethrin, lambdacyhalothrin, deltamethrin, and cyfluthrin) and DDT was assessed using females reared from larval and pupal collections from natural breeding sites. Results The blood meal origins of 2967 freshly fed Anopheles mosquitoes were determined. An. arabiensis was the predominant species (75%), and it fed mainly on cattle. The densities of both freshly fed An. arabiensis and those fed on human blood followed similar seasonal patterns. The overall human blood index (HBI) of An. arabiensis, including mixed blood meals, was 44% and the bovine blood index (BBI) was 69%. The HBI of An. arabiensis from CDC light trap collections was 75% and this was higher than those for PSC (38%) and outdoor pit shelter collections (13%), while the BBI was 65% for PSC, 68% for outdoor pit shelters and 72% for CDC light traps. More freshly fed and human blood-fed An. arabiensis were sampled from houses close to the shore of Lake Abaya (the major breeding site). A high proportion of An. arabiensis was resistant to the pyrethroid insecticides, with a mortality rate of 56% for lambdacyhalothrin, 50% for cyfluthrin and alphacypermethrin, 47% for deltamethrin, and 10% for DDT. Conclusion Anopheles arabiensis is

Short-Term, Intermittent Fasting Induces Long-Lasting Gut Health and TOR-Independent Lifespan Extension.

PubMed

Catterson, James H; Khericha, Mobina; Dyson, Miranda C; Vincent, Alec J; Callard, Rebecca; Haveron, Steven M; Rajasingam, Arjunan; Ahmad, Mumtaz; Partridge, Linda

2018-06-04

Intermittent fasting (IF) can improve function and health during aging in laboratory model organisms, but the mechanisms at work await elucidation. We subjected fruit flies (Drosophila melanogaster) to varying degrees of IF and found that just one month of a 2-day fed:5-day fasted IF regime at the beginning of adulthood was sufficient to extend lifespan. This long-lasting, beneficial effect of early IF was not due to reduced fecundity. Starvation resistance and resistance to oxidative and xenobiotic stress were increased after IF. Early-life IF also led to higher lipid content in 60-day-old flies, a potential explanation for increased longevity. Guts of flies 40 days post-IF showed a significant reduction in age-related pathologies and improved gut barrier function. Improved gut health was also associated with reduced relative bacterial abundance. Early IF thus induced profound long-term changes. Pharmacological and genetic epistasis analysis showed that IF acted independently of the TOR pathway because rapamycin and IF acted additively to extend lifespan, and global expression of a constitutively active S6K did not attenuate the IF-induced lifespan extension. We conclude that short-term IF during early life can induce long-lasting beneficial effects, with robust increase in lifespan in a TOR-independent manner, probably at least in part by preserving gut health. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

EFFECTS OF TWO PYRETHROID INSECTICIDES ON MOTOR ACTIVITY AND THE ACOUSTIC STARTLE RESPONSE IN THE RAT

EPA Science Inventory

To better characterize the behavioral toxicity of pyrethroid insecticides, comparisons were made of the effects of cismethrin and deltamethrin exposure on motor activity and the acoustic startle response in male Long-Evans rats. Acute dose-effect, acute time course, and 30-day re...

Role of neonicotinyl insecticides in Washington apple integrated pest management. Part I. Control of lepidopteran pests

PubMed Central

Brunner, J. F.; Beers, E. H.; Dunley, J. E.; Doerr, M.; Granger, K.

2005-01-01

Three neonicotinyl insecticides, acetamiprid, thiacloprid and clothianidin, were evaluated for their impact on four species of lepidopteran pests of apple in Washington, the codling moth, Cydia pomonella (L.), the Pandemis leafroller, Pandemis pyrusana Kearfott, and the obliquebanded leafroller, Choristoneura rosaceana (Harris), and Lacanobia subjuncta (Grote & Robinson). None of the neonicotinyl insecticides demonstrated sufficient activity against P. pyrusana, C. rosaceana, or L. subjuncta to warrant field trials. Conversely, all had some activity against one or more stages of C. pomonella. Acetamiprid was highly toxic to larvae in laboratory bioassays, and had relatively long activity of field-aged residues (21 days). It also showed some toxicity to C. pomonella eggs (via topical exposure) and adults. Acetamiprid provided the highest level of fruit protection from C. pomonella attack in field trials conducted over five years in experimental orchards with extremely high codling moth pressure. Thiacloprid performed similarly in bioassays, but fruit protection in field trials was slightly lower than acetamiprid. Clothianidin showed moderate to high toxicity in bioassays, depending on the C. pomonella stage tested, but poor fruit protection from attack in field trials. None of the neonicotinyl insecticides were as toxic to larvae or effective in protecting fruit as the current standard organophosphate insecticide used for C. pomonella control, azinphosmethyl. However, both acetamiprid and thiacloprid should provide acceptable levels of C. pomonella control in commercial orchards where densities are much lower than in the experimental orchards used for our trials. The advantages and disadvantages of the neonicotinyl insecticides as replacements for the organophosphate insecticides and their role in a pest management system for Washington apple orchards are discussed. Abbreviation: MFR Maximum field rate PMID:16341246

20 CFR 416.960 - When we will consider your vocational background.

Code of Federal Regulations, 2011 CFR

2011-04-01

... § 416.960 When we will consider your vocational background. (a) General. If you are age 18 or older and... past 15 years, that was substantial gainful activity, and that lasted long enough for you to learn to... are not disabled. We will not consider your vocational factors of age, education, and work experience...

Simulating cholinesterase inhibition in birds caused by dietary insecticide exposure

USGS Publications Warehouse

Corson, M.S.; Mora, M.A.; Grant, W.E.

1998-01-01

We describe a stochastic simulation model that simulates avian foraging in an agricultural landscape to evaluate factors affecting dietary insecticide exposure and to predict post-exposure cholinesterase (ChE) inhibition. To evaluate the model, we simulated published field studies and found that model predictions of insecticide decay and ChE inhibition reasonably approximated most observed results. Sensitivity analysis suggested that foraging location usually influenced ChE inhibition more than diet preferences or daily intake rate. Although organophosphorus insecticides usually caused greater inhibition than carbamate insecticides, insecticide toxicity appeared only moderately important. When we simulated impact of heavy insecticide applications during breeding seasons of 15 wild bird species, mean maximum ChE inhibition in most species exceeded 20% at some point. At this level of inhibition, birds may experience nausea and/or may exhibit minor behavioral changes. Simulated risk peaked in April–May and August–September and was lowest in July. ChE inhibition increased with proportion of vegetation in the diet. This model, and ones like it, may help predict insecticide exposure of and sublethal ChE inhibition in grassland animals, thereby reducing dependence of ecological risk assessments on field studies alone.

Evaluation of the effectiveness of insecticide trunk injections for control of Latoia lepida (Cramer) in the sweet olive tree Osmanthus fragrans

PubMed Central

Li, Yan; Shi, Xiao-Hua

2016-01-01

The screening of suitable insecticides is a key factor in successfully applying trunk injection technology to ornamental plants. In this study, six chemical pesticides were selected and injected into the trunks of Osmanthus fragrans to control the nettle caterpillar, Latoia lepida (Lepidoptera: Limacodidae), using a no-pressure injection system. The absorption rate of the insecticides, the leaf loss due to insect damage, and the mortality and frass amount of L. lepida larvae were evaluated after 77 and 429 days. The results showed that 4% imidacloprid + carbosulfan and 21% abamectin + imidacloprid + omethoate had the fastest conductivity and were completely absorbed into the trunkswithin14 days; however, the efficiencies of these insecticides in controlling L. lepidawere extremely low. Additionally, the treatment 10% emamectin benzoate + clothianidin and 2.5% emamectin benzoate was almost completely absorbed within 30 days and exhibited a longer duration of insecticide efficiency (>80% mortality) in the upper and lower leaves of the canopy. Treatment with these insecticides also resulted in significantly lower leaf loss and frass amounts. We conclude that emamectin benzoate and emamectin benzoate + clothianidin have a rapid uptake into O. fragrans, and are effective as insecticides over long durations. Hence, they may be a suitable control option for L. lepida in O. fragrans plants. PMID:27688974

Evaluation of the effectiveness of insecticide trunk injections for control of Latoia lepida (Cramer) in the sweet olive tree Osmanthus fragrans.

PubMed

Huang, Jun; Zhang, Juan; Li, Yan; Li, Jun; Shi, Xiao-Hua

2016-01-01

The screening of suitable insecticides is a key factor in successfully applying trunk injection technology to ornamental plants. In this study, six chemical pesticides were selected and injected into the trunks of Osmanthus fragrans to control the nettle caterpillar, Latoia lepida (Lepidoptera: Limacodidae), using a no-pressure injection system. The absorption rate of the insecticides, the leaf loss due to insect damage, and the mortality and frass amount of L. lepida larvae were evaluated after 77 and 429 days. The results showed that 4% imidacloprid + carbosulfan and 21% abamectin + imidacloprid + omethoate had the fastest conductivity and were completely absorbed into the trunkswithin14 days; however, the efficiencies of these insecticides in controlling L. lepidawere extremely low. Additionally, the treatment 10% emamectin benzoate + clothianidin and 2.5% emamectin benzoate was almost completely absorbed within 30 days and exhibited a longer duration of insecticide efficiency (>80% mortality) in the upper and lower leaves of the canopy. Treatment with these insecticides also resulted in significantly lower leaf loss and frass amounts. We conclude that emamectin benzoate and emamectin benzoate + clothianidin have a rapid uptake into O. fragrans, and are effective as insecticides over long durations. Hence, they may be a suitable control option for L. lepida in O. fragrans plants.

Short and long-lasting behavioral consequences of agonistic encounters between male Drosophila melanogaster.

PubMed

Trannoy, Séverine; Penn, Jill; Lucey, Kenia; Popovic, David; Kravitz, Edward A

2016-04-26

In many animal species, learning and memory have been found to play important roles in regulating intra- and interspecific behavioral interactions in varying environments. In such contexts, aggression is commonly used to obtain desired resources. Previous defeats or victories during aggressive interactions have been shown to influence the outcome of later contests, revealing loser and winner effects. In this study, we asked whether short- and/or long-term behavioral consequences accompany victories and defeats in dyadic pairings between male Drosophila melanogaster and how long those effects remain. The results demonstrated that single fights induced important behavioral changes in both combatants and resulted in the formation of short-term loser and winner effects. These decayed over several hours, with the duration depending on the level of familiarity of the opponents. Repeated defeats induced a long-lasting loser effect that was dependent on de novo protein synthesis, whereas repeated victories had no long-term behavioral consequences. This suggests that separate mechanisms govern the formation of loser and winner effects. These studies aim to lay a foundation for future investigations exploring the molecular mechanisms and circuitry underlying the nervous system changes induced by winning and losing bouts during agonistic encounters.

Evaluation of the efficacy of insecticidal coatings based on teflutrin and chlorpyrifos against Rhynchophorus ferrugineus.

PubMed

Pugliese, Massimo; Rettori, Andrea Alberto; Martinis, Roberto; Al-Rohily, Khalid; Velate, Suresh; Moideen, Mohamed Ashraf; Al-Maashi, Ali

2017-08-01

The date palm (Phoenix dactylifera L.), an important economic resource for many nations worldwide, has recently been threatened by the presence of different insect pests, like the red palm weevil (RPW) Rhynchophorus ferrugineus. Two products, a glue (polyvinyl acetate) and an oil (raw linseed oil) were used as coatings and applied together with a repellent and two insecticides (teflutrin and chlorpyrifos) at different dosages on two species of palm (P. dactylifera and P. canariensis). Phytotoxic effects of the treatments were evaluated in a greenhouse on 260 potted palms (130 P. dactylifera and 130 P. canariensis) and no negative effects were observed. Afterwards, a trial lasting 400 days was carried out in a nursery located in Sicily (south Italy), treating 572 potted palm trees (286 P. dactylifera and 286 P. canariensis) with an average diameter at the base of 18-20 cm. After 400 days, 48% of the untreated palms were infested, while only 3% of date palms and 7% of Canary palms treated with insecticide at lower dosages were infested. The application of an insecticide-based coating is a good strategy to control and prevent the red palm weevil infestation, in particular on date palms. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Insecticide susceptibility status of Phlebotomus (Paraphlebotomus) sergenti and Phlebotomus (Phlebotomus) papatasi in endemic foci of cutaneous leishmaniasis in Morocco

PubMed Central

2012-01-01

Background In Morocco, cutaneous leishmaniasis is transmitted by Phlebotomus sergenti and Ph. papatasi. Vector control is mainly based on environmental management but indoor residual spraying with synthetic pyrethroids is applied in many foci of Leishmania tropica. However, the levels and distribution of sandfly susceptibility to insecticides currently used has not been studied yet. Hence, this study was undertaken to establish the susceptibility status of Ph. sergenti and Ph. papatasi to lambdacyhalothrin, DDT and malathion. Methods The insecticide susceptibility status of Ph. sergenti and Ph. papatasi was assessed during 2011, following the standard WHO technique based on discriminating dosage. A series of twenty-five susceptibility tests were carried out on wild populations of Ph. sergenti and Ph. papatasi collected by CDC light traps from seven villages in six different provinces. Knockdown rates (KDT) were noted at 5 min intervals during the exposure to DDT and to lambdacyhalothrin. After one hour of exposure, sandflies were transferred to the observation tubes for 24 hours. After this period, mortality rate was calculated. Data were analyzed by Probit analysis program to determine the knockdown time 50% and 90% (KDT50 and KDT90) values. Results Study results showed that Ph.sergenti and Ph. papatasi were susceptible to all insecticides tested. Comparison of KDT values showed a clear difference between the insecticide knockdown effect in studied villages. This effect was lower in areas subject to high selective public health insecticide pressure in the framework of malaria or leishmaniasis control. Conclusion Phlebotomus sergenti and Ph. papatasi are susceptible to the insecticides tested in the seven studied villages but they showed a low knockdown effect in Azilal, Chichaoua and Settat. Therefore, a study of insecticide susceptibility of these vectors in other foci of leishmaniasis is recommended and the level of their susceptibility should be regularly

