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Leslie Hammack - One of the best experts on this subject based on the ideXlab platform.
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Spermatophore Size in Relation to Body Size and Pairing Duration in Northern Corn Rootworm (Coleoptera: Chrysomelidae)
Annals of The Entomological Society of America, 2012Co-Authors: B. Wade French, Leslie HammackAbstract:Female insects may choose to mate with males providing the largest nuptial gift via the spermatophore, which may correlate with fitness related characters such as body size. Here, we examined spermatophore size of northern corn rootworm, Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae), in relation to body size of males and females and in relation to pairing duration. Virgin males and females of known ages were weighed before and after pairing. Pairs were noted as copulating or not copulating. Copulating males lost significantly more weight than did noncopulating males, whereas copulating females gained significantly more weight than did noncopulating females. For copulating pairs, male and female weight before pairing correlated positively. Spermatophore weight correlated positively with male weight before pairing and was estimated to be 0.37 or 0.38 mg, depending on whether weight change data from males or females were used for estimation. Spermatophore mass accounted for ≈4.4% of male body weight. An effect of pairing duration on spermatophore weight was demonstrable only when weight change data from females were used. Implications of the results for management of rootworm resistance to genetically modified maize are discussed.
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Multiple Mating, Fecundity, and Longevity in Female Northern Corn Rootworm (Coleoptera: Chrysomelidae) in Relation to Body Size
Annals of The Entomological Society of America, 2011Co-Authors: B. Wade French, Leslie HammackAbstract:Diabroticite corn rootworms are significant maize, Zea mays L., pests that have evolved resistance to cultural and chemical management methods. Transgenic maize synthesizing a rootworm-toxic protein originating from the bacterium Bacillus thuringiensis Berliner is an important new management technology. Its use requires a refuge of nontransgenic maize to delay evolution of resistance by generating susceptible beetles capable of copulating with any resistant individuals surviving on the transgenic crop. The evolution of such resistance may concurrently influence a variety of fitness-related characters. Here, we examined multiple mating by female Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae) in relation to the following fitness-related traits: female longevity, fecundity, and body size of males and females at the first copulation. For the first copulation, large and small males were reciprocally paired to large and small females for comparison with average-sized beetles. Once-mated females were then maintained under conditions conducive to oviposition and paired with averaged-sized males at weekly intervals until death. Although female age at second copulation varied significantly with size category, female age at first copulation, longevity and fecundity did not. Females that mated multiple times lived longer and laid more eggs than did those that mated once. The results suggest that resistance management models may need to consider those females deriving fitness benefits from a second mating.
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Reproductive Traits of Northern Corn Rootworm (Coleoptera: Chrysomelidae) in Relation to Female and Male Body Size
Annals of The Entomological Society of America, 2010Co-Authors: B. Wade French, Leslie HammackAbstract:Diabrotica spp. are serious pests of maize, Zea mays L., and have evolved resistance to cultural and chemical management practices. Transgenic maize producing a rootworm-toxic protein derived from the bacterium Bacillus thuringiensis Berliner provides a new approach to Diabrotica spp. management. Its use requires a refuge of nontransgenic maize to produce susceptible beetles able to mate with any resistant individuals developing on the transgenic variety to slow the evolution of resistance. Such evolution may simultaneously affect fitness related traits such as longevity, fecundity, and body size. We examined the mating behavior and reproductive biology of Diabrotica Barberi Smith & Lawrence in relation to male and female body size. Large and small males were reciprocally paired to large and small females for comparison with average sized beetles. Neither the proportion of pairs that copulated nor the precopulation duration varied significantly with size category; however, the duration of copulation was shortest for large males crossed with small females and longest for the reciprocal cross. Large females lived the longest regardless of mating partner. Although small females mated to small males tended to lay the fewest eggs, size category did not significantly affect egg numbers per week of life during a 12-wk oviposition period. Egg production peaked during the first 4 to 5 wk and then steadily declined. These results suggest that resistance to transgenic maize, if associated with small body size, could provide a reproductive disadvantage for resistant females but not males that could prolong efficacy of the transgenic maize.
