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Sample records for rootworm diabrotica virgifera

  1. Historical and contemporary demography of United States populations of Western Corn Rootworm (Diabrotica virgifera virgifera)

    EPA Science Inventory

    Western corn rootworm (Diabrotica virgifera virgifera; WCR) was sampled across much of its U.S. range for population genetic analyses. We assayed sequence variation at the mitochondrial cytochrome oxidase subunit I (COI) locus and allelic variation at eleven microsatellite loci. ...

  2. Entomopathogenic fungi in cornfields and their potential to manage larval western corn rootworm Diabrotica virgifera virgifera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Entomopathogenic Ascomycete fungi are ubiquitous in soil and on phylloplanes, and are important natural enemies of many arthropods, including larval western corn rootworm, Diabrotica virgifera virgifera, which is a major pest of corn. We measured the prevalence of Beauveria bassiana and Metarhizium...

  3. Synthetic feeding stimulants enhance insecticide activity against western corn rootworm larvae, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In behavioral 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 (LC...

  4. Quantitative trait locus mapping and functional genomics of an organophosphate resistance trait in the western corn rootworm, Diabrotica virgifera virgifera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The western corn rootworm (WCR), 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 among WCR populations, resulting in...

  5. A NOVEL CADHERIN-LIKE GENE FROM WESTERN CORN ROOTWORM, DIABROTICA VIRGIFERA VIRGIFERA (COLEOPTERA: CHRYSOMELIDAE), LARVAL MIDGUT TISSUE

    EPA Science Inventory

    A cadherin-like gene and its mRNA were cloned from western corn rootworm (Diabrotica virgifera virgifera: Coleoptera), an economically important agricultural pest in North America and Europe. The full length cDNA (5371 bp in length) encodes an open reading frame for a 1688 amino ...

  6. RNAi as a management tool for the western corn rootworm, Diabrotica virgifera virgifera.

    PubMed

    Fishilevich, Elane; Vélez, Ana M; Storer, Nicholas P; Li, Huarong; Bowling, Andrew J; Rangasamy, Murugesan; Worden, Sarah E; Narva, Kenneth E; Siegfried, Blair D

    2016-09-01

    The western corn rootworm (WCR), Diabrotica virgifera virgifera, is the most important pest of corn in the US Corn Belt. Economic estimates indicate that costs of control and yield loss associated with WCR damage exceed $US 1 billion annually. Historically, corn rootworm management has been extremely difficult because of its ability to evolve resistance to both chemical insecticides and cultural control practices. Since 2003, the only novel commercialized developments in rootworm management have been transgenic plants expressing Bt insecticidal proteins. Four transgenic insecticidal proteins are currently registered for rootworm management, and field resistance to proteins from the Cry3 family highlights the importance of developing traits with new modes of action. One of the newest approaches for controlling rootworm pests involves RNA interference (RNAi). This review describes the current understanding of the RNAi mechanisms in WCR and the use of this technology for WCR management. Further, the review addresses ecological risk assessment of RNAi and insect resistance management of RNAi for corn rootworm. © 2016 Society of Chemical Industry. PMID:27218412

  7. Entomopathogenic fungi in cornfields and their potential to manage larval western corn rootworm Diabrotica virgifera virgifera.

    PubMed

    Rudeen, Melissa L; Jaronski, Stefan T; Petzold-Maxwell, Jennifer L; Gassmann, Aaron J

    2013-11-01

    Entomopathogenic ascomycete fungi are ubiquitous in soil and on phylloplanes, and are important natural enemies of many soil-borne arthropods including larval western corn rootworm, Diabrotica virgifera virgifera, which is a major pest of corn. We measured the prevalence of Beauveria bassiana and Metarhizium anisopliae sensu lato in ten cornfields in Iowa, USA by baiting with larval insects. B. bassiana and M. anisopliae s.l. were present in 60% ± 6.3% and 55% ± 6.4% of soil samples, respectively. Subsequent laboratory bioassays found that some M. anisopliae s.l. strains collected from cornfields killed a greater proportion of D.v. virgifera larvae than a standard commercial strain. PMID:24120889

  8. Molecular Evolution of Glycoside Hydrolase Genes in the Western Corn Rootworm (Diabrotica virgifera virgifera)

    PubMed Central

    Eyun, Seong-il; Wang, Haichuan; Pauchet, Yannick; ffrench-Constant, Richard H.; Benson, Andrew K.; Valencia-Jiménez, Arnubio; Moriyama, Etsuko N.; Siegfried, Blair D.

    2014-01-01

    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. PMID:24718603

  9. Broad-spectrum resistance to Bacillus thuringiensis toxins by western corn rootworm (Diabrotica virgifera virgifera)

    PubMed Central

    Jakka, Siva R. K.; Shrestha, Ram B.; Gassmann, Aaron J.

    2016-01-01

    The evolution of resistance and cross-resistance threaten the sustainability of genetically engineered crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of maize and has been managed with Bt maize since 2003. We conducted laboratory bioassays with maize hybrids producing Bt toxins Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34/35Ab1, which represent all commercialized Bt toxins for management of western corn rootworm. We tested populations from fields where severe injury to Cry3Bb1 maize was observed, and populations that had never been exposed to Bt maize. Consistent with past studies, bioassays indicated that field populations were resistant to Cry3Bb1 maize and mCry3A maize, and that cross-resistance was present between these two types of Bt maize. Additionally, bioassays revealed resistance to eCry3.1Ab maize and cross-resistance among Cry3Bb1, mCry3A and eCry3.1Ab. However, no resistance or cross-resistance was detected for Cry34/35Ab1 maize. This broad-spectrum resistance illustrates the potential for insect pests to develop resistance rapidly to multiple Bt toxins when structural similarities are present among toxins, and raises concerns about the long-term durability of Bt crops for management of some insect pests. PMID:27297953

  10. Broad-spectrum resistance to Bacillus thuringiensis toxins by western corn rootworm (Diabrotica virgifera virgifera).

    PubMed

    Jakka, Siva R K; Shrestha, Ram B; Gassmann, Aaron J

    2016-01-01

    The evolution of resistance and cross-resistance threaten the sustainability of genetically engineered crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of maize and has been managed with Bt maize since 2003. We conducted laboratory bioassays with maize hybrids producing Bt toxins Cry3Bb1, mCry3A, eCry3.1Ab, and Cry34/35Ab1, which represent all commercialized Bt toxins for management of western corn rootworm. We tested populations from fields where severe injury to Cry3Bb1 maize was observed, and populations that had never been exposed to Bt maize. Consistent with past studies, bioassays indicated that field populations were resistant to Cry3Bb1 maize and mCry3A maize, and that cross-resistance was present between these two types of Bt maize. Additionally, bioassays revealed resistance to eCry3.1Ab maize and cross-resistance among Cry3Bb1, mCry3A and eCry3.1Ab. However, no resistance or cross-resistance was detected for Cry34/35Ab1 maize. This broad-spectrum resistance illustrates the potential for insect pests to develop resistance rapidly to multiple Bt toxins when structural similarities are present among toxins, and raises concerns about the long-term durability of Bt crops for management of some insect pests. PMID:27297953

  11. Validation of Reference Housekeeping Genes for Gene Expression Studies in Western Corn Rootworm (Diabrotica virgifera virgifera)

    PubMed Central

    Barros Rodrigues, Thaís; Khajuria, Chitvan; Wang, Haichuan; Matz, Natalie; Cunha Cardoso, Danielle; Valicente, Fernando Hercos; Zhou, Xuguo; Siegfried, Blair

    2014-01-01

    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. PMID:25356627

  12. Binary toxins from Bacillus thuringiensis active against the western corn rootworm, Diabrotica virgifera virgifera LeConte.

    PubMed

    Baum, James A; Chu, Chi-Rei; Rupar, Mark; Brown, Gregory R; Donovan, William P; Huesing, Joseph E; Ilagan, Oliver; Malvar, Thomas M; Pleau, Michael; Walters, Matthew; Vaughn, Ty

    2004-08-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte, is a significant pest of corn in the United States. The development of transgenic corn hybrids resistant to rootworm feeding damage depends on the identification of genes encoding insecticidal proteins toxic to rootworm larvae. In this study, a bioassay screen was used to identify several isolates of the bacterium Bacillus thuringiensis active against rootworm. These bacterial isolates each produce distinct crystal proteins with approximate molecular masses of 13 to 15 kDa and 44 kDa. Insect bioassays demonstrated that both protein classes are required for insecticidal activity against this rootworm species. The genes encoding these proteins are organized in apparent operons and are associated with other genes encoding crystal proteins of unknown function. The antirootworm proteins produced by B. thuringiensis strains EG5899 and EG9444 closely resemble previously described crystal proteins of the Cry34A and Cry35A classes. The antirootworm proteins produced by strain EG4851, designated Cry34Ba1 and Cry35Ba1, represent a new binary toxin. Genes encoding these proteins could become an important component of a sustainable resistance management strategy against this insect pest.

  13. The western corn rootworm diabrotica Virgifera virgifera en route to Germany.

    PubMed

    Hummel, H E; Bertossa, M; Hein, D F; Wudtke, A; Urek, G; Modic, S; Ulrichs, Ch

    2005-01-01

    The western corn rootworm Diabrotica virgifera virgifera LeConte (Col.:Chrysomelidae) (D.v.v.) is one of the most important maize pests in North America. Ever since its invasion into Europe and its detection near Belgrade airport by BACA in 1993 it quickly spread all over southeastern Europe and is now advancing towards central Europe. Up until summer 2004 considered free of D.v.v., Germany is, with the exception of its northern and northeastern borders, surrounded by countries with proven D.v.v. infestations. In addition to simultaneous spot introductions by airplanes, three main routes for terrestrial introduction into Germany are likely: 1. from south to north via Lombardy (Italy) through Switzerland to the State of Baden-Wuerttemberg in the southwest; 2. from south east to northwest via Croatia, Slovenia, Austria into the State of Bavaria; and 3. from Belgium and the Netherlands in southeasterly direction to the state of Northrhine-Westfalia. From these, progress of D.v.v. along route 1 is so far the most advanced. It follows the well established network of road and rail connections through Switzerland and underscores the active role mankind and its technology plays as an active distribution vector for D.v.v. Mandatory crop rotation in the Swiss Canton of Ticino did slow down but could not prevent the northbound advance of D.v.v. in 2004. Considering the recent discovery of D.v.vu near the South German border, its introduction into German territory is only a matter of time and may be ecologically unavoidable. In Slovenla, another relatively small southern transit state, the D.v.v. population density is still much lower than in Switzerland but with significantly increasing trend during 2004 and with special emphasis in its southeastern provinces. Considering its relatively short distance to southeastern Bavaria and the well developed transalpine rail, road and tunnel system, Slovenia as a transit state may provide another access route for D.v.v. of lesser but

  14. Assembly and annotation of full mitochondrial genomes for the corn rootworm species, Diabrotica virgifera virgifera and D. barberi (Insecta: Coleoptera: Chrysomelidae), using Next Generation Sequence data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Complete mitochondrial genomes for two corn rootworm species, Diabrotica v. virgifera (16,747 bp) and D. 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...