The effect of abrupt climate changes and climate background conditions in Southern Europe during the last glacial

NASA Astrophysics Data System (ADS)

Knorr, Gregor; Martin-Puertas, Celia; Brauer, Achim; Lohmann, Gerrit

2015-04-01

The last glacial period is characterized by abrupt and large temperature shifts in Greenland and the North Atlantic realm. Pollen and sediment data from Lago Grande di Monticchio (MON) have demonstrated a clear imprint of these fluctuations operating at millennial time-scales. Interestingly, basic mean environmental condition changes with respect to temperature and precipitation occurred during MIS4, separating warm and dry conditions during MIS5 from relatively cold and humid conditions within MIS3. This general climate background shift is superposed by distinct millennial-scale variability at MON. Using a fully coupled atmosphere-ocean general circulation model applying boundary conditions at 32 ka BP and pre-industrial conditions as a surrogate for MIS3 and MIS5, we have simulated and analysed characteristic changes in Southern Europe during the last glacial. We find that changes in the mean state at MON are mainly related to a partial shift of the North Atlantic deep water (NADW) convection sites from the Nordic Seas to South of Iceland, the presence of the Fennoscandian ice sheet and lower greenhouse gas concentrations. These background characteristics provide the basis for enhanced zonal moisture transport from the eastern North Atlantic to Middle and Southern Europe. Furthermore, simulations of abrupt climate change scenarios show that a deactivation of the convection sites South of Iceland during MIS3 leads to cooler and dryer conditions at MON. Such temperature and precipitation changes are thought to provide a counter-acting effect on woody vegetation and associated pollen signals at MON. This is in contrast to the impact of abrupt climate perturbation scenarios during MIS5, where no significant precipitation changes are detected. Hence, the simulated changes and underlying mechanisms are largely consistent with the recorded proxy evidence with respect to both, mean state and millennial-scale changes.

Exploring the molecular basis of insecticide resistance in the dengue vector Aedes aegypti: a case study in Martinique Island (French West Indies)

PubMed Central

Marcombe, Sébastien; Poupardin, Rodolphe; Darriet, Frederic; Reynaud, Stéphane; Bonnet, Julien; Strode, Clare; Brengues, Cecile; Yébakima, André; Ranson, Hilary; Corbel, Vincent; David, Jean-Philippe

2009-01-01

Background The yellow fever mosquito Aedes aegypti is a major vector of dengue and hemorrhagic fevers, causing up to 100 million dengue infections every year. As there is still no medicine and efficient vaccine available, vector control largely based on insecticide treatments remains the only method to reduce dengue virus transmission. Unfortunately, vector control programs are facing operational challenges with mosquitoes becoming resistant to commonly used insecticides. Resistance of Ae. aegypti to chemical insecticides has been reported worldwide and the underlying molecular mechanisms, including the identification of enzymes involved in insecticide detoxification are not completely understood. Results The present paper investigates the molecular basis of insecticide resistance in a population of Ae. aegypti collected in Martinique (French West Indies). Bioassays with insecticides on adults and larvae revealed high levels of resistance to organophosphate and pyrethroid insecticides. Molecular screening for common insecticide target-site mutations showed a high frequency (71%) of the sodium channel 'knock down resistance' (kdr) mutation. Exposing mosquitoes to detoxification enzymes inhibitors prior to bioassays induced a significant increased susceptibility of mosquitoes to insecticides, revealing the presence of metabolic-based resistance mechanisms. This trend was biochemically confirmed by significant elevated activities of cytochrome P450 monooxygenases, glutathione S-transferases and carboxylesterases at both larval and adult stages. Utilization of the microarray Aedes Detox Chip containing probes for all members of detoxification and other insecticide resistance-related enzymes revealed the significant constitutive over-transcription of multiple detoxification genes at both larval and adult stages. The over-transcription of detoxification genes in the resistant strain was confirmed by using real-time quantitative RT-PCR. Conclusion These results suggest

Long-lasting antifog plasma modification of transparent plastics.

PubMed

Di Mundo, Rosa; d'Agostino, Riccardo; Palumbo, Fabio

2014-10-08

Antifog surfaces are necessary for any application requiring optical efficiency of transparent materials. Surface modification methods aimed toward increasing solid surface energy, even when supposed to be permanent, in fact result in a nondurable effect due to the instability in air of highly hydrophilic surfaces. We propose the strategy of combining a hydrophilic chemistry with a nanotextured topography, to tailor a long-lasting antifog modification on commercial transparent plastics. In particular, we investigated a two-step process consisting of self-masked plasma etching followed by plasma deposition of a silicon-based film. We show that the deposition of the silicon-based coatings on the flat (pristine) substrates allows a continuous variation of wettability from hydrophobic to superhydrophilic, due to a continuous reduction of carbon-containing groups, as assessed by Fourier transform infrared and X-ray photoelectron spectroscopies. By depositing these different coatings on previously nanotextured substrates, the surface wettability behavior is changed consistently, as well as the condensation phenomenon in terms of microdroplets/liquid film appearance. This variation is correlated with advancing and receding water contact angle features of the surfaces. More importantly, in the case of the superhydrophilic coating, though its surface energy decreases with time, when a nanotextured surface underlies it, the wetting behavior is maintained durably superhydrophilic, thus durably antifog.

Sensitivity of Bemisia tabaci (Hemiptera: Aleyrodidae) to several new insecticides in China: effects of insecticide type and whitefly species, strain, and stage.

PubMed

Xie, Wen; Liu, Yang; Wang, Shaoli; Wu, Qingjun; Pan, Huipeng; Yang, Xin; Guo, Litao; Zhang, Youjun

2014-01-01

Whitefly biotypes B and Q are the two most damaging members of the Bemisia tabaci (Hemiptera: Aleyrodidae) species complex. Control of B. tabaci (and especially of Q) has been impaired by resistance to commonly used insecticides. To find new insecticides for B. tabaci management in China, we investigated the sensitivity of eggs, larvae, and adults of laboratory strains of B and Q (named Lab-B and Lab-Q) and field strains of Q to several insecticides. For eggs, larvae, and adults of B. tabaci and for six insecticides (cyantraniliprole, chlorantraniliprole, pyriproxyfen, buprofezin, acetamiprid, and thiamethoxam), LC50 values were higher for Lab-Q than for Lab-B; avermectin LC50 values, however, were low for adults of both Lab-Q and Lab-B. Based on the laboratory results, insecticides were selected to test against eggs, larvae, and adults of four field strains of B. tabaci Q. Although the field strains differed in their sensitivity to the insecticides, the eggs and larvae of all strains were highly sensitive to cyantraniliprole, and the adults of all strains were highly sensitive to avermectin. The eggs, larvae, and adults of B. tabaci Q were generally more resistant than those of B. tabaci B to the tested insecticides. B. tabaci Q eggs and larvae were sensitive to cyantraniliprole and pyriproxyfen, whereas B. tabaci Q adults were sensitive to avermectin. Field trials should be conducted with cyantraniliprole, pyriproxyfen, and avermectin for control of B. tabaci Q and B in China. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

Autoregulation of glial cell line-derived neurotrophic factor expression: implications for the long-lasting actions of the anti-addiction drug, Ibogaine.

PubMed

He, Dao-Yao; Ron, Dorit

2006-11-01

We recently showed that the up-regulation of the glial cell line-derived neurotrophic factor (GDNF) pathway in the midbrain, is the molecular mechanism by which the putative anti-addiction drug Ibogaine mediates its desirable action of reducing alcohol consumption. Human reports and studies in rodents have shown that a single administration of Ibogaine results in a long-lasting reduction of drug craving (humans) and drug and alcohol intake (rodents). Here we determine whether, and how, Ibogaine exerts its long-lasting actions on GDNF expression and signaling. Using the dopaminergic-like SHSY5Y cell line as a culture model, we observed that short-term Ibogaine exposure results in a sustained increase in GDNF expression that is mediated via the induction of a long-lasting autoregulatory cycle by which GDNF positively regulates its own expression. We show that the initial exposure of cells to Ibogaine or GDNF results in an increase in GDNF mRNA, leading to protein expression and to the corresponding activation of the GDNF signaling pathway. This, in turn, leads to a further increase in the mRNA level of the growth factor. The identification of a GDNF-mediated, autoregulatory long-lasting feedback loop could have important implications for GDNF's potential value as a treatment for addiction and neurodegenerative diseases.

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.

Resistance to bio-insecticides or how to enhance their sustainability: a review

PubMed Central

Siegwart, Myriam; Graillot, Benoit; Blachere Lopez, Christine; Besse, Samantha; Bardin, Marc; Nicot, Philippe C.; Lopez-Ferber, Miguel

2015-01-01

After more than 70 years of chemical pesticide use, modern agriculture is increasingly using biological control products. Resistances to conventional insecticides are wide spread, while those to bio-insecticides have raised less attention, and resistance management is frequently neglected. However, a good knowledge of the limitations of a new technique often provides greater sustainability. In this review, we compile cases of resistance to widely used bio-insecticides and describe the associated resistance mechanisms. This overview shows that all widely used bio-insecticides ultimately select resistant individuals. For example, at least 27 species of insects have been described as resistant to Bacillus thuringiensis toxins. The resistance mechanisms are at least as diverse as those that are involved in resistance to chemical insecticides, some of them being common to bio-insecticides and chemical insecticides. This analysis highlights the specific properties of bio-insecticides that the scientific community should use to provide a better sustainability of these products. PMID:26150820

Resistance to bio-insecticides or how to enhance their sustainability: a review.

PubMed

Siegwart, Myriam; Graillot, Benoit; Blachere Lopez, Christine; Besse, Samantha; Bardin, Marc; Nicot, Philippe C; Lopez-Ferber, Miguel

2015-01-01

After more than 70 years of chemical pesticide use, modern agriculture is increasingly using biological control products. Resistances to conventional insecticides are wide spread, while those to bio-insecticides have raised less attention, and resistance management is frequently neglected. However, a good knowledge of the limitations of a new technique often provides greater sustainability. In this review, we compile cases of resistance to widely used bio-insecticides and describe the associated resistance mechanisms. This overview shows that all widely used bio-insecticides ultimately select resistant individuals. For example, at least 27 species of insects have been described as resistant to Bacillus thuringiensis toxins. The resistance mechanisms are at least as diverse as those that are involved in resistance to chemical insecticides, some of them being common to bio-insecticides and chemical insecticides. This analysis highlights the specific properties of bio-insecticides that the scientific community should use to provide a better sustainability of these products.

Changes in insecticide resistance of the rice striped stem borer (Lepidoptera: Crambidae).

PubMed

Su, Jianya; Zhang, Zhenzhen; Wu, Min; Gao, Congfen

2014-02-01

Application of insecticides is the most important method to control Chilo suppressalis (Walker) (Lepidoptera: Crambidae), and continuous use of individual insecticides has driven the rapid development of insecticide resistance in C. suppressalis during the past 30 yr. Monitoring insecticide resistance provides information essential for integrated pest management. Insecticide resistance of field populations to monosultap, triazophos, chlorpyrifos, and abamectin in China was examined in 2010 and 2011. The results indicated that the resistance levels of 14 field populations to four insecticides were significantly different. Four populations showed moderate resistance, and other populations possessed low-level resistance or were susceptible to monosultap. Nine populations displayed an extremely high or a high level of resistance to triazophos, whereas four populations were sensitive to this agent. Five populations exhibited a low level of resistance to abamectin, while the others remained sensitive. When compared with historical data, resistance to monosultap and triazophos decreased significantly, and the percentage of populations with high-level or extremely high-level resistance was obviously reduced. By contrast, the resistance to abamectin increased slightly. The increasing and decreasing resistance levels reported in this study highlight the different evolutionary patterns of insecticide resistance in C. suppressalis. An overreliance on one or two insecticides may promote rapid development of resistance. Slow development of resistance to abamectin, which was used mainly in mixtures with other insecticides, implies that the use of insecticide mixtures may be an effective method to delay the evolution of resistance to insecticides.

Low-frequency stimulation cancels the high-frequency-induced long-lasting effects in the rat medial vestibular nuclei.

PubMed

Grassi, S; Pettorossi, V E; Zampolini, M

1996-05-15

In rat brainstem slices, we investigated the effects of low-frequency stimulation (LFS) of the primary vestibular afferents on the amplitude of the field potentials evoked in the medial vestibular nuclei (MVN). LFS induced long-term effects, the sign of which depended on whether the vestibular neurons were previously conditioned by HFS. In unconditioned slices, LFS evoked modifications of the responses that were similar to those observed after HFS but had a smaller extension. In fact, LFS caused long-lasting potentiation of the N1 wave in the MVN ventral portion (Vp) and long-lasting depression of the N2 wave in the MVN dorsal portion (Dp), whereas it provoked small and variable effects on the N1 wave. By contrast, when the synaptic transmission was already conditioned, LFS influenced the synaptic responses oppositely, reducing or annulling the HFS long-term effects. This phenomenon was specifically induced by LFS, because HFS was not able to cause it. The involvement of NMDA receptors in mediating the LFS long-term effects was supported by the fact that AP-5 prevented their induction. In addition, the annulment of HFS long-term effects by LFS was also demonstrated by the shift in the latency of the evoked unitary potentials after LFS. In conclusion, we suggest that the reduction of the previously induced conditioning could represent a cancellation mechanism, useful to quickly adapt the vestibular system to continuous different needs and to avoid saturation.

