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Blair D Siegfried - One of the best experts on this subject based on the ideXlab platform.
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the use of insecticides to manage the western corn rootworm Diabrotica virgifera virgifera leconte history field evolved resistance and associated mechanisms
Insects, 2021Co-Authors: Lance J Meinke, Dariane Souza, Blair D SiegfriedAbstract:The western corn rootworm, Diabrotica virgifera virgifera LeConte (Dvv) is a significant insect pest of maize in the United States (U.S.). This paper reviews the history of insecticide use in Dvv management programs, Dvv adaptation to insecticides, i.e., field-evolved resistance and associated mechanisms of resistance, plus the current role of insecticides in the transgenic era. In the western U.S. Corn Belt where continuous maize is commonly grown in large irrigated monocultures, broadcast-applied soil or foliar insecticides have been extensively used over time to manage annual densities of Dvv and other secondary insect pests. This has contributed to the sequential occurrence of Dvv resistance evolution to cyclodiene, organophosphate, carbamate, and pyrethroid insecticides since the 1950s. Mechanisms of resistance are complex, but both oxidative and hydrolytic metabolism contribute to organophosphate, carbamate, and pyrethroid resistance facilitating cross-resistance between insecticide classes. History shows that Dvv insecticide resistance can evolve quickly and may persist in field populations even in the absence of selection. This suggests minimal fitness costs associated with Dvv resistance. In the transgenic era, insecticides function primarily as complementary tools with other Dvv management tactics to manage annual Dvv densities/crop injury and resistance over time.
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systemic rnai in western corn rootworm Diabrotica virgifera virgifera does not involve transitive pathways
Insect Science, 2018Co-Authors: Andrew J. Bowling, Blair D Siegfried, Murugesan Rangasamy, Chitvan Khajuria, Premchand Gandra, Heather E Pence, Robert E Mcewan, Kenneth E NarvaAbstract:Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) is highly sensitive to orally delivered double-stranded RNA (dsRNA). RNAi in WCR is systemic and spreads throughout the insect body. This raises the question whether transitive RNAi is a mechanism that functions in WCR to amplify the RNAi response via production of secondary siRNA. Secondary siRNA production is achieved through RNA-dependent RNA polymerase (RdRP) activity in other eukaryotic organisms, but RdRP has not been identified in WCR and any other insects. This study visualized the spread of the RNAi-mediated knockdown of Dv v-ATPase C mRNA throughout the WCR gut and other tissues using high-sensitivity branched DNA in situ hybridization. Furthermore, we did not detect either secondary siRNA production or transitive RNAi in WCR through siRNA sequence profile analysis. Nucleotide mismatched sequences introduced into either the sense or antisense strand of v-ATPase C dsRNAs were maintained in siRNAs derived from WCR fed with the mismatched dsRNAs in a strand specific manner. The distribution of all siRNAs was restricted to within the original target sequence regions, which may indicate the lack of new dsRNA synthesis leading to production of secondary siRNA. Thus, the systemic spread of RNAi in WCR may be derived from the original dsRNA molecules taken up from the gut lumen. These results indicate that the initial dsRNA dose is important for a lethal systemic RNAi response in WCR and have implications in developing effective dsRNA traits to control WCR and in resistance management to prolong the durability of RNAi trait technology.