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Sexual Dimorphism of Basitarsi in Pest Species of Diabrotica and Cerotoma (Coleoptera: Chrysomelidae)
Annals of The Entomological Society of America, 2007Co-Authors: Leslie Hammack, Bryan Wade FrenchAbstract:Sexual dimorphism in basitarsal pad morphology is described for prothoracic and mesothoracic legs of Diabrotica virgifera virgifera LeConte, Diabrotica Barberi Smith & Lawrence, and Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae) and for prothoracic legs of Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae). On the indicated legs of these diabroticite beetles, the typical structure of the hairy tarsal pads of chrysomelid beetles is replaced proximally on tarsomere 1 of males by a hairless planar ovoid patch that may facilitate maintenance of the mating posture of males upon the elytra of females. This basitarsal patch proved as reliable as the standard supra-anal plate character for establishing sex of these important crop pests.
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Field Capture of Northern and Western Corn Rootworm Beetles Relative to Attractant Structure and Volatility
Journal of Chemical Ecology, 2004Co-Authors: Leslie Hammack, Richard J. PetroskiAbstract:We used field assays to study attraction of feral northern and western corn rootworm beetles ( Diabrotica Barberi and D. virgifera virgifera ) to a series of mostly nitrogenous and benzenoid synthetic compounds allied with host plant and floral aromas. Vaporization rates were obtained for most field-tested compounds and selected additional lures under both ideal and field-representative, but constant, conditions. Although many test compounds showed at least trace activity for one or both species, methyl benzoate and some of its derivatives, notably methyl anthranilate and methyl 4-methoxybenzoate, merited emphasis as effective new lures for females. Structural alteration of methyl benzoate had consistently negative effects on northern corn rootworm captures despite variable effects on release rate, whereas western corn rootworm was more strongly attracted to methyl anthranilate and methyl 4-methoxybenzoate than to the considerably more volatile parent compound. Phenylacetaldoxime was attractive to females of both species, but no more so than syn -benzaldoxime, included as reference. Release rate was disproportionately low for benzaldoxime, as well as other nitrogenous lures, under field compared with ideal conditions. The attractiveness of salicylaldoxime to northern corn rootworm, despite its low field release rate, and the unattractiveness of methyl salicylate, having a methyl ester in place of the oxime group, similarly highlighted importance of the oxime moiety for reactivity of this species.
Brad S Coates - One of the best experts on this subject based on the ideXlab platform.
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assembly and annotation of full mitochondrial genomes for the corn rootworm species Diabrotica virgifera virgifera and Diabrotica Barberi insecta coleoptera chrysomelidae using next generation sequence data
Gene, 2014Co-Authors: Brad S CoatesAbstract:Abstract Complete mitochondrial genomes for two corn rootworm species, Diabrotica virgifera virgifera (16,747 bp) and Diabrotica Barberi (16,632; Insecta: Coleoptera: Chrysomelidae), were assembled from Illumina HiSeq2000 read data. Annotation indicated that the order and orientation of 13 protein coding genes (PCGs), and 22 tRNA and 2 rRNA sequences were in typical of insect mitochondrial genomes. Non-standard nad4 and cox3 stop codons were composed of single T nucleotides and likely completed by adenylation, and atypical TTT start codons was predicted for both D. v. virgifera and D. Barberi nad1 genes. The D. v. virgifera and D. Barberi haplotypes showed 819 variable nucleotide positions within PCG regions (7.36% divergence), which suggest that speciation may have occurred ~ 3.68 million years ago assuming a linear rate of short-term substitution. Phylogenetic analyses of Coleopteran MtD genome show clustering based on family level, and may have the capacity to resolve the evolutionary history within this Order of insects.
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inheritance of an extended diapause trait in the northern corn rootworm Diabrotica Barberi coleoptera chrysomelidae
Journal of Applied Entomology, 2014Co-Authors: B W French, Brad S Coates, Thomas W SappingtonAbstract:Diapause is an adaptive trait that delays development or reproduction under unfavourable circumstances. The northern corn rootworm, Diabrotica Barberi Smith & Lawrence, an important maize, Zea mays L., pest in the Diabroticite species complex, overwinters in diapause during the egg stage. Some NCR populations are adapted to crop rotation by expressing an extended diapause (ED) trait that delays embryonic development for 2 years. This ED trait has increased in frequency and geographic distribution since first reported in Illinois in 1932. Reciprocal single pair crosses among beetles from a laboratory colony with the ancestral 1-year diapause trait and field collected beetles with the 2-year ED trait indicated that ED females laid significantly more ED eggs than did females with the 1-year diapause trait regardless of male genotype. The ED trait was highly heritable [realized heritability (h 2 ) = 0.698 ± 0.314], with genetic dominance (D) of the trait strongly influenced by female genotype. Selection of the ED trait and maintenance of polymorphic diapause phenotypes within maize-soybean cropping systems is discussed in relation to response to a fluctuating environment and as a potentially advantageous life history adaptation.
