Phenotypic changes in laboratory-reared colonies of the maize herbivore, Diabrotica virgifera virgifera

USDA-ARS?s Scientific Manuscript database

The North American and European maize pest Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) was used to assess whether environmental conditions of the natal field, subsequent laboratory rearing, or genetic population characteristics affect phenotypic traits of fitness, activity, or...

Protandry of western corn rootworm (Coleoptera: Chrysomelidae) beetle emergence partially due to earlier egg hatch of males

USDA-ARS?s Scientific Manuscript database

The western corn rootworm, Diabrotica virgifera virgifera LeConte, exhibits protandry. The contribution of pre-hatch development to protandry in western corn rootworm was previously investigated with a small set of data from one population. To verify the contribution of pre-hatch development to prot...

The effect of western corn rootworm (Coleoptera: Chrysomelidae) and water deficit on maize performance under controlled conditions

USDA-ARS?s Scientific Manuscript database

A series of greenhouse experiments using three infestation levels of the western corn rootworm, Diabrotica virgifera virgifera LeConte, under well-watered, moderately dry, and very dry soil moisture levels were conducted to quantify the interaction of western corn rootworm and soil water deficit on ...

Comparative assessment of four Steinernematidae and three Heterorhabditidae species for infectivity of larval Diabrotica virgifera virgifera

USDA-ARS?s Scientific Manuscript database

Larval Diabrotica virgifera virgifera LeConte were exposed to seven different entomopathogenic nematode species to test their potential infectivity in a laboratory setting. Known D. virgifera infecting nematode species Heterorhabditis bacteriophora Poinar, H. megidis Poinar, Jackson & Klein, Steiner...

Effect of transgenic corn hybrids and a soil insecticide on corn rootworm (Coleoptera: Chrysomelidae) beetle emergence in North Dakota

USDA-ARS?s Scientific Manuscript database

Northern, Diabrotica barberi Smith & Lawrence, and western corn rootworms, D. virgifera virgifera LeConte, are economic pests of corn, Zea mays L. (Poaceae) in North Dakota. Many area corn growers rely on transgenic Bt (Bacillus thuringiensis) corn hybrids to manage corn rootworms. Our objective was...

Development and characterization of MIR604 resistance in a western corn rootworm population (Coleoptera: Chrysomelidae)

USDA-ARS?s Scientific Manuscript database

mCry3A is one of only four proteins licensed for commercial use in Diabrotica control. Utilizing a colony of western corn rootworm, Diabrotica virgifera virgifera LeConte, selected for resistance to mCry3A, we evaluated how mCry3A resistance was inherited and whether fitness costs were associated wi...

Evidence of resistance to Cry34/35Ab1 corn by western corn rootworm: root injury in the field and larval survival in plant-based bioassays

USDA-ARS?s Scientific Manuscript database

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a serious pest of corn in the United States and recent management of western corn rootworm has included planting of Bt corn. Beginning in 2009, western corn rootworm populations with resistance to Cry3Bb1 c...

Diet improvement for western corn rootworm (Coleoptera: Chrysomelidae) larvae

USDA-ARS?s Scientific Manuscript database

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is the most serious insect pest of corn (Zea mays L.) in the United States and parts of Europe, and arguably the world’s most expensive pest to control. Several diet formulations are currently used by industry and researchers t...

Monogalactosyldiacylglycerols as host recognition cues for western corn rootworm larvae (Coleoptera: Chrysomelidae)

USDA-ARS?s Scientific Manuscript database

Monogalactosyldiacylglycerol (MGDG) was identified as a host recognition cue for larvae of the western corn rootworm Diabrotica virgifera virgifera LeConte. An active glycolipid fraction obtained from an extract of germinating maize roots was isolated with thin layer chromatography using a bioassay-...

Monitoring Diabrotica v. virgifera (Col.: Chrysomelidae) in southeastern Slovenia: increasing population trend and host spectrum expansion.

PubMed

Ulrichs, C; Dinnesen, S; Nedelev, T; Hummel, H E; Modic, S; Urek, G

2008-01-01

Ever since the western corn rootworm (WCR) (Diabrotica virgifera virgifera), an alien invasive species from North America, has been introduced into Europe on at least 3 separate occasions, it spread within 15 years over the entire area of south-eastern and central Europe (except Denmark). Until quite recently, Zea mays L. was the only known host plant whereas in North America WCR also attacks members of the plant family Cucurbitaceae. In August of 2006, we were able to validate these findings also in the Old World by observing WCR visiting blossoms of oil pumpkin (Cucurbita pepo L.). Beside this first report of WCR on this regionally and economically important crop, a population increase in Gaberje near Lendava, Eastern Slovenia, was observed. Some future consequences of multiple hosts for integrated pest management (IPM) of WCR are being discussed.

Minnesota field population of western corn rootworm (Coleoptera: Chrysomelidae) shows incomplete resistance to Cry34Ab1/Cry35Ab1 and Cry3Bb1

USDA-ARS?s Scientific Manuscript database

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is commonly managed with corn (Zea mays L.) expressing insecticidal proteins from the bacteria Bacillus thuringiensis (Bt). Under laboratory conditions, populations of western corn rootworm have been selected for resistance to each c...

Susceptibility of Nebraska Western Corn Rootworm (Coleoptera: Chrysomelidae) Populations to Bt Corn Events

USDA-ARS?s Scientific Manuscript database

Transgenic plants have been widely adopted by growers to manage the western corn rootworm, Diabrotica virgifera virgifera LeConte, in field corn. Because of reduced efficacy in some Nebraska fields after repeated use of Cry3Bb1 expressing hybrids, single plant bioassays were conducted in 2012 and 20...

A core set of microsatellite markers for Western Corn Rootworm (Coleoptera: Chrysomelidae) population genetics studies

EPA Science Inventory

Interest in the ecological and population genetics of the western corn rootworm, Diabrotica virgifera virgifera LeConte, has grown rapidly in the last few years in North America and Europe. This interest is a result of a number of converging issues related to increasing difficult...

Semi field trials to evaluate undersowings in maize for management of western corn rootworm larvae

USDA-ARS?s Scientific Manuscript database

Western corn rootworm larvae (Diabrotica virgifera virgifera) need to feed on maize roots after hatching from overwintering eggs. It was hypothesized that the roots of undersown plants mixed with maize roots disrupt the host finding of the larvae, lowering their survival and subsequently reducing la...

Field-based assessment of resistance to Bt Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae)

USDA-ARS?s Scientific Manuscript database

Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of corn and is managed with Bt corn that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Beginning in 2009, severe injury to Bt corn producing Cry3Bb1 was observed in some cornfields ...

Toxic and behavioral effects of free fatty acids on western corn rootworm (Coleoptera: Chrysomelidae) larvae

USDA-ARS?s Scientific Manuscript database

Feeding behavior, feeding intensity and staying behavior of neonate western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae were evaluated in response to synthetic feeding stimulant blends. All of the treatments contained a 3-sugar blend (glucose:fructose:sucrose, 30:4:4 mg per ml) an...

Selection for Cry3Bb1 resistance in a genetically diverse population of nondiapausing Western Corn Rootworm (Coleoptera: Chrysomelidae)

EPA Science Inventory

Five short-diapause laboratory lines of western corn rootworm (Diabrotica virgifera virgifera) were selected for resistance to MON863, a variety of corn genetically modified with the Bacillus thuringiensis (Bt) transgene that expresses the Cry3Bb1 endotoxin. Three of the selecte...

crw1- A novel maize mutant highly susceptible to foliar damage by the Western corn rootworm beetle

USDA-ARS?s Scientific Manuscript database

Western corn rootworm (WCR), Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae), is the most destructive insect pest of corn (Zea mays L) in the United States. The adult WCR beetles derive their nourishment from multiple sources including corn pollen and silks as well as the pollen o...

Larval mortality and development for rotation-resistant and rotation-susceptible populations of the western corn rootworm on Bt corn

USDA-ARS?s Scientific Manuscript database

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is one of the most economically important insect pests threatening the production of corn, Zea mays (L.), in the United States. Throughout its history, this insect has displayed considerable adaptability by overcoming a variety of pe...

Selection for resistance to the Cry3Bb1 protein in a genetically diverse population of non-diapausing Western Corn Rootworm

EPA Science Inventory

The western corn rootworm (WCR, Diabrotica virgifera virgifera) is a serious economic pest of corn, and historically has evolved resistance to many chemical insecticides when used to manage their populations. In 2003 the U.S. Environmental Protection Agency (EPA) approved for com...

A new artificial diet for western corn rootworm larvae is compatible with and detects resistance to all current Bt toxins

USDA-ARS?s Scientific Manuscript database

Insect resistance to transgenic crops expressing one or more genes from Bacillus thuringiensis Berliner (Bt) is a growing concern for farmers, regulatory agencies, the seed industry, and researchers alike. Western corn rootworm (Diabrotica virgifera virgifera LeConte) is a pest of corn (Zea mays L.)...

Selection for Cry3Bb1 resistance in a genetically diverse population of non-diapausing western corn rootworm (Coleoptera: Chrysomelidae)

USDA-ARS?s Scientific Manuscript database

Five short-diapause laboratory lines of western corn rootworm (Diabrotica virgifera virgifera) were selected for resistance to MON863, a variety of corn genetically modified with the Bacillus thuringiensis (Bt) transgene that expresses the Cry3Bb1 d-endotoxin. Three of the selected lines were develo...

A maize inbred exhibits resistance against western corn root worm, Diabrotica vergifera vergifera.

USDA-ARS?s Scientific Manuscript database

Plants respond to insect infestations with a suite of natural defenses that vary depending on their genetic and phenotypic traits. Insect resistance traits against root herbivores like western corn rootworm (WCR, Diabrotica virgifera) are not well understood in non-transgenic maize. Using biomechani...

Quantitative trait loci mapping of western corn rootworm (Coleoptera: Chrysomelidae) host plant resistance in two populations of doubled haploid lines in maize (Zea mays L.)

USDA-ARS?s Scientific Manuscript database

Over the last 70 years, more than 12,000 maize accessions have been screened for their level of resistance to western corn rootworm, Diabrotica virgifera virgifera LeConte, larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Sele...

Fitness Costs Related To Selection for Resistance to the Cry3Bb1 Protein in a Genetically Diverse Population of Non-diapausing Western Corn Rootworm

USDA-ARS?s Scientific Manuscript database

The western corn rootworm (Diabrotica virgifera virgifera LeConte) is an important pest of maize in North America. Since approved for commercial use in 2003, the acreage planted to maize (Zea mays L.) expressing the Bt derived Cry3Bb1 protein has significantly increased each year in the United State...

Cry3Bb1-Resistant Western Corn Rootworm, Diabrotica virgifera virgifera (LeConte) Does Not Exhibit Cross-Resistance to DvSnf7 dsRNA.

PubMed

Moar, William; Khajuria, Chitvan; Pleau, Michael; Ilagan, Oliver; Chen, Mao; Jiang, Changjian; Price, Paula; McNulty, Brian; Clark, Thomas; Head, Graham

2017-01-01

There is a continuing need to express new insect control compounds in transgenic maize against western corn rootworm, Diabrotica virgifera virgifera (LeConte) (WCR). In this study three experiments were conducted to determine cross-resistance between the new insecticidal DvSnf7 dsRNA, and Bacillus thuringiensis (Bt) Cry3Bb1; used to control WCR since 2003, with field-evolved resistance being reported. Laboratory susceptible and Cry3Bb1-resistant WCR were evaluated against DvSnf7 dsRNA in larval diet-incorporation bioassays. Additionally, the susceptibility of seven field and one field-derived WCR populations to DvSnf7 (and Cry3Bb1) was assessed in larval diet-overlay bioassays. Finally, beetle emergence of laboratory susceptible and Cry3Bb1-resistant WCR was evaluated with maize plants in the greenhouse expressing Cry3Bb1, Cry34Ab1/Cry35Ab1, or DvSnf7 dsRNA singly, or in combination. The Cry3Bb1-resistant colony had slight but significantly (2.7-fold; P<0.05) decreased susceptibility to DvSnf7 compared to the susceptible colony, but when repeated using a field-derived WCR population selected for reduced Cry3Bb1 susceptibility, there was no significant difference (P<0.05) in DvSnf7 susceptibility compared to that same susceptible population. Additionally, this 2.7-fold difference in susceptibility falls within the range of DvSnf7 susceptibility among the seven field populations tested. Additionally, there was no correlation between susceptibility to DvSnf7 and Cry3Bb1 for all populations evaluated. In greenhouse studies, there were no significant differences (P<0.05) between beetle emergence of susceptible and Cry3Bb1-resistant colonies on DvSnf7 and Cry34Ab1/Cry35Ab1, and between DvSnf7 and MON 87411 (DvSnf7 + Cry3Bb1) for the Cry3Bb1-resistant colony. These results demonstrate no cross-resistance between DvSnf7 and Cry3Bb1 against WCR. Therefore, pyramiding DvSnf7 with Bt proteins such as Cry3Bb1 and Cry34Ab1/Cry35Ab1 will provide a valuable IRM tool against WCR

A Western Corn Rootworm Cadherin-like Protein is not Involved in the Binding and Toxicity of Cry34/35Ab1 and Cry3Aa Bacillus Thuringiensis Proteins

USDA-ARS?s Scientific Manuscript database

The western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte is an important insect pest of corn. Bacillus thuringiensis (Bt) insecticidal proteins Cry3Aa (as mCry3A) and Cry34Ab1/Cry35Ab1 have been expressed in transgenic corn and are used to control the insect in the U.S. To date, there ...

Cry3Bb1-Resistant Western Corn Rootworm, Diabrotica virgifera virgifera (LeConte) Does Not Exhibit Cross-Resistance to DvSnf7 dsRNA

PubMed Central

Khajuria, Chitvan; Pleau, Michael; Ilagan, Oliver; Chen, Mao; Jiang, Changjian; Price, Paula; McNulty, Brian; Clark, Thomas; Head, Graham

2017-01-01

Background and Methodology There is a continuing need to express new insect control compounds in transgenic maize against western corn rootworm, Diabrotica virgifera virgifera (LeConte) (WCR). In this study three experiments were conducted to determine cross-resistance between the new insecticidal DvSnf7 dsRNA, and Bacillus thuringiensis (Bt) Cry3Bb1; used to control WCR since 2003, with field-evolved resistance being reported. Laboratory susceptible and Cry3Bb1-resistant WCR were evaluated against DvSnf7 dsRNA in larval diet-incorporation bioassays. Additionally, the susceptibility of seven field and one field-derived WCR populations to DvSnf7 (and Cry3Bb1) was assessed in larval diet-overlay bioassays. Finally, beetle emergence of laboratory susceptible and Cry3Bb1-resistant WCR was evaluated with maize plants in the greenhouse expressing Cry3Bb1, Cry34Ab1/Cry35Ab1, or DvSnf7 dsRNA singly, or in combination. Principal Findings and Conclusions The Cry3Bb1-resistant colony had slight but significantly (2.7-fold; P<0.05) decreased susceptibility to DvSnf7 compared to the susceptible colony, but when repeated using a field-derived WCR population selected for reduced Cry3Bb1 susceptibility, there was no significant difference (P<0.05) in DvSnf7 susceptibility compared to that same susceptible population. Additionally, this 2.7-fold difference in susceptibility falls within the range of DvSnf7 susceptibility among the seven field populations tested. Additionally, there was no correlation between susceptibility to DvSnf7 and Cry3Bb1 for all populations evaluated. In greenhouse studies, there were no significant differences (P<0.05) between beetle emergence of susceptible and Cry3Bb1-resistant colonies on DvSnf7 and Cry34Ab1/Cry35Ab1, and between DvSnf7 and MON 87411 (DvSnf7 + Cry3Bb1) for the Cry3Bb1-resistant colony. These results demonstrate no cross-resistance between DvSnf7 and Cry3Bb1 against WCR. Therefore, pyramiding DvSnf7 with Bt proteins such as Cry3Bb1 and

Experiences with population dynamics of Diabrotica virgifera virgifera LeConte in the Swiss canton of Ticino up to 2007.

PubMed

Bertossa, M; Hummel, Hans E

2008-01-01

The Western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is a vexing alien invasive insect pest. It occupies the attention of entomologists in most countries of Europe and beyond. In spite of numerous research advances (e.g., Diabrotica symposium at Engelberg, Switzerland 2004) its behavior is still incompletely understood and cannot be predicted for a specific growing season with any degree of certainty. Nonetheless, by comparing several years in sequence a somewhat consistent and coherent picture is emerging that is subject of this contribution. The Ticino province received first beetles from the major infestation in Lombardy in 2000 across the geographically open border at Chiasso. The rapid advance of WCR in northerly direction along the river valleys of Ticino and Misox posed a threat to cantons north of the mountain chain of the Alps and beyond, a scenario outlined by Bertossa (2004), Wudtke et al. (2005) and subsequent papers. Following the Swiss Federal rule of crop rotation obligation around infested regions introduced in 2001, the rapid increase in population density leveled off. Careful monitoring by both Metcalf type pheromone and kairomone baited sticky traps and Hungarian traps provided a reliable tool for judging the success of any quarantine measures taken up until 2007. (1) Trends in population development of 2006 were confirmed. (2) However, for reasons not well understood, the overall population encountered in 2007 was significantly smaller in Ticino and neighboring areas of Lombardy, Italy, but also in other areas south of the Alps. This may be a consequence of the rather mild winter 2006-2007. (3) At the mountain pass of Monte Ceneri (some 600 m above sea level) no beetles were trapped in 2007, while 3 WCR were seen in 2006. (4) No new WCR were encountered in Swiss cantons north of the main chain of the Alps. (5) Metcalf sticky traps proved to be 4-5 times as sensitive as Hungarian traps used for

Knockdown of RNA interference pathway genes impacts the fitness of western corn rootworm.

PubMed

Davis-Vogel, Courtney; Ortiz, Angel; Procyk, Lisa; Robeson, Jonathan; Kassa, Adane; Wang, Yiwei; Huang, Emily; Walker, Carl; Sethi, Amit; Nelson, Mark E; Sashital, Dipali G

2018-05-18

Western corn rootworm (Diabrotica virgifera virgifera) is a serious agricultural pest known for its high adaptability to various management strategies, giving rise to a continual need for new control options. Transgenic maize expressing insecticidal RNAs represents a novel mode of action for rootworm management that is dependent on the RNA interference (RNAi) pathways of the insect for efficacy. Preliminary evidence suggests that western corn rootworm could develop broad resistance to all insecticidal RNAs through changes in RNAi pathway genes; however, the likelihood of field-evolved resistance occurring through this mechanism remains unclear. In the current study, eight key genes involved in facilitating interference in the microRNA and small interfering RNA pathways were targeted for knockdown in order to evaluate impact on fitness of western corn rootworm. These genes include drosha, dicer-1, dicer-2, pasha, loquacious, r2d2, argonaute 1, and argonaute 2. Depletion of targeted transcripts in rootworm larvae led to changes in microRNA expression, decreased ability to pupate, reduced adult beetle emergence, and diminished reproductive capacity. The observed effects do not support evolution of resistance through changes in expression of these eight genes due to reduced insect fitness.

Resistance evolution to the first generation of genetically modified Diabrotica-active Bt-maize events by western corn rootworm: management and monitoring considerations.