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validation of reference housekeeping genes for gene expression studies in western corn rootworm Diabrotica virgifera virgifera
PLOS ONE, 2014Co-Authors: Thais Barros Rodrigues, Haichuan Wang, Xuguo Zhou, Chitvan Khajuria, Natalie Matz, Danielle Cunha Cardoso, F H Valicente, Blair D SiegfriedAbstract:Quantitative Real-time PCR (qRT-PCR) is a powerful technique to investigate comparative gene expression. In general, normalization of results using a highly stable housekeeping gene (HKG) as an internal control is recommended and necessary. However, there are several reports suggesting that regulation of some HKGs is affected by different conditions. The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a serious pest of corn in the United States and Europe. The expression profile of target genes related to insecticide exposure, resistance, and RNA interference has become an important experimental technique for study of western corn rootworms; however, lack of information on reliable HKGs under different conditions makes the interpretation of qRT-PCR results difficult. In this study, four distinct algorithms (Genorm, NormFinder, BestKeeper and delta-CT) and five candidate HKGs to genes of reference (β-actin; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; β-tubulin; RPS9, ribosomal protein S9; EF1a, elongation factor-1α) were evaluated to determine the most reliable HKG under different experimental conditions including exposure to dsRNA and Bt toxins and among different tissues and developmental stages. Although all the HKGs tested exhibited relatively stable expression among the different treatments, some differences were noted. Among the five candidate reference genes evaluated, β-actin exhibited highly stable expression among different life stages. RPS9 exhibited the most similar pattern of expression among dsRNA treatments, and both experiments indicated that EF1a was the second most stable gene. EF1a was also the most stable for Bt exposure and among different tissues. These results will enable researchers to use more accurate and reliable normalization of qRT-PCR data in WCR experiments.
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molecular evolution of glycoside hydrolase genes in the western corn rootworm Diabrotica virgifera virgifera
PLOS ONE, 2014Co-Authors: Seongil Eyun, Arnubio Valenciajimenez, Yannick Pauchet, Haichuan Wang, Richard H Ffrenchconstant, Andrew K Benson, Etsuko N. Moriyama, Blair D SiegfriedAbstract:Cellulose is an important nutritional resource for a number of insect herbivores. Digestion of cellulose and other polysaccharides in plant-based diets requires several types of enzymes including a number of glycoside hydrolase (GH) families. In a previous study, we showed that a single GH45 gene is present in the midgut tissue of the western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). However, the presence of multiple enzymes was also suggested by the lack of a significant biological response when the expression of the gene was silenced by RNA interference. In order to clarify the repertoire of cellulose-degrading enzymes and related GH family proteins in D. v. virgifera, we performed next-generation sequencing and assembled transcriptomes from the tissue of three different developmental stages (eggs, neonates, and third instar larvae). Results of this study revealed the presence of seventy-eight genes that potentially encode GH enzymes belonging to eight families (GH45, GH48, GH28, GH16, GH31, GH27, GH5, and GH1). The numbers of GH45 and GH28 genes identified in D. v. virgifera are among the largest in insects where these genes have been identified. Three GH family genes (GH45, GH48, and GH28) are found almost exclusively in two coleopteran superfamilies (Chrysomeloidea and Curculionoidea) among insects, indicating the possibility of their acquisitions by horizontal gene transfer rather than simple vertical transmission from ancestral lineages of insects. Acquisition of GH genes by horizontal gene transfers and subsequent lineage-specific GH gene expansion appear to have played important roles for phytophagous beetles in specializing on particular groups of host plants and in the case of D. v. virgifera, its close association with maize.
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molecular cloning and functional characterization of an endogenous endoglucanase belonging to ghf45 from the western corn rootworm Diabrotica virgifera virgifera
Gene, 2013Co-Authors: Arnubio Valencia, Analiza P Alves, Blair D SiegfriedAbstract:A novel insect β-1,4-endoglucanase (DvvENGaseI) gene belonging to the glycoside hydrolase family (GHF) 45 was identified from the western corn rootworm, Diabrotica virgifera virgifera. The cDNA of the DvvENGaseI consisted of a 720 bp open reading frame encoding a 239 amino-acid protein. Analysis of the amino acid sequence revealed that DvvENGaseI exhibits 60% protein sequence identity when compared with an endoglucanase belonging to GHF45 from another beetle, Leptinotarsa decemlineata. Western blot analyses using a polyclonal antiserum developed from a partial peptide sequence revealed that DvvENGaseI expression coincided with body regions corresponding to the fore-, mid- and hindgut, although regions corresponding to the midgut and hindgut were the primary sites for DvvENGaseI expression. Functional analysis of the DvvENGaseI by RNA interference (RNAi) indicated that nearly complete knock-down of gene expression could be obtained by injection of dsRNA based on qRT-PCR and western blot analysis. However, suppression only resulted in slight developmental delays suggesting that this gene may be part of a larger system of cellulose degrading enzymes.