Adding yeasts with sugar to increase the number of effective insecticide classes to manage Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) in cherry.

PubMed

Knight, Alan L; Basoalto, Esteban; Yee, Wee; Hilton, Rick; Kurtzman, Cletus P

2016-08-01

Drosophila suzukii is a major pest of cherry in the western United States. We evaluated whether the addition of sugary baits could improve the efficacy of two classes of insecticides not considered to be sufficiently effective for this pest, diamides and spinosyns, in laboratory and field trials in cherry. Adding cane sugar alone or in combination with the yeasts Saccharomyces cerevisiae or Aureobasidium pullulans significantly improved insecticide efficacy. However, the significance of adding yeasts to the sugar plus insecticide on fly mortality varied with respect to both the insecticide and yeast species. The addition of S. cerevisiae to sugar also did not significantly reduce egg densities in fruit compared with sugar alone. The addition of a yeast plus sugar significantly reduced egg densities in three field trials with cyantraniliprole and in two out of three trials with spinosad. The addition of cane sugar with or without yeast can improve the effectiveness of diamide and spinosyn insecticides for D. suzukii in cherry. Inclusion of these two insecticides in D. suzukii management programs may alleviate the strong selection pressure currently being imposed on a few mode-of-action insecticide classes used by growers to maintain fly suppression over long continuous harvest periods of mixed cultivars. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Degradation of Organophosphorus and Pyrethroid Insecticides in Beverages: Implications for Risk Assessment.

PubMed

Radford, Samantha A; Panuwet, Parinya; Hunter, Ronald E; Barr, Dana Boyd; Ryan, P Barry

2018-02-02

Since urinary insecticide metabolites are commonly used as biomarkers of exposure, it is important that we quantify whether insecticides degrade in food and beverages in order to better perform risk assessment. This study was designed to quantify degradation of organophosphorus and pyrethroid insecticides in beverages. Purified water, white grape juice, orange juice, and red wine were fortified with 500 ng/mL diazinon, malathion, chlorpyrifos, permethrin, cyfluthrin, cypermethrin, and deltamethrin, and aliquots were extracted several times over a 15-day storage period at 2.5 °C. Overall, statistically significant loss of at least one insecticide was observed in each matrix, and at least five out of seven insecticides demonstrated a statistically significant loss in all matrices except orange juice. An investigation of an alternative mechanism of insecticide loss-adsorption onto the glass surface of the storage jars-was carried out, which indicated that this mechanism of loss is insignificant. Results of this work suggest that insecticides degrade in these beverages, and this degradation may lead to pre-existing insecticide degradates in the beverages, suggesting that caution should be exercised when using urinary insecticide metabolites to assess exposure and risk.

Degradation of Organophosphorus and Pyrethroid Insecticides in Beverages: Implications for Risk Assessment

PubMed Central

Panuwet, Parinya; Hunter, Ronald E.; Barr, Dana Boyd; Ryan, P. Barry

2018-01-01

Since urinary insecticide metabolites are commonly used as biomarkers of exposure, it is important that we quantify whether insecticides degrade in food and beverages in order to better perform risk assessment. This study was designed to quantify degradation of organophosphorus and pyrethroid insecticides in beverages. Purified water, white grape juice, orange juice, and red wine were fortified with 500 ng/mL diazinon, malathion, chlorpyrifos, permethrin, cyfluthrin, cypermethrin, and deltamethrin, and aliquots were extracted several times over a 15-day storage period at 2.5 °C. Overall, statistically significant loss of at least one insecticide was observed in each matrix, and at least five out of seven insecticides demonstrated a statistically significant loss in all matrices except orange juice. An investigation of an alternative mechanism of insecticide loss—adsorption onto the glass surface of the storage jars—was carried out, which indicated that this mechanism of loss is insignificant. Results of this work suggest that insecticides degrade in these beverages, and this degradation may lead to pre-existing insecticide degradates in the beverages, suggesting that caution should be exercised when using urinary insecticide metabolites to assess exposure and risk. PMID:29393904

Determination of the predictive factors of long-lasting insecticide-treated net ownership and utilisation in the Bamenda Health District of Cameroon.

PubMed

Fokam, Eric B; Kindzeka, Germaine F; Ngimuh, Leonard; Dzi, Kevin T J; Wanji, Samuel

2017-03-16

Malaria is a serious health concern in Africa. In Cameroon, an endemic country where malaria remains a major public health problem, several control measures have been put in place among which the use of insecticide-treated bednets (LLINs/ITNs) is considered one of the core vector control strategies. However, the greatest challenges include ownership and utilisation by individuals and households. Factors such as age, marital status, gender, education and occupation of the household head, household size, knowledge of bednets, socioeconomic status, and environmental factors have been suggested to have an impact on bednet ownership and utilisation in different settings. The present study sought to determine bednet ownership and utilisation rates and to assess the impact of predictive factors on bednet ownership and use in the Bamenda Health District (BHD) of Cameroon. A cross-sectional study involving 384 households was conducted in six health areas in the BHD. A structured and semi-structured questionnaire was used to collect data on demographic and household characteristics as well as information on their bednet ownership and utilisation. Descriptive statistics, bivariate and multivariate logistic regression analysis were performed. Frequency of bednet ownership was relatively high (63.5%) with LLINs being most abundant (91.9%); the majority of households (87.7%) obtained their bednets during the 2011 free distribution campaign. Utilisation was relatively high (69.3%), with negligence (29.3%) and heat discomfort (26.7%) accounting most for non-usage of bednets. Children less than 5 years (63%) and pregnant women (60%) most often used these nets. Households headed by a married couple, those with older household heads, household with smaller size (5-12 persons), and knowledge of bednets (good knowledge) had positive impacts on bednet ownership (p < 0.05). The gender of the household head (males), their educational level, environmental conditions (presence of

Assessing the fate and effects of an insecticidal formulation.

PubMed

de Perre, Chloé; Williard, Karl W J; Schoonover, Jon E; Young, Bryan G; Murphy, Tracye M; Lydy, Michael J

2015-01-01

A 3-yr study was conducted on a corn field in central Illinois, USA, to understand the fate and effects of an insecticidal formulation containing the active ingredients phostebupirim and cyfluthrin. The objectives were to determine the best tillage practice (conventional vs conservation tillage) in terms of grain yields and potential environmental risk, to assess insecticidal exposure using concentrations measured in soil and runoff water and sediments, to compare measured insecticidal concentrations with predicted concentrations from selected risk assessment exposure models, and to calculate toxicity benchmarks from laboratory bioassays performed on reference aquatic and terrestrial nontarget organisms, using individual active ingredients and the formulation. Corn grain yields were not significantly different based on tillage treatment. Similarly, field concentrations of insecticides were not significantly (p > 0.05) different in strip tillage versus conventional tillage, suggesting that neither of the tillage systems would enable greater environmental risk from the insecticidal formulation. Risk quotients were calculated from field concentrations and toxicity data to determine potential risk to nontarget species. The insecticidal formulation used at the recommended rate resulted in soil, sediment, and water concentrations that were potentially harmful to aquatic and terrestrial invertebrates, if exposure occurred, with risk quotients up to 34. © 2014 SETAC.

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport.

PubMed

Giorio, Chiara; Safer, Anton; Sánchez-Bayo, Francisco; Tapparo, Andrea; Lentola, Andrea; Girolami, Vincenzo; van Lexmond, Maarten Bijleveld; Bonmatin, Jean-Marc

2017-11-05

With the exponential number of published data on neonicotinoids and fipronil during the last decade, an updated review of literature has been conducted in three parts. The present part focuses on gaps of knowledge that have been addressed after publication of the Worldwide Integrated Assessment (WIA) on systemic insecticides in 2015. More specifically, new data on the mode of action and metabolism of neonicotinoids and fipronil, and their toxicity to invertebrates and vertebrates, were obtained. We included the newly detected synergistic effects and/or interactions of these systemic insecticides with other insecticides, fungicides, herbicides, adjuvants, honeybee viruses, and parasites of honeybees. New studies have also investigated the contamination of all environmental compartments (air and dust, soil, water, sediments, and plants) as well as bees and apicultural products, food and beverages, and the exposure of invertebrates and vertebrates to such contaminants. Finally, we review new publications on remediation of neonicotinoids and fipronil, especially in water systems. Conclusions of the previous WIA in 2015 are reinforced; neonicotinoids and fipronil represent a major threat worldwide for biodiversity, ecosystems, and all the services the latter provide.

Effects of Insecticidal Ketones Present in Mint Plants on GABAA Receptor from Mammalian Neurons

PubMed Central

Sánchez-Borzone, Mariela Eugenia; Marin, Leticia Delgado; García, Daniel Asmed

2017-01-01

Background: The genus Mentha, an important member of the Lamiaceae family, is represented by many species commonly known as mint. The insecticidal activity of Mentha oil and its main components has been tested and established against various insects/pests. Among these, the ketone monoterpenes that are most common in different Mentha species demonstrated insect toxicity, with pulegone being the most active, followed by carvone and menthone. Considering that the GABAA receptor (GABAA-R) is one of the main insecticide targets on neurons, and that pulegone would modulate the insect GABA system, it may be expected that the insecticidal properties of Mentha ketones are mediated by their interaction with this receptor. Objective: In order to discern the pharmacological actions of these products when used as insecticides on mammalian organisms, we evaluated the pharmacologic activity of ketones, commonly present in Mentha plants, on native GABAA-R from rats. Materials and Methods: Determination of ketones effects on allosterically enhanced benzodiazepine binding, using primary cultures of cortical neurons, which express functional receptors and MTT assay to evaluate their cell toxicity. Results: Our results seem to indicate that ketone components of Mentha, with proven repellent or insecticide activity, were able to behave as GABAA-R negative allosteric modulators in murine cells and consequently could exhibit convulsant activity in mammalians. Only pulegone at the highest assayed concentration (2 mM) showed a significant reduction in cell viability after exposure for 24 hr. Conclusion: The present results strongly suggest that the ketone components of Mentha are able to exhibit convulsant activity in mammalian organisms, but functional assays and in vivo experiments would be necessary to corroborate this proposed action. SUMMARY The pharmacological activity of insecticide ketones, commonly present in Mentha plants, was evaluated on native GABAA receptor from mammalian

Decaleside: a new class of natural insecticide targeting tarsal gustatory sites

NASA Astrophysics Data System (ADS)

Rajashekar, Yallappa; Rao, Lingamallu J. M.; Shivanandappa, Thimmappa

2012-10-01

Natural sources for novel insecticide molecules hold promise in view of their eco-friendly nature, selectivity, and mammalian safety. Recent progress in understanding the biology of insect olfaction and taste offers new strategies for developing selective pest control agents. We have isolated two natural insecticidal molecules from edible roots of Decalepis hamiltonii named Decalesides I and II, which are novel trisaccharides, highly toxic to household insect pests and stored-product insects. We have experimentally shown that insecticidal activity requires contact with tarsi on the legs but is not toxic orally. The insecticidal activity of molecules is lost by hydrolysis, and various sugars modify toxic response, showing that the insecticidal activity is via gustatory sites on the tarsi. Selective toxicity to insects by virtue of their gustatory site of action and the mammalian safety of the new insecticides is inherent in their chemical structure with 1-4 or 1-1 α linkage that is easily hydrolyzed by digestive enzymes of mammals. Decalesides represent a new chemical class of natural insecticides with a unique mode of action targeting tarsal chemosensory/gustatory system of insects.

Malaria burden and costs of intensified control in Bhutan, 2006-14: an observational study and situation analysis.

PubMed

Wangdi, Kinley; Banwell, Cathy; Gatton, Michelle L; Kelly, Gerard C; Namgay, Rinzin; Clements, Archie C A

2016-05-01

The number of malaria cases has fallen in Bhutan in the past two decades, and the country has a goal of complete elimination of malaria by 2016. The aims of this study are to ascertain the trends and burden of malaria, the costs of intensified control activities, the main donors of funding for the control activities, and the costs of different preventive measures in the pre-elimination phase (2006-14) in Bhutan. We undertook a descriptive analysis of malaria surveillance data from 2006 to 2014, using data from the Vector-borne Disease Control Programme (VDCP) run by the Department of Public Health of Bhutan's Ministry of Health. Malaria morbidity and mortality in local Bhutanese people and foreign nationals were analysed. The cost of different control and preventive measures were calculated, and the average numbers of long-lasting insecticidal nests per person were estimated. A total of 5491 confirmed malaria cases occurred in Bhutan between 2006 and 2014. By 2013, there was an average of one long-lasting insecticidal net for every 1·51 individuals. The cost of procuring long-lasting insecticidal nets accounted for more than 90% of the total cost of prevention measures. The Global Fund to Fight AIDS, Tuberculosis and Malaria was the main international donor, accounting for more than 80% of the total funds. The malaria burden in Bhutan decreased significantly during the study period with high coverage of long-lasting insecticidal nets. The foreseeable challenges that require national attention to maintain a malaria-free status after elimination are importation of malaria, especially from India; continued protection of the population in endemic districts through complete coverage with long-lasting insecticidal nets and indoor residual spraying; and exploration of local funding modalities post-elimination in the event of a reduction in international funding. None. Copyright © 2016 Wangdi et al. Open Access article distributed under the terms of CC BY. Published by

Insecticide resistance management strategies against the western flower thrips, Frankliniella occidentalis.

PubMed

Bielza, Pablo

2008-11-01

Western flower thrips (WFT), Frankliniella occidentalis (Pergande), is an economically important pest of a wide range of crops grown throughout the world. Insecticide resistance has been documented in many populations of WFT. Biological and behavioural characteristics and pest management practices that promote insecticide resistance are discussed. In addition, an overview is provided of the development of insecticide resistance in F. occidentalis populations and the resistance mechanisms involved. Owing to widespread resistance to most conventional insecticides, a new approach to insecticide resistance management (IRM) of F. occidentalis is needed. The IRM strategy proposed consists of two parts. Firstly, a general strategy to minimise the use of insecticides in order to reduce selection pressure. Secondly, a strategy designed to avoid selection of resistance mechanisms, considering cross-resistance patterns and resistance mechanisms. Copyright (c) 2008 Society of Chemical Industry.