PubMed

Devos, Yann; Meihls, Lisa N; Kiss, József; Hibbard, Bruce E

2013-04-01

Western corn rootworm (Diabrotica virgifera virgifera; WCR) is a major coleopteran maize pest in North America and the EU, and has traditionally been managed through crop rotation and broad-spectrum soil insecticides. Genetically modified Bt-maize offers an additional management tool for WCR and has been valuable in reducing insecticide use and increasing farm income. A concern is that the widespread, repeated, and exclusive deployment of the same Bt-maize transformation event will result in the rapid evolution of resistance in WCR. This publication explores the potential of WCR to evolve resistance to plant-produced Bt-toxins from the first generation of Diabrotica-active Bt-maize events (MON 863 and MON 88017, DAS-59122-7 and MIR604), and whether currently implemented risk management strategies to delay and monitor resistance evolution are appropriate. In twelve of the twelve artificial selection experiments reported, resistant WCR populations were yielded rapidly. Field-selected resistance of WCR to Cry3Bb1 is documented in some US maize growing areas, where an increasing number of cases of unexpected damage of WCR larvae to Bt-maize MON 88017 has been reported. Currently implemented insect resistance management measures for Bt-crops usually rely on the high dose/refuge (HDR) strategy. Evidence (including laboratory, greenhouse and field data) indicates that several conditions contributing to the success of the HDR strategy may not be met for the first generation of Bt-maize events and WCR: (1) the Bt-toxins are expressed heterogeneously at a low-to-moderate dose in roots; (2) resistance alleles may be present at a higher frequency than initially assumed; (3) WCR may mate in a non-random manner; (4) resistance traits could have non-recessive inheritance; and (5) fitness costs may not necessarily be associated with resistance evolution. However, caution must be exercised when extrapolating laboratory and greenhouse results to field conditions. Model predictions

Increased expression of a cGMP-dependent protein kinase in rotation-adapted western corn rootworm (Diabrotica virgifera virgifera L.).

PubMed

Garabagi, Freydoun; Wade French, B; Schaafsma, Arthur W; Peter Pauls, K

2008-07-01

A new 'variant' behavior in western corn rootworm (WCR) has resulted in egg-laying into non-cornfields, compared to 'normal' deposition of eggs in cornfields, allowing these insects to circumvent crop rotation. No morphological or genetic characteristics have been defined to differentiate between the normal and variant biotypes. Cyclic GMP-dependent protein kinases (PKG) have been implicated in the regulation of behaviors in vertebrates, insects, and nematodes, including foraging behavior in Drosophila. A cDNA with homology to the Drosophila melanogaster foraging gene (called Dvfor1) was cloned from WCR. The deduced DvFOR1 protein is approximately 70% similar to FOR proteins in Drosophila, silkworm (Bombyx mori) and honeybee (Apis mellifera). It contains a coiled-coil region, two tandem cyclic nucleotide-binding domains, a serine/threonine kinase catalytic domain, and a serine/threonine kinase catalytic domain extension, which are all characteristically found in PKG proteins. Real-time PCR assays of foraging transcript levels in heads of normal and rotation adapted females of WCR obtained from lab-reared insect colonies indicated that the variants had higher levels (25%) of PKG expression than normals. The magnitude of this increase is similar to that observed in Drosophila rover phenotypes compared to sitter phenotypes. However, Diabrotica contains at least two different foraging gene transcripts, which complicates establishing a direct link between the level of gene expression and insect behavior.

Germline transformation of the western corn rootworm, Diabrotica virgifera virgifera.

PubMed

Chu, F; Klobasa, W; Wu, P; Pinzi, S; Grubbs, N; Gorski, S; Cardoza, Y; Lorenzen, M D

2017-08-01

The western corn rootworm (WCR), a major pest of maize, is notorious for rapidly adapting biochemically, behaviourally and developmentally to a variety of control methods. Despite much effort, the genetic basis of WCR adaptation remains a mystery. Since transformation-based applications such as transposon tagging and enhancer trapping have facilitated genetic dissection of model species such as Drosophila melanogaster, we developed a germline-transformation system for WCR in an effort to gain a greater understanding of the basic biology of this economically important insect. Here we report the use of a fluorescent-marked Minos element to create transgenic WCR. We demonstrate that the transgenic strains express both an eye-specific fluorescent marker and piggyBac transposase. We identified insertion-site junction sequences via inverse PCR and assessed insertion copy number using digital droplet PCR (ddPCR). Interestingly, most WCR identified as transgenic via visual screening for DsRed fluorescence proved to carry multiple Minos insertions when tested via ddPCR. A total of eight unique insertion strains were created by outcrossing the initial transgenic strains to nontransgenic WCR mates. Establishing transgenic technologies for this beetle is the first step towards bringing a wide range of transformation-based tools to bear on understanding WCR biology. © 2017 The Royal Entomological Society.

Field-Evolved Resistance to Bt Maize by Western Corn Rootworm

PubMed Central

Gassmann, Aaron J.; Petzold-Maxwell, Jennifer L.; Keweshan, Ryan S.; Dunbar, Mike W.

2011-01-01

Background Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are planted on millions of hectares annually, reducing the use of conventional insecticides and suppressing pests. However, the evolution of resistance could cut short these benefits. A primary pest targeted by Bt maize in the United States is the western corn rootworm Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). Methodology/Principal Findings We report that fields identified by farmers as having severe rootworm feeding injury to Bt maize contained populations of western corn rootworm that displayed significantly higher survival on Cry3Bb1 maize in laboratory bioassays than did western corn rootworm from fields not associated with such feeding injury. In all cases, fields experiencing severe rootworm feeding contained Cry3Bb1 maize. Interviews with farmers indicated that Cry3Bb1 maize had been grown in those fields for at least three consecutive years. There was a significant positive correlation between the number of years Cry3Bb1 maize had been grown in a field and the survival of rootworm populations on Cry3Bb1 maize in bioassays. However, there was no significant correlation among populations for survival on Cry34/35Ab1 maize and Cry3Bb1 maize, suggesting a lack of cross resistance between these Bt toxins. Conclusions/Significance This is the first report of field-evolved resistance to a Bt toxin by the western corn rootworm and by any species of Coleoptera. Insufficient planting of refuges and non-recessive inheritance of resistance may have contributed to resistance. These results suggest that improvements in resistance management and a more integrated approach to the use of Bt crops may be necessary. PMID:21829470

A Simple and Sensitive Plant-Based Western Corn Rootworm Bioassay Method for Resistance Determination and Event Selection.

PubMed

Wen, Zhimou; Chen, Jeng Shong

2018-05-26

We report here a simple and sensitive plant-based western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), bioassay method that allows for examination of multiple parameters for both plants and insects in a single experimental setup within a short duration. For plants, injury to roots can be visually examined, fresh root weight can be measured, and expression of trait protein in plant roots can be analyzed. For insects, in addition to survival, larval growth and development can be evaluated in several aspects including body weight gain, body length, and head capsule width. We demonstrated using the method that eCry3.1Ab-expressing 5307 corn was very effective against western corn rootworm by eliciting high mortality and significantly inhibiting larval growth and development. We also validated that the method allowed determination of resistance in an eCry3.1Ab-resistant western corn rootworm strain. While data presented in this paper demonstrate the usefulness of the method for selection of events of protein traits and for determination of resistance in laboratory populations, we envision that the method can be applied in much broader applications.

Root herbivory: molecular analysis of the maize transcriptome upon infestation by Southern corn rootworm, Diabrotica undecimpunctata howardi

USDA-ARS?s Scientific Manuscript database

While many studies have characterized the transcriptome of plants attacked by herbivorous insect pests, few have undertaken an examination of the genes affected by root pests. We have subjected maize seedlings to infestation by southern corn rootworm (SCR) Diabrotica undecimpunctata howardi and usin...

A novel method for estimating soybean herbivory in western corn rootworm (Coleoptera: Chrysomelidae).

PubMed

Seiter, Nicholas J; Richmond, Douglas S; Holland, Jeffrey D; Krupke, Christian H

2010-08-01

The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is the key pest of corn, Zea mays L., in North America. The western corn rootworm variant is a strain found in some parts of the United States that oviposits in soybean, Glycine max (L.) Merr., thereby circumventing crop rotation. Soybean herbivory is closely associated with oviposition; therefore, evidence of herbivory could serve as a proxy for rotation resistance. A digital image analysis method based on the characteristic green abdominal coloration of rootworm adults with soybean foliage in their guts was developed to estimate soybean herbivory rates of adult females. Image analysis software was used to develop and apply threshold limits that allowed only colors within the range that is characteristic of soybean herbivory to be displayed. When this method was applied to adult females swept from soybean fields in an area with high levels of rotation resistance, 54.3 +/- 2.1% were estimated to have fed on soybean. This is similar to a previously reported estimate of 54.8%. Results when laboratory-generated negative controls were analyzed showed an acceptably low frequency of false positives. This method could be developed into a management tool if user-friendly software were developed for its implementation. In addition, researchers may find the method useful as a rapid, standardized screen for measuring frequencies of soybean herbivory.

Examining Cuphea as a potential host for western corn rootworm (Coleoptera: Chrysomelidae): larval development.

PubMed

Behle, Robert W; Hibbard, Bruce E; Cermak, Steven C; Isbell, Terry A

2008-06-01

In previous crop rotation research, adult emergence traps placed in plots planted to Cuphea PSR-23 (a selected cross of Cuphea viscosissma Jacq. and Cuphea lanceolata Ait.) caught high numbers of adult western corn rootworms, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), suggesting that larvae may have completed development on this broadleaf plant. Because of this observation, a series of greenhouse and field experiments were conducted to test the hypothesis that Cuphea could serve as a host for larval development. Greenhouse-grown plants infested with neonates of a colonized nondiapausing strain of the beetle showed no survival of larvae on Cuphea, although larvae did survive on the positive control (corn, Zea mays L.) and negative control [sorghum, Sorghum bicolor (L.) Moench] plants. Soil samples collected 20 June, 7 July, and 29 July 2005 from field plots planted to Cuphea did not contain rootworm larvae compared with means of 1.28, 0.22, and 0.00 rootworms kg(-1) soil, respectively, for samples collected from plots planted to corn. Emergence traps captured a peak of eight beetles trap(-1) day(-1) from corn plots on 8 July compared with a peak of 0.5 beetle trap(-1) day(-1) on 4 August from Cuphea plots. Even though a few adult beetles were again captured in the emergence traps placed in the Cuphea plots, it is not thought to be the result of successful larval development on Cuphea roots. All the direct evidence reported here supports the conventional belief that rootworm larvae do not survive on broadleaf plants, including Cuphea.

Dietary risk assessment of v-ATPase A dsRNAs on monarch butterfly larvae

USDA-ARS?s Scientific Manuscript database

The goal of this study is to assess the risks of RNA interference (RNAi)-based genetically engineered crops on a non-target arthropod, monarch butterfly, Danaus plexippus. We hypothesize that an insecticidal double-stranded (ds) RNA targeting western corn rootworm, Diabrotica virgifera virgifera, ha...

Dynamic precision phenotyping reveals mechanism of crop tolerance to root herbivory

USDA-ARS?s Scientific Manuscript database

The western corn rootworm, Diabrotica virgifera virgifera (LeConte) is a major pest of maize, Zea mays L. Over the years, this pest has repeatedly shown its resilience and adaptability not only to traditional crop management strategies including chemical pesticides and crop rotation, but also to de...

Quantitative Trait Loci Mapping of Western Corn Rootworm (Coleoptera: Chrysomelidae) Host Plant Resistance in Two Populations of Doubled Haploid Lines in Maize (Zea mays L.).

PubMed

Bohn, Martin O; Marroquin, Juan J; Flint-Garcia, Sherry; Dashiell, Kenton; Willmot, David B; Hibbard, Bruce E

2018-02-09

Over the last 70 yr, more than 12,000 maize accessions have been screened for their level of resistance to western corn rootworm, Diabrotica virgifera virgifera (LeConte; Coleoptera: Chrysomelidae), larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Selected genotypes were mostly characterized by large root systems and superior root regrowth after root damage caused by western corn rootworm larvae. However, no hybrids claiming native (i.e., host plant) resistance to western corn rootworm larval feeding are currently commercially available. We investigated the genetic basis of western corn rootworm resistance in maize materials with improved levels of resistance using linkage disequilibrium mapping approaches. Two populations of topcrossed doubled haploid maize lines (DHLs) derived from crosses between resistant and susceptible maize lines were evaluated for their level of resistance in three to four different environments. For each DHL topcross an average root damage score was estimated and used for quantitative trait loci (QTL) analysis. We found genomic regions contributing to western corn rootworm resistance on all maize chromosomes, except for chromosome 4. Models fitting all QTL simultaneously explained about 30 to 50% of the genotypic variance for root damage scores in both mapping populations. Our findings confirm the complex genetic structure of host plant resistance against western corn rootworm larval feeding in maize. Interestingly, three of these QTL regions also carry genes involved in ascorbate biosynthesis, a key compound we hypothesize is involved in the expression of western corn rootworm resistance. © 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.

Control of Larval Northern Corn Rootworm. (Diabrotica barberi) with Two Steinernematid Nematode Species

PubMed Central

Thurston, G. S.; Yule, W. N.

1990-01-01

The entomogenous nematodes Steinerema feltiae and S. bibionis did not penetrate the roots of corn, Zea mays, to infect larval northern corn rootworm (NCR), Diabrotica barberi, feeding within. Laboratory bioassays against first instar NCR indicated that S. feltiae, Mexican strain (LD₅₀ = 49 nematodes/insect) is more virulent than S. bibionis (LD₅₀ = 100). Numbers of NCR larvae in a grain corn crop were reduced by both nematode species applied at corn seeding time at the rate of 10,000 infective-stage juveniles per linear meter of corn row. The chemical insecticide fonofos provided significantly better control than either nematode species. PMID:19287699

Distribution of MCA-coated grits in maize fields after high wheel tractor application for disrupting orientation of Diabrotica virgifera virgifera LeConte.

PubMed

Wennemann, Ludger; Hummel, Hans E

2002-01-01

High wheel tractor applications of 4-methoxycinnamaldehyde (MCA)-coated corn granules ('grits') were conducted in Ruski Krstur (Serbia) in summer 2001 in a 5 ha corn field. Grits are a by-product after corn is harvested and separated from the cob and used as a carrier medium to disseminate MCA into the corn field. MCA is a kairomone mimic derived form Cucurbita maxima (Duchesne) used to disrupt orientation of Diabrotica virgifera virgifera LeConte towards different MCA and pheromone baited traps. The ultimate goal is to investigate the use of MCA as a mating disruptant. MCA was dissolved in an organic solvent and mixed in a cement machine with the grits. Grits were applied at rates of 17.39, 17.1 and 12.45 kg/ha on July 4th, July 19th and August 3rd. Before the impact of MCA as a disruptant can be addressed, the distribution patterns of MCA coated grits have to be thoroughly investigated. They were evaluated by counting girts deposited in 16 or 20 plastic dishes of 30-cm diameter positioned along 2 rows through the field directly after the grit application by tractor. Additionally, grits deposited on corn plant surface such as leaves, leaf axils and corn cobs were counted. Total number of grits collected in plastic dishes revealed even application rates at the first and second application but not on the third application date. Number of grits collected on plant surfaces were significantly different from each other regarding each application date. Altogether, grit distribution in the dishes as well as on the plant surface was variable. However, distribution patterns achieved so far hold promise to disseminate MCA coated grits into corn fields for orientation disruption or mating disruption of D. virgifera virgifera.

Orientation disruption of Diabrotica virgifera virgifera in maize by a liquid MCA formulation released from paper squares in the Banat region of Serbia and Montenegro.

PubMed

Hummel, H E; Baca, F I; Erski, P

2003-01-01

Serbia-Montenegro, formerly the Republic of Yugoslavia, is the first European Country where Diabrotica virgifera virgifera Le Conte (Col.: Chrysomelidae) (D.v.v.) was reported in 1992 as an invasive alien pest species, Baca (1993), Camprag and Baca, (1995): From a focal point near Belgrade airport, the maize pest quickly spread in all directions reaching the economic threshold in a number of surrounding countries around 1995. The field experiments described took place in the Banat region east of Belgrade in July of 2002. The plant kairomone mimic 4-methoxycinnamaldehyde (MCA) dissolved in acetone was slowly volatilized from paper squares. It permeated a maize field of known D.v.v. history of 0.5 ha size 3 km north of the village of Crepaja. With release rates of 266 g/ha, max. orientation disruption levels of 55% were achieved. The total amount of MCA was distributed in two manual applications. Readings of orientation levels were continued for eleven days during the latter part of July and into early August of 2002.

Assessment of Inheritance and Fitness Costs Associated with Field-Evolved Resistance to Cry3Bb1 Maize by Western Corn Rootworm.

PubMed

Paolino, Aubrey R; Gassmann, Aaron J

2017-05-11

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is among the most serious insect pests of maize in North America. One strategy used to manage this pest is transgenic maize that produces one or more crystalline (Cry) toxins derived from the bacterium Bacillus thuringiensis (Bt). To delay Bt resistance by insect pests, refuges of non-Bt maize are grown in conjunction with Bt maize. Two factors influencing the success of the refuge strategy to delay resistance are the inheritance of resistance and fitness costs, with greater delays in resistance expected when inheritance of resistance is recessive and fitness costs are present. We measured inheritance and fitness costs of resistance for two strains of western corn rootworm with field-evolved resistance to Cry3Bb1 maize. Plant-based and diet-based bioassays revealed that the inheritance of resistance was non-recessive. In a greenhouse experiment, in which larvae were reared on whole maize plants in field soil, no fitness costs of resistance were detected. In a laboratory experiment, in which larvae experienced intraspecific and interspecific competition for food, a fitness cost of delayed larval development was identified, however, no other fitness costs were found. These findings of non-recessive inheritance of resistance and minimal fitness costs, highlight the potential for the rapid evolution of resistance to Cry3Bb1 maize by western corn rootworm, and may help to improve resistance management strategies for this pest.

Geographic information systems in corn rootworm management

USDA-ARS?s Scientific Manuscript database

Corn rootworms (Diabrotica spp. Coleoptera: Chrysomelidae) are serious pests of corn (Zea mays) in the United States and Europe. Control measures for corn rootworms (CRW) were historically based upon chemical pesticides and crop rotation. Pesticide use created environmental and economic concerns. In...

Field Trial Performance of Herculex XTRA (Cry34Ab1/Cry35Ab1) and SmartStax (Cry34Ab1/Cry35Ab1 + Cry3Bb1) Hybrids and Soil Insecticides Against Western and Northern Corn Rootworms (Coleoptera: Chrysomelidae).

PubMed

Johnson, K D; Campbell, L A; Lepping, M D; Rule, D M

2017-06-01

Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae), are important insect pests in corn, Zea mays L. For more than a decade, growers have been using transgenic plants expressing proteins from the bacterium Bacillus thuringiensis (Bt) to protect corn roots from feeding. In 2011, western corn rootworm populations were reported to have developed resistance to Bt hybrids expressing Cry3Bb1 and later found to be cross-resistant to hybrids expressing mCry3A and eCry3.1Ab. The identification of resistance to Cry3 (Cry3Bb1, mCry3A, and eCry3.1Ab) hybrids led to concerns about durability and efficacy of products with single traits and of products containing a pyramid of a Cry3 protein and the binary Bt proteins Cry34Ab1 and Cry35Ab1. From 2012 to 2014, 43 field trials were conducted across the central United States to estimate root protection provided by plants expressing Cry34Ab1/Cry35Ab1 alone (Herculex RW) or pyramided with Cry3Bb1 (SmartStax). These technologies were evaluated with and without soil-applied insecticides to determine if additional management measures provided benefit where Cry3 performance was reduced. Trials were categorized for analysis based on rootworm damage levels on Cry3-expressing hybrids and rootworm feeding pressure within each trial. Across scenarios, Cry34Ab1/Cry35Ab1 hybrids provided excellent root protection. Pyramided traits provided greater root and yield protection than non-Bt plus a soil-applied insecticide, and only in trials where larval feeding pressure exceeded two nodes of damage did Cry34Ab1/Cry35Ab1 single-trait hybrids and pyramided hybrids show greater root protection from the addition of soil-applied insecticides. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Gut bacteria facilitate adaptation to crop rotation in the western corn rootworm

PubMed Central

Chu, Chia-Ching; Spencer, Joseph L.; Curzi, Matías J.; Zavala, Jorge A.; Seufferheld, Manfredo J.