Stefan Toepfer - One of the best experts on this subject based on the ideXlab platform.
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Missing temporal effects of soil insecticides and entomopathogenic nematodes in reducing the maize pest Diabrotica virgifera virgifera
Journal of Pest Science, 2020Co-Authors: Szabolcs Toth, Márk Szalai, Jozsef Kiss, Stefan ToepferAbstract:Control methods for the larvae of the maize pest Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) are known to produce inconsistent results under field conditions. To better understand the effects of plant protection products on the root-feeding larvae, we looked for changes in efficacy of the granular soil insecticides chlorpyrifos, cypermethrin, and tefluthrin during a cropping season, as well as a fluid-applied entomopathogenic nematode Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae). Twelve field-scale experiments carried out in Hungary between 2010 and 2018 revealed that treatments, whether chemical or biological, are able to reduce D. v. virgifera . However, results were variable with failures in about a quarter of the experiments. Unexpectedly, our findings indicated only limited effect of time on treatments, meaning all products appeared capable of continuously reducing larvae during their time in the soil. Only chlorpyrifos seemed to slightly lose and tefluthrin to slightly increase efficacy over time. Nevertheless, there is no major evidence that failure of treatments is due to temporal effects. Other factors may play a larger role and merit investigation under field conditions.
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Secondary contact and admixture between independently invading populations of the western corn rootworm, Diabrotica virgifera virgifera in Europe.
PLoS ONE, 2012Co-Authors: Gérald Bermond, Stefan Toepfer, Lorenzo Furlan, Marc Ciosi, Eric Lombaert, Aurelie Blin, Marco Boriani, Thomas GuillemaudAbstract:The western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae), is one of the most destructive pests of corn in North America and is currently invading Europe. The two major invasive outbreaks of rootworm in Europe have occurred, in North-West Italy and in Central and South-Eastern Europe. These two outbreaks originated from independent introductions from North America. Secondary contact probably occurred in North Italy between these two outbreaks, in 2008. We used 13 microsatellite markers to conduct a population genetics study, to demonstrate that this geographic contact resulted in a zone of admixture in the Italian region of Veneto. We show that i) genetic variation is greater in the contact zone than in the parental outbreaks; ii) several signs of admixture were detected in some Venetian samples, in a bayesian analysis of the population structure and in an approximate bayesian computation analysis of historical scenarios and, finally, iii) allelic frequency clines were observed at microsatellite loci. The contact between the invasive outbreaks in North-West Italy and Central and South-Eastern Europe resulted in a zone of admixture, with particular characteristics. The evolutionary implications of the existence of a zone of admixture in Northern Italy and their possible impact on the invasion success of the western corn rootworm are discussed.
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Generational growth rate estimates of Diabrotica virgifera virgifera populations (Coleoptera: Chrysomelidae)
Journal of Pest Science, 2011Co-Authors: Márk Szalai, Jozsef Kiss, Renata Bažok, Judit Papp Komáromi, Jasminka Igrc Barčić, Stefan ToepferAbstract:Modelling population dynamics of the maize pest Diabrotica virgifera virgifera LeConte (western corn rootworm; Coleoptera: Chrysomelidae) requires knowledge on the growth rate (=net reproductive rate) of the species. We investigated the generational (=annual) growth rate of D. v. virgifera in isolated maize fields in southern Hungary and eastern Croatia over several years. The population densities of D. v. virgifera were assessed by absolute counts of emerging adults in 90 gauze cages per study field. Emergence ranged from 1.3 to 30.7 adults per m^2 in continuous maize field sections, and from 0.3 to 5.1 adults per m^2 in adjacent first-year maize sections. The annual growth rates of D. v. virgifera ranged from 0.5 to 13, and averaged in close to 4. These experimentally assessed growth rates could complement growth estimates in population dynamic models, particularly those for forecasting the population growth to economic thresholds or for estimating population build-ups after new introductions of this alien species in Europe. As an example, the determined growth rate was used to estimate that the first documented successful introduction of this species into Europe occurred between 1979 and 1984, which is 8–13 years before the detection of this species and its larval damage in maize fields near Belgrade, Serbia, in 1992.