Lance J Meinke - One of the best experts on this subject based on the ideXlab platform.
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Optimizing Egg Recovery From Wild Northern Corn Rootworm Beetles (Coleoptera: Chrysomelidae)
Journal of Economic Entomology, 2019Co-Authors: Adriano E. Pereira, Ryan W Geisert, Lance J Meinke, Daniel Moellenbeck, Dalton C. Ludwick, Julie Barry, Mark R. Ellersieck, Jordan D. Reinders, Keiran Hyte, Amanda ErnwallAbstract:The northern corn rootworm, Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae), is one of the most important insect pests in the U.S. Corn Belt. Efforts to obtain eggs from wild northern corn rootworm populations using techniques developed for other rootworm species have been unsuccessful due to lack of oviposition. In 2016, we evaluated four oviposition media in choice tests within each of three female densities in 30.5 × 30.5 × 30.5 cm BugDorm cages. The number of eggs laid per female was significantly affected by female density and the interaction of female density × oviposition media, but oviposition was relatively poor in all oviposition media (1.2 eggs per female when averaging the three female densities and all oviposition media). Single females were also evaluated in nonchoice assays in 6 cm × 6 cm × 8 cm clear plastic boxes and averaged up to 108 eggs per female depending on the oviposition media. In 2017, the cumulative number of eggs laid per female in boxes with one female was not significantly different from the number of eggs laid per female in boxes with 3 females. In 2018, the cumulative number of eggs laid per female was not significantly different between female densities of 1, 3, 5, or 10 females per box. Total egg production per box therefore increased as female density increased. More than 27,000 wild northern corn rootworm eggs were collected from just 190 females when collected relatively early in the field season. We now have an efficient and robust system for obtaining eggs from wild northern corn rootworm females.
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Effect of Seed Blends and Soil-Insecticide on Western and Northern Corn Rootworm Emergence from mCry3A + eCry3.1Ab Bt Maize
Journal of Economic Entomology, 2015Co-Authors: Daniel L. Frank, Lance J Meinke, Aaron J. Gassmann, Michael E. Gray, Ryan Kurtz, Nicholas A. Tinsley, Daniel Moellenbeck, Larry W. Bledsoe, Christian H. Krupke, Ronald E. EstesAbstract:ABSTRACT Seed blends containing various ratios of transgenic Bt maize (Zea mays L.) expressing the mCry3A + eCry3.1Ab proteins and non-Bt maize (near-isoline maize) were deployed alone and in combination with a soil applied pyrethroid insecticide (Force CS) to evaluate the emergence of the western corn rootworm, Diabrotica virgifera virgifera LeConte, in a total of nine field environments across the Midwestern United States in 2010 and 2011. Northern corn rootworm, Diabrotica Barberi Smith & Lawrence emergence was also evaluated in four of these environments. Both western and northern corn rootworm beetle emergence from all Bt treatments was significantly reduced when compared with beetle emergence from near-isoline treatments. Averaged across all environments, western corn rootworm beetle emergence from 95:5, 90:10, and 80:20 seed blend ratios of mCry3A + eCry3.1Ab: near-isoline were 2.6-, 4.2-, and 6.7-fold greater than that from the 100:0 ratio treatment. Northern corn rootworm emergence from the same ...
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Effect of Bt Maize and Soil Insecticides on Yield, Injury, and Rootworm Survival: Implications for Resistance Management
Journal of Economic Entomology, 2013Co-Authors: Jennifer L. Petzold-maxwell, Lance J Meinke, Michael E. Gray, Ronald E. Estes, Aaron J. GassmannAbstract:ABSTRACT A 2-yr field experiment was conducted to determine the effects on Diabrotica spp. (Coleoptera: Chrysomelidae) of an insecticidal seed treatment (Poncho 1250, (AI) /clothianidin) and a granular insecticide (Aztec 2.1G, (AI)/tebupirimphos and cyfluthrin) alone and in combination with maize producing the insectidical toxin Cry3Bb1 derived from the bacterium Bacillus thuringiensis (Bt). Yields for Bt maize plots were significantly greater than for non-Bt maize; however, insecticides did not significantly affect yield. Insecticides significantly decreased root injury in non-Bt maize plots, but there were no significant differences in root injury between Bt maize with or without either insecticide. Maize producing the Bt toxin Cry3Bb1 and the soil-applied insecticide Aztec significantly decreased survival of western corn rootworm (Diabrotica virgifera virgifera LeConte), while only Bt maize significantly decreased survival of the northern corn rootworm (Diabrotica Barberi Smith & Lawrence). For both sp...