ANDROGEN RECEPTOR ANTAGONISM BY THE ORGANOPHOSPHATE INSECTICIDE FENITROTHION

EPA Science Inventory

Androgen receptor antagonism by the organophosphate insecticide fenitrothion. Tamura, H., Maness, S.C., Reischmann, K. Dorman, D.C., Gray, L.E., and Gaido, K.W. (2000). Toxicol. Sci.

Organophosphate insecticides represent one of the most widely used classes of pesticide...

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

Analysis of Insecticides in Dead Wild Birds in Korea from 2010 to 2013.

PubMed

Kim, Soohee; Park, Mi-Young; Kim, Hyo-Jin; Shin, Jin Young; Ko, Kyung Yuk; Kim, Dong-Gyu; Kim, MeeKyung; Kang, Hwan-Goo; So, ByungJae; Park, Sung-Won

2016-01-01

Wild birds are exposed to insecticides in a variety of ways, at different dose levels and via multiple routes, including ingestion of contaminated food items, and dermal, inhalation, preening, and embryonic exposure. Most poisoning by insecticides occurs as a result of misuse or accidental exposure, but intentional killing of unwanted animals also occurs. In this study, we investigated insecticides in the gastric contents of dead wild birds that were suspected to have died from insecticide poisoning based on necropsy. The wild birds were found dead in various regions and locations such as in mountains, and agricultural and urban areas. A total of 182 dead wild birds of 27 species were analyzed in this study, and insecticide residue levels were determined in 60.4% of the total samples analyzed. Monocrotophos and phosphamidon were the most common insecticides identified at rates of 50.0% and 30.7% of the insecticide-positive samples, respectively. Other insecticides identified in dead wild birds included organophosphorous, organochlorine and carbamate insecticides. However, there was limited evidence to conclusively establish the cause of death related to insecticides in this study. Nevertheless, considering the level of insecticide exposure, it is speculated that the exposure was mainly a result of accidental or intentional killing, and not from environmental residue.

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

PubMed Central

Behrens, Janina R.; Kraft, Antje; Irlbacher, Kerstin; Gerhardt, Holger; Olma, Manuel C.; Brandt, Stephan A.

2017-01-01

Understanding processes performed by an intact visual cortex as the basis for developing methods that enhance or restore visual perception is of great interest to both researchers and medical practitioners. Here, we explore whether contrast sensitivity, a main function of the primary visual cortex (V1), can be improved in healthy subjects by repetitive, noninvasive anodal transcranial direct current stimulation (tDCS). Contrast perception was measured via threshold perimetry directly before and after intervention (tDCS or sham stimulation) on each day over 5 consecutive days (24 subjects, double-blind study). tDCS improved contrast sensitivity from the second day onwards, with significant effects lasting 24 h. After the last stimulation on day 5, the anodal group showed a significantly greater improvement in contrast perception than the sham group (23 vs. 5%). We found significant long-term effects in only the central 2–4° of the visual field 4 weeks after the last stimulation. We suspect a combination of two factors contributes to these lasting effects. First, the V1 area that represents the central retina was located closer to the polarization electrode, resulting in higher current density. Second, the central visual field is represented by a larger cortical area relative to the peripheral visual field (cortical magnification). This is the first study showing that tDCS over V1 enhances contrast perception in healthy subjects for several weeks. This study contributes to the investigation of the causal relationship between the external modulation of neuronal membrane potential and behavior (in our case, visual perception). Because the vast majority of human studies only show temporary effects after single tDCS sessions targeting the visual system, our study underpins the potential for lasting effects of repetitive tDCS-induced modulation of neuronal excitability. PMID:28860969

Radio observations of GRB 100418a: Test of an energy injection model explaining long-lasting GRB afterglows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moin, A.; Wang, Z.; Chandra, P.

We present the results of our radio observational campaign of gamma-ray burst (GRB) 100418a, for which we used the Australia Telescope Compact Array, the Very Large Array, and the Very Long Baseline Array. GRB 100418a was a peculiar GRB with unusual X-ray and optical afterglow profiles featuring a plateau phase with a very shallow rise. This observed plateau phase was believed to be due to a continued energy injection mechanism that powered the forward shock, giving rise to an unusual and long-lasting afterglow. The radio afterglow of GRB 100418a was detectable several weeks after the prompt emission. We conducted long-termmore » monitoring observations of the afterglow and attempted to test the energy injection model advocating that the continuous energy injection is due to shells of material moving at a wide range of Lorentz factors. We obtained an upper limit of γ < 7 for the expansion rate of the GRB 100418a radio afterglow, indicating that the range-of-Lorentz factor model could only be applicable for relatively slow-moving ejecta. A preferred explanation could be that continued activity of the central engine may have powered the long-lasting afterglow.« less

Horizontal Transfer of Diatomaceous Earth and Botanical Insecticides in the Common Bed Bug, Cimex lectularius L.; Hemiptera: Cimicidae

PubMed Central

Akhtar, Yasmin; Isman, Murray B.

2013-01-01

Background Horizontal transfer of insecticide occurs when insects contact or ingest an insecticide, return to an aggregation or a nest, and transfer the insecticide to other conspecific insects through contact. This phenomenon has been reported in a number of insects including social insects, however it has not been reported in bed bugs. Since horizontal transfer can facilitate the spread of insecticide into hard to reach spaces, it could contribute greatly to the management of these public health pests. Methodology/Results To demonstrate horizontal transfer of diatomaceous earth and botanical insecticides in C. lectularius, an exposed (donor) bed bug, following a 10-minute acquisition period, was placed with unexposed (recipient) bed bugs. Mortality data clearly demonstrates that diatomaceous earth (DE 51) was actively transferred from a single exposed bug to unexposed bugs in a concentration dependent manner. LC50 values varied from 24.4 mg at 48 h to 5.1 mg at 216 h when a single exposed bed bug was placed with 5 unexposed bed bugs. LT50 values also exhibited a concentration response. LT50 values varied from 1.8 days to 8.4 days when a ‘donor’ bug exposed to 20 and 5 mg of dust respectively was placed with 5 ‘recipient’ bugs. Dust was also actively transferred from adult bed bugs to the nymphs. In addition we observed horizontal transfer of botanical insecticides including neem, ryania, and rotenone to varying degrees. Conclusion/Significance Our data clearly demonstrate horizontal transfer of diatomaceous earth and botanical insecticides in the common bed bug, C. lectularius. Use of a fluorescent dust provided visual confirmation that contaminated bed bugs transfer dust to untreated bed bugs in harborage. This result is important because bedbugs live in hard-to-reach places and interaction between conspecifics can be exploited for delivery and dissemination of management products directed at this public health pest. PMID:24086593

Deltamethrin-incorporated nets as an integrated pest management tool for the invasive Halyomorpha halys (Hemiptera: Pentatomidae)

USDA-ARS?s Scientific Manuscript database

Long-lasting insecticide nets (LLINs), which have insecticide incorporated within the fibers, have been widely used for the control of malaria and other insect-vectored diseases. Only recently have researchers begun exploring their use for control of agricultural pests. In this study, we evaluated...

Ecotoxicological Study of Insecticide Effects on Arthropods in Common Bean

PubMed Central

de Barros, Emerson Cristi; Ventura, Hudson Vaner; Gontijo, Pablo Costa; Pereira, Renata Ramos; Picanço, Marcelo Coutinho

2015-01-01

Arthropods are an important group of macroorganisms that work to maintain ecosystem health. Despite the agricultural benefits of chemical control against arthropod pests, insecticides can cause environmental damage. We examined the effects of one and two applications of the insecticides chlorfenapyr (0.18 liters a.i. ha-1) and methamidophos (0.45 liters a.i. ha-1), both independently and in combination, on arthropods in plots of common bean. The experiment was repeated for two growing seasons. Principal response curve, richness estimator, and Shannon–Wiener diversity index analyses were performed. The insecticides generally affected the frequency, richness, diversity, and relative abundance of the arthropods. In addition, the arthropods did not experience recovery after the insecticide applications. The results suggest that the insecticide impacts were sufficiently drastic to eliminate many taxa from the studied common bean plots. PMID:25700537

Insecticides for Suppression of Nylanderia fulva

PubMed Central

Oi, Faith; Oi, David; Mannion, Catharine

2017-01-01

Nylanderia fulva (Mayr) is an invasive ant that is a serious pest in the southern United States. Pest control operators and homeowners are challenged to manage pest populations below acceptable thresholds. Contact and bait insecticides are key components of an Integrated Pest Management (IPM) strategy, however, little is known about their efficacy. In repellency and efficacy bioassays, N. fulva were not completely repelled by any insecticide tested, although fewer ants crossed a surface treated with Temprid®. Few insecticides provided rapid control. Termidor® and Temprid® were the best performing with mean mortality of 100% in 13.4 and 19.0 days, respectively. In no-choice bait acceptance studies, it was shown that N. fulva generally had greater acceptance of carbohydrate-based ant baits (Advion®, InTiceTM (gel), and InTiceTM (granular)). However, mortality was low for the InTiceTM baits in a 7-day bioassay. Maxforce® Ant Killer Bait Gel and Advance® 375A in the spring and Maxforce® Complete in the summer and fall required the fewest days to reach 100% mortality. Bait active ingredients that resulted in the highest mortality were hydramethylnon and fipronil. These data on the efficacy of commercially available contact and bait insecticides provide valuable information to manage this invasive pest. PMID:28858251

Long-lasting changes in stress-induced corticosterone response and anxiety-like behaviors as a consequence of neonatal maternal separation in Long-Evans rats.

PubMed

Kalinichev, Mikhail; Easterling, Keith W; Plotsky, Paul M; Holtzman, Stephen G

2002-08-01

Early neonatal environmental factors appear to have powerful and long-lasting influences on an organism's physiology and behavior. Long-Evans male rats separated from their dam for 3 h daily over the first 2 weeks of life (maternally separated, MS rats) when tested as adults exhibit exaggerated behavioral and neuroendocrine responses to stress compared to 15-min separated (handled, H) animals. The purpose of this study was to compare male and female adult rats that were MS, H or were undisturbed (nonhandled, NH) as neonates in anxiety-like behaviors, in the elevated plus-maze, and in response to startle-inducing auditory stimuli. We confirmed that MS males oversecrete corticosterone (CORT; 2.5-5 times) in response to mild handling stress. MS males and females were less likely to explore open arms of the plus-maze. MS males exhibited 35% higher startle amplitudes compared to controls. Furthermore, MS males were more likely to emit ultrasonic vocalizations in response to startle than were H controls. However, MS and control females did not differ in auditory startle response or in startle-induced ultrasonic vocalizations. Therefore, experiencing maternal separation results in a long-lasting increase in anxiety-like behaviors that occurs in a sex-dependent manner.

Gut Microbiota Mediate Insecticide Resistance in the Diamondback Moth, Plutella xylostella (L.)

PubMed Central

Xia, Xiaofeng; Sun, Botong; Gurr, Geoff M.; Vasseur, Liette; Xue, Minqian; You, Minsheng

2018-01-01

The development of insecticide resistance in insect pests is a worldwide concern and elucidating the underlying mechanisms is critical for effective crop protection. Recent studies have indicated potential links between insect gut microbiota and insecticide resistance and these may apply to the diamondback moth, Plutella xylostella (L.), a globally and economically important pest of cruciferous crops. We isolated Enterococcus sp. (Firmicutes), Enterobacter sp. (Proteobacteria), and Serratia sp. (Proteobacteria) from the guts of P. xylostella and analyzed the effects on, and underlying mechanisms of insecticide resistance. Enterococcus sp. enhanced resistance to the widely used insecticide, chlorpyrifos, in P. xylostella, while in contrast, Serratia sp. decreased resistance and Enterobacter sp. and all strains of heat-killed bacteria had no effect. Importantly, the direct degradation of chlorpyrifos in vitro was consistent among the three strains of bacteria. We found that Enterococcus sp., vitamin C, and acetylsalicylic acid enhanced insecticide resistance in P. xylostella and had similar effects on expression of P. xylostella antimicrobial peptides. Expression of cecropin was down-regulated by the two compounds, while gloverin was up-regulated. Bacteria that were not associated with insecticide resistance induced contrasting gene expression profiles to Enterococcus sp. and the compounds. Our studies confirmed that gut bacteria play an important role in P. xylostella insecticide resistance, but the main mechanism is not direct detoxification of insecticides by gut bacteria. We also suggest that the influence of gut bacteria on insecticide resistance may depend on effects on the immune system. Our work advances understanding of the evolution of insecticide resistance in this key pest and highlights directions for research into insecticide resistance in other insect pest species. PMID:29410659

Gut Microbiota Mediate Insecticide Resistance in the Diamondback Moth, Plutella xylostella (L.).