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Influence of soil on the efficacy of entomopathogenic nematodes in reducing Diabrotica virgifera virgifera in maize
Journal of Pest Science, 2010Co-Authors: Stefan Toepfer, B. Kurtz, Ulrich KuhlmannAbstract:The use of entomopathogenic nematodes is one potential non-chemical approach to control the larvae of the invasive western corn rootworm ( Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) in Europe. This study investigated the efficacy of Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), Heterorhabditis megidis Poinar, Jackson and Klein (Rh., Heterorhabditidae) and Steinernema feltiae Filipjev (Rh., Steinernematidae) in reducing D. v. virgifera as a function of soil characteristics. A field experiment was repeated four times in southern Hungary using artificially infested maize plants potted into three different soils. Sleeve gauze cages were used to assess the number of emerging adult D. v. virgifera from the treatments and untreated controls. Results indicate that nematodes have the potential to reduce D. v. virgifera larvae in most soils; however, their efficacy can be higher in maize fields with heavy clay or silty clay soils than in sandy soils, which is in contrast to the common assumption that nematodes perform better in sandy soils than in heavy soils.
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spatial clustering of Diabrotica virgifera virgifera and agriotes ustulatus in small scale maize fields without topographic relief drift
Entomologia Experimentalis Et Applicata, 2007Co-Authors: Stefan Toepfer, Michael M Ellsbury, Rene Eschen, U. KuhlmannAbstract:The soil-living larvae of Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) and Agriotes ustulatus Schaller (Coleoptera: Elateridae) can cause economic damage to maize roots, Zea mays L. (Poaceae). This study investigated the spatial clustering of both pests in four small-scale maize fields in southern Hungary, where clustering had been observed but not expected due to the lack of topographic relief drifts and soil structuring. Between 2000 and 2002, numbers of D. v. virgifera larvae and adults and of A. ustulatus larvae were determined at four randomly chosen georeferenced maize plants in each of 24 plots per field. Soil moisture, soil bulk density, and vegetational characteristics were assessed. Moran’s I test for spatial autocorrelations, semivariogram analyses, and interpolated mapping revealed that D. v. virgifera larvae and adults were spatially clustered in 67 and 50% of cases, respectively. Larvae of A. ustulatus were clustered in 75% of cases. Diabrotica virgifera virgifera larval distributions were mainly determined by increasing weed density (negative correlation), in particular with high densities of Cirsium arvense (L.) (Asteraceae), as well as by increasing soil moisture (negative correlation). Adult distributions of D. v. virgifera were mainly determined by the density distribution of flowering maize. They were moreover correlated with larval distribution and with the adult distribution of the previous year. The density distributions of male adults differed from those of females. Female density was additionally correlated with higher soil moisture and Poaceae density, e.g., with Sorghum halepense (L.) Pers. No relation was found between the larvae of A. ustulatus and D. v. virgifera . Agriotes ustulatus larval distributions were mainly determined by vegetational cover (correlation with less cover). Conclusively, male and female D. v. virgifera adults, larvae of D. v. virgifera , and larvae of A. ustulatus will display different spatial clustering even within ostensibly homogeneous habitats of flat small-scale maize fields.
Bruce E. Hibbard - One of the best experts on this subject based on the ideXlab platform.
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Comparative Assessment of Four Steinernematidae and Three Heterorhabditidae Species for Infectivity of Larval Diabrotica virgifera virgifera.