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frequency and distribution of extended diapause in nebraska populations of Diabrotica Barberi coleoptera chrysomelidae
Journal of Economic Entomology, 2013Co-Authors: Ryan W Geisert, Lance J MeinkeAbstract:ABSTRACT The frequency of extended diapause in populations of the northern corn rootworm, Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae), was measured in eastern Nebraska. Adult collections were made during late summer in 2008 and 2009 from eight sites each year (seven sites were consistent over years). Eggs were obtained from 12 to 20 females per site and were held on moist soil under appropriate temperature profiles to facilitate egg survival, diapause development, and diapause termination. Percentage egg hatch was recorded after the first and second year for the 2008 and 2009 collections. Additional extended diapause expression was estimated for the 2008 and 2009 collections by counting remaining live eggs after the second-year egg hatch was completed. These data also were used to estimate each site's maximum egg viability. Results collectively indicate that the extended diapause trait was present in all eastern Nebraska populations; however, significant variation in the frequency of e...
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field introgression of Diabrotica Barberi and Diabrotica longicornis coleoptera chrysomelidae based on genetic and morphological characters
Annals of The Entomological Society of America, 2011Co-Authors: Laura A Campbell, Lance J Meinke, Thomas L Clark, Pete Clark, John E FosterAbstract:ABSTRACT Diabrotica Barberi Smith & Lawrence and Diabrotica longicornis (Say) (Coleoptera: Chrysomelidae) are considered to be sister species, and it has been proposed that the two species may hybridize under field conditions. The objective of this study was to examine genetic and morphological characters of D. Barberi and D. longicornis for evidence of field introgression. Both species were collected from sympatric and allopatric areas. Amplified fragment length polymorphisms and morphological characters (color and head capsule width) were used to examine variation within and among populations of D. Barberi and D. longicornis. Relatively little of the overall genetic variation was explained by the putative species designation, and most of the genetic variation, both between and within species, was found within populations. In addition, genetic differences were not correlated with geographic location. Beetle color did differ significantly between putative species, with the darkest individuals occurring at...
Aaron J. Gassmann - One of the best experts on this subject based on the ideXlab platform.
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Effects of Field History on Corn Root Injury and Adult Abundance of Northern and Western Corn Rootworm (Coleoptera: Chrysomelidae).
Journal of Economic Entomology, 2016Co-Authors: Mike W. Dunbar, Matthew E. O'neal, Aaron J. GassmannAbstract:Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), and northern corn rootworm, Diabrotica Barberi Smith & Lawrence, are major pests of corn ( Zea mays L.). Corn producing Bacillus thuringiensis (Bt) toxins are widely used to manage Diabrotica spp.; however, Bt resistance by D. v. virgifera has led to high levels of feeding injury in the field. We tested whether field history affected root injury and abundance of adult Diabrotica spp. In 2013 and 2014, four types of cornfields were sampled: 1) recently rotated fields, 2) continuous cornfields, 3) fields with a history of injury to Bt corn (past problem fields), and 4) fields with greater than one node of injury to Bt corn at the time of sampling (current problem fields). Data were collected on field history, root injury, and the abundance of adult Diabrotica spp. from each field. Root injury and the abundance of D. v. virgifera were significantly greater in current problem fields compared to the other field types, while D. Barberi were significantly more abundant in recently rotated fields. Root injury and the abundance of D. v. virgifera did not differ among recently rotated fields, continuous cornfields, and past problem fields. Analysis of field history showed that recently rotated fields were characterized by significantly less Bt corn, soil-applied insecticides, and years planted to corn continuously. These results suggest that greater cropping practice diversity can reduce management inputs for Diabrotica spp.; however, its effects on resistance evolution remain undetermined.