PubMed

Xia, Xiaofeng; Sun, Botong; Gurr, Geoff M; Vasseur, Liette; Xue, Minqian; You, Minsheng

2018-01-01

The development of insecticide resistance in insect pests is a worldwide concern and elucidating the underlying mechanisms is critical for effective crop protection. Recent studies have indicated potential links between insect gut microbiota and insecticide resistance and these may apply to the diamondback moth, Plutella xylostella (L.), a globally and economically important pest of cruciferous crops. We isolated Enterococcus sp. (Firmicutes), Enterobacter sp. (Proteobacteria), and Serratia sp. (Proteobacteria) from the guts of P. xylostella and analyzed the effects on, and underlying mechanisms of insecticide resistance. Enterococcus sp. enhanced resistance to the widely used insecticide, chlorpyrifos, in P. xylostella , while in contrast, Serratia sp. decreased resistance and Enterobacter sp. and all strains of heat-killed bacteria had no effect. Importantly, the direct degradation of chlorpyrifos in vitro was consistent among the three strains of bacteria. We found that Enterococcus sp., vitamin C, and acetylsalicylic acid enhanced insecticide resistance in P. xylostella and had similar effects on expression of P. xylostella antimicrobial peptides. Expression of cecropin was down-regulated by the two compounds, while gloverin was up-regulated. Bacteria that were not associated with insecticide resistance induced contrasting gene expression profiles to Enterococcus sp. and the compounds. Our studies confirmed that gut bacteria play an important role in P. xylostella insecticide resistance, but the main mechanism is not direct detoxification of insecticides by gut bacteria. We also suggest that the influence of gut bacteria on insecticide resistance may depend on effects on the immune system. Our work advances understanding of the evolution of insecticide resistance in this key pest and highlights directions for research into insecticide resistance in other insect pest species.

Evaluation of Liquid and Bait Insecticides against the Dark Rover Ant (Brachymyrmex patagonicus)

PubMed Central

Miguelena, Javier G.; Baker, Paul B.

2014-01-01

Dark rover ants (Brachymyrmex patagonicus, Mayr) are an exotic ant species native to South America that has recently spread through the southern US. We evaluated the residual activity of three liquid insecticides (indoxacarb, fipronil and lambda-cyhalothrin) as potential barrier treatments against these ants. The factors we considered include the use of a porous or non-porous surface, a short or long exposure time and the changes in insecticide activity after treatment during a 90 day period. We also tested the effect of baits containing three different active ingredients (imidacloprid, sodium tetraborate and indoxacarb) on colony fragments of this species for a 15 day period. Both lambda-cyhalothrin® and indoxacarb® resulted in high levels of ant mortality up to 90 days after application. The results of exposure to fipronil® resembled those from the control treatment. Application of insecticides on a porous surface and the shorter exposure time generally resulted in greater ant survival. Of the baits tested, only the imidacloprid based one decreased ant survival significantly during the evaluation period. Within three days, the imidacloprid bait produced over 50% mortality which increased to over 95% by the end of the experiment. Results from the other two bait treatments were not significantly different from the control. PMID:26462943

Metaflumizone is a novel sodium channel blocker insecticide.

PubMed

Salgado, V L; Hayashi, J H

2007-12-15

Metaflumizone is a novel semicarbazone insecticide, derived chemically from the pyrazoline sodium channel blocker insecticides (SCBIs) discovered at Philips-Duphar in the early 1970s, but with greatly improved mammalian safety. This paper describes studies confirming that the insecticidal action of metaflumizone is due to the state-dependent blockage of sodium channels. Larvae of the moth Spodoptera eridania injected with metaflumizone became paralyzed, concomitant with blockage of all nerve activity. Furthermore, tonic firing of abdominal stretch receptor organs from Spodoptera frugiperda was blocked by metaflumizone applied in the bath, consistent with the block of voltage-dependent sodium channels. Studies on native sodium channels, in primary-cultured neurons isolated from the CNS of the larvae of the moth Manduca sexta and on Para/TipE sodium channels heterologously expressed in Xenopus (African clawed frog) oocytes, confirmed that metaflumizone blocks sodium channels by binding selectively to the slow-inactivated state, which is characteristic of the SCBIs. The results confirm that metaflumizone is a novel sodium channel blocker insecticide.

Novel insecticides and acaricides

NASA Astrophysics Data System (ADS)

Grapov, Artur F.

1999-08-01

This review outlines the major achievements in design of novel chemical insecticides and acaricides, especially those with non-standard mechanisms of action, viz., neonicotinoids and oxidative phosphorylation decouplers. The bibliography includes 119 references.

Insecticides and Biological Control

ERIC Educational Resources Information Center

Furness, G. O.

1972-01-01

Use of insecticides has been questioned due to their harmful effects on edible items. Biological control of insects along with other effective practices for checking spread of parasites on crops are discussed. (PS)

Design features of a proposed insecticidal sugar trap for biting midges.

PubMed

Cohnstaedt, Lee William; Snyder, Darren

2016-09-30

Insecticidal sugar baits for mosquitoes and house ies have proven e cacy to reduce insect populations and consequently, disease transmission rates. The new insecticidal sugar trap (IST) is designed speci cally for controlling biting midge disease vector populations around livestock and near larval habitats. The trap operates by combining light-emitting diode (LED) technology with insecticidal sugar baits. The positive photo attraction of Culicoides elicited by the LEDs, draws the insects to the insecticidal sugar bait, which can be made from various commercial insecticide formulations (pyrethroids, neonicotinoids, etc.) or naturally derived formulations (boric acid, garlic oil, etc.) lethal to Culicoides. Insecticidal sugar trap advantages include: customizable LED lights, they can be used with several di erent oral insecticides that have di erent modes of action to help combat the evolution of pesticide resistance, screening on the trap reduces non-target insect feeding (for example bees and butter ies), targets males and females of the species because both must feed on sugar, and low energy LEDs and a solar panel reduce trap maintenance to re lling sugar baits, rather than replacing batteries. This article discusses key components of an IST, which increase the traps e ectiveness for biting midge control.

Comparative toxicities of organophosphate and pyrethroid insecticides to aquatic macroarthropods.

PubMed

Halstead, Neal T; Civitello, David J; Rohr, Jason R

2015-09-01

As agricultural expansion and intensification increase to meet the growing global food demand, so too will insecticide use and thus the risk of non-target effects. Insecticide pollution poses a particular threat to aquatic macroarthropods, which play important functional roles in freshwater ecosystems. Thus, understanding the relative toxicities of insecticides to non-target functional groups is critical for predicting effects on ecosystem functions. We exposed two common macroarthropod predators, the crayfish Procambarus alleni and the water bug Belostoma flumineum, to three insecticides in each of two insecticide classes (three organophosphates: chlorpyrifos, malathion, and terbufos; and three pyrethroids: esfenvalerate, λ-cyhalothrin, and permethrin) to assess their toxicities. We generated 150 simulated environmental exposures using the US EPA Surface Water Contamination Calculator to determine the proportion of estimated peak environmental concentrations (EECs) that exceeded the US EPA level of concern (0.5×LC50) for non-endangered aquatic invertebrates. Organophosphate insecticides generated consistently low-risk exposure scenarios (EECs<0.5×LC50) for both P. alleni and B. flumineum. Pyrethroid exposure scenarios presented consistently high risk (EECs>0.5×LC50) to P. alleni, but not to B. flumineum, where only λ-cyhalothrin produced consistently high-risk exposures. Survival analyses demonstrated that insecticide class accounted for 55.7% and 91.1% of explained variance in P. alleni and B. flumineum survival, respectively. Thus, risk to non-target organisms is well predicted by pesticide class. Identifying insecticides that pose low risk to aquatic macroarthropods might help meet increased demands for food while mitigating against potential negative effects on ecosystem functions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Specificity determinants for Cry insecticidal proteins: Insights from their mode of action.

PubMed

Jurat-Fuentes, Juan Luis; Crickmore, Neil

2017-01-01

Insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are used as active components of biopesticides and as plant incorporated protectants in transgenic crops. One of the most relevant attributes of these Bt protein-based insecticidal technologies is their high specificity, which assures lack of detrimental effects on non-target insects, vertebrates and the environment. The identification of specificity determinants in Bt insecticidal proteins could guide risk assessment for novel insecticidal proteins currently considered for commercialization. In this work we review the available data on specificity determinants of crystal (Cry) insecticidal proteins as the Bt toxins most well characterized and used in transgenic crops. The multi-step mode of action of the Cry insecticidal proteins allows various factors to potentially affect specificity determination and here we define seven levels that could influence specificity. The relative relevance of each of these determinants on efficacy of transgenic crops producing Cry insecticidal proteins is also discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

Production of Insecticide Degradates in Juices: Implications for Risk Assessment.

PubMed

Radford, Samantha A; Panuwet, Parinya; Hunter, Ronald E; Barr, Dana Boyd; Ryan, P Barry

2016-06-08

This study was designed to observe the production of degradates of two organophosphorus insecticides and one pyrethroid insecticide in beverages. Purified water, white grape juice, apple juice, and red grape juice were fortified with 500 ng/g malathion, chlorpyrifos, and permethrin, and aliquots were extracted for malathion dicarboxylic acid (MDA), 3,5,6-trichloro-2-pyridinol (TCPy), and 3-phenoxybenzoic acid (3-PBA) several times over a 15 day period of being stored in the dark at 2.5 °C. Overall, first-order kinetics were observed for production of MDA, and statistically significant production of TCPy was also observed. Statistically significant production of 3-phenoxybenzoic acid was not observed. Results indicate that insecticides degrade in food and beverages, and this degradation may lead to preexisting insecticide metabolites in the beverages. Therefore, it is suggested that caution should be exercised when using urinary insecticide metabolites to assess exposure and risk.

Amplification of a Cytochrome P450 Gene Is Associated with Resistance to Neonicotinoid Insecticides in the Aphid Myzus persicae

PubMed Central

Puinean, Alin M.; Foster, Stephen P.; Oliphant, Linda; Denholm, Ian; Field, Linda M.; Millar, Neil S.; Williamson, Martin S.; Bass, Chris

2010-01-01

The aphid Myzus persicae is a globally significant crop pest that has evolved high levels of resistance to almost all classes of insecticide. To date, the neonicotinoids, an economically important class of insecticides that target nicotinic acetylcholine receptors (nAChRs), have remained an effective control measure; however, recent reports of resistance in M. persicae represent a threat to the long-term efficacy of this chemical class. In this study, the mechanisms underlying resistance to the neonicotinoid insecticides were investigated using biological, biochemical, and genomic approaches. Bioassays on a resistant M. persicae clone (5191A) suggested that P450-mediated detoxification plays a primary role in resistance, although additional mechanism(s) may also contribute. Microarray analysis, using an array populated with probes corresponding to all known detoxification genes in M. persicae, revealed constitutive over-expression (22-fold) of a single P450 gene (CYP6CY3); and quantitative PCR showed that the over-expression is due, at least in part, to gene amplification. This is the first report of a P450 gene amplification event associated with insecticide resistance in an agriculturally important insect pest. The microarray analysis also showed over-expression of several gene sequences that encode cuticular proteins (2–16-fold), and artificial feeding assays and in vivo penetration assays using radiolabeled insecticide provided direct evidence of a role for reduced cuticular penetration in neonicotinoid resistance. Conversely, receptor radioligand binding studies and nucleotide sequencing of nAChR subunit genes suggest that target-site changes are unlikely to contribute to resistance to neonicotinoid insecticides in M. persicae. PMID:20585623

Amplification of a cytochrome P450 gene is associated with resistance to neonicotinoid insecticides in the aphid Myzus persicae.

PubMed

Puinean, Alin M; Foster, Stephen P; Oliphant, Linda; Denholm, Ian; Field, Linda M; Millar, Neil S; Williamson, Martin S; Bass, Chris

2010-06-24

The aphid Myzus persicae is a globally significant crop pest that has evolved high levels of resistance to almost all classes of insecticide. To date, the neonicotinoids, an economically important class of insecticides that target nicotinic acetylcholine receptors (nAChRs), have remained an effective control measure; however, recent reports of resistance in M. persicae represent a threat to the long-term efficacy of this chemical class. In this study, the mechanisms underlying resistance to the neonicotinoid insecticides were investigated using biological, biochemical, and genomic approaches. Bioassays on a resistant M. persicae clone (5191A) suggested that P450-mediated detoxification plays a primary role in resistance, although additional mechanism(s) may also contribute. Microarray analysis, using an array populated with probes corresponding to all known detoxification genes in M. persicae, revealed constitutive over-expression (22-fold) of a single P450 gene (CYP6CY3); and quantitative PCR showed that the over-expression is due, at least in part, to gene amplification. This is the first report of a P450 gene amplification event associated with insecticide resistance in an agriculturally important insect pest. The microarray analysis also showed over-expression of several gene sequences that encode cuticular proteins (2-16-fold), and artificial feeding assays and in vivo penetration assays using radiolabeled insecticide provided direct evidence of a role for reduced cuticular penetration in neonicotinoid resistance. Conversely, receptor radioligand binding studies and nucleotide sequencing of nAChR subunit genes suggest that target-site changes are unlikely to contribute to resistance to neonicotinoid insecticides in M. persicae.

Field and Laboratory Evaluations of Insecticides for Southern Pine Beetle Control

Treesearch

Felton L. Hastings; Jack E. Coster; [Editors

1981-01-01

Reports results of laboratory screenings and field studies of insecticides for use against the southern pine beetle. Preventive as webas remedial efficacywere observed, along with phytotoxicity to pine and understory hardwood species, effects of insecticides on soil microbial and mesofaunal populations, and degradation of insecticides by selected soil microbes.

Scepticism towards insecticide treated mosquito nets for malaria control in rural community in north-western Tanzania.

PubMed

Nnko, Soori E; Whyte, Susan R; Geissler, Wenzel P; Aagaard-Hansen, Jens

2012-04-01

Despite existence of effective tools for malaria control, malaria continues to be one of the leading killer diseases especially among under-five year children and pregnant women in poor rural populations of Sub Saharan Africa. In Tanzania Mainland the disease contributes to 39.4% of the total OPD attendances. In terms of mortality, malaria is known to be responsible for more than one third of deaths among children of age below 5 years and also contributes for up to one fifth of deaths among pregnant women. This paper is based on a study conducted in a rural community along the shores of Lake Victoria in Mwanza region, North-Western Tanzania. The study explores reasons for scepticism and low uptake of insecticide treated mosquito nets (ITNs) that were promoted through social marketing strategy for malaria control prior to the introduction of long lasting nets (LLN). The paper breaks from traditional approach that tend to study low uptake of health interventions in terms of structural practical constraints--cost, accessibility, everyday priorities--or in terms of cognition--insufficient knowledge of benefits e.g. ignorance of public health messages. This paper has shown that, the majority of people who could afford the prices of ITNs and who knew where to obtain the insecticides did not necessarily buy them. This suggests that, although people tend to report cost-related factors as a barrier against the use of ITNs, there are other critical concerns at work. Without underestimating the practical factors, our study have recommended to consider critical examinations of those other concerns that hinder optimal utilization of ITN for malaria control, and the basis for those concerns.