Journal of economic entomology, 2018Co-Authors: Ryan W Geisert, Dorothy J. Cheruiyot, Bruce E. Hibbard, Kent S. Shelby, Thomas A. CoudronAbstract:Larval Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) 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, Heterorhabditis megidis Poinar, Jackson & Klein, Steinernema feltiae Filipjev, and Steinernema carpocapsae Weiser were tested in a concerted experiment alongside Steinernema diaprepesi Nguyen & Duncan, Steinernema riobrave Cabanillas, Poinar & Raulston, and a Missouri wild-type H. bacteriophora which have not been previously tested on D. virgifera. The species S. rarum Doucet was tested separately for D. virgifera infectivity. Third-instar D. virgifera were exposed to either 60 or 120 nematodes per larva for 6 d. Following exposure, mortality was recorded and larvae were examined to determine the presence of active nematode infections. Results indicated a significantly higher proportion of larvae with active infections from the Heterorhabditidae species and S. diaprepesi than the other Steinernematidae species for both exposure rates; mortality data indicated a similar trend. Steinernema rarum showed almost no infectivity in laboratory experiments.
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Neonate larvae of the specialist herbivore Diabrotica virgifera virgifera do not exploit the defensive volatile (E)-β-caryophyllene in locating maize roots
Journal of Pest Science, 2016Co-Authors: Ivan Hiltpold, Bruce E. HibbardAbstract:The behavior of the neonate larvae of the western corn rootworm (WCR) Diabrotica virgifera virgifera LeConte, a major pest of maize, was assessed in the presence of maize roots constitutively emitting ( E )-β-caryophyllene (EβC). This root volatile has been shown to attract both second instar WCR and insect-killing nematodes, and may offer innovative alternatives in helping to manage WCR. Under greenhouse conditions, the maize inbred line HiII, lacking the ability to emit EβC, was planted 75 cm from the maize inbred line 201-L1, the HiII inbred genetically engineered to constitutively emit EβC. WCR eggs were infested in the center of the two lines and neonate attraction toward either root system was recorded after collecting WCR larvae established on the plants. Whereas marginally more larvae were found on EβC-emitting plants, counts of recovered WCR neonates did not significantly differ between the two lines. This supports the postulate that CO_2 is the primary attractant for WCR neonate larvae. The chemical ecology of WCR larvae is discussed. A conceptual model of the foraging behavior of this pest is proposed, summarizing our current knowledge on chemically mediated interactions between WCR larvae and maize roots.
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effects of refuges on the evolution of resistance to transgenic corn by the western corn rootworm Diabrotica virgifera virgifera leconte
Pest Management Science, 2016Co-Authors: Jennifer Deitloff, Bruce E. Hibbard, Mike W Dunbar, David A Ingber, Aaron J. GassmannAbstract:BACKGROUND Diabrotica virgifera virgifera LeConte is a major pest of corn and causes over a billion dollars of economic loss annually through yield reductions and management costs. Corn producing toxins derived from Bacillus thuringiensis (Bt) has been developed to help manage D. v. virgifera. However, previous studies have demonstrated the ability of this species to evolve resistance to Bt toxins in both laboratory and field settings. RESULTS We used an experimental evolution approach to test the refuge strategies for delaying resistance of D. v. virgifera to corn producing Bt toxin Cry34/35Ab1. In the absence of refuges, D. v. virgifera developed resistance to Bt corn after three generations of selection. In some cases, non-Bt refuges reduced the level of resistance compared with the strain selected in the absence of refuges, but refuge strains did show reduced susceptibility to Bt corn compared with the unselected strain. CONCLUSIONS In this study, non-Bt refuges delayed resistance to Bt corn by D. v. virgifera in some cases but not others. Combining the refuge strategy with pyramids of multiple Bt toxins and applying other pest management strategies will likely be necessary to delay resistance of D. v. virgifera to Bt corn. © 2015 Society of Chemical Industry
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synthetic feeding stimulants enhance insecticide activity against western corn rootworm larvae Diabrotica virgifera virgifera coleoptera chrysomelidae
Journal of Applied Entomology, 2011Co-Authors: E J Bernklau, Louis B Bjostad, Bruce E. HibbardAbstract:In bioassays, the addition of a synthetic feeding stimulant blend improved the efficacy of the insecticide thiamethoxam against neonate western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae. In 4-h bioassays, the concentration of thiamethoxam required for 50% mortality (LC50) was 2800 pg/ml for the insecticide alone, but was reduced to 0.0075 pg/ml when the synthetic feeding stimulant blend was added (more than a 100,000-fold difference). Dilutions of thiamethoxam and tefluthrin (ranging from 0 pg/ml to 10 lg/ml) were tested in behavioural bioassays alone and in conjunction with a feeding stimulant blend containing 30 : 4 : 4 : 1 mg/ml glucose : fructose : sucrose : linoleic acid. Larvae were placed on insecticide-treated filter paper disks in an arena that allowed them to leave the treated area at will. In 30-min bioassays, and in 4-h bioassays, significantly more larvae fed on thiamethoxam-treated disks when the feeding stimulant blend was present for every concentration of insecticide tested. Larvae fed readily on disks treated with tefluthrin when the feeding stimulants were added, but the feeding stimulant blend did not affect the activity of tefluthrin insecticide at any concentration tested.