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Effect of Seed Blends and Soil-Insecticide on Western and Northern Corn Rootworm Emergence from mCry3A + eCry3.1Ab Bt Maize
Journal of Economic Entomology, 2015Co-Authors: Daniel L. Frank, Lance J Meinke, Aaron J. Gassmann, Michael E. Gray, Ryan Kurtz, Nicholas A. Tinsley, Daniel Moellenbeck, Larry W. Bledsoe, Christian H. Krupke, Ronald E. EstesAbstract:ABSTRACT Seed blends containing various ratios of transgenic Bt maize (Zea mays L.) expressing the mCry3A + eCry3.1Ab proteins and non-Bt maize (near-isoline maize) were deployed alone and in combination with a soil applied pyrethroid insecticide (Force CS) to evaluate the emergence of the western corn rootworm, Diabrotica virgifera virgifera LeConte, in a total of nine field environments across the Midwestern United States in 2010 and 2011. Northern corn rootworm, Diabrotica Barberi Smith & Lawrence emergence was also evaluated in four of these environments. Both western and northern corn rootworm beetle emergence from all Bt treatments was significantly reduced when compared with beetle emergence from near-isoline treatments. Averaged across all environments, western corn rootworm beetle emergence from 95:5, 90:10, and 80:20 seed blend ratios of mCry3A + eCry3.1Ab: near-isoline were 2.6-, 4.2-, and 6.7-fold greater than that from the 100:0 ratio treatment. Northern corn rootworm emergence from the same ...
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Effects of Pyramided Bt Corn and Blended Refuges on Western Corn Rootworm and Northern Corn Rootworm (Coleoptera: Chrysomelidae)
Journal of Economic Entomology, 2015Co-Authors: Ryan S. Keweshan, Graham P. Head, Aaron J. GassmannAbstract:ABSTRACT The western corn rootworm, Diabrotica virgifera virgifera LeConte, and the northern corn rootworm, Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae), are major pests of corn (Zea mays L). Several transgenic corn events producing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) kill corn rootworm larvae and reduce injury to corn roots. However, planting of Bt corn imposes selection on rootworm populations to evolve Bt resistance. The refuge strategy and pyramiding of multiple Bt toxins can delay resistance to Bt crops. In this study, we assessed the impact of four treatments——1) non-Bt corn, 2) Cry3Bb1 corn, 3) corn pyramided with Cry3Bb1 and Cry34/35Ab1, and 4) pyramided corn with a blended refuge——on survival, time of adult emergence, and size of western and northern corn rootworm. All treatments with Bt corn led to significant reductions in the number of adults that emerged per plot.However, at one location, we identified Cry3Bb1-resistant western corn ro...
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Effects of Rag1 on the Preference and Performance of Soybean Defoliators
Journal of Economic Entomology, 2013Co-Authors: Robert F. Bruner, Erin W. Hodgson, Aaron J. GassmannAbstract:ABSTRACT The Rag1 gene confers antibiotic resistance to soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), and in 2010, varieties expressing Rag1 were released for commercial use in the United States. We do not know how Rag1 varieties will influence the broader community of defoliating insects that inhabit soybean fields. In 2010 and 2011, the preference and performance of pest insects that defoliate soybeans [Glycines max (L.) Merr] were tested using Rag1 and aphidsusceptible varieties. Three coleopterans and four lepidopterans were used: northern corn rootworm, Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae); southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae); bean leaf beetle, Ceratoma trifurcata Forster (Coleoptera: Chrysomelidae); fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae); corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae); soybean looper, Chrysodeix includens (Walker) (Lepidoptera: ...
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Effect of Bt Maize and Soil Insecticides on Yield, Injury, and Rootworm Survival: Implications for Resistance Management
Journal of Economic Entomology, 2013Co-Authors: Jennifer L. Petzold-maxwell, Lance J Meinke, Michael E. Gray, Ronald E. Estes, Aaron J. GassmannAbstract:ABSTRACT A 2-yr field experiment was conducted to determine the effects on Diabrotica spp. (Coleoptera: Chrysomelidae) of an insecticidal seed treatment (Poncho 1250, (AI) /clothianidin) and a granular insecticide (Aztec 2.1G, (AI)/tebupirimphos and cyfluthrin) alone and in combination with maize producing the insectidical toxin Cry3Bb1 derived from the bacterium Bacillus thuringiensis (Bt). Yields for Bt maize plots were significantly greater than for non-Bt maize; however, insecticides did not significantly affect yield. Insecticides significantly decreased root injury in non-Bt maize plots, but there were no significant differences in root injury between Bt maize with or without either insecticide. Maize producing the Bt toxin Cry3Bb1 and the soil-applied insecticide Aztec significantly decreased survival of western corn rootworm (Diabrotica virgifera virgifera LeConte), while only Bt maize significantly decreased survival of the northern corn rootworm (Diabrotica Barberi Smith & Lawrence). For both sp...