  15. 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.

    PubMed

    Coates, Brad S

    2014-06-01

    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. barberinad1 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. PMID:24657060

  16. The western corn rootworm (Diabrotica virgifera virgifera) and its first appearance in Germany 2007.

    PubMed

    Hummel, H E; Deuker, A; Eberhard, D; Glas, M; Leithold, G

    2008-01-01

    Diabrotica v. virgifera (WCR) is one of the most successful invasive insect species and owes this success to its close association with mankind, to worldwide trade and commerce connections, and to widely practiced, monoculturally oriented production patterns which are characteristic for contemporary agriculture in several parts of the world. Without a drastic change in attitudes and approaches of a globalizing agriculture, WCR will in the foreseeable future have invaded all maize growing areas. WCR is continuing its spreading within Europe with its first documented appearance in Germany 2007, where two major and three minor sites of invasion are identified. Unfortunately, WCR already has secondary hosts and, through accelerated microevolution, soon may acquire more of them. The beetle may be seen as a clever follower in the footsteps of Homo sapiens and may thrive on worldwide ecological imbalances. Without major new paradigms in control and management approaches, WCR will be one of the big winners of globalization and mercilessly occupy the niches opening up. Some biotechnical and cultural alternatives are discussed which, in combination with biocontrol, may assist in evironmentally compatible management of WCR. PMID:19226788

  17. Review on Resistance Breeding Options Targeting Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) in Europe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1. This review intends to present the part of the EU funded Project FP6, SSA: DIABR-ACT: Harmonise the strategies for fighting Diabrotica virgifera virgifera. Faculty of Agriculture in Osijek, Croatia, coordinated the part of the DIABR-ACT project concerning “resistance breeding” and reveal the lat...

  18. Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) Population Dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Much has been learned about the population dynamics of the western corn rootworm over the last half-century of intensive study, and this knowledge has helped humans manage this destructive pest of corn relatively successfully. However, this insect is something of a moving target when it comes to un...

  19. POLYMORPHIC MICROSATELLITE LOCI FROM NORTHERN AND MEXICAN CORN ROOTWORMS (INSECTA: COLEOPTERA: CHRYSOMELIDAE) AND CROSS-AMPLIFICATION WITH OTHER DIABROTICA SPP

    EPA Science Inventory

    The northern corn rootworm (Diabrotica barberi) and Mexican corn rootworm (Diabrotica virgifera zeae) are significant agricultural pests. For the northern corn rootworm, and to a lesser extent, the Mexican corn rootworm, high resolution molecular markers are needed. Here we pres...

  20. Antifeedant effects of proteinase inhibitors on feeding behaviors of adult western corn rootworm (Diabrotica virgifera virgifera).

    PubMed

    Kim, Jae Hak; Mullin, Christopher A

    2003-04-01

    Low-molecular-weight peptidyl proteinase inhibitors (PIs) including leupeptin, calpain inhibitor I, and calpeptin were found to be potent antifeedants for adult western corn rootworm (WCR) against the phagostimulation of cucurbitacin B (Cuc B) or a corn pollen extract (CPE). Leupeptin was the strongest (ED50 = 0.36 and 0.55 nmol/disk for Cuc B and CPE, respectively) among PIs tested with an antifeedant potency much stronger than the steroid progesterone (ED50 = 2.29 and 5.05 nmol/disk for Cuc B and CPE, respectively), but slightly less than the reference alkaloid, strychnine (ED50 = 0.17 and 0.37 nmol/disk for Cuc B and CPE, respectively). All active PIs contain a di- or tripeptidyl aldehyde moiety, indicating that PIs exert their antifeedant effects by covalent interaction with putative sulfhydryl (SH) groups on taste receptors as do these PIs with cysteine proteinases. However, opposite inhibition potency against Cuc B versus CPE by two thiol-group reducing agents, DTT and L-cysteine, and the results with other cysteine-modifying reagents obscure the net functional role of SH groups at WCR taste chemoreceptors. Surprisingly, the model phagostimulant for diabroticites, Cuc B, was more easily counteracted by these feeding deterrents than the stimulants present in CPE. Three-dimensional structure-antifeedant relationships for the PIs suggest that a novel taste chemoreception mechanism exists for these peptidyl aldehydes or that they fit partially into a strychnine binding pocket on protein chemoreceptors. Favorable economic benefit may be achieved if PIs are discovered to be useful in adult WCR control, since both pre- and postingestive sites would be targeted. PMID:12775144

  1. Knockdown of RNA Interference Pathway Genes in Western Corn Rootworms (Diabrotica virgifera virgifera Le Conte) Demonstrates a Possible Mechanism of Resistance to Lethal dsRNA.

    PubMed

    Vélez, Ana María; Khajuria, Chitvan; Wang, Haichuan; Narva, Kenneth E; Siegfried, Blair D

    2016-01-01

    RNA interference (RNAi) is being developed as a potential tool for insect pest management. Increased understanding of the RNAi pathway in target insect pests will provide information to use this technology effectively and to inform decisions related to resistant management strategies for RNAi based traits. Dicer 2 (Dcr2), an endonuclease responsible for formation of small interfering RNA's and Argonaute 2 (Ago2), an essential catalytic component of the RNA-induced silencing complex (RISC) have both been associated with the RNAi pathway in a number of different insect species including the western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). We identified both genes from a transcriptome library generated from different tissues and developmental stages of the western corn rootworm, an important target pest for transgenic plants expressing dsRNA targeting essential genes. The expression of these genes was suppressed by more than 90% after injecting gene specific dsRNA into adult rootworms. The injected beetles were then fed vATPase A dsRNA which has previously been demonstrated to cause mortality in western corn rootworm adults. The suppression of both RNAi pathway genes resulted in reduced mortality after subsequent exposure to lethal concentrations of vATPase A dsRNA as well as increased vATPase A expression relative to control treatments. Injections with dsRNA for a non-lethal target sequence (Laccase 2) did not affect mortality or expression caused by vATPase A dsRNA indicating that the results observed with Argo and Dicer dsRNA were not caused by simple competition among different dsRNA's. These results confirm that both genes play an important role in the RNAi pathway for western corn rootworms and indicate that selection pressures that potentially affect the expression of these genes may provide a basis for future studies to understand potential mechanisms of resistance. PMID:27310918

  2. Knockdown of RNA Interference Pathway Genes in Western Corn Rootworms (Diabrotica virgifera virgifera Le Conte) Demonstrates a Possible Mechanism of Resistance to Lethal dsRNA

    PubMed Central

    Vélez, Ana María; Khajuria, Chitvan; Wang, Haichuan; Narva, Kenneth E.; Siegfried, Blair D.

    2016-01-01

    RNA interference (RNAi) is being developed as a potential tool for insect pest management. Increased understanding of the RNAi pathway in target insect pests will provide information to use this technology effectively and to inform decisions related to resistant management strategies for RNAi based traits. Dicer 2 (Dcr2), an endonuclease responsible for formation of small interfering RNA’s and Argonaute 2 (Ago2), an essential catalytic component of the RNA-induced silencing complex (RISC) have both been associated with the RNAi pathway in a number of different insect species including the western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). We identified both genes from a transcriptome library generated from different tissues and developmental stages of the western corn rootworm, an important target pest for transgenic plants expressing dsRNA targeting essential genes. The expression of these genes was suppressed by more than 90% after injecting gene specific dsRNA into adult rootworms. The injected beetles were then fed vATPase A dsRNA which has previously been demonstrated to cause mortality in western corn rootworm adults. The suppression of both RNAi pathway genes resulted in reduced mortality after subsequent exposure to lethal concentrations of vATPase A dsRNA as well as increased vATPase A expression relative to control treatments. Injections with dsRNA for a non-lethal target sequence (Laccase 2) did not affect mortality or expression caused by vATPase A dsRNA indicating that the results observed with Argo and Dicer dsRNA were not caused by simple competition among different dsRNA’s. These results confirm that both genes play an important role in the RNAi pathway for western corn rootworms and indicate that selection pressures that potentially affect the expression of these genes may provide a basis for future studies to understand potential mechanisms of resistance. PMID:27310918

  3. Effects of refuges on the evolution of resistance to transgenic corn by western corn rootworm, Diabrotica virgifera virgifera LeConte

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabrotica virgifera virgifera LeConte is a major pest of corn causing millions of dollars of economic loss annually through yield reductions and preventative management practices. Corn producing toxins derived from Bacillus thuringiensis (Bt) have been developed to help manage D. v. virgifera. Sinc...

  4. Physiological and Cellular Responses Caused by RNAi- Mediated Suppression of Snf7 Orthologue in Western Corn Rootworm (Diabrotica virgifera virgifera) Larvae

    PubMed Central

    Ramaseshadri, Parthasarathy; Segers, Gerrit; Flannagan, Ronald; Wiggins, Elizabeth; Clinton, William; Ilagan, Oliver; McNulty, Brian; Clark, Thomas; Bolognesi, Renata

    2013-01-01

    Ingestion of double stranded RNA (dsRNA) has been previously demonstrated to be effective in triggering RNA interference (RNAi) in western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte), providing potential novel opportunities for insect pest control. The putative Snf7 homolog of WCR (DvSnf7) has previously been shown to be an effective RNAi target for insect control, as DvSnf7 RNAi leads to lethality of WCR larvae. Snf7 functions as a part of the ESCRT (Endosomal Sorting Complex Required for Transport) pathway which plays a crucial role in cellular housekeeping by internalization, transport, sorting and lysosomal degradation of transmembrane proteins. To understand the effects that lead to death of WCR larvae by DvSnf7 RNAi, we examined some of the distinct cellular processes associated with ESCRT functions such as de-ubiquitination of proteins and autophagy. Our data indicate that ubiquitinated proteins accumulate in DvSnf7 dsRNA-fed larval tissues and that the autophagy process seems to be impaired. These findings suggest that the malfunctioning of these cellular processes in both midgut and fat body tissues triggered by DvSnf7 RNAi were the main effects leading to the death of WCR. This study also illustrates that Snf7 is an essential gene in WCR and its functions are consistent with biological functions described for other eukaryotes. PMID:23349844

  5. Evidence of Field-Evolved Resistance to Bifenthrin in Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) Populations in Western Nebraska and Kansas

    PubMed Central

    Pereira, Adriano E.; Wang, Haichuan; Zukoff, Sarah N.; Meinke, Lance J.; French, B. Wade; Siegfried, Blair D.