Biological alterations and self-reported symptoms among insecticides-exposed workers in Burkina Faso

PubMed Central

Toe, Adama M.; Ilboudo, Sylvain; Ouedraogo, Moustapha; Guissou, Pierre I.

2012-01-01

Occupationally exposed workers, farm workers and plant protection agents in the Sahel region of Burkina Faso were interviewed to assess adverse health effects of insecticides. The subjects were also examined for changes in both hematological and biochemical parameters. The prevalence of liver and kidney dysfunction was found to be quite high among insecticide applicators, especially among plant protection agents. The prevalence of biochemical alterations seems to be correlated to the frequency of insecticide use. However, no significant differences were found between the hematological parameters among farm workers and plant protection agents. The hematological parameters of all the insecticide applicators were normal. The great majority of insecticide applicators (85%) reported symptoms related to insecticide exposure. The use of insecticides in the agriculture of Burkina Faso is threatening to human health. PMID:22783149

Biological alterations and self-reported symptoms among insecticides-exposed workers in Burkina Faso.

PubMed

Toe, Adama M; Ilboudo, Sylvain; Ouedraogo, Moustapha; Guissou, Pierre I

2012-03-01

Occupationally exposed workers, farm workers and plant protection agents in the Sahel region of Burkina Faso were interviewed to assess adverse health effects of insecticides. The subjects were also examined for changes in both hematological and biochemical parameters. The prevalence of liver and kidney dysfunction was found to be quite high among insecticide applicators, especially among plant protection agents. The prevalence of biochemical alterations seems to be correlated to the frequency of insecticide use. However, no significant differences were found between the hematological parameters among farm workers and plant protection agents. The hematological parameters of all the insecticide applicators were normal. The great majority of insecticide applicators (85%) reported symptoms related to insecticide exposure. The use of insecticides in the agriculture of Burkina Faso is threatening to human health.

Quantitative structure-activity relationship (QSAR) for insecticides: development of predictive in vivo insecticide activity models.

PubMed

Naik, P K; Singh, T; Singh, H

2009-07-01

Quantitative structure-activity relationship (QSAR) analyses were performed independently on data sets belonging to two groups of insecticides, namely the organophosphates and carbamates. Several types of descriptors including topological, spatial, thermodynamic, information content, lead likeness and E-state indices were used to derive quantitative relationships between insecticide activities and structural properties of chemicals. A systematic search approach based on missing value, zero value, simple correlation and multi-collinearity tests as well as the use of a genetic algorithm allowed the optimal selection of the descriptors used to generate the models. The QSAR models developed for both organophosphate and carbamate groups revealed good predictability with r(2) values of 0.949 and 0.838 as well as [image omitted] values of 0.890 and 0.765, respectively. In addition, a linear correlation was observed between the predicted and experimental LD(50) values for the test set data with r(2) of 0.871 and 0.788 for both the organophosphate and carbamate groups, indicating that the prediction accuracy of the QSAR models was acceptable. The models were also tested successfully from external validation criteria. QSAR models developed in this study should help further design of novel potent insecticides.

Insecticide cytotoxicology in China: Current status and challenges.

PubMed

Zhong, Guohua; Cui, Gaofeng; Yi, Xin; Sun, Ranran; Zhang, Jingjing

2016-09-01

The insecticide cytotoxicology, as a new branch of toxicology, has rapidly developed in China. During the past twenty years, thousands of investigations have sprung up to evaluate the damages and clarify the mechanisms of insecticidal chemical substances to insect cells in vivo or in vitro. The mechanisms of necrosis, apoptosis or autophagy induced by synthetic or biogenic pesticides and virus infections have been systematically illuminated in many important models, including S2, BmN, SL-1, Sf21 and Sf9 cell lines. In addition, a variety of methods have also been applied to examine the effects of insecticides and elaborate the modes of action. As a result, many vital factors and pathways, such as cytochrome c, the Bcl-2 family and caspases, in mitochondrial signaling pathways, intracellular free calcium and lysosome signal pathways have been illuminated and drawn much attention. Benefiting from the application of insecticide cytotoxicology, natural products purifications, biological activities assessments of synthetic compounds and high throughput screening models have been accelerated in China. However, many questions remained, and there exist great challenges, especially in theory system, evaluation criterion, evaluation model, relationship between activity in vitro and effectiveness in vivo, and the toxicological mechanism. Fortunately, the generation of "omics" could bring opportunities for the development of insecticide cytotoxicology. Copyright © 2016 Elsevier B.V. All rights reserved.

Risks of large-scale use of systemic insecticides to ecosystem functioning and services.

PubMed

Chagnon, Madeleine; Kreutzweiser, David; Mitchell, Edward A D; Morrissey, Christy A; Noome, Dominique A; Van der Sluijs, Jeroen P

2015-01-01

Large-scale use of the persistent and potent neonicotinoid and fipronil insecticides has raised concerns about risks to ecosystem functions provided by a wide range of species and environments affected by these insecticides. The concept of ecosystem services is widely used in decision making in the context of valuing the service potentials, benefits, and use values that well-functioning ecosystems provide to humans and the biosphere and, as an endpoint (value to be protected), in ecological risk assessment of chemicals. Neonicotinoid insecticides are frequently detected in soil and water and are also found in air, as dust particles during sowing of crops and aerosols during spraying. These environmental media provide essential resources to support biodiversity, but are known to be threatened by long-term or repeated contamination by neonicotinoids and fipronil. We review the state of knowledge regarding the potential impacts of these insecticides on ecosystem functioning and services provided by terrestrial and aquatic ecosystems including soil and freshwater functions, fisheries, biological pest control, and pollination services. Empirical studies examining the specific impacts of neonicotinoids and fipronil to ecosystem services have focused largely on the negative impacts to beneficial insect species (honeybees) and the impact on pollination service of food crops. However, here we document broader evidence of the effects on ecosystem functions regulating soil and water quality, pest control, pollination, ecosystem resilience, and community diversity. In particular, microbes, invertebrates, and fish play critical roles as decomposers, pollinators, consumers, and predators, which collectively maintain healthy communities and ecosystem integrity. Several examples in this review demonstrate evidence of the negative impacts of systemic insecticides on decomposition, nutrient cycling, soil respiration, and invertebrate populations valued by humans. Invertebrates

Quantitative structure-toxicity relationship (QSTR) studies on the organophosphate insecticides.

PubMed

Can, Alper

2014-11-04

Organophosphate insecticides are the most commonly used pesticides in the world. In this study, quantitative structure-toxicity relationship (QSTR) models were derived for estimating the acute oral toxicity of organophosphate insecticides to male rats. The 20 chemicals of the training set and the seven compounds of the external testing set were described by means of using descriptors. Descriptors for lipophilicity, polarity and molecular geometry, as well as quantum chemical descriptors for energy were calculated. Model development to predict toxicity of organophosphate insecticides in different matrices was carried out using multiple linear regression. The model was validated internally and externally. In the present study, QSTR model was used for the first time to understand the inherent relationships between the organophosphate insecticide molecules and their toxicity behavior. Such studies provide mechanistic insight about structure-toxicity relationship and help in the design of less toxic insecticides. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Averting a malaria disaster: will insecticide resistance derail malaria control?

PubMed

Hemingway, Janet; Ranson, Hilary; Magill, Alan; Kolaczinski, Jan; Fornadel, Christen; Gimnig, John; Coetzee, Maureen; Simard, Frederic; Roch, Dabiré K; Hinzoumbe, Clément Kerah; Pickett, John; Schellenberg, David; Gething, Peter; Hoppé, Mark; Hamon, Nicholas

2016-04-23

World Malaria Day 2015 highlighted the progress made in the development of new methods of prevention (vaccines and insecticides) and treatment (single dose drugs) of the disease. However, increasing drug and insecticide resistance threatens the successes made with existing methods. Insecticide resistance has decreased the efficacy of the most commonly used insecticide class of pyrethroids. This decreased efficacy has increased mosquito survival, which is a prelude to rising incidence of malaria and fatalities. Despite intensive research efforts, new insecticides will not reach the market for at least 5 years. Elimination of malaria is not possible without effective mosquito control. Therefore, to combat the threat of resistance, key stakeholders need to rapidly embrace a multifaceted approach including a reduction in the cost of bringing new resistance management methods to market and the streamlining of associated development, policy, and implementation pathways to counter this looming public health catastrophe. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection and determination of organophosphorus insecticides in tissues by thin-layer chromatography.

PubMed

Tewari, S N; Harpalani, S P

1977-01-11

The toxicological analysis of 12 common organophosphorus insecticides is described. Suitable methods for the extraction of organophosphorus insecticides from tissues are proposed. The detection, identification and estimation of these insecticides by thin-layer chromatography is described for 25 solvent systems and a series of chromogenic reagents. The distribution of insecticides in human body tissues in five cases of poisoning by ethyl parathion, malathion, dimethoate, sumithion and phosphamidon has also been studied.

Photodynamic treatment of culture medium containing serum induces long-lasting toxicity in vitro.

PubMed

Olivier, David; Douillard, Samuel; Lhommeau, Isabelle; Patrice, Thierry

2009-10-01

Photodynamic therapy (PDT) produces singlet oxygen and reactive oxygen species (ROS) that damage tumor cells and the vasculature. The resulting effect is a balance between photo-oxidations through primary or secondary ROS and scavenging activity. Sensitizers are distributed in the extracellular space before and during cell sensitization, suggesting that PDT could act directly on cell structures and on extracellular compartments, including sera. In this study we endeavored to determine whether the application of PDT to culture medium could affect cell survival. Culture medium [RPMI 1640 supplemented with fetal calf serum (FCS)] was incubated with Rose Bengal and irradiated before being added to cells for various contact times as a replacement for untreated medium. Cells were then kept in darkness until the survival assay. Treated medium reduced cell survival by up to 40% after 30 min of contact for 10 microg/ml of Rose Bengal and 20 J/cm(2). Rose Bengal or m-THPC alone or irradiated in water had no effect. This effect was dependent on the doses of Rose Bengal and light and decreased when FCS was replaced by human serum mixed with FCS. The reduction in survival observed with treated medium was more pronounced when the cell doubling time was shorter. Analysis of ROS or peroxide production in treated medium by DCFH added at the end of irradiation of Rose Bengal in serum-containing medium revealed a long-lasting oxidizing activity. Our findings support the hypothesis of an ROS- or peroxide-mediated, PDT-induced, long-lasting cell toxicity.

Evaluation of the Insecticidal Efficacy of Wild Type and Recombinant Baculoviruses.

PubMed

Popham, Holly J R; Ellersieck, Mark R; Li, Huarong; Bonning, Bryony C

2016-01-01

A considerable amount of work has been undertaken to genetically enhance the efficacy of baculovirus insecticides. Following construction of a genetically altered baculovirus, laboratory bioassays are used to quantify various parameters of insecticidal activity such as the median lethal concentration (or dose) required to kill 50 % of infected larvae (LC50 or LD50), median survival of larvae infected (ST50), and feeding damage incurred by infected larvae. In this chapter, protocols are described for a variety of bioassays and the corresponding data analyses for assessment of the insecticidal activity of baculovirus insecticides.

Guide to testing insecticides on coniferous forest defoliators

Treesearch

Carroll B Jr. Williams; David A. Sharpnack; Liz Maxwell; Patrick J. Shea; Mark D. McGregor

1985-01-01

This report provides a guide to techniques for designing field tests of candidate insecticides, and for carrying out pilot tests and control projects. It describes experimental designs for testing hypotheses, and for sampling trees to estimate insect population densities and percent reduction after treatments. Directions for applying insecticides by aircraft and for...

Insecticide resistance, control failure likelihood and the First Law of Geography.

PubMed

Guedes, Raul Narciso C

2017-03-01

Insecticide resistance is a broadly recognized ecological backlash resulting from insecticide use and is widely reported among arthropod pest species with well-recognized underlying mechanisms and consequences. Nonetheless, insecticide resistance is the subject of evolving conceptual views that introduces a different concept useful if recognized in its own right - the risk or likelihood of control failure. Here we suggest an experimental approach to assess the likelihood of control failure of an insecticide allowing for consistent decision-making regarding management of insecticide resistance. We also challenge the current emphasis on limited spatial sampling of arthropod populations for resistance diagnosis in favor of comprehensive spatial sampling. This necessarily requires larger population sampling - aiming to use spatial analysis in area-wide surveys - to recognize focal points of insecticide resistance and/or control failure that will better direct management efforts. The continuous geographical scale of such surveys will depend on the arthropod pest species, the pattern of insecticide use and many other potential factors. Regardless, distance dependence among sampling sites should still hold, following the maxim that the closer two things are, the more they resemble each other, which is the basis of Tobler's First Law of Geography. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Insect P450 inhibitors and insecticides: challenges and opportunities.