2013-01-01

Insects are constantly adapting to human-driven landscape changes; however, the roles of their gut microbiota in these processes remain largely unknown. The western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) (Coleoptera: Chrysomelidae) is a major corn pest that has been controlled via annual rotation between corn (Zea mays) and nonhost soybean (Glycine max) in the United States. This practice selected for a “rotation-resistant” variant (RR-WCR) with reduced ovipositional fidelity to cornfields. When in soybean fields, RR-WCRs also exhibit an elevated tolerance of antiherbivory defenses (i.e., cysteine protease inhibitors) expressed in soybean foliage. Here we show that gut bacterial microbiota is an important factor facilitating this corn specialist’s (WCR's) physiological adaptation to brief soybean herbivory. Comparisons of gut microbiota between RR- and wild-type WCR (WT-WCR) revealed concomitant shifts in bacterial community structure with host adaptation to soybean diets. Antibiotic suppression of gut bacteria significantly reduced RR-WCR tolerance of soybean herbivory to the level of WT-WCR, whereas WT-WCR were unaffected. Our findings demonstrate that gut bacteria help to facilitate rapid adaptation of insects in managed ecosystems. PMID:23798396

Evidence of field-evolved resistance to bifenthrin in western corn rootworm (Diabrotica virgifera virgifera LeConte) populations in western Nebraska and Kansas

USDA-ARS?s Scientific Manuscript database

Pyrethroid insecticides are widely used to control larvae or adult western corn rootworm, a key pest of corn in the United States. In response to reports of reduced efficacy of pyrethroids in WCR management programs in southwestern areas of Nebraska and Kansas the present research was designed to es...

Evaluation of Cuphea as a rotation crop for control of western corn rootworm (Coleoptera: Chrysomelidae).

PubMed

Behle, Robert W; Isbell, Terry A

2005-12-01

The ability to prevent significant root feeding damage to corn, Zea mays L., by the western corn rootworm, Diabrotica virgifera virgifera LeConte, by crop rotation with soybean, Glycine max (L.) Merr., has been lost in portions of the Corn Belt because this pest has adapted to laying eggs in soybean fields. Cuphea spp. has been proposed as a new broadleaf crop that may provide an undesirable habitat for rootworm adults because of its sticky surface and therefore may reduce or prevent oviposition in these fields. A 4-yr study (1 yr to establish seven rotation programs followed by 3 yr of evaluation) was conducted to determine whether crop rotation with Cuphea would provide cultural control of corn rootworm. In support of Cuphea as a rotation crop, fewer beetles were captured by sticky traps in plots of Cuphea over the 4 yr of this study compared with traps in corn and soybean, suggesting that fewer eggs may be laid in plots planted to Cuphea. Also, corn grown after Cuphea was significantly taller during vegetative growth, had significantly lower root damage ratings for 2 of 3 yr, and had significantly higher yields for 2 of 3 yr compared with continuous corn plots. In contrast to these benefits, growing Cuphea did not prevent economic damage to subsequent corn crops as indicated by root damage ratings > 3.0 recorded for corn plants in plots rotated from Cuphea, and sticky trap catches that exceeded the threshold of five beetles trap(-1) day(-1). Beetle emergence from corn plots rotated from Cuphea was significantly lower, not different and significantly higher compared with beetle emergence from continuous corn plots for 2002, 2003 and 2004 growing seasons, respectively. A high number of beetles were captured by emergence cages in plots planted to Cuphea, indicating that rootworm larvae may be capable of completing larval development by feeding on roots of Cuphea, although peak emergence lagged approximately 4 wk behind peak emergence from corn. Based on these data

IPM Use With the Deployment of a Non-High Dose Bt Pyramid and Mitigation of Resistance for Western Corn Rootworm (Diabrotica virgifera virgifera).

PubMed

Martinez, J C; Caprio, M A

2016-03-27

Recent detection of western corn rootworm resistance to Bt (Bacillus thuringiensis) corn prompted recommendations for the use of integrated pest management (IPM) with planting refuges to prolong the durability of Bt technologies. We conducted a simulation experiment exploring the effectiveness of various IPM tools at extending durability of pyramided Bt traits. Results indicate that some IPM practices have greater merits than others. Crop rotation was the most effective strategy, followed by increasing the non-Bt refuge size from 5 to 20%. Soil-applied insecticide use for Bt corn did not increase the durability compared with planting Bt with refuges alone, and both projected lower durabilities. When IPM participation with randomly selected management tools was increased at the time of Bt commercialization, durability of pyramided traits increased as well. When non-corn rootworm expressing corn was incorporated as an IPM option, the durability further increased.For corn rootworm, a local resistance phenomenon appeared immediately surrounding the resistant field (hotspot) and spread throughout the local neighborhood in six generations in absence of mitigation. Hotspot mitigation with random selection of strategies was ineffective at slowing resistance, unless crop rotation occurred immediately; regional mitigation was superior to random mitigation in the hotspot and reduced observed resistance allele frequencies in the neighborhood. As resistance alleles of mobile pests can escape hotspots, the scope of mitigation should extend beyond resistant sites. In the case of widespread resistance, regional mitigation was less effective at prolonging the life of the pyramid than IPM with Bt deployment at the time of commercialization. Published by Oxford University Press on behalf of Entomological Society of America 2016. This work is written by US Government employees and is in the public domain in the United States.

Susceptibility of northern corn rootworm Diabrotica barberi (Coleoptera: Chrysomelidae) to mCry3A and eCry3.1Ab Bacillus thuringiensis proteins.

PubMed

Oyediran, Isaac O; Matthews, Phillip; Palekar, Narendra; French, Wade; Conville, Jared; Burd, Tony

2016-12-01

The susceptibility of the northern corn rootworm Diabrotica barberi (Smith & Lawrence) to mCry3A and eCry3.1Ab proteins derived from Bacillus thuringiensis (Bt) was determined using a diet bioassay. Northern corn rootworm neonates were exposed to different concentrations of mCry3A and eCry3.1Ab, incorporated into artificial diet. Larval mortality was evaluated after 7 d. The mCry3A and eCry3.1Ab proteins were found to be toxic to the northern corn rootworm larvae. The LC 50 and LC 99 values for mCry3A were 5.13 and 2482.31 μg/mL, respectively. For eCry3.1Ab, the LC 50 and LC 99 values were 0.49 and 213.01 μg/mL. Based on the estimated lethal concentrations, eCry3.1Ab protein was more efficacious to northern corn rootworm larvae than mCry3A. These lethal concentration values will be used as diagnostic doses for routine annual monitoring for change in susceptibility of field collected northern corn rootworm to mCry3A, and eCry3.1Ab toxins. © 2015 Institute of Zoology, Chinese Academy of Sciences.

Time of planting and choice of maize hybrids in controlling WCR (Diabrotica virgifera virgifera Le Conte) in Serbia and Montenegro.

PubMed

Baca, F; Videnovic, Z; Erski, P; Stankovic, R; Dobrikovic, Danica

2003-01-01

increased from 16.0 to 63.9%. To successfully decrease the size and intensity of attacks of the Diabrotica v. virgifera population under conditions of applying insecticides or not, it is necessary to use maize hybrids of the earliest possible maturity group and to plant the seed on the earliest date possible in the first year of growing maize, if maize is to be followed by maize in the next year.

Corn rootworm-active RNA DvSnf7: Repeat dose oral toxicology assessment in support of human and mammalian safety.

PubMed

Petrick, Jay S; Frierdich, Gregory E; Carleton, Stephanie M; Kessenich, Colton R; Silvanovich, Andre; Zhang, Yuanji; Koch, Michael S

2016-11-01

Genetically modified (GM) crops have been developed and commercialized that utilize double stranded RNAs (dsRNA) to suppress a target gene(s), producing virus resistance, nutritional and quality traits. MON 87411 is a GM maize variety that leverages dsRNAs to selectively control corn rootworm through production of a 240 base pair (bp) dsRNA fragment targeting for suppression the western corn rootworm (Diabrotica virgifera virgifera) Snf7 gene (DvSnf7). A bioinformatics assessment found that endogenous corn small RNAs matched ∼450 to 2300 unique RNA transcripts that likely code for proteins in rat, mouse, and human, demonstrating safe dsRNA consumption by mammals. Mice were administered DvSnf7 RNA (968 nucleotides, including the 240 bp DvSnf7 dsRNA) at 1, 10, or 100 mg/kg by oral gavage in a 28-day repeat dose toxicity study. No treatment-related effects were observed in body weights, food consumption, clinical observations, clinical chemistry, hematology, gross pathology, or histopathology endpoints. Therefore, the No Observed Adverse Effect Level (NOAEL) for DvSnf7 RNA was 100 mg/kg, the highest dose tested. These results demonstrate that dsRNA for insect control does not produce adverse health effects in mammals at oral doses millions to billions of times higher than anticipated human exposures and therefore poses negligible risk to mammals. Copyright © 2016 Monsanto Company. Published by Elsevier Inc. All rights reserved.

Selection for Cry3Bb1 resistance in a genetically diverse population of nondiapausing western corn rootworm (Coleoptera: Chrysomelidae).

PubMed

Oswald, Kenneth J; French, B Wade; Nielson, Chad; Bagley, Mark

2011-06-01

Five short-diapause laboratory lines of western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), were selected for resistance to MON863, a variety of corn genetically modified with the Bacillus thuringiensis Berliner (Bt) transgene that expresses the Cry3Bb1 delta-endotoxin. Three of the selected lines were developed by incremental increase in the duration of exposure to MON863 over 11 generations (moderate selected lines). Two selected lines were developed from a control group by constant exposure to MON863 for at least 14 d posthatch over seven generations (intense selected lines). At the end of the experiment, survivorship, as measured by adult emergence, was approximately 4 times higher in each of the selected lines reared on MON863 compared with control lines. Estimates of realized heritabilities (h2) were 0.16 and 0.15 for the moderate and intense selected lines, respectively, and are consistent with h2 estimates reported previously from a variety of pest insects. These lines provide data necessary for evaluating the potential for Bt resistance within diabroticite beetles and will be useful for developing improved insect resistance management strategies.

A promising biotechnical approach to pest management of Diabrotica virgifera virgifera in Illinois maize fields under kairomonal shielding with the new MSD technique.

PubMed

Hummel, H E; Shaw, J T; Hein, D F

2005-01-01

Environmentally compatible and sustainable plant protection requires novel approaches to pest management characterized by minimal emphasis on toxicants. Classical toxicants traditionally dominated economic entomology for half a century. But worldwide problems with environmental pollution and with increasing resistance levels in all major pesticide classes and in many key insect species including Diabrotica virgifera virgifera (D.v.v.) strongly advocate a rethinking and a change in management paradigms used. Soft, minimally invasive, biological, biotechnical and cultural approaches should replace hard pesticides which are in favor up to now. Fortunately, pheromones, kairomones, plant attractants, better traps, new plant varieties and cultural methods like crop rotation, in short more sophisticated methods are now available as pressure for finding and exploring novel strategies increases. Facing this situation, a new biotechnical approach of population reduction of D.v.v., called "MSD" technique, is introduced. MSD is characterized as an approach combining mass trapping, shielding and deflecting of adult insects along an invisible odor barrier of synthetic kairomone which diminishes the flux of insects across a high capacity trap line baited with kairomone, thus reducing both the population fluctuation and number and its reproductive success within the shielded area. In the case of D.v.v. in Zea mays fields, effects realized by the MSD technique have been measured simultaneously by a number of independent criteria during the summers of 2003 and 2004 at 2 different locations in Illinois maize fields of up to one half hectare size. Results observed are statistically significant and cannot be explained by mass trapping alone. There is also an additional shielding and deflection, in short "diversion" effect whose basic sensory and behavioral mechanisms call for future exploration.

Wing shape and size of the western corn rootworm (Coleoptera: Chrysomelidae) is related to sex and resistance to soybean-maize crop rotation.

PubMed

Mikac, K M; Douglas, J; Spencer, J L

2013-08-01

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is a major pest of maize in the United States and more recently, Europe. Understanding the dispersal dynamics of this species will provide crucial information for its management. This study used geometric morphometric analysis of hind wing venation based on 13 landmarks in 223 specimens from nine locations in Illinois, Nebraska, Iowa, and Missouri, to assess whether wing shape and size differed between rotated and continuously grown maize where crop rotation-resistant and susceptible individuals are found, respectively. Before assessing differences between rotation-resistant and susceptible individuals, sexual dimorphism was investigated. No significant difference in wing (centroid) size was found between males and females; however, females had significantly different shaped (more elongated) wings compared with males. Wing shape and (centroid) size were significantly larger among individuals from rotated maize where crop-rotation resistance was reported; however, cross-validation of these results revealed that collection site resistance status was an only better than average predictor of shape in males and females. This study provides preliminary evidence of wing shape and size differences in D. v. virgifera from rotated versus continuous maize. Further study is needed to confirm whether wing shape and size can be used to track the movement of rotation-resistant individuals and populations as a means to better inform management strategies.

Monitoring presence and advance of the alien invasive western corn rootworm beetle in eastern Slovenia with highly sensitive Metcalf traps.

PubMed

Hummel, H E; Urek, G; Modic, S; Hein, D F

2005-01-01

The American Chrysomelid beetle Diabrotica virgifera virgifera LeConte (D.v.v.), also called the western corn rootworm, spread from the location of its original introduction into Europe, Belgrade airport (BACA 1993), in all directions. Within a decade it occupied almost all countries of South-eastern and Central Europe. However, it reached Slovenia as late as 2003: Only 19 specimen were found in maize fields of the eastern and also western provinces. Already in the summer of 2004, their number had risen to 386 which were mainly found in the eastern provinces near the borders to Croatia, Austria and Hungary. For their monitoring, a simple trap is being described which can be acquired in high numbers at a very low price and can guaranty a most sensitive detection of beetles. The Metcalf cup trap which in Slovenia so far has been unknown performed the task of monitoring quite well at five locations. It will also facilitate the future search for new and increasing infestations. Comparing 2004 with the year 2003, D.v.v. expanded its range in eastern Slovenia by about 15 km. These new infestations will include territories in which fields of the regionally Important oil seed pumpkin Cucurbita pepo are located. With important traffic connections between South-eastern and Central Europe, Slovenia will occupy a bridgehead function in the preventive protection of maize from D.v.v. spreading into more northerly European regions including western Austria and southern Germany.

Attraction of Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae) to eugenol-baited traps in soybean

USDA-ARS?s Scientific Manuscript database

Diabrotica barberi Smith and Lawrence (the northern corn rootworm) is a native North American leaf beetle and a major pest of corn. However, adult D. barberi forage in various habitats outside of corn, including soybean, roadside vegetation, and prairie. Eugenol is a common floral volatile that ha...

Differential effects of RNAi treatments on field populations of the western corn rootworm.

PubMed

Chu, Chia-Ching; Sun, Weilin; Spencer, Joseph L; Pittendrigh, Barry R; Seufferheld, Manfredo J

2014-03-01

RNA interference (RNAi) mediated crop protection against insect pests is a technology that is greatly anticipated by the academic and industrial pest control communities. Prior to commercialization, factors influencing the potential for evolution of insect resistance to RNAi should be evaluated. While mutations in genes encoding the RNAi machinery or the sequences targeted for interference may serve as a prominent mechanism of resistance evolution, differential effects of RNAi on target pests may also facilitate such evolution. However, to date, little is known about how variation of field insect populations could influence the effectiveness of RNAi treatments. To approach this question, we evaluated the effects of RNAi treatments on adults of three western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) populations exhibiting different levels of gut cysteine protease activity, tolerance of soybean herbivory, and immune gene expression; two populations were collected from crop rotation-resistant (RR) problem areas and one from a location where RR was not observed (wild type; WT). Our results demonstrated that RNAi targeting DvRS5 (a highly expressed cysteine protease gene) reduced gut cysteine protease activity in all three WCR populations. However, the proportion of the cysteine protease activity that was inhibited varied across populations. When WCR adults were treated with double-stranded RNA of an immune gene att1, different changes in survival among WT and RR populations on soybean diets occurred. Notably, for both genes, the sequences targeted for RNAi were the same across all populations examined. These findings indicate that the effectiveness of RNAi treatments could vary among field populations depending on their physiological and genetic backgrounds and that the consistency of an RNAi trait's effectiveness on phenotypically different populations should be considered or tested prior to wide deployment. Also, genes that are potentially subjected

Agriculture sows pests: how crop domestication, host shifts, and agricultural intensification can create insect pests from herbivores.

PubMed

Bernal, Julio S; Medina, Raul F

2018-04-01

We argue that agriculture as practiced creates pests. We use three examples (Corn leafhopper, Dalbulus maidis; Western corn rootworm, Diabrotica virgifera virgifera; Cotton fleahopper, Pseudatomoscelis seriatus) to illustrate: firstly, how since its origins, agriculture has proven conducive to transforming selected herbivores into pests, particularly through crop domestication and spread, and agricultural intensification, and; secondly, that the herbivores that became pests were among those hosted by crop wild relatives or associates, and were pre-adapted either as whole species or component subpopulations. Two of our examples, Corn leafhopper and Western corn rootworm, illustrate how following a host shift to a domesticated host, emergent pests 'hopped' onto crops and rode expansion waves to spread far beyond the geographic ranges of their wild hosts. Western corn rootworm exemplifies how an herbivore-tolerant crop was left vulnerable when it was bred for yield and protected with insecticides. Cotton fleahopper illustrates how removing preferred wild host plants from landscapes and replacing them with crops, allows herbivores with flexible host preferences to reach pest-level populations. We conclude by arguing that in the new geological epoch we face, the Anthropocene, we can improve agriculture by looking to our past to identify and avoid missteps of early and recent farmers. Copyright © 2018 Elsevier Inc. All rights reserved.

Assessment of fitness costs in Cry3Bb1 resistant and susceptible western corn rootworm (Coleoptera:Chrysomelidae) laboratory colonies

EPA Science Inventory

Maize production in the United States is dominated by plants genetically modified with transgenes from Bacillus thuringiensis (Bt). Varieties of Bt maize expressing Cry3Bb endotoxins that specifically target corn rootworms (genus Diabrotica) have proven highly efficacious. Howeve...

Cross-resistance and synergism bioassays suggest multiple mechanisms of pyrethroid resistance in western corn rootworm populations

PubMed Central

Souza, Dariane; Zukoff, Sarah N.; Meinke, Lance J.; Siegfried, Blair D.

2017-01-01

Recently, resistance to the pyrethroid bifenthrin was detected and confirmed in field populations of western corn rootworm, Diabrotica virgifera virgifera LeConte from southwestern areas of Nebraska and Kansas. As a first step to understand potential mechanisms of resistance, the objectives of this study were i) to assess adult mortality at diagnostic concentration-LC99 to the pyrethroids bifenthrin and tefluthrin as well as DDT, ii) estimate adult and larval susceptibility to the same compounds as well as the organophosphate methyl-parathion, and iii) perform synergism experiments with piperonyl butoxide (PBO) (P450 inhibitor) and S,S,S-tributyl-phosphorotrithioate (DEF) (esterase inhibitor) in field populations. Most of the adult field populations exhibiting some level of bifenthrin resistance exhibited significantly lower mortality to both pyrethroids and DDT than susceptible control populations at the estimated LC99 of susceptible populations. Results of adult dose-mortality bioassays also revealed elevated LC50 values for bifenthrin resistant populations compared to the susceptible control population with resistance ratios ranging from 2.5 to 5.5-fold for bifenthrin, 28 to 54.8-fold for tefluthrin, and 16.3 to 33.0 for DDT. These bioassay results collectively suggest some level of cross-resistance between the pyrethroids and DDT. In addition, both PBO and DEF reduced the resistance ratios for resistant populations although there was a higher reduction in susceptibility of adults exposed to PBO versus DEF. Susceptibility in larvae varied among insecticides and did not correlate with adult susceptibility to tefluthrin and DDT, as most resistance ratios were < 5-fold when compared to the susceptible population. These results suggest that both detoxifying enzymes and target site insensitivity might be involved as resistance mechanisms. PMID:28628635

Assessment of fitness costs in Cry3Bb1 resistant and susceptible western corn rootworm (Coleoptera: Chrysomelidae) laboratory colonies

USDA-ARS?s Scientific Manuscript database

Maize production in the United States is dominated by plants genetically modified with transgenes from Bacillus thuringiensis (Bt). Varieties of Bt maize expressing Cry3Bb d endotoxins that specifically target corn rootworms (genus Diabrotica) have proven highly efficacious. However, development of ...