    2015-01-01

    Pyrethroid insecticides have been used to control larvae or adults of the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, a key pest of field 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 establish a baseline of susceptibility to the pyrethroid insecticide, bifenthrin, using susceptible laboratory populations and to compare this baseline with susceptibility of field populations. Concentration-response bioassays were performed to estimate the baseline susceptibility. From the baseline data, a diagnostic concentration (LC99) was determined and used to test adults of both laboratory and field populations. Larval susceptibility was also tested using both laboratory and field populations. Significant differences were recorded in adult and larval susceptibility among WCR field and laboratory populations. The highest LC50 for WCR adults was observed in populations from Keith 2 and Chase Counties, NE, with LC50s of 2.2 and 1.38 μg/vial, respectively, and Finney County 1, KS, with 1.43 μg/vial, as compared to a laboratory non-diapause population (0.24 μg/vial). For larvae, significant differences between WCR field and laboratory populations were also recorded. Significant differences in mortalities at the diagnostic bifenthrin concentration (LC99) were observed among WCR adult populations with western Corn Belt populations exhibiting lower susceptibility to bifenthrin, especially in southwestern Nebraska and southwestern Kansas. This study provides evidence that resistance to bifenthrin is evolving in field populations that have been exposed for multiple years to pyrethroid insecticides. Implications to sustainable rootworm management are discussed. PMID:26566127

  6. Parental RNA interference of genes involved in embryonic development of the western corn rootworm, Diabrotica virgifera virgifera LeConte.

    PubMed

    Khajuria, Chitvan; Vélez, Ana M; Rangasamy, Murugesan; Wang, Haichuan; Fishilevich, Elane; Frey, Meghan L F; Carneiro, Newton Portilho; Gandra, Premchand; Narva, Kenneth E; Siegfried, Blair D

    2015-08-01

    RNA interference (RNAi) is being developed as a potential tool for insect pest management and one of the most likely target pest species for transgenic plants that express double stranded RNA (dsRNA) is the western corn rootworm. Thus far, most genes proposed as targets for RNAi in rootworm cause lethality in the larval stage. In this study, we describe RNAi-mediated knockdown of two developmental genes, hunchback (hb) and brahma (brm), in the western corn rootworm delivered via dsRNA fed to adult females. dsRNA feeding caused a significant decrease in hb and brm transcripts in the adult females. Although total oviposition was not significantly affected, there was almost complete absence of hatching in the eggs collected from females exposed to dsRNA for either gene. These results confirm that RNAi is systemic in nature for western corn rootworms. These results also indicate that hunchback and brahma play important roles in rootworm embryonic development and could provide useful RNAi targets in adult rootworms to prevent crop injury by impacting the population of larval progeny of exposed adults. The ability to deliver dsRNA in a trans-generational manner by feeding to adult rootworms may offer an additional approach to utilizing RNAi for rootworm pest management. The potential to develop parental RNAi technology targeting progeny of adult rootworms in combination with Bt proteins or dsRNA lethal to larvae may increase opportunities to develop sustainable approaches to rootworm management involving RNAi technologies for rootworm control.

  7. Characterization of the spectrum of insecticidal activity of a double-stranded RNA with targeted activity against Western Corn Rootworm (Diabrotica virgifera virgifera LeConte).

    PubMed

    Bachman, Pamela M; Bolognesi, Renata; Moar, William J; Mueller, Geoffrey M; Paradise, Mark S; Ramaseshadri, Parthasarathy; Tan, Jianguo; Uffman, Joshua P; Warren, Joanne; Wiggins, B Elizabeth; Levine, Steven L

    2013-12-01

    The sequence specificity of the endogenous RNA interference pathway allows targeted suppression of genes essential for insect survival and enables the development of durable and efficacious insecticidal products having a low likelihood to adversely impact non-target organisms. The spectrum of insecticidal activity of a 240 nucleotide (nt) dsRNA targeting the Snf7 ortholog in Western Corn Rootworm (WCR; Diabrotica virgifera virgifera) was characterized by selecting and testing insects based upon their phylogenetic relatedness to WCR. Insect species, representing 10 families and 4 Orders, were evaluated in subchronic or chronic diet bioassays that measured potential lethal and sublethal effects. When a specific species could not be tested in diet bioassays, the ortholog to the WCR Snf7 gene (DvSnf7) was cloned and corresponding dsRNAs were tested against WCR and Colorado potato beetle (Leptinotarsa decemlineata); model systems known to be sensitive to ingested dsRNA. Bioassay results demonstrate that the spectrum of activity for DvSnf7 is narrow and activity is only evident in a subset of beetles within the Galerucinae subfamily of Chrysomelidae (>90% identity with WCR Snf7 240 nt). This approach allowed for evaluating the relationship between minimum shared nt sequence length and activity. A shared sequence length of ≥ 21 nt was required for efficacy against WCR (containing 221 potential 21-nt matches) and all active orthologs contained at least three 21 nt matches. These results also suggest that WCR resistance to DvSnf7 dsRNA due to single nucleotide polymorphisms in the target sequence of 240 nt is highly unlikely. PMID:23748931

  8. Characterization of the spectrum of insecticidal activity of a double-stranded RNA with targeted activity against Western Corn Rootworm (Diabrotica virgifera virgifera LeConte).

    PubMed

    Bachman, Pamela M; Bolognesi, Renata; Moar, William J; Mueller, Geoffrey M; Paradise, Mark S; Ramaseshadri, Parthasarathy; Tan, Jianguo; Uffman, Joshua P; Warren, Joanne; Wiggins, B Elizabeth; Levine, Steven L

    2013-12-01

    The sequence specificity of the endogenous RNA interference pathway allows targeted suppression of genes essential for insect survival and enables the development of durable and efficacious insecticidal products having a low likelihood to adversely impact non-target organisms. The spectrum of insecticidal activity of a 240 nucleotide (nt) dsRNA targeting the Snf7 ortholog in Western Corn Rootworm (WCR; Diabrotica virgifera virgifera) was characterized by selecting and testing insects based upon their phylogenetic relatedness to WCR. Insect species, representing 10 families and 4 Orders, were evaluated in subchronic or chronic diet bioassays that measured potential lethal and sublethal effects. When a specific species could not be tested in diet bioassays, the ortholog to the WCR Snf7 gene (DvSnf7) was cloned and corresponding dsRNAs were tested against WCR and Colorado potato beetle (Leptinotarsa decemlineata); model systems known to be sensitive to ingested dsRNA. Bioassay results demonstrate that the spectrum of activity for DvSnf7 is narrow and activity is only evident in a subset of beetles within the Galerucinae subfamily of Chrysomelidae (>90% identity with WCR Snf7 240 nt). This approach allowed for evaluating the relationship between minimum shared nt sequence length and activity. A shared sequence length of ≥ 21 nt was required for efficacy against WCR (containing 221 potential 21-nt matches) and all active orthologs contained at least three 21 nt matches. These results also suggest that WCR resistance to DvSnf7 dsRNA due to single nucleotide polymorphisms in the target sequence of 240 nt is highly unlikely.

  9. Containment of the western corn rootworm Diabrotica v.virgifera: continued successful management 2008 in southern Switzerland by monitoring and crop rotation.

    PubMed

    Hummel, Hans E; Bertossa, M

    2009-01-01

    Diabrotica virgifera virgifera LeConte (Col.: Chrysomelidae), known as western corn rootworm (WCR) and endemic in North America, invaded Europe about two decades ago. Various unsuccessful attempts have been made to eradicate it from the Old World. Management with a variety of strategies is the option now remaining. WCR management in Southern Switzerland by a unique containment approach has been practiced successfully since 2003 using biotechnical means. Without any chemical pesticides or GMO input, the Swiss government mandated adherence to strict crop rotation. In addition to the economic benefits of this relatively simple approach, the environment was saved a considerable burden of pesticide applications. Other countries are invited to follow this example of sustainable pest management. PMID:20222583

  10. Containment of the western corn rootworm Diabrotica v.virgifera: continued successful management 2008 in southern Switzerland by monitoring and crop rotation.

    PubMed

    Hummel, Hans E; Bertossa, M

    2009-01-01

    Diabrotica virgifera virgifera LeConte (Col.: Chrysomelidae), known as western corn rootworm (WCR) and endemic in North America, invaded Europe about two decades ago. Various unsuccessful attempts have been made to eradicate it from the Old World. Management with a variety of strategies is the option now remaining. WCR management in Southern Switzerland by a unique containment approach has been practiced successfully since 2003 using biotechnical means. Without any chemical pesticides or GMO input, the Swiss government mandated adherence to strict crop rotation. In addition to the economic benefits of this relatively simple approach, the environment was saved a considerable burden of pesticide applications. Other countries are invited to follow this example of sustainable pest management.

  11. Characterizing the Mechanism of Action of Double-Stranded RNA Activity against Western Corn Rootworm (Diabrotica virgifera virgifera LeConte)

    PubMed Central

    Bolognesi, Renata; Ramaseshadri, Parthasarathy; Anderson, Jerry; Bachman, Pamela; Clinton, William; Flannagan, Ronald; Ilagan, Oliver; Lawrence, Christina; Levine, Steven; Moar, William; Mueller, Geoffrey; Tan, Jianguo; Uffman, Joshua; Wiggins, Elizabeth; Heck, Gregory; Segers, Gerrit

    2012-01-01

    RNA interference (RNAi) has previously been shown to be effective in western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte) larvae via oral delivery of synthetic double-stranded RNA (dsRNA) in an artificial diet bioassay, as well as by ingestion of transgenic corn plant tissues engineered to express dsRNA. Although the RNAi machinery components appear to be conserved in Coleopteran insects, the key steps in this process have not been reported for WCR. Here we characterized the sequence of events that result in mortality after ingestion of a dsRNA designed against WCR larvae. We selected the Snf7 ortholog (DvSnf7) as the target mRNA, which encodes an essential protein involved in intracellular trafficking. Our results showed that dsRNAs greater than or equal to approximately 60 base-pairs (bp) are required for biological activity in artificial diet bioassays. Additionally, 240 bp dsRNAs containing a single 21 bp match to the target sequence were also efficacious, whereas 21 bp short interfering (si) RNAs matching the target sequence were not. This result was further investigated in WCR midgut tissues: uptake of 240 bp dsRNA was evident in WCR midgut cells while a 21 bp siRNA was not, supporting the size-activity relationship established in diet bioassays. DvSnf7 suppression was observed in a time-dependent manner with suppression at the mRNA level preceding suppression at the protein level when a 240 bp dsRNA was fed to WCR larvae. DvSnf7 suppression was shown to spread to tissues beyond the midgut within 24 h after dsRNA ingestion. These events (dsRNA uptake, target mRNA and protein suppression, systemic spreading, growth inhibition and eventual mortality) comprise the overall mechanism of action by which DvSnf7 dsRNA affects WCR via oral delivery and provides insights as to how targeted dsRNAs in general are active against insects. PMID:23071820

  12. Predator responses to novel haemolymph defences of Western corn rootworm (Diabrotica virgifera) larvae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many herbivorous arthropods use defensive chemistry to discourage predators from attacking. This chemistry relies on the ability of predators to rapidly learn to recognize and avoid offensive stimuli. Western corn rootworm (WCR) employs multifaceted chemical defences in its haemolymph, which may c...