PubMed

Feyereisen, René

2015-06-01

P450 enzymes are encoded by a large number of genes in insects, often over a hundred. They play important roles in insecticide metabolism and resistance, and growing numbers of P450 enzymes are now known to catalyse important physiological reactions, such as hormone metabolism or cuticular hydrocarbon synthesis. Ways to inhibit P450 enzymes specifically or less specifically are well understood, as P450 inhibitors are found as drugs, as fungicides, as plant growth regulators and as insecticide synergists. Yet there are no P450 inhibitors as insecticides on the market. As new modes of action are constantly needed to support insecticide resistance management, P450 inhibitors should be considered because of their high potential for insect selectivity, their well-known mechanisms of action and the increasing ease of rational design and testing. © 2014 Society of Chemical Industry.

Sublethal effects of insecticides used in soybean on the parasitoid Trichogramma pretiosum.

PubMed

de Paiva, Ana Clara Ribeiro; Beloti, Vitor Hugo; Yamamoto, Pedro Takao

2018-05-01

To control crop pests, parasitoid wasps of the genus Trichogramma are one alternative to the use of insecticides. Since a wide variety of agrochemicals may be applied to the same crops, it is essential to assess the selectivity of insecticides used for pest control on Trichogramma pretiosum. Information on which insecticides are less harmful to T. pretiosum can improve biological control using this insect, an important tactic in IPM programs for field crops. This study aimed to determine the effects of insecticides on the pupal stage and on the parasitism capacity of T. pretiosum. Lambda-cyhalothrin + thiamethoxam were slightly harmful and chlorpyriphos was moderately harmful to the pupal stage, while acephate, chlorfenapyr and flubendiamide, although considered innocuous, affected the succeeding generations of wasps, with low emergence of F 1 . Chlorfenapyr, chlorpyriphos and lambda-cyhalothrin + thiamethoxam reduced the parasitism, and acephate had a deleterious effect on the generation that contacted the insecticide residue. For an effective IPM program, it is important to apply selective insecticides. Further studies are needed to determine the selectivity of these insecticides under field conditions.

The Effect of Early Mosquito Insecticides Exposure on Spraque Dawley Rat Testis: A Histopathological Feature Towards Malignancy?

NASA Astrophysics Data System (ADS)

Indah Winarni, Tri; Auzan Aziman, Milzam; Abshar Andar, Anindyo; Pawitra, Ika

2017-02-01

The incidence of health problems associated with endocrine-disruption have increased. Many studies suggesting that endocrine disruptor chemicals (EDC) do contribute to cancer through estrogen-related receptors. Many chemicals have EDCs properties including insecticides. Early life exposure to EDCs can increased the risk of testicular cancer have been reported in the last decade. This study was aimed to determine the effect of insecticides exposure on histopathological tumor cell development of germ and Leydig cell. True experiment research design with posttest only control group design was applied. Sprague Dawley (SD) rat (n = 25) were randomly divided into 5 groups (control group, 25 mg β estradiol 3-benzoate, spiral mosquito coil repellent, 3 ml of liquid mosquito repellent, and 4 ml of liquid mosquito repellent). The exposure were administered for 20 days started at aged 3 days. At the age of 100 days (older adult), testis was stained using Hematoxyllin Eosin (HE) and histological features predicting malignancy were observed. The number of tumor cell development in both testicular germ cells and Leydig cells significantly increased in all treated group compared to those of control and the changes towards malignancy were also observed in all treated group. Exposure to mosquito insecticides causes significant changes in testicular germ and Leydig cell histological features that leads to malignancy.

Cross-induction of detoxification genes by environmental xenobiotics and insecticides in the mosquito Aedes aegypti: impact on larval tolerance to chemical insecticides.

PubMed

Poupardin, Rodolphe; Reynaud, Stéphane; Strode, Clare; Ranson, Hilary; Vontas, John; David, Jean-Philippe

2008-05-01

The effect of exposure of Aedes aegypti larvae to sub-lethal doses of the pyrethroid insecticide permethrin, the organophosphate temephos, the herbicide atrazine, the polycyclic aromatic hydrocarbon fluoranthene and the heavy metal copper on their subsequent tolerance to insecticides, detoxification enzyme activities and expression of detoxification genes was investigated. Bioassays revealed a moderate increase in larval tolerance to permethrin following exposure to fluoranthene and copper while larval tolerance to temephos increased moderately after exposure to atrazine, copper and permethrin. Cytochrome P450 monooxygenases activities were induced in larvae exposed to permethrin, fluoranthene and copper while glutathione S-transferase activities were induced after exposure to fluoranthene and repressed after exposure to copper. Microarray screening of the expression patterns of all detoxification genes following exposure to each xenobiotic with the Aedes Detox Chip identified multiple genes induced by xenobiotics and insecticides. Further expression studies using real-time quantitative PCR confirmed the induction of multiple CYP genes and one carboxylesterase gene by insecticides and xenobiotics. Overall, this study reveals the potential of xenobiotics found in polluted mosquito breeding sites to affect their tolerance to insecticides, possibly through the cross-induction of particular detoxification genes. Molecular mechanisms involved and impact on mosquito control strategies are discussed.

29 CFR 37.21 - How long will the recipient's obligation under the assurance last, and how broad is the obligation?

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 1 2010-07-01 2010-07-01 true How long will the recipient's obligation under the assurance last, and how broad is the obligation? 37.21 Section 37.21 Labor Office of the Secretary of Labor...'s obligation under the assurance last, and how broad is the obligation? (a) Where the WIA Title I...

29 CFR 37.21 - How long will the recipient's obligation under the assurance last, and how broad is the obligation?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 1 2012-07-01 2012-07-01 false How long will the recipient's obligation under the assurance last, and how broad is the obligation? 37.21 Section 37.21 Labor Office of the Secretary of Labor...'s obligation under the assurance last, and how broad is the obligation? (a) Where the WIA Title I...

29 CFR 37.21 - How long will the recipient's obligation under the assurance last, and how broad is the obligation?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 29 Labor 1 2014-07-01 2013-07-01 true How long will the recipient's obligation under the assurance last, and how broad is the obligation? 37.21 Section 37.21 Labor Office of the Secretary of Labor...'s obligation under the assurance last, and how broad is the obligation? (a) Where the WIA Title I...

29 CFR 37.21 - How long will the recipient's obligation under the assurance last, and how broad is the obligation?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 1 2011-07-01 2011-07-01 false How long will the recipient's obligation under the assurance last, and how broad is the obligation? 37.21 Section 37.21 Labor Office of the Secretary of Labor...'s obligation under the assurance last, and how broad is the obligation? (a) Where the WIA Title I...

29 CFR 37.21 - How long will the recipient's obligation under the assurance last, and how broad is the obligation?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 1 2013-07-01 2013-07-01 false How long will the recipient's obligation under the assurance last, and how broad is the obligation? 37.21 Section 37.21 Labor Office of the Secretary of Labor...'s obligation under the assurance last, and how broad is the obligation? (a) Where the WIA Title I...

Reducing Insecticide Use in Broad-Acre Grains Production: An Australian Study

PubMed Central

Macfadyen, Sarina; Hardie, Darryl C.; Fagan, Laura; Stefanova, Katia; Perry, Kym D.; DeGraaf, Helen E.; Holloway, Joanne; Spafford, Helen; Umina, Paul A.

2014-01-01

Prophylactic use of broad-spectrum insecticides is a common feature of broad-acre grains production systems around the world. Efforts to reduce pesticide use in these systems have the potential to deliver environmental benefits to large areas of agricultural land. However, research and extension initiatives aimed at decoupling pest management decisions from the simple act of applying a cheap insecticide have languished. This places farmers in a vulnerable position of high reliance on a few products that may lose their efficacy due to pests developing resistance, or be lost from use due to regulatory changes. The first step towards developing Integrated Pest Management (IPM) strategies involves an increased efficiency of pesticide inputs. Especially challenging is an understanding of when and where an insecticide application can be withheld without risking yield loss. Here, we quantify the effect of different pest management strategies on the abundance of pest and beneficial arthropods, crop damage and yield, across five sites that span the diversity of contexts in which grains crops are grown in southern Australia. Our results show that while greater insecticide use did reduce the abundance of many pests, this was not coupled with higher yields. Feeding damage by arthropod pests was seen in plots with lower insecticide use but this did not translate into yield losses. For canola, we found that plots that used insecticide seed treatments were most likely to deliver a yield benefit; however other insecticides appear to be unnecessary and economically costly. When considering wheat, none of the insecticide inputs provided an economically justifiable yield gain. These results indicate that there are opportunities for Australian grain growers to reduce insecticide inputs without risking yield loss in some seasons. We see this as the critical first step towards developing IPM practices that will be widely adopted across intensive production systems. PMID:24586535

Reducing insecticide use in broad-acre grains production: an Australian study.

PubMed

Macfadyen, Sarina; Hardie, Darryl C; Fagan, Laura; Stefanova, Katia; Perry, Kym D; DeGraaf, Helen E; Holloway, Joanne; Spafford, Helen; Umina, Paul A

2014-01-01

Prophylactic use of broad-spectrum insecticides is a common feature of broad-acre grains production systems around the world. Efforts to reduce pesticide use in these systems have the potential to deliver environmental benefits to large areas of agricultural land. However, research and extension initiatives aimed at decoupling pest management decisions from the simple act of applying a cheap insecticide have languished. This places farmers in a vulnerable position of high reliance on a few products that may lose their efficacy due to pests developing resistance, or be lost from use due to regulatory changes. The first step towards developing Integrated Pest Management (IPM) strategies involves an increased efficiency of pesticide inputs. Especially challenging is an understanding of when and where an insecticide application can be withheld without risking yield loss. Here, we quantify the effect of different pest management strategies on the abundance of pest and beneficial arthropods, crop damage and yield, across five sites that span the diversity of contexts in which grains crops are grown in southern Australia. Our results show that while greater insecticide use did reduce the abundance of many pests, this was not coupled with higher yields. Feeding damage by arthropod pests was seen in plots with lower insecticide use but this did not translate into yield losses. For canola, we found that plots that used insecticide seed treatments were most likely to deliver a yield benefit; however other insecticides appear to be unnecessary and economically costly. When considering wheat, none of the insecticide inputs provided an economically justifiable yield gain. These results indicate that there are opportunities for Australian grain growers to reduce insecticide inputs without risking yield loss in some seasons. We see this as the critical first step towards developing IPM practices that will be widely adopted across intensive production systems.

Evaluation of mosquito responses to pyrethroid insecticides topically applied to sheep.

PubMed

Johnson, G D; Goosey, H B; Rolston, M G; Miller, W L; Hokit, D G; Redden, R R; Kott, R W

2013-06-01

A rise in the incidence of mosquito-transmitted Cache Valley virus (CVV) in lambs in 2011 prompted a study to evaluate on-animal pyrethroid insecticides to reduce mosquito attacks on sheep. Using enclosure traps for 1 night per wk for 6 wk, we compared engorgement rates of mosquitoes given the opportunity to feed on untreated sheep and sheep treated with 1 Python insecticide ear tag (containing 10% zeta-cypermethrin and 20% piperonyl butoxide) per animal or 2 synergized permethrin body spray treatments (containing 2.5% permethrin and 2.5% piperonyl butoxide). During the 6-wk study, 18,920 mosquitoes were collected in the animal-baited enclosure traps. Thirteen species were identified from these collections with the floodwater species Aedes increpitus and Ae. idahoensis making up 68% of the total. Potential CVV vector species, making up 25% of the samples, included Ae. vexans, Ae. dorsalis, Culex tarsalis, and Culiseta inornata. Traps baited with untreated sheep collected 9,701 mosquitoes with 65% of these engorged. Traps baited with sheep treated with Python ear tags or permethrin spray collected 4,034 and 4,555, respectively, with engorgement rates of 23% and 35%. Blood feeding on ear-tagged sheep was significantly reduced by as much as 90% compared to the untreated sheep, and protection lasted 4 wk or longer. Permethrin spray treatments were most effective within 24 h after application and provided better protection against Ae. dorsalis than the Python tag. Effectiveness of the permethrin spray diminished 1 wk after the 2nd application was made. The effect of these treatments appeared to be repellency because negligible mosquito mortality was observed at the time of collection. Further evaluation of these insecticides under conditions of natural exposure to a mosquito-borne pathogen is warranted.

Retrospective attention in short-term memory has a lasting effect on long-term memory across age.

PubMed

Strunk, Jonathan; Morgan, Lauren; Reaves, Sarah; Verhaeghen, Paul; Duarte, Audrey

2018-04-13

Declines in both short- and long-term memory are typical of healthy aging. Recent findings suggest that retrodictive attentional cues ("retro-cues") that indicate the location of to-be-probed items in short-term memory (STM) have a lasting impact on long-term memory (LTM) performance in young adults. Whether older adults can also use retro-cues to facilitate both STM and LTM is unknown. Young and older adults performed a visual STM task in which spatially informative retro-cues or non-informative neutral-cues were presented during STM maintenance of real-world objects. We tested participants' memory at both STM and LTM delays for objects that were previously cued with retrodictive or neutral cues during STM order to measure the lasting impact of retrospective attention on LTM. Older adults showed reduced STM and LTM capacity compared to young adults. However, they showed similar magnitude retro-cue memory benefits as young adults at both STM and LTM delays. To the best of our knowledge, this is the first study to investigate whether retro-cues in STM facilitate the encoding of objects into LTM such that they are more likely to be subsequently retrieved by older adults. Our results support the idea that retrospective attention can be an effective means by which older adults can improve their short and long-term memory performance, even in the context of reduced memory capacity.

Long-lasting hydrophilicity on nanostructured Si-incorporated diamond-like carbon films.