Isolation of transcripts from Diabrotica virgifera virgifera LeConte responsive to the Bacillus thuringiensis toxin Cry3Bb1

EPA Science Inventory

Crystal proteins derived from Bacillus thuringiensis (Bt) have been widely used as a method of insect pest management for several decades. In recent years, a transgenic corn expressing the Cry3Bb1 toxin has been successfully used for protection against corn rootworm larvae (Genus...

Metathesis-mediated synthesis of (R)-10-methyl-2-tridecanone, the southern corn rootworm pheromone.

PubMed

Shikichi, Yasumasa; Mori, Kenji

2012-01-01

(R)-10-Methyl-2-tridecanone, the female sex pheromone of the southern corn rootworm (Diabrotica undecimpunctata howardi Barber), was synthesized in 9 steps from methyl (S)-3-hydroxy-2-methylpropanoate in a 15.7% overall yield. Olefin cross metathesis between (R)-6-methyl-1-nonene and 5-hexen-2-one employing Grubbs' first-generation catalyst was the key step of the synthesis.

Diabrotica collicola (Coleoptera: Chrysomelidae)a new species of leaf beetle from Argentina Discussion and key to some similar species of the Diabrotica virgifera group

USDA-ARS?s Scientific Manuscript database

The new species Diabrotica collicola Cabrera & Cabrera Walsh is described and illustrated based on specimens collected from Balcozna, Catamarca Province (Argentina). A full description is provided and includes morphological characters of the mouthparts, hind wing venation, binding patch, metendoster...

Abnormally high digestive enzyme activity and gene expression explain the contemporary evolution of a Diabrotica biotype able to feed on soybeans

PubMed Central

Curzi, Matías J; Zavala, Jorge A; Spencer, Joseph L; Seufferheld, Manfredo J

2012-01-01

Western corn rootworm (Diabrotica virgifera) (WCR) depends on the continuous availability of corn. Broad adoption of annual crop rotation between corn (Zea mays) and nonhost soybean (Glycine max) exploited WCR biology to provide excellent WCR control, but this practice dramatically reduced landscape heterogeneity in East-central Illinois and imposed intense selection pressure. This selection resulted in behavioral changes and “rotation-resistant” (RR) WCR adults. Although soybeans are well defended against Coleopteran insects by cysteine protease inhibitors, RR-WCR feed on soybean foliage and remain long enough to deposit eggs that will hatch the following spring and larvae will feed on roots of planted corn. Other than documenting changes in insect mobility and egg laying behavior, 15 years of research have failed to identify any diagnostic differences between wild-type (WT)- and RR-WCR or a mechanism that allows for prolonged RR-WCR feeding and survival in soybean fields. We documented differences in behavior, physiology, digestive protease activity (threefold to fourfold increases), and protease gene expression in the gut of RR-WCR adults. Our data suggest that higher constitutive activity levels of cathepsin L are part of the mechanism that enables populations of WCR to circumvent soybean defenses, and thus, crop rotation. These new insights into the mechanism of WCR tolerance of soybean herbivory transcend the issue of RR-WCR diagnostics and management to link changes in insect gut proteolytic activity and behavior with landscape heterogeneity. The RR-WCR illustrates how agro-ecological factors can affect the evolution of insects in human-altered ecosystems. PMID:22957201

No impact of DvSnf7 RNA on honey bee (Apis mellifera L.) adults and larvae in dietary feeding tests.

PubMed

Tan, Jianguo; Levine, Steven L; Bachman, Pamela M; Jensen, Peter D; Mueller, Geoffrey M; Uffman, Joshua P; Meng, Chen; Song, Zihong; Richards, Kathy B; Beevers, Michael H

2016-02-01

The honey bee (Apis mellifera L.) is the most important managed pollinator species worldwide and plays a critical role in the pollination of a diverse range of economically important crops. This species is important to agriculture and historically has been used as a surrogate species for pollinators to evaluate the potential adverse effects for conventional, biological, and microbial pesticides, as well as for genetically engineered plants that produce pesticidal products. As part of the ecological risk assessment of MON 87411 maize, which expresses a double-stranded RNA targeting the Snf7 ortholog (DvSnf7) in western corn rootworm (Diabrotica virgifera virgifera), dietary feeding studies with honey bee larvae and adults were conducted. Based on the mode of action of the DvSnf7 RNA in western corn rootworm, the present studies were designed to be of sufficient duration to evaluate the potential for adverse effects on larval survival and development through emergence and adult survival to a significant portion of the adult stage. Testing was conducted at concentrations of DvSnf7 RNA that greatly exceeded environmentally relevant exposure levels based on expression levels in maize pollen. No adverse effects were observed in either larval or adult honey bees at these high exposure levels, providing a large margin of safety between environmental exposure levels and no-observed-adverse-effect levels. © 2015 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

Predator community structure and trophic linkage strength to a focal prey.

PubMed

Lundgren, Jonathan G; Fergen, Janet K

2014-08-01

Predator abundance and community structure can affect the suppression of lower trophic levels, although studies of these interactions under field conditions are relatively few. We investigated how the frequency of consumption (measured using PCR-based gut content analysis) is affected by predator abundance, community diversity and evenness under realistic conditions. Soil arthropod communities in sixteen maize fields were measured (number of predators, diversity [Shannon H] and evenness [J]), and predator guts were searched for DNA of the focal subterranean herbivore, the corn rootworm (Diabrotica virgifera). Predator abundance and diversity were positively correlated with trophic linkage strength (the proportion positive for rootworm DNA), although the latter characteristic was not significantly so. The diversity and evenness of the predator community with chewing mouthparts were strongly correlated with their linkage strength to rootworms, whereas the linkage strength of fluid-feeding predators was unaffected by their community characteristics. Within this community, chewing predators are more affected by the rootworm's hemolymph defence. This research clearly shows that predator abundance and diversity influence the strength of a community's trophic linkage to a focal pest and that these community characteristics may be particularly important for less palatable or protected prey species. We also make the case for conserving diverse and abundant predator communities within agroecosystems as a form of pest management. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

RNA interference as a method for target-site screening in the Western Corn Rootworm, Diabrotica virgifera virgifera

USDA-ARS?s Scientific Manuscript database

RNA interference (RNAi) is one of the most powerful and extraordinarily-specific means by which to silence genes. The ability of RNAi to silence genes makes it possible to ascertain function from genomic data, thereby making it an excellent choice for target-site screening. To test the efficacy of...

Bt maize and integrated pest management--a European perspective.

PubMed

Meissle, Michael; Romeis, Jörg; Bigler, Franz

2011-09-01

The European corn borer (Ostrinia nubilalis), the Mediterranean corn borer (Sesamia nonagrioides) and the western corn rootworm (Diabrotica virgifera virgifera) are the main arthropod pests in European maize production. Practised pest control includes chemical control, biological control and cultural control such as ploughing and crop rotation. A pest control option that is available since 1996 is maize varieties that are genetically engineered (GE) to produce insecticidal compounds. GE maize varieties available today express one or several genes from Bacillus thuringiensis (Bt) that target corn borers or corn rootworms. Incentives to growing Bt maize are simplified farm operations, high pest control efficiency, improved grain quality and ecological benefits. Limitations include the risk of resistance evolution in target pest populations, risk of secondary pest outbreaks and increased administration to comply with licence agreements. Growers willing to plant Bt maize in the European Union (EU) often face the problem that authorisation is denied. Only one Bt maize transformation event (MON810) is currently authorised for commercial cultivation, and some national authorities have banned cultivation. Spain is the only EU member state where Bt maize adoption levels are currently delivering farm income gains near full potential levels. In an integrated pest management (IPM) context, Bt maize can be regarded as a preventive (host plant resistance) or a responsive pest control measure. In any case, Bt maize is a highly specific tool that efficiently controls the main pests and allows combination with other preventive or responsive measures to solve other agricultural problems including those with secondary pests. Copyright © 2011 Society of Chemical Industry.

Corn rootworms and Bt resistance

USDA-ARS?s Scientific Manuscript database

Corn rootworms have been a major pest of corn for many years. As their name suggests, corn rootworms damage corn plants by feeding on the roots. Western and northern corn rootworms have overcome practices farmers use to keep their population numbers down, such as insecticides and crop rotation. Cor...

Hemolymph Defense against an Invasive Herbivore: Its Breadth of Effectiveness Against Predators

USDA-ARS?s Scientific Manuscript database

Defensive characteristics of organisms shape the trophic linkages within food webs and influence the ability of invasive organisms to expand their range. Diabrotica virgifera virgifera is an invasive herbivore in European maize, and its subterranean larval feeding affects the entire maize ecosystem....

Direct and indirect plant defenses are not suppressed by endosymbionts of a specialist root herbivore

USDA-ARS?s Scientific Manuscript database

Insect endosymbionts influence many important metabolic and developmental processes of their host. It has been speculated that they may also help to manipulate and suppress plant defenses to the benefit of herbivores. Recently, endosymbionts of the root herbivore Diabrotica virgifera virgifera have ...

Physiological time model for predicting adult emergence of western corn rootworm (Coleoptera: Chrysomelidae) in the Texas High Plains.

PubMed

Stevenson, Douglass E; Michels, Gerald J; Bible, John B; Jackman, John A; Harris, Marvin K

2008-10-01

Field observations at three locations in the Texas High Plains were used to develop and validate a degree-day phenology model to predict the onset and proportional emergence of adult Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) adults. Climatic data from the Texas High Plains Potential Evapotranspiration network were used with records of cumulative proportional adult emergence to determine the functional lower developmental temperature, optimum starting date, and the sum of degree-days for phenological events from onset to 99% adult emergence. The model base temperature, 10 degrees C (50 degrees F), corresponds closely to known physiological lower limits for development. The model uses a modified Gompertz equation, y = 96.5 x exp (-(exp(6.0 - 0.00404 x (x - 4.0), where x is cumulative heat (degree-days), to predict y, cumulative proportional emergence expressed as a percentage. The model starts degree-day accumulation on the date of corn, Zea mays L., emergence, and predictions correspond closely to corn phenological stages from tasseling to black layer development. Validation shows the model predicts cumulative proportional adult emergence within a satisfactory interval of 4.5 d. The model is flexible enough to accommodate early planting, late emergence, and the effects of drought and heat stress. The model provides corn producers ample lead time to anticipate and implement adult control practices.

Influence of calcareous soil on Cry3Bb1 expression and efficacy in the field.

PubMed

Wangila, David S; Valencia J, Arnubio; Wang, Haichuan; Siegfried, Blair D; Meinke, Lance J

2017-06-01

Greater than expected injury by western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) to Cry3Bb1 expressing maize hybrids (Zea mays L.) has been reported in southwestern Nebraska. Affected areas of some fields are often associated with high pH calcareous soils where maize growth is poor and iron chlorosis is common. As part of a comprehensive study to understand potential causes of unexpected injury, experiments were conducted during 2013 and 2014 to ascertain whether the calcareous soil conditions and associated poor maize growth negatively affect the expression of Cry3Bb1. Quantitative determination of Cry3Bb1 protein expression levels in root tissues was carried out on plants at V5-V6 growth stage using the enzyme-linked immunosorbent assay. Cry3Bb1 and non-Bt near isoline maize hybrids were artificially infested with Cry3Bb1-susceptible WCR eggs to measure survival and efficacy of Cry3Bb1 maize in calcareous and non-calcareous soils. Results showed that there was not a significant difference in expression of Cry3Bb1 protein between plants from calcareous and non-calcareous soils (18.9-21.2 µg/g fresh weight). Western corn rootworm survival was about sevenfold greater from the non-Bt isoline than Cry3Bb1 maize indicating that Cry3Bb1 performed as expected when infested with a Cry3Bb1 susceptible rootworm population. When survival from calcareous and non-calcareous soils was compared, no significant differences were observed in each soil. A significant positive correlation between soil pH and expression of Cry3Bb1 protein in roots was detected from samples collected in 2014 but not in 2013. No such correlation was found between soil pH and survival of WCR. Results suggest that Cry3Bb1 expression levels were sufficient to provide adequate root protection against WCR regardless of soil environment, indicating that lowered Cry3Bb1 expression is not a contributing factor to the greater than expected WCR injury observed in some southwestern Nebraska

Framework to Delay Corn Rootworm Resistance

EPA Pesticide Factsheets

This proposed framework is intended to delay the corn rootworm pest becoming resistant to corn genetically engineered to produce Bt proteins, which kill corn rootworms but do not affect people or wildlife. It includes requirements on Bt corn manufacturers.

Dietary Risk Assessment of v-ATPase A dsRNAs on Monarch Butterfly Larvae.

PubMed

Pan, Huipeng; Yang, Xiaowei; Bidne, Keith; Hellmich, Richard L; Siegfried, Blair D; Zhou, Xuguo

2017-01-01

By suppressing the expression of genes with essential biological functions, in planta RNAi can negatively affect the development and survival of target pests. As a part of a concerted effort to assess the risks of RNAi transgenic crops on non-target organisms, we developed an in vivo toxicity assay to examine the impacts of ingested dsRNAs incurred to the monarch butterfly, Danaus plexippus (L.), an iconic eco-indicator in North America. To create the worst case scenario, the full-length v-ATPase A cDNAs from the target pest, western corn rootworm, Diabrotica virgifera virgifera , and the non-target D. plexippus were respectively cloned. A 400 bp fragment with the highest sequence similarity between the two species was used as the template to synthesize dsRNAs for the subsequent dietary RNAi toxicity assay. Specifically, newly hatched neonates were provisioned with leaf disks surface-coated with v-ATPase A dsRNAs synthesized from D. v. virgifera and D. plexippus , respectively, a control dsRNA, β -glucoruronidase , from plants, and H 2 O. The endpoint measurements included gene expressions and life history traits. The 2283 bp D. plexippus v-ATPase A cDNA contains a 99 bp 5'-untranslated region, a 330 bp 3'-untranslated region, and an 1851 bp ORF encoding 617 amino acids. The temporal RNAi study did not detect any impact to D. plexippus v-ATPase A expression by the assay days and treatments. This was reflected in the phenotypic impacts of dietary RNAi, in which both survival rate and development time were not affected by the uptake of ingested dsRNAs. These combined results suggest that D. plexippus larvae are not susceptible to dietary RNAi, therefore, the impact of transgenic RNAi plants on this non-target organism is, likely, negligible.

A specialist root herbivore exploits defensive metabolites to locate nutritious tissues

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

Erb M.; Babst B.; Robert, C.A.M.

2011-10-01

The most valuable organs of plants are often particularly rich in essential elements, but also very well defended. This creates a dilemma for herbivores that need to maximise energy intake while minimising intoxication. We investigated how the specialist root herbivore Diabrotica virgifera solves this conundrum when feeding on wild and cultivated maize plants. We found that crown roots of maize seedlings were vital for plant development and, in accordance, were rich in nutritious primary metabolites and contained higher amounts of the insecticidal 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) and the phenolic compound chlorogenic acid. The generalist herbivores Diabrotica balteata and Spodoptera littoralis were deterredmore » from feeding on crown roots, whereas the specialist D. virgifera preferred and grew best on these tissues. Using a 1,4-benzoxazin-3-one-deficient maize mutant, we found that D. virgifera is resistant to DIMBOA and other 1,4-benzoxazin-3-ones and that it even hijacks these compounds to optimally forage for nutritious roots.« less

Corn rootworm areawide management program: United States Department of Agriculture-Agricultural Research Service.

PubMed

Chandler, Laurence D

2003-01-01

The corn rootworm areawide management program was implemented by USDA-ARS in 1995 at five locations across the USA. This program is based on the use of a semiochemical insecticide bait applied to maize (Zea mays L) during peak adult corn rootworm activity. Managing adult rootworms minimizes the number of eggs laid, resulting in fewer larvae available to economically damage maize roots in the following growing season. To date, rootworm populations have been significantly reduced at all participating locations and new bait products have been developed and evaluated for use in rootworm-infested areas.

Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms

USDA-ARS?s Scientific Manuscript database

Upon attack by leaf-herbivores, many plants reallocate photoassimilates below ground. However, little is known about how plants respond when the roots themselves come under attack. We investigated this aspect in maize seedlings infested by the specialist root herbivore Diabrotica virgifera. By using...

Multiple transatlantic introductions of the western corn rootworm.

PubMed

Miller, Nicholas; Estoup, Arnaud; Toepfer, Stefan; Bourguet, Denis; Lapchin, Laurent; Derridj, Sylvie; Kim, Kyung Seok; Reynaud, Philippe; Furlan, Lorenzo; Guillemaud, Thomas

2005-11-11

The invasion of Europe by the western corn rootworm, North America's most destructive corn pest, is ongoing and represents a serious threat to European agriculture. Because this pest was initially introduced in Central Europe, it was believed that subsequent outbreaks in Western Europe originated from this area. Using model-based Bayesian analyses of the genetic variability of the western corn rootworm, we demonstrate that this belief is false: There have been at least three independent introductions from North America during the past two decades. This result raises questions about changing circumstances that have enabled a sudden burst of transatlantic introductions.

A suite of models to support the quantitative assessment of spread in pest risk analysis.

PubMed

Robinet, Christelle; Kehlenbeck, Hella; Kriticos, Darren J; Baker, Richard H A; Battisti, Andrea; Brunel, Sarah; Dupin, Maxime; Eyre, Dominic; Faccoli, Massimo; Ilieva, Zhenya; Kenis, Marc; Knight, Jon; Reynaud, Philippe; Yart, Annie; van der Werf, Wopke

2012-01-01

Pest Risk Analyses (PRAs) are conducted worldwide to decide whether and how exotic plant pests should be regulated to prevent invasion. There is an increasing demand for science-based risk mapping in PRA. Spread plays a key role in determining the potential distribution of pests, but there is no suitable spread modelling tool available for pest risk analysts. Existing models are species specific, biologically and technically complex, and data hungry. Here we present a set of four simple and generic spread models that can be parameterised with limited data. Simulations with these models generate maps of the potential expansion of an invasive species at continental scale. The models have one to three biological parameters. They differ in whether they treat spatial processes implicitly or explicitly, and in whether they consider pest density or pest presence/absence only. The four models represent four complementary perspectives on the process of invasion and, because they have different initial conditions, they can be considered as alternative scenarios. All models take into account habitat distribution and climate. We present an application of each of the four models to the western corn rootworm, Diabrotica virgifera virgifera, using historic data on its spread in Europe. Further tests as proof of concept were conducted with a broad range of taxa (insects, nematodes, plants, and plant pathogens). Pest risk analysts, the intended model users, found the model outputs to be generally credible and useful. The estimation of parameters from data requires insights into population dynamics theory, and this requires guidance. If used appropriately, these generic spread models provide a transparent and objective tool for evaluating the potential spread of pests in PRAs. Further work is needed to validate models, build familiarity in the user community and create a database of species parameters to help realize their potential in PRA practice.

Structural and Biophysical Characterization of Bacillus thuringiensis Insecticidal Proteins Cry34Ab1 and Cry35Ab1

PubMed Central

Kelker, Matthew S.; Berry, Colin; Evans, Steven L.; Pai, Reetal; McCaskill, David G.; Wang, Nick X.; Russell, Joshua C.; Baker, Matthew D.; Yang, Cheng; Pflugrath, J. W.; Wade, Matthew; Wess, Tim J.; Narva, Kenneth E.