  13. Role of a gamma-aminobutryic acid (GABA) receptor mutation in the evolution and spread of Diabrotica virgifera virgifera resistance to cyclodiene insecticides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An alanine to serine amino acid substitution within the Rdl subunit of the gamma-aminobutyric acid (GABA) receptor confers resistance to cyclodiene insecticides in many species. The corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was partially controlled by ...

  14. Neonate larvae of the specialist herbivore Diabrotica virgifera virgifera do not exploit the defensive volatile (E)-ß-caryophyllene to assist in locating maize roots

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The behavior of the neonate larvae of Diabrotica virgifera virgifera LeConte (western corn rootworm, WCR) was assessed in presence of maize root constitutively emitting (E)-ß-caryophylene (EßC). This root volatile has been shown to attract both second instar WCR and insect-killing nematodes, offerin...

  15. Evaluation of potential fitness costs associated with eCry3.1Ab resistance in Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Both an eCry3.1Ab resistant and paired control western corn rootworm, Diabrotica virgifera virgifera colony were tested for adult longevity, egg oviposition, egg viability, and larval development in order to evaluate the potential fitness costs associated with eCry3.1Ab resistance in the western cor...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  17. Increased Expression of a cGMP-Dependent Protein Kinase in Rotation-Adapted Western Corn Rootworm (Diabrotica virgifera virgifera L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 th...

  18. The Glycolytic Enzymes Activity in the Midgut of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) adult and their Seasonal Changes

    PubMed Central

    Guzik, Joanna; Nakonieczny, Mirosław; Tarnawska, Monika; Bereś, Paweł K.; Drzewiecki, Sławomir; Migula, Paweł

    2015-01-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is an important pest of maize. The diet of the D. virgifera imago is rich in starch and other polysaccharides present in cereals such as maize. Therefore, knowledge about enzymes involved in digestion of such specific food of this pest seems to be important. The paper shows, for the first time, the activities of main glycolytic enzymes in the midgut of D. virgifera imago: endoglycosidases (α-amylase, cellulase, chitinase, licheninase, laminarinase); exoglycosidases (α- and β-glucosidases, α- and β-galactosidases) and disaccharidases (maltase, isomaltase, sucrase, trehalase, lactase, and cellobiase). Activities of α-amylase, α-glucosidase, and maltase were the highest among assayed endoglycosidases, exoglycosidases, and disaccharidases, respectively. This indicates that in the midgut of D. virgifera imago α-amylase, α-glucosidase and maltase are important enzymes in starch hydrolysis and products of its digestion. These results lead to conclusion that inhibition of most active glycolytic enzymes of D. virgifera imago may be another promising method for chemical control of this pest of maize.

  19. Modeling evolution of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) to transgenic corn with two insecticidal traits.

    PubMed

    Onstad, David W; Meinke, Lance J

    2010-06-01

    A simulation model of the population dynamics and genetics of western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), was created to evaluate the use of refuges in the management of resistance to transgenic insecticidal corn, Zea mays L., expressing one or two toxin traits. Hypothetical scenarios and a case study of a corn hybrid pyramided with existing toxins are simulated. In the hypothetical situations, results demonstrated that evolution is generally delayed by pyramids compared with deployment of a single-toxin corn hybrid. However, soil insecticide use in the refuge reduced this delay and quickened the evolution of resistance. Results were sensitive to the degree of male beetle dispersal before mating and to the effectiveness of both toxins in the pyramid. Resistance evolved faster as fecundity increased for survivors of insecticidal corn. Thus, effects on fecundity must be measured to predict which resistance management plans will work well. Evolution of resistance also occurred faster if the survival rate due to exposure to the two toxins was not calculated by multiplication of two independent survival rates (one for each insect gene) but was equivalent to the minimum of the two. Furthermore, when single-trait and pyramided corn hybrids were planted within rootworm-dispersal distance of each other, the toxin traits lost efficacy more quickly than they did in scenarios without single-trait corn. For the case study involving transgenic corn expressing Cry34/35Ab1 and Cry3Bb1, the pyramid delayed evolution longer than a single trait corn hybrid and longer than a sequence of toxins based on at least one resistance-allele frequency remaining below 50%. Results are discussed within the context of a changing transgenic corn marketplace and the landscape dynamics of resistance management.

  20. Proliferation and copy number variation of BEL-like long terminal repeat retrotransposons within the Diabrotica virgifera virgifera genome.

    PubMed

    Coates, Brad S; Fraser, Lisa M; French, B Wade; Sappington, Thomas W

    2013-10-25

    The proliferation of retrotransposons within a genome can contribute to increased size and affect the function of eukaryotic genes. BEL/Pao-like long-terminal repeat (LTR) retrotransposons were annotated from the highly adaptable insect species Diabrotica virgifera virgifera, the western corn rootworm, using survey sequences from bacterial artificial chromosome (BAC) inserts and contigs derived from a low coverage next-generation genome sequence assembly. Eleven unique D. v. virgifera BEL elements were identified that contained full-length gag-pol coding sequences, whereas 88 different partial coding regions were characterized from partially assembled elements. Estimated genome copy number for full and partial BEL-like elements ranged from ~8 to 1,582 among individual contigs using a normalized depth of coverage (DOC) among Illumina HiSeq reads (total genome copy number ~8,821). BEL element copy number was correlated among different D. v. virgifera populations (R(2)=0.9846), but individual element numbers varied≤1.68-fold and the total number varied by ~527 copies. These data indicate that BEL element proliferation likely contributed to a large genome size, and suggest that differences in copy number are a source of genetic variability among D. v. virgifera.

  1. Proliferation and copy number variation of BEL-like long terminal repeat retrotransposons within the Diabrotica virgifera virgifera genome.

    PubMed

    Coates, Brad S; Fraser, Lisa M; French, B Wade; Sappington, Thomas W

    2014-01-25

    The proliferation of retrotransposons within a genome can contribute to increased size and affect the function of eukaryotic genes. BEL/Pao-like long-terminal repeat (LTR) retrotransposons were annotated from the highly adaptable insect species Diabrotica virgifera virgifera, the Western corn rootworm, using survey sequences from bacterial artificial chromosome (BAC) inserts and contigs derived from a low coverage next-generation genome sequence assembly. Eleven unique D. v. virgifera BEL elements were identified that contained full-length gag-pol coding sequences, whereas 88 different partial coding regions were characterized from partially assembled elements. Estimated genome copy number for full and partial BEL-like elements ranged from ~8 to 1582 among individual contigs using a normalized depth of coverage (DOC) among Illumina HiSeq reads (total genome copy number ~8821). BEL element copy number was correlated among different D. v. virgifera populations (R2=0.9846), but individual element numbers varied ≤ 1.68-fold and the total number varied by ~527 copies. These data indicate that BEL element proliferation likely contributed to a large genome size, and suggest that differences in copy number are a source of genetic variability among D. v. virgifera.

  2. CONTROL OF DIABROTICA VIRGIFERA VIRGIFERA LE CONTE IN MAIZE SEED TREATMENT.

    PubMed

    Inđić, D; Vuković, S; Kljajić, P; Gvozdenac, S; Tanasković, S; Andrić, G

    2014-01-01

    During the last decade of XX century, Diabrotica virgifera virgifera Le Conte became an important introduced harmful species in maize production in the northern Serbia region. The aim of this work was to assess the efficacy of imidacloprid based insecticides formulated for seed treatment in the control of D. v. virgifera. Experiments were set at two localities (Čurug--two-year maize culturing; Bečej--four-year maize culturing) in 2013, according to OEPP (PP 1/212(1) 2004) method. Imidacloprid based insecticide (600 g a.i./L) was applied at rates 0.36; 0.55; 0,7 and 0.8 L/100 kg of maize seeds (hybrids NS 5041 and NS 640 Ultra). The degree of maize root damage was determined according to scale 1-6 (http://www.ent.iastate.edu/-pest/rootworm/nodeinjury/nodeinjury.htm). A number of damaged plants was also registered and expressed in percents, as well as the development of adventitious roots. Significance of differences between root damages and number of damaged plants between treatments was tested using ANOVA. Regardless on localities and applied rates, maize roots in treatments with imidacloprid were significantly less damaged by larvae D. v. virgifera (1.1-1.4) compared to the control (3.7-4.1). Also, a significant reduction in percent of damaged plants (5.0-20%) was registered compared to the control (90-97.5%). At both localities in treatments with imidacloprid adventitious roots were well developed in 60.5 to 91% of plants compared to the control were it was the case in 10-27.5% plants. It is important to emphasize that roots were significantly more developed in treated variants compared to the control. Based on the obtained results it can be concluded that imidacloprid, regardless on its future status and restraints/limitations in maize seed treatment, provided efficient protection of maize roots from D. v. virgifera larvae, even at rate twice lower (0.36) than recommended (0.8 L/100 kg seeds), which justifies the application of lower quantities of imidacloprid

  3. Abundance and distribution of western and northern corn rootworm (Diabrotica spp.) and prevalence of rotation resistance in eastern Iowa.

    PubMed

    Dunbar, Mike W; Gassmann, Aaron J

    2013-02-01

    The western corn rootworm Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) and the northern corn rootworm Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae) are major pests of corn (Zea mays L.). Historically, crop rotation has been an effective management strategy, but both species have adapted to crop rotation in the Midwest. For both species in eastern Iowa, we measured abundance and prevalence of rotation resistance using sticky traps and emergence cages in fields of corn and soybean (Glycine max L.). Based on currently available data, we calculated the economic thresholds for these pests at two Diabrotica spp. per trap per day in cornfields and 1.5 D. v. virgifera per trap per day in soybean fields. The economic injury level of rotation-resistant D. barberi was determined to be 3.5 adult insects per emergence cage per year. Peak abundance of rootworm adults in cornfields was below economic thresholds in the majority of fields sampled, suggesting that management of rootworm larvae in continuous cornfields may not always be necessary. Rotation-resistant D. barberi was found throughout eastern Iowa using emergence cages in first-year cornfields, however, the abundance was below levels expected to impose economic injury in 14 of 17 fields evaluated. The presence of rotation-resistant D. v. virgifera, as measured by the occurrence of this insect in soybean fields, occurred only in northeastern Iowa and was also below the economic threshold. These data suggests that crop rotation remains a viable pest management strategy in eastern Iowa.