B. Wade French - One of the best experts on this subject based on the ideXlab platform.
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Field-Evolved Resistance of Northern and Western Corn Rootworm (Coleoptera: Chrysomelidae) Populations to Corn Hybrids Expressing Single and Pyramided Cry3Bb1 and Cry34/35Ab1 Bt Proteins in North Dakota
Journal of Economic Entomology, 2019Co-Authors: Veronica Calles-torrez, B. Wade French, Janet J. Knodel, Mark A. Boetel, Billy W. Fuller, Joel K. RansomAbstract:Northern, Diabrotica Barberi Smith & Lawrence, and western, D. virgifera virgifera LeConte, corn rootworms (Coleoptera: Chrysomelidae) are major economic pests of corn, Zea mays L., in North America. Corn hybrids expressing Bacillus thuringiensis Berliner (Bt) toxins are commonly used by growers to manage these pests. Several cases of field-evolved resistance to insecticidal proteins expressed by Bt corn hybrids have been documented in many corn-producing areas of North America, but only for D. v. virgifera. In 2016, beetles of both species were collected from five eastern North Dakota corn fields and reared in a growth chamber. In 2017, larvae reared from those populations were subjected to single-plant bioassays to screen for potential resistance to Cry3Bb1, Cry34/35Ab1, and pyramided Cry3Bb1 + Cry34/35Ab1 Bt toxins. Our results provide the first documented report of field-evolved resistance in D. Barberi to corn hybrids expressing Cry3Bb1 (Arthur problem population) and Cry34/35Ab1 (Arthur and Page problem populations, and the Ransom and Sargent populations) proteins in North America. Resistance to Cry3Bb1 was also observed in the Ransom population of D. v. virgifera. Increased larval survival on the pyramided Cry3Bb1 + Cry34/35Ab1 hybrid was observed in both species. No cross-resistance was evident between Cry3Bb1 and Cry34/35Ab1 in any of the D. Barberi populations tested. Our experiments identified field-evolved resistance to Bt toxins in some North Dakota populations of D. Barberi and D. v. virgifera. Thus, more effective control tools and improved resistance management strategies are needed to prolong the durability of this technology for managing these important pests.
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Multidimensional approach to formulating a specialized diet for northern corn rootworm larvae
Scientific Reports, 2019Co-Authors: Man P. Huynh, Bruce E. Hibbard, B. Wade French, Stephen L. Lapointe, Randall P. Niedz, Adriano E. Pereira, Deborah L. Finke, Kent S. Shelby, Thomas A. CoudronAbstract:The northern corn rootworm (NCR), Diabrotica Barberi Smith & Lawrence, is a major pest of maize ( Zea mays L.). This pest has developed resistance to insecticides and adapted to crop rotation and may already be in the early stages of adaptation to toxins produced by Bacillus thuringiensis (Bt). Toxicity bioassays using artificial diet have proven to be valuable for monitoring resistance in many species, but no artificial diet has been developed specifically for NCR larvae. Toward this end, we first evaluated known Diabrotica diets to identify a starting media. We then developed a specialized diet for NCR using an iterative approach. Screening designs including 8 diet components were performed to identify the principal nutritional components contributing to multiple developmental parameters (survival, weight, and molting). We then applied mixture designs coupled with response surface modeling to optimize a blend of those components. Finally, we validated an improved NCR diet formulation that supports approximately 97% survival and molting, and a 150% increase in larval weight after 10 days of feeding compared with the best previously published artificial diet. This formulation appears suitable for use in diet bioassays as a tool for evaluating the resistance of NCR populations to insecticides.