2014-01-01

Bacillus thuringiensis strains are well known for the production of insecticidal proteins upon sporulation and these proteins are deposited in parasporal crystalline inclusions. The majority of these insect-specific toxins exhibit three domains in the mature toxin sequence. However, other Cry toxins are structurally and evolutionarily unrelated to this three-domain family and little is known of their three dimensional structures, limiting our understanding of their mechanisms of action and our ability to engineer the proteins to enhance their function. Among the non-three domain Cry toxins, the Cry34Ab1 and Cry35Ab1 proteins from B. thuringiensis strain PS149B1 are required to act together to produce toxicity to the western corn rootworm (WCR) Diabrotica virgifera virgifera Le Conte via a pore forming mechanism of action. Cry34Ab1 is a protein of ∼14 kDa with features of the aegerolysin family (Pfam06355) of proteins that have known membrane disrupting activity, while Cry35Ab1 is a ∼44 kDa member of the toxin_10 family (Pfam05431) that includes other insecticidal proteins such as the binary toxin BinA/BinB. The Cry34Ab1/Cry35Ab1 proteins represent an important seed trait technology having been developed as insect resistance traits in commercialized corn hybrids for control of WCR. The structures of Cry34Ab1 and Cry35Ab1 have been elucidated to 2.15 Å and 1.80 Å resolution, respectively. The solution structures of the toxins were further studied by small angle X-ray scattering and native electrospray ion mobility mass spectrometry. We present here the first published structure from the aegerolysin protein domain family and the structural comparisons of Cry34Ab1 and Cry35Ab1 with other pore forming toxins. PMID:25390338

A Suite of Models to Support the Quantitative Assessment of Spread in Pest Risk Analysis

PubMed Central

Robinet, Christelle; Kehlenbeck, Hella; Kriticos, Darren J.; Baker, Richard H. A.; Battisti, Andrea; Brunel, Sarah; Dupin, Maxime; Eyre, Dominic; Faccoli, Massimo; Ilieva, Zhenya; Kenis, Marc; Knight, Jon; Reynaud, Philippe; Yart, Annie; van der Werf, Wopke

2012-01-01

Pest Risk Analyses (PRAs) are conducted worldwide to decide whether and how exotic plant pests should be regulated to prevent invasion. There is an increasing demand for science-based risk mapping in PRA. Spread plays a key role in determining the potential distribution of pests, but there is no suitable spread modelling tool available for pest risk analysts. Existing models are species specific, biologically and technically complex, and data hungry. Here we present a set of four simple and generic spread models that can be parameterised with limited data. Simulations with these models generate maps of the potential expansion of an invasive species at continental scale. The models have one to three biological parameters. They differ in whether they treat spatial processes implicitly or explicitly, and in whether they consider pest density or pest presence/absence only. The four models represent four complementary perspectives on the process of invasion and, because they have different initial conditions, they can be considered as alternative scenarios. All models take into account habitat distribution and climate. We present an application of each of the four models to the western corn rootworm, Diabrotica virgifera virgifera, using historic data on its spread in Europe. Further tests as proof of concept were conducted with a broad range of taxa (insects, nematodes, plants, and plant pathogens). Pest risk analysts, the intended model users, found the model outputs to be generally credible and useful. The estimation of parameters from data requires insights into population dynamics theory, and this requires guidance. If used appropriately, these generic spread models provide a transparent and objective tool for evaluating the potential spread of pests in PRAs. Further work is needed to validate models, build familiarity in the user community and create a database of species parameters to help realize their potential in PRA practice. PMID:23056174

New species of Diabrotica Chevrolat (Coleoptera: Chrysomelidae: Galerucinae) and a key to Diabrotica and related genera: results of a synopsis of North and Central American Diabrotica species

USDA-ARS?s Scientific Manuscript database

The following 18 new species of Diabrotica are described and illustrated as a result of the synopsis of North and Centrla American species: D. barclayi nov. sp. Guatemala, D. caveyi nov. sp. Costa Rica, D. costaricensis nov. sp. Costa Rica, D. dmitryogloblini nov. sp. Mexico, D. duckworthae nov. sp....

Mating Success, Longevity, and Fertility of Diabrotica virgifera virgifera LeConte (Chrysomelidae: Coleoptera) in Relation to Body Size and Cry3Bb1-Resistant and Cry3Bb1-Susceptible Genotypes

PubMed Central

French, Bryan Wade; Hammack, Leslie; Tallamy, Douglas W.

2015-01-01

Insect resistance to population control methodologies is a widespread problem. The development of effective resistance management programs is often dependent on detailed knowledge regarding the biology of individual species and changes in that biology associated with resistance evolution. This study examined the reproductive behavior and biology of western corn rootworm beetles of known body size from lines resistant and susceptible to the Cry3Bb1 protein toxin expressed in transgenic Bacillus thuringiensis maize. In crosses between, and within, the resistant and susceptible genotypes, no differences occurred in mating frequency, copulation duration, courtship duration, or fertility; however, females mated with resistant males showed reduced longevity. Body size did not vary with genotype. Larger males and females were not more likely to mate than smaller males and females, but larger females laid more eggs. Moderately strong, positive correlation occurred between the body sizes of successfully mated males and females; however, weak correlation also existed for pairs that did not mate. Our study provided only limited evidence for fitness costs associated with the Cry3Bb1-resistant genotype that might reduce the persistence in populations of the resistant genotype but provided additional evidence for size-based, assortative mating, which could favor the persistence of resistant genotypes affecting body size. PMID:26569315

Assessment of acute toxicity tests and rhizotron experiments to characterize lethal and sublethal control of soil-based pests.

PubMed

Agatz, Annika; Schumann, Mario M; French, Bryan W; Brown, Colin D; Vidal, Stefan

2018-03-24

Characterizing lethal and sublethal control of soil-based pests with plant protection products is particularly challenging due to the complex and dynamic interplay of the system components. Here, we present two types of studies: acute toxcity experiments (homogenous exposure of individuals in soil) and rhizotron experiments (heterogeneous exposure of individuals in soil) to investigate their ability to strengthen our understanding of mechanisms driving the effectivness of the plant protection product. Experiments were conducted using larvae of the western corn rootworm Diabrotica virgifera LeConte and three pesticide active ingredients: clothianidin (neonicotinoid), chlorpyrifos (organophosphate) and tefluthrin (pyrethroid). The order of compound concentrations needed to invoke a specific effect intensity (EC 50 values) within the acute toxicity tests was chlorpyrifos > tefluthrin > clothianidin. This order changed for the rhizotron experiments because application type, fate and transport of the compounds in the soil profile, and sublethal effects on larvae also influence their effectiveness in controlling larval feeding on corn roots. Beyond the pure measurement of efficacy through observing relative changes in plant injury to control plants, the tests generate mechanistic understanding for drivers of efficacy apart from acute toxicity. The experiments have the potential to enhance efficacy testing and product development, and might be useful tools for assessing resistance development in the future. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

Ecological risk assessment for DvSnf7 RNA: A plant-incorporated protectant with targeted activity against western corn rootworm.

PubMed

Bachman, Pamela M; Huizinga, Kristin M; Jensen, Peter D; Mueller, Geoffrey; Tan, Jianguo; Uffman, Joshua P; Levine, Steven L

2016-11-01

MON 87411 maize, which expresses DvSnf7 RNA, was developed to provide an additional mode of action to confer protection against corn rootworm (Diabrotica spp.). A critical step in the registration of a genetically engineered crop with an insecticidal trait is performing an ecological risk assessment to evaluate the potential for adverse ecological effects. For MON 87411, an assessment plan was developed that met specific protection goals by characterizing the routes and levels of exposure, and testing representative functional taxa that would be directly or indirectly exposed in the environment. The potential for toxicity of DvSnf7 RNA was evaluated with a harmonized battery of non-target organisms (NTOs) that included invertebrate predators, parasitoids, pollinators, soil biota as well as aquatic and terrestrial vertebrate species. Laboratory tests evaluated ecologically relevant endpoints such as survival, growth, development, and reproduction and were of sufficient duration to assess the potential for adverse effects. No adverse effects were observed with any species tested at, or above, the maximum expected environmental concentration (MEEC). All margins of exposure for NTOs were >10-fold the MEEC. Therefore, it is reasonable to conclude that exposure to DvSnf7 RNA, both directly and indirectly, is safe for NTOs at the expected field exposure levels. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Taxonomic changes in the genus Diabrotica Chevrolat (Coleoptera: Chrysomelidae: Galerucinae): results of a synopsis of North and Central America Diabrotica species

USDA-ARS?s Scientific Manuscript database

The following new synonyms in Diabrotica Chevrolat are proposed: D. flaviventris Jacoby 1887 = D. tibialis Jacoby 1887 = D. adelpha Harold 1875; D. peckii Bowditch 1911 = D. bioculata Bowditch 1911; D. circulata Harold 1875 = D. nummularis Harold 1877; D. linensis Bechyné 1956 = D. trifurcata Jacoby...

Effects of cysteine proteinase inhibitors scN and E-64 on southern corn rootworm larval development

USDA-ARS?s Scientific Manuscript database

The southern corn rootworm (SCRW) can be a serious pest of peanut pods. A laboratory bioassay was developed to test feeding cysteine proteinase inhibitors soyacystatin N (scN) and E-64 against southern corn rootworm reared on artificial diet to determine the effects on larvae development and mortal...

A Physiological and Behavioral Mechanism for Leaf Herbivore-Induced Systemic Root Resistance1[OPEN

PubMed Central

Erb, Matthias; Robert, Christelle A.M.; Marti, Guillaume; Lu, Jing; Doyen, Gwladys R.; Villard, Neil; Barrière, Yves; Wolfender, Jean-Luc; Turlings, Ted C.J.

2015-01-01

Indirect plant-mediated interactions between herbivores are important drivers of community composition in terrestrial ecosystems. Among the most striking examples are the strong indirect interactions between spatially separated leaf- and root-feeding insects sharing a host plant. Although leaf feeders generally reduce the performance of root herbivores, little is known about the underlying systemic changes in root physiology and the associated behavioral responses of the root feeders. We investigated the consequences of maize (Zea mays) leaf infestation by Spodoptera littoralis caterpillars for the root-feeding larvae of the beetle Diabrotica virgifera virgifera, a major pest of maize. D. virgifera strongly avoided leaf-infested plants by recognizing systemic changes in soluble root components. The avoidance response occurred within 12 h and was induced by real and mimicked herbivory, but not wounding alone. Roots of leaf-infested plants showed altered patterns in soluble free and soluble conjugated phenolic acids. Biochemical inhibition and genetic manipulation of phenolic acid biosynthesis led to a complete disappearance of the avoidance response of D. virgifera. Furthermore, bioactivity-guided fractionation revealed a direct link between the avoidance response of D. virgifera and changes in soluble conjugated phenolic acids in the roots of leaf-attacked plants. Our study provides a physiological mechanism for a behavioral pattern that explains the negative effect of leaf attack on a root-feeding insect. Furthermore, it opens up the possibility to control D. virgifera in the field by genetically mimicking leaf herbivore-induced changes in root phenylpropanoid patterns. PMID:26430225

Distribution patterns of MCA-coated granules aerially applied to corn fields of Southern Hungary between 2000 and 2002.

PubMed

Wennemann, L; Hummel, H E

2003-01-01

Field studies in corn (Zea mays L.) were conducted to evaluate distribution patterns of 4-methoxy-cinnamaldehyde (MCA) coated corn grits after aerial application with a Dromader fixed wing aircraft. The kairomone mimic MCA is synthetically available and a quite specific and efficient adult attractant for the invasive alien maize pest western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte. Orientation disruptive properties of MCA for WCR when applied at unphysiologically high concentrations are currently under investigation. For successful implementation of the MCA disruption technique, the distribution patterns of MCA coated corn granules ('grits') in the field are important. Grits are degrained corn cobs, shredded to different sizes, coated with MCA and used as a carrier material to disseminate MCA vapors into corn fields. Granules of 10-12 mesh size were aerially applied eight times at rates ranging from 12.4 to 25.0 kg/ha. The goal is to evaluate distribution patterns of corn grits treated with MCA in three fields located at Csanadpalota, Kardoskút and Mezöhegyes in Southern Hungary between 2000 and 2002. Increasing rates reflect our attempts in finding and optimising the most even distribution of granules in the field. Field experiments were evaluated by collecting grits in 30-cm plastic saucers and by counting grits accumulated on corn plant parts. Variation in grit number per unit area and frequency of corn granule number per plant showed some transient technical application problems. Analysis of grits collected in the saucers revealed some statistical difference between the different application dates as well as differences in rates applied. Altogether grits in saucers were more evenly distributed in comparison to the grits collected on plant parts. As the corn plants age, their leaves and whorls present a smaller and smaller surface area where granules can accumulate. Altogether, however, grit distribution patterns indicate that aerial

Corn rootworms (Coleoptera: Chrysomelidae) in space and time

NASA Astrophysics Data System (ADS)

Park, Yong-Lak

Spatial dispersion is a main characteristic of insect populations. Dispersion pattern provides useful information for developing effective sampling and scouting programs because it affects sampling accuracy, efficiency, and precision. Insect dispersion, however, is dynamic in space and time and largely dependent upon interactions among insect, plant and environmental factors. This study investigated the spatial and temporal dynamics of corn rootworm dispersion at different spatial scales by using the global positioning system, the geographic information system, and geostatistics. Egg dispersion pattern was random or uniform in 8-ha cornfields, but could be aggregated at a smaller scale. Larval dispersion pattern was aggregated regardless of spatial scales used in this study. Soil moisture positively affected corn rootworm egg and larval dispersions. Adult dispersion tended to be aggregated during peak population period and random or uniform early and late in the season and corn plant phenology was a major factor to determine dispersion patterns. The dispersion pattern of root injury by corn rootworm larval feeding was aggregated and the degree of aggregation increased as the root injury increased within the range of root injury observed in microscale study. Between-year relationships in dispersion among eggs, larvae, adult, and environment provided a strategy that could predict potential root damage the subsequent year. The best prediction map for the subsequent year's potential root damage was the dispersion maps of adults during population peaked in the cornfield. The prediction map was used to develop site-specific pest management that can reduce chemical input and increase control efficiency by controlling pests only where management is needed. This study demonstrated the spatio-temporal dynamics of insect population and spatial interactions among insects, plants, and environment.

Gene silencing in Tribolium castaneum as a tool for the targeted identification of candidate RNAi targets in crop pests.

PubMed

Knorr, Eileen; Fishilevich, Elane; Tenbusch, Linda; Frey, Meghan L F; Rangasamy, Murugesan; Billion, Andre; Worden, Sarah E; Gandra, Premchand; Arora, Kanika; Lo, Wendy; Schulenberg, Greg; Valverde-Garcia, Pablo; Vilcinskas, Andreas; Narva, Kenneth E

2018-02-01

RNAi shows potential as an agricultural technology for insect control, yet, a relatively low number of robust lethal RNAi targets have been demonstrated to control insects of agricultural interest. In the current study, a selection of lethal RNAi target genes from the iBeetle (Tribolium castaneum) screen were used to demonstrate efficacy of orthologous targets in the economically important coleopteran pests Diabrotica virgifera virgifera and Meligethes aeneus. Transcript orthologs of 50 selected genes were analyzed in D. v. virgifera diet-based RNAi bioassays; 21 of these RNAi targets showed mortality and 36 showed growth inhibition. Low dose injection- and diet-based dsRNA assays in T. castaneum and D. v. virgifera, respectively, enabled the identification of the four highly potent RNAi target genes: Rop, dre4, ncm, and RpII140. Maize was genetically engineered to express dsRNA directed against these prioritized candidate target genes. T 0 plants expressing Rop, dre4, or RpII140 RNA hairpins showed protection from D. v. virgifera larval feeding damage. dsRNA targeting Rop, dre4, ncm, and RpII140 in M. aeneus also caused high levels of mortality both by injection and feeding. In summary, high throughput systems for model organisms can be successfully used to identify potent RNA targets for difficult-to-work with agricultural insect pests.

Volatile chemicals associated with host plants of the strawberry rootworm

USDA-ARS?s Scientific Manuscript database

The strawberry rootworm (SRW), Paria fragariae Wilcox (Coleoptera: Chrysomelidae: Eumolpinae), hinders profitable production of azaleas and other containerized ornamental crops at nurseries throughout the Southeast. Properly timed early-season insecticide applications are critical to reducing poten...

Developing an in vivo toxicity assay for RNAi risk assessment in honey bees, Apis mellifera L.

PubMed

Vélez, Ana María; Jurzenski, Jessica; Matz, Natalie; Zhou, Xuguo; Wang, Haichuan; Ellis, Marion; Siegfried, Blair D

2016-02-01

Maize plants expressing dsRNA for the management of Diabrotica virgifera virgifera are likely to be commercially available by the end of this decade. Honey bees, Apis mellifera, can potentially be exposed to pollen from transformed maize expressing dsRNA. Consequently, evaluation of the biological impacts of RNAi in honey bees is a fundamental component for ecological risk assessment. The insecticidal activity of a known lethal dsRNA target for D. v. virgifera, the vATPase subunit A, was evaluated in larval and adult honey bees. Activity of both D. v. virgifera (Dvv)- and A. mellifera (Am)-specific dsRNA was tested by dietary exposure to dsRNA. Larval development, survival, adult eclosion, adult life span and relative gene expression were evaluated. The results of these tests indicated that Dvv vATPase-A dsRNA has limited effects on larval and adult honey bee survival. Importantly, no effects were observed upon exposure of Am vATPase-A dsRNA suggesting that the lack of response involves factors other than sequence specificity. The results from this study provide guidance for future RNAi risk analyses and for the development of a risk assessment framework that incorporates similar hazard assessments. Copyright © 2015 Elsevier Ltd. All rights reserved.

Screening of botanical extracts for repellence against western corn rootworm larvae

USDA-ARS?s Scientific Manuscript database

The ability of Western corn rootworm (WCR) to develop resistance to various management practices enforces the development of new control options. Repellent substances can act as efficacy enhancing agents in WCR control with biological control agents. The present study investigated the potential repe...

Plant Bio-Wars: Maize Protein Networks Reveal Tissue-Specific Defense Strategies in Response to a Root Herbivore.

PubMed

Castano-Duque, Lina; Helms, Anjel; Ali, Jared Gregory; Luthe, Dawn S

2018-06-21

In this study we examined global changes in protein expression in both roots and leaves of maize plants attacked by the root herbivore, Western corn rootworm (WCR, Diabrotica virgifera virgifera). The changes in protein expression Are indicative of metabolic changes during WCR feeding that enable the plant to defend itself. This is one of the first studies to look above- and below-ground at global protein expression patterns of maize plants grown in soil and infested with a root herbivore. We used advanced proteomic and network analyses to identify metabolic pathways that contribute to global defenses deployed by the insect resistant maize genotype, Mp708, infested with WCR. Using proteomic analysis, 4878 proteins in roots and leaves were detected and of these 863 showed significant changes of abundance during WCR infestation. Protein abundance patterns were analyzed using hierarchical clustering, protein correlation and protein-protein interaction networks. All three data analysis pipelines showed that proteins such as jasmonic acid biosynthetic enzymes, serine proteases, protease inhibitors, proteins involved in biosynthesis and signaling of ethylene, and enzymes producing reactive oxygen species and isopentenyl pyrophosphate, a precursor for volatile production, were upregulated in roots during WCR infestation. In leaves, highly abundant proteins were involved in signal perception suggesting activation of systemic signaling. We conclude that these protein networks contribute to the overall herbivore defense mechanisms in Mp708. Because the plants were grown in potting mix and not sterilized sand, we found that both microbial and insect defense-related proteins were present in the roots. The presence of the high constitutive levels of reduced ascorbate in roots and benzothiazole in the root volatile profiles suggest a tight tri-trophic interaction among the plant, soil microbiomes and WCR-infested roots suggesting that defenses against insects coexist with

Male lifetime mating success in relation to body size in Diabrotica barberi

USDA-ARS?s Scientific Manuscript database

Body size is often an important component of male lifetime mating success in insects, especially when males are capable of mating several times over their lifespan. We paired either a large or small male northern corn rootworm with a female of random size and noted copulation success. We observed co...

Risk Assessment of Genetically Engineered Maize Resistant to Diabrotica spp.: Influence on Above-Ground Arthropods in the Czech Republic.