  4. No clear effect of admixture between two European invading outbreaks of Diabrotica virgifera virgifera in natura.

    PubMed

    Bermond, Gérald; Cavigliasso, Fanny; Mallez, Sophie; Spencer, Joseph; Guillemaud, Thomas

    2014-01-01

    In this study, we challenged the hypothesis that admixture may have had a positive impact in the context of the European invasion of the western corn rootworm (WCR), Diabrotica virgifera virgifera, LeConte. This beetle was introduced in Europe from the USA several times since the 1980's. The multiple introductions of this major pest of cultivated corn led to the formation of two major outbreaks in North Western (NW) Italy and in Central and South Eastern (CSE) Europe that eventually merged into a secondary contact zone where insects from both outbreaks interbreed. We collected about 600 insects from this contact zone and genotyped them using 13 microsatellite markers. Three types of information were obtained from the collected individuals: (i) their survival under starvation; (ii) their admixed status, determined through a Bayesian method of genetic clustering and (iii) their mating probability, studied via the detection, isolation and genotyping of sperm in female spermathecae. Twenty six % and 12% of the individuals were assigned to the NW Italy or the CSE Europe parental types, respectively, and 23% and 39% to the F1 and backcross hybrid types, respectively. Globally, our results do not reveal any significant impact of the admixed status on the mating probability and on the choice of mating partners. However the admixed status had a sex- and sampling site-dependent effect on survival in adults under starvation. In addition sex had an effect on survival, with mortality hazard about 3 times larger in males than in females. The consequences of these findings for the evolution of the admixture zone of northern Italy are discussed. PMID:25170837

  5. Baseline Susceptibility of Western Corn Rootworm (Coleoptera: Chrysomelidae) to Clothianidin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Western corn rootworm, Diabrotica virgifera virgifera LeConte, neonate susceptibility to clothianidin, a highly effective contact and systemic neonicotinoid insecticide, was determined from both laboratory and field collected populations. Neonates were exposed to filter paper treated with increasing...

  6. Generalist-feeding subterranean mites as potential biological control agents of immature corn rootworms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Predatory mites are important components of subterranean food webs and may help regulate densities of agricultural pests, including western corn rootworms (Chrysomelidae: Diabrotica virgifera virgifera). Implementing conservation and/or classical biocontrol tactics could enhance densities of special...

  7. 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

  8. 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

  9. Evaluation of Potential Fitness Costs Associated With eCry3.1Ab Resistance in Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

    PubMed

    Geisert, Ryan W; Hibbard, Bruce E

    2016-08-01

    Both an eCry3.1Ab-selected and paired control western corn rootworm, Diabrotica virgifera virgifera LeConte, colony were tested for adult longevity, egg oviposition, egg viability, and larval development in order to evaluate the potential fitness costs associated with eCry3.1Ab resistance. Adult longevity experiments were conducted by pairing virgin males and females together in plastic boxes supplied with food, water, and ovipositional medium and observed for survival time. Eggs were also collected from the ovipositional medium once a week to determine average egg oviposition and egg viability. Larval development time experiments were conducted by infesting seedling assays with 25 neonate larvae and recording larval recovery after several days. Adult longevity, average egg oviposition, and larval development time results indicated a lack of fitness costs associated with eCry3.1Ab resistance in the western corn rootworm. Results of egg viability indicated a fitness advantage for the eCry3.1Ab-selected colony with a significantly higher egg hatch than the control. PMID:27151470

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crystal (Cry) 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 Diabrotica). ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  13. Screening for corn rootworm (Coleoptera: Chrysomelidae) resistance to transgenic Bt corn in North Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Western (WCR), Diabrotica virgifera virgifera LeConte, and northern corn rootworms (NCR), D. barberi Smith & Lawrence, are major economic pests of corn in much of the U.S. Corn Belt. Western corn rootworm resistance to transgenic corn expressing Bt (Bacillus thuringiensis) endotoxins has been confi...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  16. Selection for Resistance to the Cry3Bb1 Protein in a Genetically Diverse Population of Non-diapausing Western Corn Rootworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The western corn rootworm (Diabrotica virgifera virgifera) is an economically important pest of maize in North America. In 2003, the U. S. Environmental Protection Agency approved the commercial use of Monsanto’s Bt maize expressing the Cry3Bb1 protein, which is toxic to pest Diabrotica beetles. How...

  17. A Cry3Bb1-resistant Minnesota field population of western corn rootworm (Coleoptera: Chrysomelidae) shows reduced susceptibility to Cry34/35Ab1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. RNAi induced knockdown of a cadherin-like protein (EF531715) does not affect toxicity of Cry34/35Ab1 or Cry3Aa to Diabrotica virgifera virgifera larvae (Coleoptera: Chrysomelidae).

    PubMed

    Tan, Sek Yee; Rangasamy, Murugesan; Wang, Haichuan; Vélez, Ana María; Hasler, James; McCaskill, David; Xu, Tao; Chen, Hong; Jurzenski, Jessica; Kelker, Matthew; Xu, Xiaoping; Narva, Kenneth; Siegfried, Blair D

    2016-08-01

    The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important maize pest throughout most of the U.S. Corn Belt. Bacillus thuringiensis (Bt) insecticidal proteins including modified Cry3Aa and Cry34/35Ab1 have been expressed in transgenic maize to protect against WCR feeding damage. To date, there is limited information regarding the WCR midgut target sites for these proteins. In this study, we examined whether a cadherin-like gene from Diabrotica virgifera virgifera (DvvCad; GenBank accession # EF531715) associated with WCR larval midgut tissue is necessary for Cry3Aa or Cry34/35Ab1 toxicity. Experiments were designed to examine the sensitivity of WCR to trypsin activated Cry3Aa and Cry34/35Ab1 after oral feeding of the DvvCad dsRNA to knockdown gene expression. Quantitative real-time PCR confirmed that DvvCad mRNA transcript levels were reduced in larvae treated with cadherin dsRNA. Relative cadherin expression by immunoblot analysis and nano-liquid chromatography - mass spectrometry (nanoLC-MS) of WCR neonate brush border membrane vesicle (BBMV) preparations exposed to DvvCad dsRNA confirmed reduced cadherin expression when compared to BBMV from untreated larvae. However, the larval mortality and growth inhibition of WCR neonates exposed to cadherin dsRNA for two days followed by feeding exposure to either Cry3Aa or Cry34/35Ab1 for four days was not significantly different to that observed in insects exposed to either Cry3Aa or Cry34/35Ab1 alone. In combination, these results suggest that cadherin is unlikely to be involved in the toxicity of Cry3Aa or Cry34/35Ab1 to WCR. PMID:27334721

  19. Increased Survival of Western Corn Rootworm on Transgenic Corn Within Three Generations of Onplant Greenhouse Selection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The agricultural industry has adopted a high dose/refuge strategy as a means of delaying the onset of insect resistance to transgenic crops. Recently, Bt corn products developed for control of western corn rootworm (WCR), Diabrotica virgifera virgifera, have been introduced with less than high-dose...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  3. Adaptation by western corn rootworm to Bt corn: characterizing inheritance, fitness costs, and feeding preference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, we used a laboratory-selected, Bt-resistant strain of western corn rootworm, Diabrotica virgifera virgifera Le Conte, to characterize inheritance of resistance, feeding behavior, and fitness costs associated with resistance to maize producing the Bacillus thuringiensis (Bt) toxin Cry3...

  4. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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-...

  6. Methyl anthranilate as a repellent for western corn rootworm larvae (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methyl anthranilate was identified as the active compound in extracts of maize roots that were shown to be repellent to neonate western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae. A bioassay-driven approach was used to isolate the active material from diethyl ether extracts of r...

  7. Selection for resistance to mCry3A-expressing transgenic corn in western corn rootworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To investigate the development of resistance to mCry3A, a laboratory colony of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was established from field survivors of mCry3A-expressing (MIR604) corn. Feral adults emerging from MIR604 (selected) and isoline (control) field plots w...

  8. Greenhouse-selected resistance to Cry3Bb1-producing corn in three western corn rootworm populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transgenic corn producing the Bacillus thuringiensis (Bt) toxin Cry3Bb1 has been useful for controlling western corn rootworm, Diabrotica virgifera virgifera LeConte, one of the most economically important crop pests in the United States. However, rapid evolution of resistance by this beetle to Bt c...

  9. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  11. Mortality of western corn rootworm larvae on MIR604 transgenic maize roots: field survivorship has no impact on survivorship of F1 progeny on MIR604

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mortality of western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae due to MIR604 transgenic corn (Zea mays L.) expressing the modified Cry3A (mCry3A) protein relative to survivorship on corn with the same genetic background without the gene (isoline corn) was evaluated at three Misso...

  12. 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...

  13. Effect of MIR604 transgenic maize at different stages of development on western corn rootworm (Coleoptera: Chrysomelidae) in a central missouri field environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The establishment and survival of western corn rootworm, Diabrotica virgifera virgifera LeConte, was evaluated on transgenic Bt maize, Zea mays L., expressing the mCry3A protein (MIR604) and non-Bt maize with the same genetic background (isoline maize) at different stages of development in 2007 and ...

  14. Carbon isotope ratios document that the elytra of western corn rootworm reflects adult versus larval feeding and later instar larvae prefer Bt corn to alternate hosts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is a major pest of maize, Zea mays L., worldwide. While exploring conventional approaches to management and more recently bioengineering, extended research has been conducted on ways to manage its root-feeding larvae. The nee...

  15. 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

  16. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  18. Sorghum halepense (L.) Persoon (Poaceae), a new larval host for the South American corn rootworm Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabrotica speciosa is a South American corn rootworm (Coleoptera: Chrysomelidae: Galerucinae) the adult of which is a pest on many crop and ornamental plants. The list of known larval hosts, however, is limited to maize, wheat, potatoes and peanuts. In March, 2005, larvae of D. speciosa were found ...

  19. Impact of the Bt corn proteins Cry34/35Ab1 and Cry3Bb1, alone or pyramided, on western corn rootworm (Coleoptera: Chrysomelidae) beetle emergence in the field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a major pest of corn, Zea mays L. This study compared the effect of the Bt proteins Cry34/35Ab1, Cry3Bb1, singly expressed, and Cry3Bb1 plus Cry34/35Ab1 in a pyramid, with a near-isoline control, on D. virgifera adult emergence in fie...

  20. 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...

  1. Effects of Field History on Corn Root Injury and Adult Abundance of Northern and Western Corn Rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Dunbar, Mike W; O'Neal, Matthew E; Gassmann, Aaron J

    2016-10-01

    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.

  2. Transgenic approaches to western corn rootworm control.

    PubMed

    Narva, Kenneth E; Siegfried, Blair D; Storer, Nicholas P

    2013-01-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is a significant corn pest throughout the United States corn belt. Rootworm larvae feed on corn roots causing yield losses and control expenditures that are estimated to exceed US$1 billion annually. Traditional management practices to control rootworms such as chemical insecticides or crop rotation have suffered reduced effectiveness due to the development of physiological and behavioral resistance. Transgenic maize expressing insecticidal proteins are very successful in protecting against rootworm damage and preserving corn yield potential. However, the high rate of grower adoption and early reliance on hybrids expressing a single mode of action and low-dose traits threatens the durability of commercialized transgenic rootworm technology for rootworm control. A summary of current transgenic approaches for rootworm control and the corresponding insect resistance management practices is included. An overview of potential new modes of action based on insecticidal proteins, and especially RNAi targeting mRNA coding for essential insect proteins is provided.