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evaluation of corn hybrids for tolerance to corn rootworm Diabrotica virgifera virgifera leconte larval feeding
Cereal Research Communications, 2006Co-Authors: Marija Ivezic, J J Tollefson, Emilija Raspudic, Ivan Brkic, M Brmez, Bruce E. HibbardAbstract:The western corn rootworm ( Diabrotica virgifera virgifera LeConte (WCR)) is a major pest of corn in USA. The pest arrived in Croatia in 1995, and today over 250.000 ha are infested. Insecticides are regularly used to control WCR, but the cost is high, can pose environmental risks, and may become ineffective due to resistance. Growing corn that is resistant to corn rootworms would be a valuable alternative to insecticides. Nine Croatian (Institute of Agriculture, Osijek) and two Pioneer Hi-Bred Int. Inc. (Johnston, Iowa, USA) commercial corn hybrids were evaluated for WCR resistance at two locations using complete randomized block design with four replications. One location was in east Croatia (Osijek) and one was in the USA (Iowa). The hybrids’ tolerance to larval feeding was rated using root injury, root regrowth and root size. Root injury was rated using the Node-Injury Scale 0–3 and evaluation of root size and root regrowth were done by scale 1–6. In an analysis of variance combined across locations, ...
Brad S Coates - One of the best experts on this subject based on the ideXlab platform.
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structural and functional insights into the Diabrotica virgifera virgifera atp binding cassette transporter gene family
BMC Genomics, 2019Co-Authors: Folukemi Adedipe, Brad S Coates, Nathaniel Grubbs, Brian Wiegmman, Marce D LorenzenAbstract:The western corn rootworm, Diabrotica virgifera virgifera, is a pervasive pest of maize in North America and Europe, which has adapted to current pest management strategies. In advance of an assembled and annotated D. v. virgifera genome, we developed transcriptomic resources to use in identifying candidate genes likely to be involved in the evolution of resistance, starting with members of the ATP-binding cassette (ABC) transporter family. In this study, 65 putative D. v. virgifera ABC (DvvABC) transporters were identified within a combined transcriptome assembly generated from embryonic, larval, adult male, and adult female RNA-sequence libraries. Phylogenetic analysis placed the deduced amino-acid sequences of the DvvABC transporters into eight subfamilies (A to H). To supplement our sequence data with functional analysis, we identified orthologs of Tribolium castaneum ABC genes which had previously been shown to exhibit overt RNA interference (RNAi) phenotypes. We identified eight such D. v. virgifera genes, and found that they were functionally similar to their T. castaneum counterparts. Interestingly, depletion of DvvABCB_39715 and DvvABCG_3712 transcripts in adult females produced detrimental reproductive and developmental phenotypes, demonstrating the potential of these genes as targets for RNAi-mediated insect control tactics. By combining sequence data from four libraries covering three distinct life stages, we have produced a relatively comprehensive de novo transcriptome assembly for D. v. virgifera. Moreover, we have identified 65 members of the ABC transporter family and provided the first insights into the developmental and physiological roles of ABC transporters in this pest species.