PubMed

Svobodová, Zdeňka; Skoková Habuštová, Oxana; Hutchison, William D; Hussein, Hany M; Sehnal, František

2015-01-01

Transgenic maize MON88017, expressing the Cry3Bb1 toxin from Bacillus thuringiensis (Bt maize), confers resistance to corn rootworms (Diabrotica spp.) and provides tolerance to the herbicide glyphosate. However, prior to commercialization, substantial assessment of potential effects on non-target organisms within agroecosystems is required. The MON88017 event was therefore evaluated under field conditions in Southern Bohemia in 2009-2011, to detect possible impacts on the above-ground arthropod species. The study compared MON88017, its near-isogenic non-Bt hybrid DK315 (treated or not treated with the soil insecticide Dursban 10G) and two non-Bt reference hybrids (KIPOUS and PR38N86). Each hybrid was grown on five 0.5 ha plots distributed in a 14-ha field with a Latin square design. Semiquantitative ELISA was used to verify Cry3Bb1 toxin levels in the Bt maize. The species spectrum of non-target invertebrates changed during seasons and was affected by weather conditions. The thrips Frankliniella occidentalis was the most abundant species in all three successive years. The next most common species were aphids Rhopalosiphum padi and Metopolophium dirhodum. Frequently observed predators included Orius spp. and several species within the Coccinellidae. Throughout the three-year study, analysis of variance indicated some significant differences (P<0.05). Multivariate analysis showed that the abundance and diversity of plant dwelling insects was similar in maize with the same genetic background, for both Bt (MON88017) and non-Bt (DK315) untreated or insecticide treated. KIPOUS and PR38N86 showed some differences in species abundance relative to the Bt maize and its near-isogenic hybrid. However, the effect of management regime on arthropod community was insignificant and accounted only for a negligible portion of the variability.

Risk Assessment of Genetically Engineered Maize Resistant to Diabrotica spp.: Influence on Above-Ground Arthropods in the Czech Republic

PubMed Central

Svobodová, Zdeňka; Skoková Habuštová, Oxana; Hutchison, William D.; Hussein, Hany M.; Sehnal, František

2015-01-01

Transgenic maize MON88017, expressing the Cry3Bb1 toxin from Bacillus thuringiensis (Bt maize), confers resistance to corn rootworms (Diabrotica spp.) and provides tolerance to the herbicide glyphosate. However, prior to commercialization, substantial assessment of potential effects on non-target organisms within agroecosystems is required. The MON88017 event was therefore evaluated under field conditions in Southern Bohemia in 2009–2011, to detect possible impacts on the above-ground arthropod species. The study compared MON88017, its near-isogenic non-Bt hybrid DK315 (treated or not treated with the soil insecticide Dursban 10G) and two non-Bt reference hybrids (KIPOUS and PR38N86). Each hybrid was grown on five 0.5 ha plots distributed in a 14-ha field with a Latin square design. Semiquantitative ELISA was used to verify Cry3Bb1 toxin levels in the Bt maize. The species spectrum of non-target invertebrates changed during seasons and was affected by weather conditions. The thrips Frankliniella occidentalis was the most abundant species in all three successive years. The next most common species were aphids Rhopalosiphum padi and Metopolophium dirhodum. Frequently observed predators included Orius spp. and several species within the Coccinellidae. Throughout the three-year study, analysis of variance indicated some significant differences (P<0.05). Multivariate analysis showed that the abundance and diversity of plant dwelling insects was similar in maize with the same genetic background, for both Bt (MON88017) and non-Bt (DK315) untreated or insecticide treated. KIPOUS and PR38N86 showed some differences in species abundance relative to the Bt maize and its near-isogenic hybrid. However, the effect of management regime on arthropod community was insignificant and accounted only for a negligible portion of the variability. PMID:26083254

Blended Refuge and Insect Resistance Management for Insecticidal Corn

PubMed Central

Crespo, Andre L B; Pan, Zaiqi; Crain, Philip R; Thompson, Stephen D; Pilcher, Clinton D; Sethi, Amit

2018-01-01

Abstract In this review, we evaluate the intentional mixing or blending of insecticidal seed with refuge seed for managing resistance by insects to insecticidal corn (Zea mays). We first describe the pest biology and farming practices that will contribute to weighing trade-offs between using block refuges and blended refuges. Case studies are presented to demonstrate how the trade-offs will differ in different systems. We compare biological aspects of several abstract models to guide the reader through the history of modeling, which has played a key role in the promotion or denigration of blending in various scientific debates about insect resistance management for insecticidal crops. We conclude that the use of blended refuge should be considered on a case-by-case basis after evaluation of insect biology, environment, and farmer behavior. For Diabrotica virgifera virgifera, Ostrinia nubilalis, and Helicoverpa zea in the United States, blended refuge provides similar, if not longer, delays in the evolution of resistance compared to separate block refuges. PMID:29220481

Fitness of Bt-resistant Western Corn Rootworm on Mon863 and Isoline Corn

USDA-ARS?s Scientific Manuscript database

Abstract: To help ensure that insect resistance management plans mandated by the US Environmental Protection Agency are based on the best science available, we evaluated fitness costs associated with resistance development in artificially selected laboratory lines of the western corn rootworm, Diabr...

Discovery of a novel aquaporin ZmPIP2-8 from southern corn rootworm infested maize

USDA-ARS?s Scientific Manuscript database

A common paradigm of infestation by chewing insects is a jasmonic acid (JA) cascade that results in the induction of JA responsive genes. However examination of several maize genes induced by Southern corn rootworm (SCR) infestation, an insect that chews into and significantly damages maize roots, ...

First-instar western corn rootworm (Coleoptera: chrysomelidae) response to carbon dioxide

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

Strnad, S.P.; Bergman, M.K.; Fulton, W.C.

1986-08-01

Responses of first-instar western corn rootworm to CO/sub 2/ and N/sub 2/ gas gradients were studied in a laboratory test arena. Number of larvae reaching the gas source, number of turns toward and away from the gas source, larval velocity, and number of turns per cm traveled were recorded. Larvae exhibited a positive chemotactic response to CO/sub 2/ but not N/sub 2/ or air. There was no indication that a kinesis of any type was involved because velocities and turning rates were not significantly different among treatments. Results indicate that newly hatched larve may use CO/sub 2/ to locate cornmore » roots.« less

Entomopathogenic nematodes in the European biocontrol market.

PubMed

Ehlers, R U

2003-01-01

In Europe total revenues in the biocontrol market have reached approximately 200 million Euros. The sector with the highest turn-over is the market for beneficial invertebrates with a 55% share, followed by microbial agents with approximately 25%. Annual growth rates of up to 20% have been estimated. Besides microbial plant protection products that are currently in the process of re-registration, several microbial products have been registered or are in the process of registration, following the EU directive 91/414. Entomopathogenic nematodes (EPN) are exceptionally safe biocontrol agents. Until today, they are exempted from registration in most European countries, the reason why SMEs were able to offer economically reasonable nematode-based products. The development of technology for mass production in liquid media significantly reduced the product costs and accelerated the introduction of nematode products in tree nurseries, ornamentals, strawberries, mushrooms, citrus and turf. Progress in storage and formulation technology has resulted in high quality products which are more resistant to environmental extremes occurring during transportation to the user. The cooperation between science, industry and extension within the EU COST Action 819 has supported the development of quality control methods. Today four companies produce EPN in liquid culture, offering 8 different nematode species. Problems with soil insects are increasing. Grubs, like Melolontha melolontha and other scarabaeidae cause damage in orchards and turf. Since the introduction of the Western Corn Rootworm Diabrotica virgifera into Serbia in 1992, this pests as spread all over the Balkan Region and has reached Italy, France and Austria. These soil insect pests are potential targets for EPN. The development of insecticide resistance has opened another sector for EPN. Novel adjuvants used to improve formulation of EPN have enabled the foliar application against Western Flower Thrips and Plutella

Heterorhabditis sp. (Nematoda: Heterorhabditidae): A Nematode Parasite Isolated from the Banded Cucumber Beetle Diabrotica balteata

PubMed Central

Creighton, C. S.; Fassuliotis, G.

1985-01-01

A nematode identified as Heterorhabditis sp. was discovered in June 1982 in larval cadavers of the banded cucumber beetle, Diabrotica balteata, in soil on wooded land. Effective beetle control (over 95%) was obtained when larvae were exposed to potted soil containing infective stage nematode juveniles or infected larval cadavers. The nematode was propagated in vivo on larvae of D. balteata, Diaphania nitidalis (the pickleworm), and Galleria mellonella (the greater wax moth). This Heterorhabditis sp. has promising potential as a biocontrol agent for the banded cucumber beetle. PMID:19294074

Effect of seed blends and soil-insecticide on western and northern corn rootworm emergence from mCry3A + eCry3.1Ab Bt maize

USDA-ARS?s Scientific Manuscript database

Blended seed mixtures containing various ratios of transgenic Bt maize expressing the mCry3A + eCry3.1Ab proteins and non-Bt maize (near-isoline maize) were deployed alone and in combination with a soil applied insecticide (Force CS) to evaluate the survivorship of the western corn rootworm, Diabrot...

Development of a CO2 -releasing coformulation based on starch, Saccharomyces cerevisiae and Beauveria bassiana attractive towards western corn rootworm larvae.

PubMed

Vemmer, Marina; Schumann, Mario; Beitzen-Heineke, Wilhelm; French, Bryan W; Vidal, Stefan; Patel, Anant V

2016-11-01

CO 2 is known as an attractant for many soil-dwelling pests. To implement an attract-and-kill strategy for soil pest control, CO 2 -emitting formulations need to be developed. The aim of the present work was to develop a slow-release bead system in order to bridge the gap between application and hatching of western corn rootworm larvae. We compared different Ca-alginate beads containing Saccharomyces cerevisiae for their potential to release CO 2 over a period of several weeks. The addition of starch improved CO 2 release, resulting in significantly higher CO 2 concentrations in soil for at least 4 weeks. The missing amylase activity was compensated for either by microorganisms present in the soil or by coencapsulation of Beauveria bassiana. Formulations containing S. cerevisiae, starch and B. bassiana were attractive for western corn rootworm larvae within the first 4 h following exposure; however, when considering the whole testing period, the maize root systems remained more attractive for the larvae. Coencapsulation of S. cerevisiae, starch and B. bassiana is a promising approach for the development of attractive formulations for soil applications. For biological control strategies, the attractiveness needs to be increased by phagostimuli to extend contact between larvae and the entomopathogenic fungus growing out of these formulations. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Design, synthesis, and evaluation of bioactive molecules; Quantification of tricyclic pyrones from pharmacokinetic studies; Nanodelivery of siRNA; and Synthesis of viral protease inhibitors

NASA Astrophysics Data System (ADS)

Weerasekara, Sahani Manjitha

Four research projects were carried out and they are described in this dissertation. Glycogen synthase kinase-3 beta (GSK3?) plays a pivotal and central role in the pathogenesis of Alzheimer's disease (AD) and protein kinase C (PKC) controls the function of other proteins via phosphorylation and involves in tumor promotion. In pursuit of identifying novel GSK3beta and/or PKC inhibitors, substituted quinoline molecules were designed and synthesized based on the structure-activity-relationship studies. Synthesized molecules were evaluated for their neural protective activities and selected molecules were further tested for inhibitory activities on GSK3beta and PKC enzymes. Among these compounds, compound 2 was found to have better GSK3beta enzyme inhibitory and MC65 cell protection activities at low nanomolar concentrations and poor PKC inhibitory activity whereas compound 3 shows better PKC inhibitory activity. This demonstrates the potential for uses of quinoline scaffold in designing novel compounds for AD and cancer. Pharmacokinetics and distribution profiles of two anti-Alzheimer molecules, CP2 and TP70, discovered in our laboratory were assessed using HPLC/MS. Plasma samples of mice and rats fed with TP70 via different routes over various times were analyzed to quantify the amounts of TP70 in plasma of both species. Distribution profiles of TP70 in various tissues of mice were studied and results show that TP70 penetrated the blood brain barrier and accumulated in the brain tissue in significant amounts. Similarly, the amount of CP2 in plasma of mice was analyzed. The HPLC analysis revealed that both compounds have good PK profiles and bioavailability, which would make them suitable candidates for further in vivo efficacy studies. Nanodelivery of specific dsRNA for suppressing the western corn rootworm (WCR, Diabrotica virgifera virgifera) genes was studied using modified chitosan or modified polyvinylpyrrolidinone (PVP) as nanocarriers. Computational

Prediction of pest pressure on corn root nodes: the POPP-Corn model.

PubMed

Agatz, Annika; Ashauer, Roman; Sweeney, Paul; Brown, Colin D

2017-01-01

A model for the corn rootworm Diabrotica spp. combined with a temporally explicit model for development of corn roots across the soil profile was developed to link pest ecology, root damage and yield loss. Development of the model focused on simulating root damage from rootworm feeding in accordance with observations in the field to allow the virtual testing of efficacy from management interventions in the future. We present the model and demonstrate its applicability for simulating root damage by comparison between observed and simulated pest development and root damage (assessed according to the node injury scale from 0 to 3) for field studies from the literature conducted in Urbana, Illinois (US), between 1991 and 2014. The model simulated the first appearance of larvae and adults to within a week of that observed in 88 and 71 % of all years, respectively, and in all cases to within 2 weeks of the first sightings recorded for central Illinois. Furthermore, in 73 % of all years simulated root damage differed by <0.5 node injury scale points compared to the observations made in the field between 2005 and 2014 even though accurate information for initial pest pressure (i.e. number of eggs in the soil) was not measured at the sites or available from nearby locations. This is, to our knowledge, the first time that pest ecology, root damage and yield loss have been successfully interlinked to produce a virtual field. There are potential applications in investigating efficacy of different pest control measures and strategies.

Genetic Markers for Western Corn Rootworm Resistance to Bt Toxin

PubMed Central

Flagel, Lex E.; Swarup, Shilpa; Chen, Mao; Bauer, Christopher; Wanjugi, Humphrey; Carroll, Matthew; Hill, Patrick; Tuscan, Meghan; Bansal, Raman; Flannagan, Ronald; Clark, Thomas L.; Michel, Andrew P.; Head, Graham P.; Goldman, Barry S.

2015-01-01

Western corn rootworm (WCR) is a major maize (Zea mays L.) pest leading to annual economic losses of more than 1 billion dollars in the United States. Transgenic maize expressing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely used for the management of WCR. However, cultivation of Bt-expressing maize places intense selection pressure on pest populations to evolve resistance. Instances of resistance to Bt toxins have been reported in WCR. Developing genetic markers for resistance will help in characterizing the extent of existing issues, predicting where future field failures may occur, improving insect resistance management strategies, and in designing and sustainably implementing forthcoming WCR control products. Here, we discover and validate genetic markers in WCR that are associated with resistance to the Cry3Bb1 Bt toxin. A field-derived WCR population known to be resistant to the Cry3Bb1 Bt toxin was used to generate a genetic map and to identify a genomic region associated with Cry3Bb1 resistance. Our results indicate that resistance is inherited in a nearly recessive manner and associated with a single autosomal linkage group. Markers tightly linked with resistance were validated using WCR populations collected from Cry3Bb1 maize fields showing significant WCR damage from across the US Corn Belt. Two markers were found to be correlated with both diet (R2 = 0.14) and plant (R2 = 0.23) bioassays for resistance. These results will assist in assessing resistance risk for different WCR populations, and can be used to improve insect resistance management strategies. PMID:25566794

Mating success, longevity, and fertility of Diabrotica virgifera virgifera LeConte (Chrysomelidae: Coleoptera) in relation to body size and Cry3Bb1 resistant and susceptible genotypes

USDA-ARS?s Scientific Manuscript database

Insect resistance to population control methodologies is a widespread problem, with the development of effective resistance management programs often dependent on detailed knowledge regarding the biology of individual species and changes in that biology associated with resistance evolution. This stu...

Multiple assays indicate varying levels of cross resistance of Cry3Bb1-selected field populations of the western corn rootworm to mCry3A, eCry3.1Ab, and Cry34/35Ab1

USDA-ARS?s Scientific Manuscript database

Minnesota populations of the western corn rootworm (WCR) surviving Cry3Bb1-expressing corn in the field and WCR populations assumed to be susceptible to all Bt proteins were evaluated for susceptibility to Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34/35Ab1 in diet assays and three different plant-based ass...

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.

Selinene Volatiles Are Essential Precursors for Maize Defense Promoting Fungal Pathogen Resistance.

PubMed

Ding, Yezhang; Huffaker, Alisa; Köllner, Tobias G; Weckwerth, Philipp; Robert, Christelle A M; Spencer, Joseph L; Lipka, Alexander E; Schmelz, Eric A

2017-11-01

To ensure food security, maize ( Zea mays ) is a model crop for understanding useful traits underlying stress resistance. In contrast to foliar biochemicals, root defenses limiting the spread of disease remain poorly described. To better understand belowground defenses in the field, we performed root metabolomic profiling and uncovered unexpectedly high levels of the sesquiterpene volatile β-selinene and the corresponding nonvolatile antibiotic derivative β-costic acid. The application of metabolite-based quantitative trait locus mapping using biparental populations, genome-wide association studies, and near-isogenic lines enabled the identification of terpene synthase21 ( ZmTps21 ) on chromosome 9 as a β-costic acid pathway candidate gene. Numerous closely examined β-costic acid-deficient inbred lines were found to harbor Zmtps21 pseudogenes lacking conserved motifs required for farnesyl diphosphate cyclase activity. For biochemical validation, a full-length ZmTps21 was cloned, heterologously expressed in Escherichia coli , and demonstrated to cyclize farnesyl diphosphate, yielding β-selinene as the dominant product. Consistent with microbial defense pathways, ZmTps21 transcripts strongly accumulate following fungal elicitation. Challenged field roots containing functional ZmTps21 alleles displayed β-costic acid levels over 100 μg g -1 fresh weight, greatly exceeding in vitro concentrations required to inhibit the growth of five different fungal pathogens and rootworm larvae ( Diabrotica balteata ). In vivo disease resistance assays, using ZmTps21 and Zmtps21 near-isogenic lines, further support the endogenous antifungal role of selinene-derived metabolites. Involved in the biosynthesis of nonvolatile antibiotics, ZmTps21 exists as a useful gene for germplasm improvement programs targeting optimized biotic stress resistance. © 2017 American Society of Plant Biologists. All Rights Reserved.

Kernel compositions of glyphosate-tolerant and corn rootworm-protected MON 88017 sweet corn and insect-protected MON 89034 sweet corn are equivalent to that of conventional sweet corn (Zea mays).

PubMed

Curran, Kassie L; Festa, Adam R; Goddard, Scott D; Harrigan, George G; Taylor, Mary L

2015-03-25

Monsanto Co. has developed two sweet corn hybrids, MON 88017 and MON 89034, that contain biotechnology-derived (biotech) traits designed to enhance sustainability and improve agronomic practices. MON 88017 confers benefits of glyphosate tolerance and protection against corn rootworm. MON 89034 provides protection against European corn borer and other lepidopteran insect pests. The purpose of this assessment was to compare the kernel compositions of MON 88017 and MON 89034 sweet corn with that of a conventional control that has a genetic background similar to the biotech sweet corn but does not express the biotechnology-derived traits. The sweet corn samples were grown at five replicated sites in the United States during the 2010 growing season and the conventional hybrid and 17 reference hybrids were grown concurrently to provide an estimate of natural variability for all assessed components. The compositional analysis included proximates, fibers, amino acids, sugars, vitamins, minerals, and selected metabolites. Results highlighted that MON 88017 and MON 89034 sweet corns were compositionally equivalent to the conventional control and that levels of the components essential to the desired properties of sweet corn, such as sugars and vitamins, were more affected by growing environment than the biotech traits. In summary, the benefits of biotech traits can be incorporated into sweet corn with no adverse effects on nutritional quality.