  3. The Effect of Western Corn Rootworm (Coleoptera: Chrysomelidae) and Water Deficit on Maize Performance Under Controlled Conditions.

    PubMed

    Mahmoud, M A B; Sharp, R E; Oliver, M J; Finke, D L; Ellersieck, M R; Hibbard, B E

    2016-04-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect of maize, Zea mays L., but knowledge of its interaction with water deficit on maize production is lacking. A series of greenhouse experiments using three infestation levels of the western corn rootworm, D. virgifera virgifera, 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 B73×Mo17 maize growth and physiology. Three separate experiments were conducted. Soil moisture regimes were initiated 30 d postplanting for experiments using neonate and second-instar larvae and 30 d postinfestation in the experiment using eggs. In the neonate and second-instar experiments, there were no significant differences among western corn rootworm levels in their effects on leaf water potential, shoot dry weight, and root dry weight. The interaction of western corn rootworm and soil moisture significantly impacted the larval recovery in the neonate experiment, but no other significant interactions were documented between soil moisture levels and rootworm infestation levels. Overall, the results indicate that under the conditions of these experiments, the effect of water deficit was much greater on plants than the effect of western corn rootworm and that the interactions between water deficit and western corn rootworm levels minimally affected the measured parameters of plant performance.

  4. The Effect of Western Corn Rootworm (Coleoptera: Chrysomelidae) and Water Deficit on Maize Performance Under Controlled Conditions.

    PubMed

    Mahmoud, M A B; Sharp, R E; Oliver, M J; Finke, D L; Ellersieck, M R; Hibbard, B E

    2016-04-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect of maize, Zea mays L., but knowledge of its interaction with water deficit on maize production is lacking. A series of greenhouse experiments using three infestation levels of the western corn rootworm, D. virgifera virgifera, 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 B73×Mo17 maize growth and physiology. Three separate experiments were conducted. Soil moisture regimes were initiated 30 d postplanting for experiments using neonate and second-instar larvae and 30 d postinfestation in the experiment using eggs. In the neonate and second-instar experiments, there were no significant differences among western corn rootworm levels in their effects on leaf water potential, shoot dry weight, and root dry weight. The interaction of western corn rootworm and soil moisture significantly impacted the larval recovery in the neonate experiment, but no other significant interactions were documented between soil moisture levels and rootworm infestation levels. Overall, the results indicate that under the conditions of these experiments, the effect of water deficit was much greater on plants than the effect of western corn rootworm and that the interactions between water deficit and western corn rootworm levels minimally affected the measured parameters of plant performance. PMID:26896532

  5. Effects of different growing systems and fertiliser rates on attractiveness of maize crop to beetles of Diabrotica virgifera virgifera LeConte and larvae dammage.

    PubMed

    Baca, F; Jovanovic, Z; Veskovic, M; Kaitovic, Z

    2003-01-01

    Monitoring of plant lodging, yield reaction due to root injures caused by western corn rootworm larvae (WCR) (Diabroticia virgifera virgifera Le Conte) and adults abundance with yellow Multigard and Pherocone AM and pheromone Csalomon traps, were performed in three field trials. First one with 4 variants of maize growing system; maize continuous cropping, two crop rotation (wheat-maize, soybean-maize) and three crop rotation (wheat-soybean-maize), set up in 1985. Second one with 54 variants, both conducted in Zemun Polje. A large scale trial with three rates of NPK mineral fertilizers; (NPK 0 kg/ha, 170 kg/ha and 270 kg/ha with two type of N applied in side dressing (N 0 kg/ha, 50 kg/ha and 80 kg/ha) was set up in Crepaja in 1997, 1998 and 1999. Each variant of fertilizers had two combinations; one treated with insecticide and another one untreated check. Feeding on root system of WCR larvae, in the variants with insecticide application, resulted in plant lodging that ranged in average from 2.1% in 1997, to 61.6% in 1999, while in variant without insecticide application, root damage resulted in plant lodging from 19.5% in 1997, to 56.6% in 1999. Increasing of the nitrogen rates in the variants without application of insecticide tended to raise the percentage of plant lodging Yield reaction on nitrogen application was positive in 1997, first year and 1998, second year of maize monoculture, while in 1999 was negative. Larval injury affected maize yield in the higher extend in extremely dry year 2000, when yield index was 0.37 comparing 2.86 t/ha in maize monoculture to 7.66 t/ha in three crop rotation, 0.54 (2.86: 5.28 maize monoculture: wheat-maize) and 0.55 (2.86: 5.22 maize monoculture: soybean-maize). Adult abundance monitored with yellow sticky and pheromone traps indicate that maize in three crop rotation has the smallest attraction to the migratory WCR beetles. The choice of three crop rotation seems to be the most promising choice for maize growing, which

  6. The effects of a winter cover crop on Diabrotica virgifera (Coleoptera: Chrysomelidae) populations and beneficial arthropod communities in no-till maize.

    PubMed

    Lundgren, Jonathan G; Fergen, Janet K

    2010-12-01

    The effects of an autumn-planted, spring-killed, grass cover crop (Elymus trachycaulus [Link] Gould ex Shinners) on populations of Diabrotica virgifera virgifera LeConte and its predator community were evaluated in South Dakota maize fields over two seasons. Abundance and size of D. virgifera larvae and adults and sex ratio of adults were measured in maize produced under two treatments (i.e., a winter cover crop or bare soil), as were maize root damage and the abundance and diversity of the predator communities collected on the soil surface and in the soil column. First and second instars and adults of D. virgifera were similarly abundant in the two treatments, but third instars were significantly fewer in maize planted after a winter cover crop. Larvae developed at different rates in the two treatments, and second instars were significantly smaller (head capsule width and body length) in the maize planted after a cover crop. First and third instars and adults were of similar size in the two treatments, and adult sex ratios were also similar. Although initially similar, predator populations increased steadily in the cover-cropped maize, which led to a significantly greater predator population by the time D. virgifera pupated. There was significantly less root damage in the cover-cropped maize. Predator communities were similarly diverse in both treatments. Predator abundance per plot was significantly and negatively correlated with the abundance of third instars per plot. Clearly, winter cover crops reduce D. virgifera performance and their damage to the crop, and we suspect that this reduction is caused by both environmental effects of the treatment on D. virgifera size and development, and of increased predation on the third instars of the pest. Additional data on the impact of cover crops on actual predation levels, grain yield and quality, and farmer profitability, and correlations among pest performance, crop characteristics, and predator populations and

  7. Absence of genetic divergence between western corn rootworms (Coleoptera: Chrysomelidae) resistant and susceptible to control by crop rotation.

    PubMed

    Miller, N J; Kim, K S; Ratcliffe, S T; Estoup, A; Bourguet, D; Guillemaud, T

    2006-06-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of corn, Zea mays L., in North America that has recently invaded Europe. A loss of ovipositional fidelity to cornfields has allowed the species to circumvent crop rotation as a means of control in part of its range in the United States. Analyses of variation at eight microsatellite loci provided no evidence for general genetic differentiation between samples of western corn rootworm collected in soybean, Glycine max (L.) Merr., fields and those collected in cornfields both inside and outside the rotation-resistance problem area. This result suggests that few or no barriers to gene flow exist between rotation-resistant and -susceptible rootworm populations. The implications of this result for the management of western corn rootworm in North America and Europe are discussed.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  9. Effects of Pyramided Bt Corn and Blended Refuges on Western Corn Rootworm and Northern Corn Rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Keweshan, Ryan S; Head, Graham P; Gassmann, Aaron J

    2015-04-01

    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 rootworm. In some cases Bt treatments reduced size of adults and delayed time of adult emergence, with effects most pronounced for pyramided corn. For both species, the number of adults that emerged from pyramided corn with a blended refuge was significantly lower than expected, based solely on emergence from pure stands of pyramided corn and non-Bt corn. The results of this study indicate that pyramided corn with a blended refuge substantially reduces survival of both western and northern corn rootworm, and as such, should be a useful tool within the context of a broader integrated pest management strategy.

  10. Effects of Pyramided Bt Corn and Blended Refuges on Western Corn Rootworm and Northern Corn Rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Keweshan, Ryan S; Head, Graham P; Gassmann, Aaron J

    2015-04-01

    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 rootworm. In some cases Bt treatments reduced size of adults and delayed time of adult emergence, with effects most pronounced for pyramided corn. For both species, the number of adults that emerged from pyramided corn with a blended refuge was significantly lower than expected, based solely on emergence from pure stands of pyramided corn and non-Bt corn. The results of this study indicate that pyramided corn with a blended refuge substantially reduces survival of both western and northern corn rootworm, and as such, should be a useful tool within the context of a broader integrated pest management strategy. PMID:26470183

  11. Delaying corn rootworm resistance to Bt corn.

    PubMed

    Tabashnik, Bruce E; Gould, Fred

    2012-06-01

    Transgenic crops producing Bacillus thuringiensis (Bt) toxins for insect control have been successful, but their efficacy is reduced when pests evolve resistance. To delay pest resistance to Bt crops, the U.S. Environmental Protection Agency (EPA) has required refuges of host plants that do not produce Bt toxins to promote survival of susceptible pests. Such refuges are expected to be most effective if the Bt plants deliver a dose of toxin high enough to kill nearly all hybrid progeny produced by matings between resistant and susceptible pests. In 2003, the EPA first registered corn, Zea mays L., producing a Bt toxin (Cry3Bb1) that kills western corn rootworm, Diabrotica virgifera virgifera LeConte, one of the most economically important crop pests in the United States. The EPA requires minimum refuges of 20% for Cry3Bb1 corn and 5% for corn producing two Bt toxins active against corn rootworms. We conclude that the current refuge requirements are not adequate, because Bt corn hybrids active against corn rootworms do not meet the high-dose standard, and western corn rootworm has rapidly evolved resistance to Cry3Bb1 corn in the laboratory, greenhouse, and field. Accordingly, we recommend increasing the minimum refuge for Bt corn targeting corn rootworms to 50% for plants producing one toxin active against these pests and to 20% for plants producing two toxins active against these pests. Increasing the minimum refuge percentage can help to delay pest resistance, encourage integrated pest management, and promote more sustainable crop protection.

  12. Impact of MON863 transgenic roots is equivalent on western corn rootworm larvae for a wide range of maize phenologies.