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Transgenic Bt Corn, Soil Insecticide, and Insecticidal Seed Treatment Effects on Corn Rootworm (Coleoptera: Chrysomelidae) Beetle Emergence, Larval Feeding Injury, and Corn Yield in North Dakota
Journal of Economic Entomology, 2018Co-Authors: Veronica Calles-torrez, B. Wade French, Janet J. Knodel, Mark A. Boetel, Joel K. Ransom, Curt Doetkott, Kellie K Podliska, Patrick B. Beauzay, Billy W. FullerAbstract:Northern, Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae), and western, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), corn rootworms are economic pests of corn, Zea mays L. in North America. We measured the impacts of corn hybrids incorporated with Cry3Bb1, Cry34/35Ab1, and pyramided (Cry3Bb1 + Cry34/35Ab1) Bacillus thuringiensis Berliner (Bt) proteins, tefluthrin soil insecticide, and clothianidin insecticidal seed treatment on beetle emergence, larval feeding injury, and corn yield at five locations from 2013 to 2015 in eastern North Dakota. In most cases, emergence was significantly lower in Bt-protected corn than in non-Bt corn hybrids. Exceptions included Wyndmere, ND (2013), where D. Barberi emergence from Cry34/35Ab1 plots was not different from that in the non-Bt hybrid, and Arthur, ND (2013), where D. v. virgifera emergence from Cry3Bb1 plots did not differ from that in the non-Bt hybrid. Bt hybrids generally produced increased grain yield compared with non-Bt corn where rootworm densities were high, and larval root-feeding injury was consistently lower in Bt-protected plots than in non-Bt corn. The lowest overall feeding injury and emergence levels occurred in plots planted with the Cry3Bb1 + Cry34/35Ab1 hybrid. Time to 50% cumulative emergence of both species was 5-7 d later in Bt-protected than in non-Bt hybrids. Tefluthrin and clothianidin were mostly inconsequential in relation to beetle emergence and larval root injury. Our findings could suggest that some North Dakota populations could be in early stages of increased tolerance to some Bt toxins; however, Bt corn hybrids currently provide effective protection against rootworm injury in eastern North Dakota.
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Spermatophore Size in Relation to Body Size and Pairing Duration in Northern Corn Rootworm (Coleoptera: Chrysomelidae)
Annals of The Entomological Society of America, 2012Co-Authors: B. Wade French, Leslie HammackAbstract:Female insects may choose to mate with males providing the largest nuptial gift via the spermatophore, which may correlate with fitness related characters such as body size. Here, we examined spermatophore size of northern corn rootworm, Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae), in relation to body size of males and females and in relation to pairing duration. Virgin males and females of known ages were weighed before and after pairing. Pairs were noted as copulating or not copulating. Copulating males lost significantly more weight than did noncopulating males, whereas copulating females gained significantly more weight than did noncopulating females. For copulating pairs, male and female weight before pairing correlated positively. Spermatophore weight correlated positively with male weight before pairing and was estimated to be 0.37 or 0.38 mg, depending on whether weight change data from males or females were used for estimation. Spermatophore mass accounted for ≈4.4% of male body weight. An effect of pairing duration on spermatophore weight was demonstrable only when weight change data from females were used. Implications of the results for management of rootworm resistance to genetically modified maize are discussed.
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Multiple Mating, Fecundity, and Longevity in Female Northern Corn Rootworm (Coleoptera: Chrysomelidae) in Relation to Body Size
Annals of The Entomological Society of America, 2011Co-Authors: B. Wade French, Leslie HammackAbstract:Diabroticite corn rootworms are significant maize, Zea mays L., pests that have evolved resistance to cultural and chemical management methods. Transgenic maize synthesizing a rootworm-toxic protein originating from the bacterium Bacillus thuringiensis Berliner is an important new management technology. Its use requires a refuge of nontransgenic maize to delay evolution of resistance by generating susceptible beetles capable of copulating with any resistant individuals surviving on the transgenic crop. The evolution of such resistance may concurrently influence a variety of fitness-related characters. Here, we examined multiple mating by female Diabrotica Barberi Smith & Lawrence (Coleoptera: Chrysomelidae) in relation to the following fitness-related traits: female longevity, fecundity, and body size of males and females at the first copulation. For the first copulation, large and small males were reciprocally paired to large and small females for comparison with average-sized beetles. Once-mated females were then maintained under conditions conducive to oviposition and paired with averaged-sized males at weekly intervals until death. Although female age at second copulation varied significantly with size category, female age at first copulation, longevity and fecundity did not. Females that mated multiple times lived longer and laid more eggs than did those that mated once. The results suggest that resistance management models may need to consider those females deriving fitness benefits from a second mating.