A review of insecticide poisonings among domestic livestock in southern Ontario, Canada, 1982-1989

PubMed Central

Frank, Richard; Braun, Heinz E.; Wilkie, Ian; Ewing, Ronald

1991-01-01

From 1982 to 1989, inclusive, 20 poisonings were investigated by the Ontario Ministry of Agriculture and Food following ingestion by domestic livestock of granular insecticides including terbufos (13 poisonings), disulfoton (two poisonings), fonofos (two poisonings), phorate (two poisonings), and carbofuran (one poisoning); all are used for rootworm (Diabrotica spp.) control in corn. A further three poisonings of livestock occurred following the ingestion of the foliar insecticide, endosulfan (two poisonings), and the seed protectant insecticides diazinon plus lindane (one poisoning). There were six poisoning cases as a result of excessive topical applications of the three insecticides coumpahos, fenthion, and lindane as dusts or sprays to control external parasites. Together, these events caused the deaths of 258 domestic animals of which 200 were cattle, 23 were swine, and 35 were sheep. Not all deaths are reported to the Ministry and the cases reported here may only represent 30-50% of the actual deaths over the period. Based on total populations of livestock, the percent losses were very small but they represent serious losses to individual growers. The economic loss is estimated at $160,000 over the eight years, or $20,000 per annum, and this does not include veterinary costs. Some of the poisoned animals died within as little as three to four hours of ingestion while others were sick but survived for several days. Lethal doses of insecticide were found in the rumen, abomasum, or stomach of dead animals. Signs typical of cholinesterase inhibition caused by organophosphorus poisoning were observed in most cases. Cholinesterase readings were found to be zero in dying animals. Necropsy findings were rarely more than pulmonary edema or myocardial hemorrhage. Where organochlorine insecticides were ingested, convulsions were the major manifestation. Contamination of feed was most often accidental, and chemical analysis was most helpful in identifying both potent and

Meeting Materials for the December 4-6, 2013 Scientific Advisory Panel

EPA Pesticide Factsheets

Meeting Materials for the December 4-6, 2013 Scientific Advisory Panel on Scientific Uncertainties Associated with Corn Rootworm Resistance Monitoring for Bt Corn Plant Incorporated Protectants (PIPs)

Corn insect pests

USDA-ARS?s Scientific Manuscript database

Historically, the major corn insect pests in South Dakota have been the larvae of corn rootworms (northern and western), European corn borer, and black cutworm. Bt-corn hybrids are effective against most of these pests. However, there are also minor or sporadic pests of corn in South Dakota includin...

Editorial: Special issue highlighting research presented at the 25th IWGO Conference, Chicago 2014

USDA-ARS?s Scientific Manuscript database

A joint international conference was held among corn insect entomologists from 15 countries at the Allerton Hotel, Chicago, Illinois on April 13-17, 2014. It combined the 25th IWGO (International Working Group on Ostrinia and other maize pests) Conference with the 4th Diabrotica Genetics Conference,...

Transportable data from non-target arthropod field studies for the environmental risk assessment of genetically modified maize expressing an insecticidal double-stranded RNA.

PubMed

Ahmad, Aqeel; Negri, Ignacio; Oliveira, Wladecir; Brown, Christopher; Asiimwe, Peter; Sammons, Bernard; Horak, Michael; Jiang, Changjian; Carson, David

2016-02-01

As part of an environmental risk assessment, the potential impact of genetically modified (GM) maize MON 87411 on non-target arthropods (NTAs) was evaluated in the field. MON 87411 confers resistance to corn rootworm (CRW; Diabrotica spp.) by expressing an insecticidal double-stranded RNA (dsRNA) transcript and the Cry3Bb1 protein and tolerance to the herbicide glyphosate by producing the CP4 EPSPS protein. Field trials were conducted at 14 sites providing high geographic and environmental diversity within maize production areas from three geographic regions including the U.S., Argentina, and Brazil. MON 87411, the conventional control, and four commercial conventional reference hybrids were evaluated for NTA abundance and damage. Twenty arthropod taxa met minimum abundance criteria for valid statistical analysis. Nine of these taxa occurred in at least two of the three regions and in at least four sites across regions. These nine taxa included: aphid, predatory earwig, lacewing, ladybird beetle, leafhopper, minute pirate bug, parasitic wasp, sap beetle, and spider. In addition to wide regional distribution, these taxa encompass the ecological functions of herbivores, predators and parasitoids in maize agro-ecosystems. Thus, the nine arthropods may serve as representative taxa of maize agro-ecosystems, and thereby support that analysis of relevant data generated in one region can be transportable for the risk assessment of the same or similar GM crop products in another region. Across the 20 taxa analyzed, no statistically significant differences in abundance were detected between MON 87411 and the conventional control for 123 of the 128 individual-site comparisons (96.1%). For the nine widely distributed taxa, no statistically significant differences in abundance were detected between MON 87411 and the conventional control. Furthermore, no statistically significant differences were detected between MON 87411 and the conventional control for 53 out of 56 individual

EPA Registers Innovative Tool to Control Corn Rootworm

EPA Pesticide Factsheets

Ribonucleic acid interference (RNAi) based Plant Incorporated Protectant (PIP) technology is a new and innovative scientific tool utilized by U.S. growers. Learn more about RNAi technology and the 4 new products containing the RNAi based PIP called SMARTST

Groundwater quality in the Columbia Plateau, Snake River Plain, and Oahu basaltic-rock and basin-fill aquifers in the Northwestern United States and Hawaii, 1992-2010

USGS Publications Warehouse

Frans, Lonna M.; Rupert, Michael G.; Hunt, Charles D.; Skinner, Kenneth D.

2012-01-01

Oahu and the Columbia Plateau had some of the highest percentages of soil fumigant detections in groundwater in the United States. Soil fumigants are volatile organic compounds (VOCs) used as pesticides, which are applied to soils to reduce populations of plant parasitic nematodes (harmful rootworms), weeds, fungal pathogens, and other soil-borne microorganisms. They are used in Oahu and the Columbia Plateau on crops such as pineapple and potatoes. All three areas (Columbia Plateau, Snake River Plain, and Oahu) had fumigant concentrations exceeding human-health benchmarks for drinking water.

Ecological relationship between floral thermogenesis and pollination in Nelumbo lutea (Nelumbonaceae).

PubMed

Dieringer, Gregg; Leticia Cabrera, R; Mottaleb, Mohammad

2014-02-01

Floral thermogenesis is an unusual floral trait with a well-documented physiological process, and yet, there is limited understanding of how this trait influences plant reproduction. The current study was undertaken to gain a better understanding of how floral thermogenesis in Nelumbo lutea impacts pollinator attraction and consequent plant reproduction. We conducted field studies on floral thermogenesis and thermoregulation, flower sexual development, floral visitation patterns, breeding system, pollen transfer dynamics, and floral scent production. The most abundant visitors to the thermoregulatory flowers included the Phoridae (Diptera), Chrysomelidae (Coleoptera), and Hymenoptera. Chrysomelid beetles, particularly Diabrotica, were frequent visitors to both first-day female- and second-day bisexual-phase flowers, while phorid flies were most common in bisexual-phase flowers. Pollen transfer experiments indicated that Diabrotica was equally effective in depositing pollen on stigmas, as were the less frequent, but pollen-loaded halictid bees. Flowers received a taxonomically wide assemblage of floral visitors and appear adapted to attract beetles, primarily Chrysomelidae and medium-sized bees. This study is the first to provide strong support that beetles can comprise the dominant portion of floral visitors and are as effective in pollen transfer as bees. Thermogenesis aids in dispersing the main floral scent component-1,4-dimethoxybenzene-attracting both chrysomelids and bees, while thermoregulation causes chrysomelid beetles to actively seek out new flowers for evening residence. This search behavior likely results in chrysomelids affecting cross-pollination.

Checklist of leaf beetles (Coleoptera: Chrysomelidae) from the state of Morelos, Mexico.

PubMed

Niño-Maldonado, Santiago; Sánchez-Reyes, Uriel Jeshua; Clark, Shawn M; Toledo-Hernández, Victor Hugo; Corona-López, Angélica María; Jones, Robert W

2016-03-07

We record 116 genera and 366 species of Chrysomelidae from the state of Morelos, Mexico. This represents an increase of 9.3% in the species richness of these beetles for the state. Also, Morelos is currently the third most diverse state in leaf beetles within Mexico, with 16.78% of total species recorded for the country. The most diverse genera were Calligrapha, Disonycha, Blepharida, Leptinotarsa, Cryptocephalus, Systena, Alagoasa, Diabrotica and Pachybrachis, each with more than eight species. Most of these genera contain large, showy beetles. When the chrysomelid fauna is more fully understood, some of the genera of tiny beetles will likely prove to be more diverse.

Eliciting maize defense pathways aboveground attracts belowground biocontrol agents.

PubMed

Filgueiras, Camila Cramer; Willett, Denis S; Pereira, Ramom Vasconcelos; Moino Junior, Alcides; Pareja, Martin; Duncan, Larry W

2016-11-04

Plant defense pathways mediate multitrophic interactions above and belowground. Understanding the effects of these pathways on pests and natural enemies above and belowground holds great potential for designing effective control strategies. Here we investigate the effects of aboveground stimulation of plant defense pathways on the interactions between corn, the aboveground herbivore adult Diabrotica speciosa, the belowground herbivore larval D. speciosa, and the subterranean ento-mopathogenic nematode natural enemy Heterorhabditis amazonensis. We show that adult D. speciosa recruit to aboveground herbivory and methyl salicylate treatment, that larval D. speciosa are relatively indiscriminate, and that H. amazonensis en-tomopathogenic nematodes recruit to corn fed upon by adult D. speciosa. These results suggest that entomopathogenicnematodes belowground can be highly attuned to changes in the aboveground parts of plants and that biological control can be enhanced with induced plant defense in this and similar systems.

Evaluation of corn grain with the genetically modified input trait DAS-59122-7 fed to growing-finishing pigs.

PubMed

Stein, H H; Rice, D W; Smith, B L; Hinds, M A; Sauber, T E; Pedersen, C; Wulf, D M; Peters, D N

2009-04-01

A growth performance experiment was conducted to assess the feeding value of a double-stacked transgenic corn grain for growing-finishing pigs. The genetically modified corn grain contained event DAS-59122-7, which expresses the Cry34/35Ab1 binary insecticidal protein for the control of corn rootworm. This modified transgenic grain is resistant to western corn rootworm and is also tolerant to herbicides containing the active ingredient glufosinate-ammonium. The modified grain (59122), a nontransgenic near-isoline grain (control corn), and a commercial corn (Pioneer brand hybrid 35P12) were grown in a 2005 production trial in individually isolated plots that were located 201 m apart. A total of 108 pigs were allotted to corn-soybean meal diets containing 1 of the 3 grains as the sole source of corn. There were 3 pigs per pen and 12 replicate pens per treatment. Pigs were fed grower diets from 37 to 60 kg, early finisher diets from 60 to 90 kg, and late finisher diets from 90 to 127 kg. Within each phase, data for ADG, ADFI, and G:F were calculated. At the conclusion of the experiment, pigs were slaughtered and data for carcass quality were collected. Differences between 59122 and the control corn were evaluated, with statistical significance at P<0.05. No differences in ADG, ADFI, or G:F between pigs fed the control corn and pigs fed the modified corn were observed during the grower, early finisher, or late finisher phases. For the entire experimental period, no difference between pigs fed the control and the 59122 corn were observed for final BW (128.9 vs. 127.1 kg), ADG (1.02 vs. 1.00 kg), ADFI (2.88 vs. 2.80 kg), or G:F (0.356 vs. 0.345 kg/kg). Likewise, no differences in dressing percentage (76.48 vs. 76.30%), LM area (49.8 vs. 50.4 cm(2)), 10th-rib back fat (2.20 vs. 2.12 cm), and carcass lean content (52.9 vs. 53.4%) were observed between pigs fed the control and the 59122 corn grain. It was concluded that the nutritional value of the modified transgenic corn

Impact of Bt-corn MON88017 in comparison to three conventional lines on Trigonotylus caelestialium (Kirkaldy) (Heteroptera: Miridae) field densities.

PubMed

Rauschen, Stefan; Schultheis, Eva; Pagel-Wieder, Sibylle; Schuphan, Ingolf; Eber, Sabine

2009-04-01

In Europe, Bt-corn resistant against the European Corn Borer has until now been the only genetically modified plant to be grown commercially. With the advent of the Western Corn Rootworm Bt-corn varieties with resistance against Coleoptera will become important. The cultivation of Bt-plants may have negative impacts on non-target organisms, i.e. all species not explicitly targeted by a given Bt-crop. One prominent non-target group in corn are the herbivorous plant bugs (Heteroptera: Miridae). They are common, abundant and exposed to the Cry-protein. We therefore assessed the potential impact of the cultivation of the Cry3Bb1-expressing Bt-corn variety MON88017 and three conventional varieties on this group. Trigonotylus caelestialium (Kirkaldy) was the most abundant plant bug at the experimental field. There was no evidence for a negative impact of MON88017 on this species, despite its considerable exposure to Cry3Bb1 demonstrated with ELISA. The conventional corn varieties, however, had a consistent and significant influence on the field densities of this species over all three growing seasons.

Capsules containing entomopathogenic nematodes as a Trojan horse approach to control the western corn rootworm

USDA-ARS?s Scientific Manuscript database

The use of entomopathogenic nematodes in the biological control of soil insect pests is hampered by the costly and inadequate application techniques. As a possible solution we evaluated an encapsulation approach that offers effective application and may possibly attract the pest by adding attractant...

Comparison of the forage and grain composition from insect-protected and glyphosate-tolerant MON 88017 corn to conventional corn (Zea mays L.).

PubMed

McCann, Melinda C; Trujillo, William A; Riordan, Susan G; Sorbet, Roy; Bogdanova, Natalia N; Sidhu, Ravinder S

2007-05-16

The next generation of biotechnology-derived products with the combined benefit of herbicide tolerance and insect protection (MON 88017) was developed to withstand feeding damage caused by the coleopteran pest corn rootworm and over-the-top applications of glyphosate, the active ingredient in Roundup herbicides. As a part of a larger safety and characterization assessment, MON 88017 was grown under field conditions at geographically diverse locations within the United States and Argentina during the 2002 and 2003-2004 field seasons, respectively, along with a near-isogenic control and other conventional corn hybrids for compositional assessment. Field trials were conducted using a randomized complete block design with three replication blocks at each site. Corn forage samples were harvested at the late dough/early dent stage, ground, and analyzed for the concentration of proximate constituents, fibers, and minerals. Samples of mature grain were harvested, ground, and analyzed for the concentration of proximate constituents, fiber, minerals, amino acids, fatty acids, vitamins, antinutrients, and secondary metabolites. The results showed that the forage and grain from MON 88017 are compositionally equivalent to forage and grain from control and conventional corn hybrids.

Report of an Expert Panel on the reanalysis by of a 90-day study conducted by Monsanto in support of the safety of a genetically modified corn variety (MON 863).

PubMed

Doull, J; Gaylor, D; Greim, H A; Lovell, D P; Lynch, B; Munro, I C

2007-11-01

MON 863, a genetically engineered corn variety that contains the gene for modified Bacillus thuringiensis Cry3Bb1 protein to protect against corn rootworm, was tested in a 90-day toxicity study as part of the process to gain regulatory approval. This study was reanalyzed by Séralini et al. who contended that the study showed possible hepatorenal effects of MON 863. An Expert Panel was convened to assess the original study results as analyzed by the Monsanto Company and the reanalysis conducted by Séralini et al. The Expert Panel concludes that the Séralini et al. reanalysis provided no evidence to indicate that MON 863 was associated with adverse effects in the 90-day rat study. In each case, statistical findings reported by both Monsanto and Séralini et al. were considered to be unrelated to treatment or of no biological or clinical importance because they failed to demonstrate a dose-response relationship, reproducibility over time, association with other relevant changes (e.g., histopathology), occurrence in both sexes, difference outside the normal range of variation, or biological plausibility with respect to cause-and-effect. The Séralini et al. reanalysis does not advance any new scientific data to indicate that MON 863 caused adverse effects in the 90-day rat study.

High tunnels: protection for rather than from insect pests?

PubMed

Ingwell, Laura L; Thompson, Sarah L; Kaplan, Ian; Foster, Ricky E

2017-12-01

High tunnels are a season extension tool creating a hybrid of field and greenhouse growing conditions. High tunnels have recently increased in the USA and thus research on their management is lacking. One purported advantage of these structures is protection from common field pests, but evidence to support this claim is lacking. We compared insect pest populations in high tunnels with field production over two years for three crops: tomato, broccoli and cucumber. Greenhouse pests (e.g. aphids, whiteflies) were more prevalent in high tunnels, compared to field plots. Hornworms (tobacco (Manduca sexta L.) and tomato (M. quinquemaculata Haworth)), a common field pest on tomato, were also more abundant in high tunnels, requiring chemical control while field populations were low. The crucifer caterpillar complex (imported cabbageworm (Pieris rapae L.), diamondback moth (Plutella xylostella L.) and cabbage looper (Trichoplusia ni Hübner)) was also more abundant in high tunnels in 2010. Cucumber beetle (striped (Acalymma vittatum F.) and spotted (Diabrotica undecimpunctata Mannerheim)) densities were higher in high tunnels in 2010 and field plots in 2011. The common assumption that high tunnels offer protection from field pests was not supported. Instead, high tunnel growing conditions may facilitate higher pest populations. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Composition of grain and forage from insect-protected and herbicide-tolerant corn, MON 89034 × TC1507 × MON 88017 × DAS-59122-7 (SmartStax), is equivalent to that of conventional corn (Zea mays L.).

PubMed

Lundry, Denise R; Burns, J Austin; Nemeth, Margaret A; Riordan, Susan G

2013-02-27

Monsanto Company and Dow AgroSciences LLC have developed the combined-trait corn product MON 89034 × TC1507 × MON 88017 × DAS-59122-7 (SmartStax, a registered trademark of Monsanto Technology LLC). The combination of four biotechnology-derived events into a single corn product (stacking) through conventional breeding provides broad protection against lepidopteran and corn rootworm insect pests as well as tolerance to the glyphosate and glufosinate-ammonium herbicide families. The purpose of the work described here was to assess whether the nutrient, antinutrient, and secondary metabolite levels in grain and forage tissues of the combined-trait product are comparable to those in conventional corn. Compositional analyses were conducted on grain and forage from SmartStax, a near-isogenic conventional corn hybrid (XE6001), and 14 conventional reference hybrids, grown at multiple locations across the United States. No statistically significant differences between SmartStax and conventional corn were observed for the 8 components analyzed in forage and for 46 of the 52 components analyzed in grain. The six significant differences observed in grain components (p < 0.05) were assessed in context of the natural variability for that component. These results demonstrate that the stacked product, SmartStax, produced through conventional breeding of four single-event products containing eight proteins, is compositionally equivalent to conventional corn, as previously demonstrated for the single-event products.

Performance of laying hens fed diets containing DAS-59122-7 maize grain compared with diets containing nontransgenic maize grain.

PubMed

Jacobs, C M; Utterback, P L; Parsons, C M; Rice, D; Smith, B; Hinds, M; Liebergesell, M; Sauber, T

2008-03-01

An experiment using 216 Hy-Line W-36 pullets was conducted to evaluate transgenic maize grain containing the cry34Ab1 and cry35Ab1 genes from a Bacillus thuringiensis (Bt) strain and the phosphinothricin ace-tyltransferase (pat) gene from Streptomyces viridochromogenes. Expression of the cry34Ab1 and cry35Ab1 genes confers resistance to corn rootworms, and the pat gene confers tolerance to herbicides containing glufosinate-ammonium. Pullets (20 wk of age) were placed in cage lots (3 hens/cage, 2 cages/lot) and were randomly assigned to 1 of 3 corn-soybean meal dietary treatments (12 lots/treatment) formulated with the following maize grains: near-isogenic control (control), conventional maize, and transgenic test corn line 59122 containing event DAS-59122-7. Differences between 59122 and control group means were evaluated with statistical significance at P < 0.05. Body weight and gain, egg production, egg mass, and feed efficiency for hens fed the 59122 corn were not significantly different from the respective values for hens fed diets formulated with control maize grain. Egg component weights, Haugh unit measures, and egg weight class distribution were similar regardless of the corn source. This research indicates that performance of hens fed diets containing 59122 maize grain, as measured by egg production and egg quality, was similar to that of hens fed diets formulated with near-isogenic corn grain.

Identification, quantification, spatiotemporal distribution and genetic variation of major latex secondary metabolites in the common dandelion (Taraxacum officinale agg.).