PubMed

Yi, Jin Woo; Moon, Myoung-Woon; Ahmed, Sk Faruque; Kim, Haeri; Cha, Tae-Gon; Kim, Ho-Young; Kim, Seock-Sam; Lee, Kwang-Ryeol

2010-11-16

We investigated the long-lasting hydrophilic behavior of a Si-incorporated diamond-like carbon (Si-DLC) film by varying the Si fraction in DLC matrix through oxygen and nitrogen plasma surface treatments. The wetting behavior of the water droplets on the pure DLC and Si-DLC with the nitrogen or oxygen plasma treatment revealed that the Si element in the oxygen-plasma-treated Si-DLC films played a major role in maintaining a hydrophilic wetting angle of <10° for 20 days in ambient air. The nanostructured patterns with a roughness of ∼10 nm evolved because of the selective etching of the carbon matrix by the oxygen plasma in the Si-DLC film, where the chemical component of the Si-Ox bond was enriched on the top of the nanopatterns and remained for over 20 days.

Distributing insecticide-treated bednets during measles vaccination: a low-cost means of achieving high and equitable coverage.

PubMed Central

Grabowsky, Mark; Nobiya, Theresa; Ahun, Mercy; Donna, Rose; Lengor, Miata; Zimmerman, Drake; Ladd, Holly; Hoekstra, Edward; Bello, Aliu; Baffoe-Wilmot, Aba; Amofah, George

2005-01-01

OBJECTIVE: To achieve high and equitable coverage of insecticide-treated bednets by integrating their distribution into a measles vaccination campaign. METHODS: In December 2002 in the Lawra district in Ghana, a measles vaccination campaign lasting 1 week targeted all children aged 9 months-15 years. Families with one or more children less than five years old were targeted to receive a free insecticide-treated bednet. The Ghana Health Service, with support from the Ghana Red Cross and UNICEF, provided logistical support, volunteer workers and social mobilization during the campaign. Volunteers visited homes to inform caregivers about the campaign and encourage them to participate. We assessed pre-campaign coverage of bednets by interviewing caregivers leaving vaccination and distribution sites. Five months after distribution, a two-stage cluster survey using population-proportional sampling assessed bednet coverage, retention and use. Both the pre-campaign and post-campaign survey assessed household wealth using an asset inventory. FINDINGS: At the campaign exit interview 636/776 (82.0%) caregivers reported that they had received a home visit by a Red Cross volunteer before the campaign and that 32/776 (4.1%) of the youngest children in each household who were less than 5 years of age slept under an insecticide-treated bednet. Five months after distribution caregivers reported that 204/219 (93.2%) of children aged 9 months to 5 years had been vaccinated during the campaign; 234/248 (94.4%) of households were observed to have an insecticide-treated bednet; and 170/249 (68.3%) were observed to have a net hung over a bed. Altogether 222/248 (89.5%) caregivers reported receiving at least one insecticide-treated bednet during the campaign, and 153/254 (60.2%) said that on the previous night their youngest child had slept under a bednet received during the campaign. For households in the poorest quintile, post-campaign coverage of insecticide-treated bednets was 10 times

Azobenzene Modified Imidacloprid Derivatives as Photoswitchable Insecticides: Steering Molecular Activity in a Controllable Manner

NASA Astrophysics Data System (ADS)

Xu, Zhiping; Shi, Lina; Jiang, Danping; Cheng, Jiagao; Shao, Xusheng; Li, Zhong

2015-10-01

Incorporating the photoisomerizable azobenzene into imidacloprid produced a photoswitchable insecticidal molecule as the first neonicotinoid example of remote control insecticide performance with spatiotemporal resolution. The designed photoswitchable insecticides showed distinguishable activity against Musca both in vivo and in vitro upon irradiation. Molecular docking study further suggested the binding difference of the two photoisomers. The generation of these photomediated insecticides provides novel insight into the insecticidal activity facilitating further investigation on the functions of insect nicotinic acetylcholine receptors and opens a novel way to control and study insect behavior on insecticide poisoning using light.

Insecticide residues on stream sediments in Ontario, Canada.

PubMed

Miles, J R

1976-12-01

Insecticide residues on suspended and bottom sediments of streams of Ontario, Canada, have been studied in a tobacco-growing and a vegetable muck area. The proportion of TDE to DDT was less than 1 in water and greater than 1 in bottom sediments. The ratio of TDE to DDT in bottom material increased linearly from the contamination point at stream source to the mouth of Big Creek in Norfolk County, Ontario. Bed load samples contained three to six times greater concentrations of insecticides than bottom material. Adsorption of insecticides on suspended sediment decreased in order DDT greater than TDE greater than dieldrin greater than diazinon, which is consistent with the water solubility of these compounds.

Efficacy of insecticide residues on adult Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) mortality and injury in apple and peach orchards.

PubMed

Leskey, Tracy C; Short, Brent D; Lee, Doo-Hyung

2014-07-01

The primary threat from Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) originates from populations continuously dispersing from and among wild and cultivated hosts, so many individuals may not be directly sprayed with insecticides. Limited information exists regarding field-based residual activity of insecticides for management of H. halys in tree fruit. Thus, we conducted field-based bioassays in apple and peach orchards to evaluate residual activity of insecticides commonly applied against H. halys. Adults used in these trials were collected from wild and cultivated hosts less than one week prior to testing to more accurately reflect the susceptibility of wild H. halys populations in the field throughout the season. Significantly higher mortality rates of Halyomorpha halys were observed early in the growing season, when overwintered adults were prevalent, compared with populations present later in the growing season that included new generation adults. Significantly higher mortality was recorded for adults exposed to fresh insecticide applications compared with three- and seven-day old residues. Typically, the addition of an adjuvant did not enhance efficacy or residual activity of insecticides. Significantly fewer injury sites were recorded on apples treated with dinotefuran and fenpropathrin compared with the untreated apples for all residue ages. Overwintered Halyomorpha halys populations are easier to kill with insecticide applications than the first and second generation which are present in the field during the mid- to late-season. Residual activity of nearly all insecticides decreased significantly three days after application and adjuvants generally did not increase residual activity. These factors should be considered in developing season-long programs for management of this invasive species in tree fruit. © 2013 Society of Chemical Industry.

Enhancement of green long lasting phosphorescence in CaSnO3:Tb3+ by addition of alkali ions

NASA Astrophysics Data System (ADS)

Liang, Zuoqiu; Zhang, Jinsu; Sun, Jiashi; Li, Xiangping; Cheng, Lihong; Zhong, Haiyang; Fu, Shaobo; Tian, Yue; Chen, Baojiu

2013-03-01

Long lasting phosphors of CaSnO3:Tb3+ added alkali ions (Li+, Na+, K+) were prepared by solid-state reaction. The phosphorescence of samples consists of a group of green emission lines originating from 5D4→7FJ transitions of Tb3+. The afterglow spectra and concentration quenching behaviors of fluorescence were investigated in the Tb3+ mono-doped sample. The result shows the optimal doping concentration of Tb3+ is 0.3 mol%. In the co-doped samples, the doping concentrations of Tb3+ and alkali ions are both at 0.3 mol%. It is found from the afterglow decay curves that the introduction of alkali ions can prolong the phosphorescent lasting time and the sample of incorporating Na+ shows the best result. Tb3+ and alkali ions can substitute Ca2+ ions, acting as hole and electron traps, respectively. The thermoluminescence (TL) spectra are also investigated. The depths of traps for the mono- and co-doped samples are calculated to be 0.622, 0.541, 0.529 and 0.538 eV, respectively. Moreover, the possible mechanism of the green long lasting phosphorescence is proposed based on the experiment results.

Evaluation of the effects of repeated hand washing, sunlight, smoke and dirt on the persistence of deltamethrin on insecticide-treated nets.

PubMed

Kayedi, M H; Lines, J D; Haghdoost, A A; Vatandoost, M H; Rassi, Y; Khamisabady, K

2008-08-01

Field studies were carried out in Iran to evaluate the effect of various factors (washing, sun, smoke, dust and dirt) on the residual insecticidal activity of PermaNet (a brand of long-lasting insecticidal net), and on nets conventionally treated with deltamethrin (K-O Tab), using bioassay tests. Thirty-two nets were washed five or 15 times, and eight nets were not washed at all. Nets were washed vigorously in cold tap water (17 degrees C, pH 8.9) with a detergent. Hand rubbing continued for 3min. After washing, some nets were exposed to dense smoke from a dung-hay fire for 3min and were also left exposed to the dusty wind between washes. One group of nets was exposed to the sunlight for the full 3-d interval between washes; another was exposed to sunlight for just 3h after each wash; two other groups were kept in the shade. There was a significantly greater loss of activity in nets exposed to the sun throughout the 3-d interval between washes: that is, for a total of 15 to 45 d. However, short sunlight exposure (maximum 3h between washes) during drying did not have any effect. We did not find any significant effect of exposure to dirt, dust and smoke after washing. It is concluded that the effect of sun is much smaller than that of washing, and that drying nets for a few hours in the sun is not harmful.

Declining ring-necked pheasants in the Klamath Basin, California: I. Insecticide exposure

USGS Publications Warehouse

Grove, Robert A.; Buhler, D.R.; Henny, Charles J.; Drew, A.D.

1998-01-01

A study of organophosphorus (OP) insecticide exposure was conducted on a declining population of ring-necked pheasants (Phasianus colchicus) associated with agricultural lands at Tule Lake National Wildlife Refuge (TLNWR) during the summers of 1990a??92. Findings at TLNWR were compared with a nearby pheasant population at Lower Klamath National Wildlife Refuge (LKNWR) not subjected to intensive farming or OP insecticide applications. Direct toxicity of anticholinesterase (antiChE) compounds (in this case methamidophos) killed 2 young pheasants (91 and 92% brain acetylcholinesterase [AChE] inhibition), but no deaths of adult radio-equipped hens were ascribed to direct insecticide intoxication. However, within 20 days postspray of OP insecticides, 68% (28 of 41) of the adult pheasants collected at TLNWR were exposed to antiChE insecticides, and exhibited brain AChE inhibition of 19a??62%, with 15% (6 of 41) showing >55% brain AChE inhibition. The lack of radio-equipped hens dying was unexpected because >50% brain AChE inhibition has been frequently used as a diagnostic tool for evaluating cause of death from antiChE insecticides. No young were radio-equipped, so the extent of the effects of insecticide exposure on the survivorship of young was unknown. It is concluded that insecticide exposure was not the major factor impacting the pheasant population (see Grove et al., in press), although some young were acutely intoxicated. However, the loss of insects killed by insecticide use may have contributed to food shortages of young pheasants, indirectly influencing survival.

Present status of biochemical research on the insecticide resistance problem*

PubMed Central

Agosin, Moises

1963-01-01

In order to provide a rational basis for the development of new insecticides, a thorough understanding of resistance mechanisms is necessary and this presupposes a detailed knowledge of the normal biochemical pathways in insects. The author reviews recent progress in this field, particularly the work on enzymatic detoxication of insecticides which appears to be the most important single factor in the production of resistance. The mechanisms include dehydrochlorination and α-methylenic oxidation (DDT), hydrolysis by phosphatases or carboxyesterases (organophosphorus compounds), and oxidation by microsomal enzyme systems (various classes of insecticides). Much work still needs to be done on the enzyme systems involved, especially in relation to substrate specificity and the effect of enzyme inhibitors that might act as synergists of insecticides. PMID:20604178

Transgenerational effects of insecticides-implications for rapid pest evolution in agroecosystems.

PubMed

Brevik, Kristian; Lindström, Leena; McKay, Stephanie D; Chen, Yolanda H

2018-04-01

Although pesticides are a major selective force in driving the evolution of insect pests, the evolutionary processes that give rise to insecticide resistance remain poorly understood. Insecticide resistance has been widely observed to increase with frequent and intense insecticide exposure, but can be lost following the relaxation of insecticide use. One possible but rarely explored explanation is that insecticide resistance may be associated with epigenetic modifications, which influence the patterning of gene expression without changing underlying DNA sequence. Epigenetic modifications such as DNA methylation, histone modifications, and small RNAs have been observed to be heritable in arthropods, but their role in the context of rapid evolution of insecticide resistance remain poorly understood. Here, we discuss evidence supporting how: firstly, insecticide-induced effects can be transgenerationally inherited; secondly, epigenetic modifications are heritable; and thirdly, epigenetic modifications are responsive to pesticide and xenobiotic stress. Therefore, pesticides may drive the evolution of resistance via epigenetic processes. Moreover, insect pests primed by pesticides may be more tolerant of other stress, further enhancing their success in adapting to agroecosystems. Resolving the role of epigenetic modifications in the rapid evolution of insect pests has the potential to lead to new approaches for integrated pest management as well as improve our understanding of how anthropogenic stress may drive the evolution of insect pests. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparison of house spraying and insecticide-treated nets for malaria control.

PubMed Central

Curtis, C. F.; Mnzava, A. E.

2000-01-01

The efficacies of using residual house spraying and insecticide-treated nets against malaria vectors are compared, using data from six recent comparisons in Africa, Asia and Melanesia. By all the entomological and malariological criteria recorded, pyrethroid-treated nets were at least as efficacious as house spraying with dichlorodiphenyltrichloroethane (DDT), malathion or a pyrethroid. However, when data from carefully monitored house spraying projects carried out between the 1950s and 1970s at Pare-Taveta and Zanzibar (United Republic of Tanzania), Kisumu (Kenya) and Garki (Nigeria) are compared with recent insecticide-treated net trials with apparently similar vector populations, the results with the insecticide-treated nets were much less impressive. Possible explanations include the longer duration of most of the earlier spraying projects and the use of non-irritant insecticides. Non-irritant insecticides may yield higher mosquito mortalities than pyrethroids, which tend to make insects leave the site of treatment (i.e. are excito-repellent). Comparative tests with non-irritant insecticides, including their use on nets, are advocated. The relative costs and sustainability of spraying and of insecticide-treated net operations are briefly reviewed for villages in endemic and epidemic situations and in camps for displaced populations. The importance of high population coverage is emphasized, and the advantages of providing treatment free of charge, rather than charging individuals, are pointed out. PMID:11196486