    PubMed

    Hibbard, Bruce E; El Khishen, Ahmed A; Vaughn, Ty T

    2009-08-01

    The effects of maize, Zea mays L., phenology on establishment, damage, and adult emergence of the western corn rootworm, Diabrotica virgifera virgifera LeConte, on MON863 transgenic maize expressing the Cry3Bb1 protein and its isoline was evaluated in field trials in 2002 and 2003. As expected, plant damage, western corn rootworm larval recovery, and adult emergence were significantly lower on MON863 than isoline maize. The average weight of larvae and adults recovered from MON863 and isoline maize was generally not significantly different. If western corn rootworm larvae were able to establish on transgenic rootworm-resistant plants, larval growth was relatively normal. Plant damage, the number of western corn rootworm larvae recovered, and adult emergence from MON863 did not significantly differ between egg hatch times from widely varying phenologies in either year of the study. Although the extractable level of Cry3Bb1 decreased significantly from vegetative (V)4 to V9 maize in previous studies, in the current study, the amount of Cry3Bb1 did not vary from V3 to R3 in a way that affected neonate survival by western corn rootworm larvae in the field.

  13. Effect of Seed Blends and Soil-Insecticide on Western and Northern Corn Rootworm Emergence from mCry3A+eCry3.1Ab Bt Maize.

    PubMed

    Frank, Daniel L; Kurtz, Ryan; Tinsley, Nicholas A; Gassmann, Aaron J; Meinke, Lance J; Moellenbeck, Daniel; Gray, Michael E; Bledsoe, Larry W; Krupke, Christian H; Estes, Ronald E; Weber, Patrick; Hibbard, Bruce E

    2015-06-01

    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 seed blend treatments resulted in 2.8-, 3.2-, and 4.2-fold more beetles than from the 100:0 treatment. The addition of Force CS (tefluthrin) significantly reduced western corn rootworm beetle emergence for each of the three treatments to which it was applied. Force CS also significantly delayed the number of days to 50% beetle emergence in western corn rootworms. Time to 50% beetle emergence in the 100% mCry3A+eCry3.1Ab treatment with Force CS was delayed 13.7 d when compared with western corn rootworm beetle emergence on near-isoline corn. These data are discussed in terms of rootworm resistance management.

  14. Effect of Seed Blends and Soil-Insecticide on Western and Northern Corn Rootworm Emergence from mCry3A+eCry3.1Ab Bt Maize.

    PubMed

    Frank, Daniel L; Kurtz, Ryan; Tinsley, Nicholas A; Gassmann, Aaron J; Meinke, Lance J; Moellenbeck, Daniel; Gray, Michael E; Bledsoe, Larry W; Krupke, Christian H; Estes, Ronald E; Weber, Patrick; Hibbard, Bruce E

    2015-06-01

    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 seed blend treatments resulted in 2.8-, 3.2-, and 4.2-fold more beetles than from the 100:0 treatment. The addition of Force CS (tefluthrin) significantly reduced western corn rootworm beetle emergence for each of the three treatments to which it was applied. Force CS also significantly delayed the number of days to 50% beetle emergence in western corn rootworms. Time to 50% beetle emergence in the 100% mCry3A+eCry3.1Ab treatment with Force CS was delayed 13.7 d when compared with western corn rootworm beetle emergence on near-isoline corn. These data are discussed in terms of rootworm resistance management. PMID:26470254

  15. Early Detection and Mitigation of Resistance to Bt Maize by Western Corn Rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Andow, David A; Pueppke, Steven G; Schaafsma, Arthur W; Gassmann, Aaron J; Sappington, Thomas W; Meinke, Lance J; Mitchell, Paul D; Hurley, Terrance M; Hellmich, Richard L; Porter, R Pat

    2016-02-01

    Transgenic Bt maize that produces less than a high-dose has been widely adopted and presents considerable insect resistance management (IRM) challenges. Western corn rootworm, Diabrotica virgifera virgifera LeConte, has rapidly evolved resistance to Bt maize in the field, leading to local loss of efficacy for some corn rootworm Bt maize events. Documenting and responding to this resistance has been complicated by a lack of rapid diagnostic bioassays and by regulatory triggers that hinder timely and effective management responses. These failures are of great concern to the scientific and agricultural community. Specific challenges posed by western corn rootworm resistance to Bt maize, and more general concerns around Bt crops that produce less than a high-dose of Bt toxin, have caused uncertainty around current IRM protocols. More than 15 years of experience with IRM has shown that high-dose and refuge-based IRM is not applicable to Bt crops that produce less than a high-dose. Adaptive IRM approaches and pro-active, integrated IRM-pest management strategies are needed and should be in place before release of new technologies that produce less than a high-dose. We suggest changes in IRM strategies to preserve the utility of corn rootworm Bt maize by 1) targeting local resistance management earlier in the sequence of responses to resistance and 2) developing area-wide criteria to address widespread economic losses. We also favor consideration of policies and programs to counteract economic forces that are contributing to rapid resistance evolution.

  16. 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

  17. Field-evolved resistance to Bt maize by western corn rootworm: predictions from the laboratory and effects in the field.

    PubMed

    Gassmann, Aaron J

    2012-07-01

    Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) provide an effective management tool for many key insect pests. However, pest species have repeatedly demonstrated their ability to adapt to management practices. Results from laboratory selection experiments illustrate the capacity of pest species to evolve Bt resistance. Furthermore, resistance has been documented to Bt sprays in the field and greenhouse, and more recently, by some pests to Bt crops in the field. In 2009, fields were discovered in Iowa (USA) with populations of western corn rootworm, Diabrotica virgifera virgifera LeConte, that had evolved resistance to maize that produces the Bt toxin Cry3Bb1. Fields with resistant insects in 2009 had been planted to Cry3Bb1 maize for at least three consecutive years and as many as 6years. Computer simulation models predicted that the western corn rootworm might evolve resistance to Bt maize in as few as 3years. Laboratory and field data for interactions between western corn rootworm and Bt maize indicate that currently commercialized products are not high-dose events, which increases the risk of resistance evolution because non-recessive resistance traits may enhance survival on Bt maize. Furthermore, genetic analysis of laboratory strains of western corn rootworm has found non-recessive inheritance of resistance. Field studies conducted in two fields identified as harboring Cry3Bb1-resistant western corn rootworm found that survival of western corn rootworm did not differ between Cry3Bb1 maize and non-Bt maize and that root injury to Cry3Bb1 maize was higher than injury to other types of Bt maize or to maize roots protected with a soil insecticide. These first cases of field-evolved resistance to Bt maize by western corn rootworm provide an early warning and point to the need to apply better integrated pest management practices when using Bt maize to manage western corn rootworm.

  18. Independent action between DvSnf7 RNA and Cry3Bb1 protein in southern corn rootworm, Diabrotica undecimpunctata howardi and Colorado potato beetle, Leptinotarsa decemlineata.

    PubMed

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

    2015-01-01

    In recent years, corn rootworm (CRW)-resistant maize events producing two or more CRW-active Bt proteins have been commercialized to enhance efficacy against the target pest(s) by providing multiple modes of action (MoA). The maize hybrid MON 87411 has been developed that produces the CRW-active Cry3Bb1 Bt protein (hereafter Cry3Bb1) and expresses a RNAi-mediated MoA that also targets CRW. As part of an environmental risk assessment for MON 87411, the potential for an interaction between the CRW-active DvSnf7 RNA (hereafter DvSnf7) and Cry3Bb1 was assessed in 12-day diet incorporation bioassays with the southern corn rootworm (SCR, Diabrotica undecimpunctata howardi). The potential for an interaction between DvSnf7 and Cry3Bb1 was evaluated with two established experimental approaches. The first approach evaluated each substance alone and in combination over three different response levels. For all three response levels, observed responses were shown to be additive and not significantly different from predicted responses under the assumption of independent action. The second approach evaluated the potential for a fixed sub-lethal concentration of Cry3Bb1 to decrease the median lethal concentration (LC50) of DvSnf7 and vice-versa. With this approach, the LC50 value of DvSnf7 was not altered by a sub-lethal concentration of Cry3Bb1 and vice-versa. In addition, the potential for an interaction between the Cry3Bb1 and DvSnf7 was tested with Colorado potato beetle (CPB, Leptinotarsa decemlineata), which is sensitive to Cry3Bb1 but not DvSnf7. CPB assays also demonstrated that DvSnf7 does not alter the activity of Cry3Bb1. The results from this study provide multiple lines of evidence that DvSnf7 and Cry3Bb1 produced in MON 87411 have independent action. PMID:25734482

  19. Independent Action between DvSnf7 RNA and Cry3Bb1 Protein in Southern Corn Rootworm, Diabrotica undecimpunctata howardi and Colorado Potato Beetle, Leptinotarsa decemlineata

    PubMed Central

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

    2015-01-01

    In recent years, corn rootworm (CRW)-resistant maize events producing two or more CRW-active Bt proteins have been commercialized to enhance efficacy against the target pest(s) by providing multiple modes of action (MoA). The maize hybrid MON 87411 has been developed that produces the CRW-active Cry3Bb1 Bt protein (hereafter Cry3Bb1) and expresses a RNAi-mediated MoA that also targets CRW. As part of an environmental risk assessment for MON 87411, the potential for an interaction between the CRW-active DvSnf7 RNA (hereafter DvSnf7) and Cry3Bb1 was assessed in 12-day diet incorporation bioassays with the southern corn rootworm (SCR, Diabrotica undecimpunctata howardi). The potential for an interaction between DvSnf7 and Cry3Bb1 was evaluated with two established experimental approaches. The first approach evaluated each substance alone and in combination over three different response levels. For all three response levels, observed responses were shown to be additive and not significantly different from predicted responses under the assumption of independent action. The second approach evaluated the potential for a fixed sub-lethal concentration of Cry3Bb1 to decrease the median lethal concentration (LC50) of DvSnf7 and vice-versa. With this approach, the LC50 value of DvSnf7 was not altered by a sub-lethal concentration of Cry3Bb1 and vice-versa. In addition, the potential for an interaction between the Cry3Bb1 and DvSnf7 was tested with Colorado potato beetle (CPB, Leptinotarsa decemlineata), which is sensitive to Cry3Bb1 but not DvSnf7. CPB assays also demonstrated that DvSnf7 does not alter the activity of Cry3Bb1. The results from this study provide multiple lines of evidence that DvSnf7 and Cry3Bb1 produced in MON 87411 have independent action. PMID:25734482

  20. Independent action between DvSnf7 RNA and Cry3Bb1 protein in southern corn rootworm, Diabrotica undecimpunctata howardi and Colorado potato beetle, Leptinotarsa decemlineata.