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quantitative trait locus mapping and functional genomics of an organophosphate resistance trait in the western corn rootworm Diabrotica virgifera virgifera
Insect Molecular Biology, 2016Co-Authors: Brad S Coates, Haichuan Wang, Murugesan Rangasamy, Analiza P Alves, Xuguo Zhou, Timothy M Nowatzki, Hong Chen, Hugh M Robertson, Charles W Whitfield, Kimberly K O WaldenAbstract:The western corn rootworm, Diabrotica virgifera virgifera, is an insect pest of corn and population suppression with chemical insecticides is an important management tool. Traits conferring organophosphate insecticide resistance have increased in frequency amongst D. v. virgifera populations, resulting in the reduced efficacy in many corn-growing regions of the USA. We used comparative functional genomic and quantitative trait locus (QTL) mapping approaches to investigate the genetic basis of D. v. virgifera resistance to the organophosphate methyl-parathion. RNA from adult methyl-parathion resistant and susceptible adults was hybridized to 8331 microarray probes. The results predicted that 11 transcripts were significantly up-regulated in resistant phenotypes, with the most significant (fold increases ≥ 2.43) being an α-esterase-like transcript. Differential expression was validated only for the α-esterase (ST020027A20C03), with 11- to 13-fold greater expression in methyl-parathion resistant adults (P < 0.05). Progeny with a segregating methyl-parathion resistance trait were obtained from a reciprocal backcross design. QTL analyses of high-throughput single nucleotide polymorphism genotype data predicted involvement of a single genome interval. These data suggest that a specific carboyxesterase may function in field-evolved corn rootworm resistance to organophosphates, even though direct linkage between the QTL and this locus could not be established.
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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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distribution of genes and repetitive elements in the Diabrotica virgifera virgifera genome estimated using bac sequencing
BioMed Research International, 2012Co-Authors: Brad S Coates, Haichuan Wang, Thomas W Sappington, Nicholas J. Miller, Analiza P Alves, Hugh M Robertson, Kimberly K O Walden, Wade B French, Craig A AbelAbstract:Feeding damage caused by the western corn rootworm, Diabrotica virgifera virgifera, is destructive to corn plants in North America and Europe where control remains challenging due to evolution of resistance to chemical and transgenic toxins. A BAC library, DvvBAC1, containing 109,486 clones with 1 0 4 ± 3 4 . 5 kb inserts was created, which has an ~4.56X genome coverage based upon a 2.58 Gb (2.80 pg) flow cytometry-estimated haploid genome size. Paired end sequencing of 1037 BAC inserts produced 1.17 Mb of data ( ~0.05% genome coverage) and indicated ~9.4 and 16.0% of reads encode, respectively, endogenous genes and transposable elements (TEs). Sequencing genes within BAC full inserts demonstrated that TE densities are high within intergenic and intron regions and contribute to the increased gene size. Comparison of homologous genome regions cloned within different BAC clones indicated that TE movement may cause haplotype variation within the inbred strain. The data presented here indicate that the D. virgifera virgifera genome is large in size and contains a high proportion of repetitive sequence. These BAC sequencing methods that are applicable for characterization of genomes prior to sequencing may likely be valuable resources for genome annotation as well as scaffolding.
Hugo A Benitez - One of the best experts on this subject based on the ideXlab platform.
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wing shape changes a morphological view of the Diabrotica virgifera virgifera european invasion
Biological Invasions, 2016Co-Authors: Katarina M Mikac, Darija Lemic, Renata Bažok, Hugo A BenitezAbstract:An analysis of the hind wing morphology (size and shape) within and among western corn rootworm, Diabrotica virgifera virgifera LeConte, populations over a large geographic scale in Europe was conducted. The changes in hind wing shape and size detected were related to identifiable invasion processes (i.e. multiple introduction events into Europe), first characterised using genetic markers. Overall implications from this work suggest that geometric morphometric techniques can be used to detect population changes related to invasions and could therefore serve as a cheaper and more accessible alternative ‘biomarker’ to more expensive and specialised-use genetic markers, such as microsatellites or SNPs, when investigating biological invasions.