PubMed

Huber, Meret; Triebwasser-Freese, Daniella; Reichelt, Michael; Heiling, Sven; Paetz, Christian; Chandran, Jima N; Bartram, Stefan; Schneider, Bernd; Gershenzon, Jonathan; Erb, Matthias

2015-07-01

The secondary metabolites in the roots, leaves and flowers of the common dandelion (Taraxacum officinale agg.) have been studied in detail. However, little is known about the specific constituents of the plant's highly specialized laticifer cells. Using a combination of liquid and gas chromatography, mass spectrometry and nuclear magnetic resonance spectrometry, we identified and quantified the major secondary metabolites in the latex of different organs across different growth stages in three genotypes, and tested the activity of the metabolites against the generalist root herbivore Diabrotica balteata. We found that common dandelion latex is dominated by three classes of secondary metabolites: phenolic inositol esters (PIEs), triterpene acetates (TritAc) and the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G). Purification and absolute quantification revealed concentrations in the upper mgg(-1) range for all compound classes with up to 6% PIEs, 5% TritAc and 7% TA-G per gram latex fresh weight. Contrary to typical secondary metabolite patterns, concentrations of all three classes increased with plant age. The highest concentrations were measured in the main root. PIE profiles differed both quantitatively and qualitatively between plant genotypes, whereas TritAc and TA-G differed only quantitatively. Metabolite concentrations were positively correlated within and between the different compound classes, indicating tight biosynthetic co-regulation. Latex metabolite extracts strongly repelled D. balteata larvae, suggesting that the latex constituents are biologically active. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of cucurbitacin-based gustatory stimulant to facilitate cucumber beetle (Coleoptera: Chrysomelidae) management with foliar insecticides in melons.

PubMed

Pedersen, Andrew B; Godfrey, Larry D

2011-08-01

The bitter plant-derived compounds cucurbitacins are known to stimulate feeding of adult cucumber beetles (Coleoptera: Chrysomelidae). A cucurbitacin-based gustatory stimulant applied as a flowable bait combined with either spinosad or carbaryl was compared with foliar sprays of spinosad and carbaryl for controlling two cucumber beetle species (Diabrotica undecimpunctata undecimpunctata Mannerheim and Acalymma trivittatum Mannerheim) in honeydew melons (Cucumis melo L.). Field studies were conducted on the University of California-Davis plant pathology farm in 2008 and 2009. Beetle densities after applications and fruit damage from beetle feeding were compared among treatments. In addition, beetle survival was compared within field cages placed over the treated foliage infested with beetles. Using all three measures of efficacy, we determined that the addition of cucurbitacin bait had no effect on the level of cucumber beetle control with carbaryl in either 2008 or 2009. In both years, spinosad did not significantly reduce cucumber beetle densities in either field cages or field plots and did not reduce fruit damage relative to the untreated control. The addition of the bait to spinosad did not improve its efficacy. A laboratory bioassay of the spinosad formulation used in the field showed it had significant lethal effects on adults of both cucumber beetle species. Results indicated that the bait formulation used did not improve cucumber beetle control but may benefit from the addition of floral attractants or using a different type of cucurbitacin.

Selecting for resistance to the Cry3Bb1 protein in a genetically diverse population of non-diapausing Western Corn Rootworm

EPA Science Inventory

Abstract published in Resistant Pest Management Newsletter, a biannual newsletter of the Center for Integrated Plant Systems (CIPS) in cooperation with the Insecticide Resistance Action Committee (IRAC) and the Western Regional Coordinating Committee (WRCC-60).

Differential response of male and female Diabrotica speciosa (coleoptera: chrysomelidae) to bitter cucurbit-based toxic baits in relation to the treated area size

USDA-ARS?s Scientific Manuscript database

Cucurbitacins are fed on by male and female Luperini but field trials reveal that males are far more attracted to them than females. The sex ratio and number of beetles killed by an application of cucurbitacin based toxic baits was assessed at two different scales: small areas of 100 m2, and a large...

Induced Jasmonate Signaling Leads to Contrasting Effects on Root Damage and Herbivore Performance1

PubMed Central

Lu, Jing; Robert, Christelle Aurélie Maud; Riemann, Michael; Cosme, Marco; Mène-Saffrané, Laurent; Massana, Josep; Stout, Michael Joseph; Lou, Yonggen; Gershenzon, Jonathan; Erb, Matthias

2015-01-01

Induced defenses play a key role in plant resistance against leaf feeders. However, very little is known about the signals that are involved in defending plants against root feeders and how they are influenced by abiotic factors. We investigated these aspects for the interaction between rice (Oryza sativa) and two root-feeding insects: the generalist cucumber beetle (Diabrotica balteata) and the more specialized rice water weevil (Lissorhoptrus oryzophilus). Rice plants responded to root attack by increasing the production of jasmonic acid (JA) and abscisic acid, whereas in contrast to in herbivore-attacked leaves, salicylic acid and ethylene levels remained unchanged. The JA response was decoupled from flooding and remained constant over different soil moisture levels. Exogenous application of methyl JA to the roots markedly decreased the performance of both root herbivores, whereas abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid did not have any effect. JA-deficient antisense 13-lipoxygenase (asLOX) and mutant allene oxide cyclase hebiba plants lost more root biomass under attack from both root herbivores. Surprisingly, herbivore weight gain was decreased markedly in asLOX but not hebiba mutant plants, despite the higher root biomass removal. This effect was correlated with a herbivore-induced reduction of sucrose pools in asLOX roots. Taken together, our experiments show that jasmonates are induced signals that protect rice roots from herbivores under varying abiotic conditions and that boosting jasmonate responses can strongly enhance rice resistance against root pests. Furthermore, we show that a rice 13-lipoxygenase regulates root primary metabolites and specifically improves root herbivore growth. PMID:25627217

Occurrence and field densities of Coleoptera in the maize herb layer: implications for Environmental Risk Assessment of genetically modified Bt-maize.

PubMed

Rauschen, Stefan; Schaarschmidt, Frank; Gathmann, Achim

2010-10-01

Beetles (Coleoptera) are a diverse and ecologically important group of insects in agricultural systems. The Environmental Risk Assessment (ERA) of genetically modified Bt-crop varieties with insect resistances thus needs to consider and assess the potential negative impacts on non-target organisms belonging to this group. We analysed data gathered during 6 years of field-release experiments on the impact of two genetically modified Bt-maize varieties (Ostrinia-resistant MON810 and Diabrotica-resistant MON88017) on the occurrence and field densities of Coleoptera, especially the two families Coccinellidae and Chrysomelidae. Based on a statistical analysis aimed at establishing whether Bt-maize varieties are equivalent to their near-isogenic counterparts, we discuss the limitations of using field experiments to assess the effects of Bt-maize on these two beetle families. The densities of most of the beetle families recorded in the herb layer were very low in all growing seasons. Coccinellidae and Chrysomelidae were comparatively abundant and diverse, but still low in numbers. Based on their role as biological control agents, Coccinellidae should be a focus in the ERA of Bt-plants, but given the large natural variability in ladybird densities in the field, most questions need to be addressed in low-tier laboratory tests. Chrysomelidae should play a negligible role in the ERA of Bt-plants, since they occur on-crop as secondary pests only. Species occurring off-crop, however, can be addressed in a similar fashion as non-target Lepidoptera in Cry1Ab expressing Bt-maize.

Specificity of induced defenses, growth, and reproduction in lima bean (Phaseolus lunatus) in response to multispecies herbivory.

PubMed

Moreira, Xoaquín; Abdala-Roberts, Luis; Hernández-Cumplido, Johnattan; Cuny, Maximilien A C; Glauser, Gaetan; Benrey, Betty

2015-08-01

• Following herbivore attack, plants can either reduce damage by inducing defenses or mitigate herbivory effects through compensatory growth and reproduction. It is increasingly recognized that such induced defenses in plants are herbivore-specific, but less is known about the specificity of compensatory responses. Damage by multiple herbivores may also lead to synergistic effects on induction and plant fitness that differ from those caused by a single herbivore species. Although largely unstudied, the order of arrival and damage by different herbivore species might also play an important role in the impacts of herbivory on plants.• We investigated the specificity of defense induction (phenolics) and effects on growth (number of stems and leaves) and reproduction (number of seeds, seed mass, and germination rate) from feeding by two generalist leaf-chewing herbivores (Spodoptera eridania and Diabrotica balteata) on Phaseolus lunatus plants and evaluated whether simultaneous attack by both herbivores and their order of arrival influenced such dynamics.• Herbivory increased levels of leaf phenolics, but such effects were not herbivore-specific. In contrast, herbivory enhanced seed germination in an herbivore-specific manner. For all variables measured, the combined effects of both herbivore species did not differ from their individual effects. Finally, the order of herbivore arrival did not influence defense induction, plant growth, or seed number but did influence seed mass and germination.• Overall, this study highlights novel aspects of the specificity of plant responses induced by damage from multiple species of herbivores and uniquely associates such effects with plant lifetime fitness. © 2015 Botanical Society of America, Inc.

Floral transmission of Erwinia tracheiphila by cucumber beetles in a wild Cucurbita pepo.

PubMed

Sasu, M A; Seidl-Adams, I; Wall, K; Winsor, J A; Stephenson, A G

2010-02-01

Cucumber beetles, Acalymma vittatum (F.) and Diabrotica undecipunctata howardi (Barber), are specialist herbivores of cucurbits and the vector of Erwinia tracheiphila (E.F. Smith) Holland, the causative agent of wilt disease. Cucumber beetles transmit E. tracheiphila when infected frass falls onto leaf wounds at the site of beetle feeding. We show that E. tracheiphila also can be transmitted via the floral nectaries of Cucurbita pepo ssp. texana L. Andres (Texas gourd). Under field conditions, we found that beetles aggregate in flowers in the late morning, that these beetles chew the anther filaments that cover the nectaries in male flowers thereby exposing the nectary, and that beetle frass accumulates on the nectary. We use real-time polymerase chain reaction to show that most of the flowers produced during the late summer possess beetle frass containing E. tracheiphila. Greenhouse experiments, in which cultures of E. tracheiphila are deposited onto floral nectaries, show that Texas gourds can contract wilt disease through the floral nectaries. Finally, we use green fluorescent protein-transformed E. tracheiphila to document the movement of E. tracheiphila through the nectary into the xylem of the pedicel before the abscission of the flower. Together, these data show that E. tracheiphila can be transmitted through infected frass that falls on or near the floral nectaries. We hypothesize that the concentration of frass from many beetles in the flowers increases both exposure to and the concentration of E. tracheiphila and plays a major role in the dynamics of wilt disease in both wild populations and cultivated squash fields.

Decomposition rates and residue-colonizing microbial communities of Bacillus thuringiensis insecticidal protein Cry3Bb-expressing (Bt) and non-Bt corn hybrids in the field.

PubMed

Xue, Kai; Serohijos, Raquel C; Devare, Medha; Thies, Janice E

2011-02-01

Despite the rapid adoption of crops expressing the insecticidal Cry protein(s) from Bacillus thuringiensis (Bt), public concern continues to mount over the potential environmental impacts. Reduced residue decomposition rates and increased tissue lignin concentrations reported for some Bt corn hybrids have been highlighted recently as they may influence soil carbon dynamics. We assessed the effects of MON863 Bt corn, producing the Cry3Bb protein against the corn rootworm complex, on these aspects and associated decomposer communities by terminal restriction fragment length polymorphism (T-RFLP) analysis. Litterbags containing cobs, roots, or stalks plus leaves from Bt and unmodified corn with (non-Bt+I) or without (non-Bt) insecticide applied were placed on the soil surface and at a 10-cm depth in field plots planted with these crop treatments. The litterbags were recovered and analyzed after 3.5, 15.5, and 25 months. No significant effect of treatment (Bt, non-Bt, and non-Bt+I) was observed on initial tissue lignin concentrations, litter decomposition rate, or bacterial decomposer communities. The effect of treatment on fungal decomposer communities was minor, with only 1 of 16 comparisons yielding separation by treatment. Environmental factors (litterbag recovery year, litterbag placement, and plot history) led to significant differences for most measured variables. Combined, these results indicate that the differences detected were driven primarily by environmental factors rather than by any differences between the corn hybrids or the use of tefluthrin. We conclude that the Cry3Bb corn tested in this study is unlikely to affect carbon residence time or turnover in soils receiving these crop residues.

Analysis of plant-derived miRNAs in animal small RNA datasets

PubMed Central

2012-01-01

Background Plants contain significant quantities of small RNAs (sRNAs) derived from various sRNA biogenesis pathways. Many of these sRNAs play regulatory roles in plants. Previous analysis revealed that numerous sRNAs in corn, rice and soybean seeds have high sequence similarity to animal genes. However, exogenous RNA is considered to be unstable within the gastrointestinal tract of many animals, thus limiting potential for any adverse effects from consumption of dietary RNA. A recent paper reported that putative plant miRNAs were detected in animal plasma and serum, presumably acquired through ingestion, and may have a functional impact in the consuming organisms. Results To address the question of how common this phenomenon could be, we searched for plant miRNAs sequences in public sRNA datasets from various tissues of mammals, chicken and insects. Our analyses revealed that plant miRNAs were present in the animal sRNA datasets, and significantly miR168 was extremely over-represented. Furthermore, all or nearly all (>96%) miR168 sequences were monocot derived for most datasets, including datasets for two insects reared on dicot plants in their respective experiments. To investigate if plant-derived miRNAs, including miR168, could accumulate and move systemically in insects, we conducted insect feeding studies for three insects including corn rootworm, which has been shown to be responsive to plant-produced long double-stranded RNAs. Conclusions Our analyses suggest that the observed plant miRNAs in animal sRNA datasets can originate in the process of sequencing, and that accumulation of plant miRNAs via dietary exposure is not universal in animals. PMID:22873950

Event specific qualitative and quantitative polymerase chain reaction detection of genetically modified MON863 maize based on the 5'-transgene integration sequence.

PubMed

Yang, Litao; Xu, Songci; Pan, Aihu; Yin, Changsong; Zhang, Kewei; Wang, Zhenying; Zhou, Zhigang; Zhang, Dabing

2005-11-30

Because of the genetically modified organisms (GMOs) labeling policies issued in many countries and areas, polymerase chain reaction (PCR) methods were developed for the execution of GMO labeling policies, such as screening, gene specific, construct specific, and event specific PCR detection methods, which have become a mainstay of GMOs detection. The event specific PCR detection method is the primary trend in GMOs detection because of its high specificity based on the flanking sequence of the exogenous integrant. This genetically modified maize, MON863, contains a Cry3Bb1 coding sequence that produces a protein with enhanced insecticidal activity against the coleopteran pest, corn rootworm. In this study, the 5'-integration junction sequence between the host plant DNA and the integrated gene construct of the genetically modified maize MON863 was revealed by means of thermal asymmetric interlaced-PCR, and the specific PCR primers and TaqMan probe were designed based upon the revealed 5'-integration junction sequence; the conventional qualitative PCR and quantitative TaqMan real-time PCR detection methods employing these primers and probes were successfully developed. In conventional qualitative PCR assay, the limit of detection (LOD) was 0.1% for MON863 in 100 ng of maize genomic DNA for one reaction. In the quantitative TaqMan real-time PCR assay, the LOD and the limit of quantification were eight and 80 haploid genome copies, respectively. In addition, three mixed maize samples with known MON863 contents were detected using the established real-time PCR systems, and the ideal results indicated that the established event specific real-time PCR detection systems were reliable, sensitive, and accurate.

Induced jasmonate signaling leads to contrasting effects on root damage and herbivore performance.

PubMed

Lu, Jing; Robert, Christelle Aurélie Maud; Riemann, Michael; Cosme, Marco; Mène-Saffrané, Laurent; Massana, Josep; Stout, Michael Joseph; Lou, Yonggen; Gershenzon, Jonathan; Erb, Matthias

2015-03-01

Induced defenses play a key role in plant resistance against leaf feeders. However, very little is known about the signals that are involved in defending plants against root feeders and how they are influenced by abiotic factors. We investigated these aspects for the interaction between rice (Oryza sativa) and two root-feeding insects: the generalist cucumber beetle (Diabrotica balteata) and the more specialized rice water weevil (Lissorhoptrus oryzophilus). Rice plants responded to root attack by increasing the production of jasmonic acid (JA) and abscisic acid, whereas in contrast to in herbivore-attacked leaves, salicylic acid and ethylene levels remained unchanged. The JA response was decoupled from flooding and remained constant over different soil moisture levels. Exogenous application of methyl JA to the roots markedly decreased the performance of both root herbivores, whereas abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid did not have any effect. JA-deficient antisense 13-lipoxygenase (asLOX) and mutant allene oxide cyclase hebiba plants lost more root biomass under attack from both root herbivores. Surprisingly, herbivore weight gain was decreased markedly in asLOX but not hebiba mutant plants, despite the higher root biomass removal. This effect was correlated with a herbivore-induced reduction of sucrose pools in asLOX roots. Taken together, our experiments show that jasmonates are induced signals that protect rice roots from herbivores under varying abiotic conditions and that boosting jasmonate responses can strongly enhance rice resistance against root pests. Furthermore, we show that a rice 13-lipoxygenase regulates root primary metabolites and specifically improves root herbivore growth. © 2015 American Society of Plant Biologists. All Rights Reserved.

Development of a CO2 releasing co-formulation 1 based on starch, Saccharomyces cerevisiae and Beauveria bassiana attractive towards western corn rootworm larvae

USDA-ARS?s Scientific Manuscript database

CO2 is known as an attractant for many soil-dwelling pests. To implement an attract-and-kill strategy for soil pest control, CO2 emitting formulations need to be developed. This work aimed at the development of a slow release bead system in order to bridge the gap between application and hatching of...

Weather forecasting by insects: modified sexual behaviour in response to atmospheric pressure changes.

PubMed

Pellegrino, Ana Cristina; Peñaflor, Maria Fernanda Gomes Villalba; Nardi, Cristiane; Bezner-Kerr, Wayne; Guglielmo, Christopher G; Bento, José Maurício Simões; McNeil, Jeremy N

2013-01-01

Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We

Performance of lactating dairy cows fed corn as whole plant silage and grain produced from genetically modified corn containing event DAS-59122-7 compared to a nontransgenic, near-isogenic control.

PubMed

Brouk, M J; Cvetkovic, B; Rice, D W; Smith, B L; Hinds, M A; Owens, F N; Iiams, C; Sauber, T E

2011-04-01

The nutritional equivalency of grain plus whole plant silage from genetically modified corn plants containing the DAS-59122-7 (59122) event expressing the Cry34Ab1 and Cry35Ab1 proteins to grain and silage from a near-isogenic corn hybrid without this trait (control) was assessed using lactating dairy cows. Corn plants with event 59122 are resistant to western corn rootworm and tolerant to the herbicide active ingredient glufosinate-ammonium. Effects on feed intake, milk production, and milk composition were determined. The 59122 grain and the control grain were produced in 2005 from isolated plots in Richland, Iowa. Whole plant corn silage for the 59122 and control treatments were grown in isolated plots at the Kansas State University Dairy Center and ensiled in Ag-Bags. Thirty lactating Holstein cows blocked by lactation number, day of lactation, and previous energy-corrected milk production were used in a switchback design. All cows were fed diets that contained 22.7% grain plus 21.3% whole plant silage from either the 59122 or the control hybrid, in addition to 21% wet corn gluten feed, 12.3% protein mix, 8.0% whole cottonseed, and 14.7% alfalfa hay. Each period of the switchback trial included 2 wk for diet adjustment followed by 4 wk for data and sample collection. Milk samples (a.m. and p.m.) collected from 2 consecutive milkings of each collection wk were analyzed for fat, protein, lactose, solids-not-fat, milk urea nitrogen, and somatic cell count. Percentages of milk fat, protein, lactose, and solids-not-fat were not affected by dietary treatment. Yields of milk, 4% fat-corrected milk, energy-corrected milk, solids-corrected milk, and the concentrations and yields of milk fat, milk protein, milk solids, and milk lactose were not significantly different between treatments. Efficiencies of milk, fat-corrected milk, energy-corrected milk, and solids-corrected milk production also were not different when cows were fed crops from 59122 than when they were fed

Human health and ecological risk assessments for SmartStax PRO (MON 89034 x TC1507 x MON 87411 x DAS-59122-7), a plant-incorporated protectant intended to control corn rootworm through ribonucleic acid (RNA) interference

EPA Science Inventory

The use of RNA interference (RNAi) gene silencing technology, particularly RNAi for pesticidal purposes to control macroorganism pests, is a relatively recent innovation. Post-transcriptional silencing of gene function is a very rapid process where double-stranded RNA (dsRNA) dir...