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morphological integration and modularity in Diabrotica virgifera virgifera leconte coleoptera chrysomelidae hind wings
Zoologischer Anzeiger, 2014Co-Authors: Darija Lemic, Renata Bažok, Hugo A Benitez, Raffaella Bravi, Marina Buketa, Thomas A PuschelAbstract:The morphological integration of the hind wings of the western corn rootworm Diabrotica virgifera virgifera LeConte was investigated to get a better insight of the undergone by this invasive species. Geometric morphometric methods were used to test two modularity hypotheses associated with the wing development and function (hypothesis H1: anterior/posterior or H2: distal/proximal wing parts). Both hypotheses were rejected and the results showed the integrated behavior of the hind wings of D. v. virgifera. The hypothesized modules do not represent separate units of variation, so in a similar fashion as exhibited by the model species Drosophila melanogaster, the hind wings of D. v. virgifera act as a single functional unit. The moderate covariation strength found between anterior and posterior and distal and proximal parts of the hind wing of D. v. virgifera confirms its integrated behavior. We conclude that the wing shape shows internal integration, which could enable flexibility and thus enhance flight maneuverability. This study contributes to the understanding of morphological integration and modularity on a non-model organism. Additionally, these findings lay the groundwork for future flight performance and biogeographical studies on how wing shape and size vary across the endemic and expanded/invaded range in the USA and Europe infested with D. v. virgifera.
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intercontinental effect on sexual shape dimorphism and allometric relationships in the beetle pest Diabrotica virgifera virgifera leconte coleoptera chrysomelidae
Zoologischer Anzeiger – A Journal of Comparative Zoology, 2014Co-Authors: Darija Lemic, Hugo A Benitez, Renata BažokAbstract:Hind wing shape variation was examined in 686 adult Diabrotica virgifera virgifera collected from maize plants in Europe and the USA Corn Belt, using geometric morphometric techniques. Sexual dimorphism at an Intercontinental scale was assessed using canonical variates analysis, a multivariate statistical method used to find the shape characters that best distinguish among groups of specimens. Our results showed that each of the populations of D. v. virgifera investigated in this study showed high levels of sex based hind wing shape dimorphism. In particular a stronger and more obvious pattern of hind wing shape variation was found in the USA than in Europe. These results support previous studies on D. v. virgifera wing shape that show that female D. v. virgifera have more elongated wings than males. These differences raise the question of whether sexual dimorphism may be modulated by natural selection.
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evolutionary directional asymmetry and shape variation in Diabrotica virgifera virgifera coleoptera chrysomelidae an example using hind wings
Biological Journal of The Linnean Society, 2014Co-Authors: Renata Bažok, Darija Lemic, Hugo A Benitez, Claudio M Gallardoaraya, Katarina M MikacAbstract:The western corn rootworm Diabrotica virgifera virgifera LeConte is a pest of maize in the USA and Europe and especially a problem in particular regions of Croatia. In this study patterns of variation in hind wing shape were examined through two objectives. The first objective examined the influence of soil type on 10 populations of D. v. virgifera sampled from three regions in Croatia that differed according to edaphic factors and climate. The second objective investigated the potential evolutionary presence of directional asymmetry on hind wings. Geometric morphometrics was used to examine these objectives by quantifying the morphological variation within and among individuals and populations. Overall, D. v. virgifera hind wing shape changed according to major soil type classifications in Croatia. The three hind wing morphotypes found varied because of basal radial vein differences, related to landmarks 1, 3, 7 and 14. This study shows that hind wing shape in D. v. virgifera can be used to differentiate populations based on edaphic factors and may have application as a monitoring tool in the integrated management of D. v. virgifera . In an evolutionary context, the presence of directional asymmetry in the hind wings of D. v. virgifera adds to the ever growing data on the evolution of insect wings.