    PubMed

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

    2015-01-01

    In recent years, corn rootworm (CRW)-resistant maize events producing two or more CRW-active Bt proteins have been commercialized to enhance efficacy against the target pest(s) by providing multiple modes of action (MoA). The maize hybrid MON 87411 has been developed that produces the CRW-active Cry3Bb1 Bt protein (hereafter Cry3Bb1) and expresses a RNAi-mediated MoA that also targets CRW. As part of an environmental risk assessment for MON 87411, the potential for an interaction between the CRW-active DvSnf7 RNA (hereafter DvSnf7) and Cry3Bb1 was assessed in 12-day diet incorporation bioassays with the southern corn rootworm (SCR, Diabrotica undecimpunctata howardi). The potential for an interaction between DvSnf7 and Cry3Bb1 was evaluated with two established experimental approaches. The first approach evaluated each substance alone and in combination over three different response levels. For all three response levels, observed responses were shown to be additive and not significantly different from predicted responses under the assumption of independent action. The second approach evaluated the potential for a fixed sub-lethal concentration of Cry3Bb1 to decrease the median lethal concentration (LC50) of DvSnf7 and vice-versa. With this approach, the LC50 value of DvSnf7 was not altered by a sub-lethal concentration of Cry3Bb1 and vice-versa. In addition, the potential for an interaction between the Cry3Bb1 and DvSnf7 was tested with Colorado potato beetle (CPB, Leptinotarsa decemlineata), which is sensitive to Cry3Bb1 but not DvSnf7. CPB assays also demonstrated that DvSnf7 does not alter the activity of Cry3Bb1. The results from this study provide multiple lines of evidence that DvSnf7 and Cry3Bb1 produced in MON 87411 have independent action.

  1. Genetic monitoring of western corn rootworm (Coleoptera: Chrysomelidae) populations on a microgeographic scale.

    PubMed

    Ivkosic, S A; Gorman, J; Lemic, D; Mikac, K M

    2014-06-01

    Microsatellite and mitochondrial DNA genetic monitoring of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was undertaken in Croatia and Serbia from 1996 to 2011 and in the United States in 2011. The seven U.S. populations displayed the greatest allelic diversity. In Europe, the highest number of alleles was found in Rugvica, Croatia, and Surčin, Serbia, the two sites closest to international airports. The highest number of mitochondrial (mt) DNA haplotypes was recorded from Croatia in 1996. From 2009 to 2011, haplotype diversity declined, and Croatia and Serbia had a single fixed haplotype. U.S. continuous maize locations had one haplotype, while three haplotypes were found at crop-rotated locations. Minimal temporal genetic differentiation was found within and between populations in Europe and the United States. Bayesian cluster analysis identified two genetic clusters that grouped western corn rootworm from Croatia and Serbia separately from U.S. populations; however, these clusters were not neat, and numerous U.S. individuals had both European and U.S. ancestry, suggesting bidirectional gene flow. Bottlenecks were identified within most Croatian populations sampled in 1996, only two populations in 2009, and in all populations in 2011. Bottlenecks were not identified from Serbia from 1996 to 2011 or from the United States in 2011. As suspected Serbia was identified as the geographic source of western corn rootworm in Croatia. The temporal genetic monitoring undertaken allowed a deeper understanding of the population genetics of western corn rootworm in Croatia, neighboring Serbia, and its geographic source in the United States. The data obtained can be used to inform western corn rootworm pest management strategies in Croatia and Europe.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Susceptibility of the northern corn rootworm (NCR), 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. Lar...

  3. Carbon isotope ratios document that the elytra of western corn rootworm (Coleoptera: Chrysomelidae) reflects adult versus larval feeding and later instar larvae prefer Bt corn to alternate hosts.

    PubMed

    Hiltpold, Ivan; Adamczyk, John J; Higdon, Matthew L; Clark, Thomas L; Ellersieck, Mark R; Hibbard, Bruce E

    2014-06-01

    In much of the Corn Belt and parts of Europe, the western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect pest of maize. The need for additional basic knowledge of this pest has been highlighted while developing resistance management plans for insecticidal genetically modified crops. This study evaluated the possibility of tracking feeding habits of western corn rootworm larvae using stable carbon isotope signatures. Plants accumulate different ratios of (13)C:(12)C isotopes, usually expressed as δ(13)C, according to whether they use the C3 or C4 photosynthetic pathway. Herbivore biomass is expected to reflect the δ(13)C of the food they eat. For the current experiment, western corn rootworm larvae were grown on different species of plants exhibiting different δ(13)C values. The δ(13)C values were then measured in elytra of emerged beetles. When beetles were unfed, biomass reflected larval feeding. When beetles were fed for 31 d postemergence, δ(13)C values of elytra almost exclusively reflected adult feeding. These results suggest the use of caution in the interpretation of δ(13)C data aiming to document larval diet history when adult feeding history is unknown. The technique was also used to evaluate western corn rootworm larval choice between alternate hosts and maize with and without genetically modified (Bt) traits aimed at their control. Propensity for feeding on alternate hosts versus maize was biased toward feeding on maize regardless whether the maize had Bt or not, suggesting western corn rootworm larvae were not repelled by Bt. These data will be helpful for regulators in interpreting western corn rootworm feeding data on Bt maize. PMID:24874160

  4. Early Detection and Mitigation of Resistance to Bt Maize by Western Corn Rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Andow, David A; Pueppke, Steven G; Schaafsma, Arthur W; Gassmann, Aaron J; Sappington, Thomas W; Meinke, Lance J; Mitchell, Paul D; Hurley, Terrance M; Hellmich, Richard L; Porter, R Pat

    2016-02-01

    Transgenic Bt maize that produces less than a high-dose has been widely adopted and presents considerable insect resistance management (IRM) challenges. Western corn rootworm, Diabrotica virgifera virgifera LeConte, has rapidly evolved resistance to Bt maize in the field, leading to local loss of efficacy for some corn rootworm Bt maize events. Documenting and responding to this resistance has been complicated by a lack of rapid diagnostic bioassays and by regulatory triggers that hinder timely and effective management responses. These failures are of great concern to the scientific and agricultural community. Specific challenges posed by western corn rootworm resistance to Bt maize, and more general concerns around Bt crops that produce less than a high-dose of Bt toxin, have caused uncertainty around current IRM protocols. More than 15 years of experience with IRM has shown that high-dose and refuge-based IRM is not applicable to Bt crops that produce less than a high-dose. Adaptive IRM approaches and pro-active, integrated IRM-pest management strategies are needed and should be in place before release of new technologies that produce less than a high-dose. We suggest changes in IRM strategies to preserve the utility of corn rootworm Bt maize by 1) targeting local resistance management earlier in the sequence of responses to resistance and 2) developing area-wide criteria to address widespread economic losses. We also favor consideration of policies and programs to counteract economic forces that are contributing to rapid resistance evolution. PMID:26362989

  5. Methyl Anthranilate as a Repellent for Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae).

    PubMed

    Bernklau, E J; Hibbard, B E; Norton, A P; Bjostad, L B

    2016-08-01

    Methyl anthranilate was identified as the active compound in extracts of maize (Zea mays L.) roots that were shown to be repellent to neonate western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae. A bioassay-driven approach was used to isolate the active material from diethyl ether extracts of roots from germinating maize seeds. Separation of the extract on a Florisil column yielded an active fraction of 90:10 hexane:diethyl ether. Analysis with gas chromatography-mass spectrometry identified two compounds in the active fraction: indole (2,3-benzopyrrole) and methyl anthranilate (methyl 2-aminobenzoate). When tested in behavioral bioassays, methyl anthranilate elicited a significant (P < 0.05) repellent response at doses of 1, 10, and 100 µg. In subsequent single-choice bioassays, 1, 10, and 100 µg of methyl anthranilate prevented larvae from approaching 10 mmol/mol concentrations of carbon dioxide, which is normally highly attractive to the larvae. Indole, the other compound identified from the active fraction, did not elicit a behavioral response by the larvae. Methyl anthranilate has potential for development as a management tool for western corn rootworm larvae and may be best suited for use in a push-pull control strategy. PMID:27122493

  6. Methyl Anthranilate as a Repellent for Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae).

    PubMed

    Bernklau, E J; Hibbard, B E; Norton, A P; Bjostad, L B

    2016-08-01

    Methyl anthranilate was identified as the active compound in extracts of maize (Zea mays L.) roots that were shown to be repellent to neonate western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae. A bioassay-driven approach was used to isolate the active material from diethyl ether extracts of roots from germinating maize seeds. Separation of the extract on a Florisil column yielded an active fraction of 90:10 hexane:diethyl ether. Analysis with gas chromatography-mass spectrometry identified two compounds in the active fraction: indole (2,3-benzopyrrole) and methyl anthranilate (methyl 2-aminobenzoate). When tested in behavioral bioassays, methyl anthranilate elicited a significant (P < 0.05) repellent response at doses of 1, 10, and 100 µg. In subsequent single-choice bioassays, 1, 10, and 100 µg of methyl anthranilate prevented larvae from approaching 10 mmol/mol concentrations of carbon dioxide, which is normally highly attractive to the larvae. Indole, the other compound identified from the active fraction, did not elicit a behavioral response by the larvae. Methyl anthranilate has potential for development as a management tool for western corn rootworm larvae and may be best suited for use in a push-pull control strategy.

  7. Mortality of western corn rootworm larvae on MIR604 transgenic maize roots: field survivorship has no significant impact on survivorship of F1 progeny on MIR604.

    PubMed

    Hibbard, Bruce E; Clark, Thomas L; Ellersieck, Mark R; Meihls, Lisa N; El Khishen, Ahmed A; Kaster, Von; Steiner, Henry-York; Kurtz, Ryan

    2010-12-01

    Mortality of western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae due to MIR604 transgenic corn, Zea mays L., expressing the modified Cry3A (mCry3A) protein relative to survivorship on corn with the same genetic background without the gene (isoline corn) was evaluated at three Missouri sites in both 2005 and 2006. We made these comparisons by using wild-type western corn rootworm at three different egg densities (6,000, 3,000, and 1,500 eggs per m) so that the role of density-dependent mortality would be known. The mortality due to the mCry3A protein was 94.88% when averaged across all environments and both years. Fifty percent emergence of beetles was delayed approximately 5.5 d. Beetles were kept alive and their progeny evaluated on MIR604 and isoline corn in the greenhouse to determine whether survivorship on MIR604 in the field for one generation increased survivorship on MIR604 in the greenhouse in the subsequent generation. There was no significant difference in survivorship on MIR604 in greenhouse assays between larvae whose parents survived isoline and larvae whose parents survived MIR604 in the field the previous generation, indicating that many susceptible beetles survived MIR604 in the field the previous season along with any potentially resistant beetles. The data are discussed in terms of rootworm insect resistance management.

  8. Effect of MIR604 transgenic maize at different stages of development on western corn rootworm (Coleoptera: Chrysomelidae) in a central Missouri field environment.

    PubMed

    Frank, Daniel L; Bukowsky, Rebecca; French, B Wade; Hibbard, Bruce E

    2011-12-01

    The establishment and survival of western corn rootworm, Diabrotica virgifera virgifera LeConte, was evaluated on transgenic Bacillus thuringiensis Berliner maize, Zea mays L., expressing the mCry3A protein (MIR604) and non-Bt maize with the same genetic background (isoline maize) at different stages of development in 2007 and 2008. Overall, western corn rootworm larval recovery, root damage, and adult emergence were significantly higher on isoline maize compared with MIR604. The number of larvae and adults collected from MIR604 did not significantly differ among egg hatch dates from each maize developmental stage evaluated in either year. In 2007, damage to isoline maize roots was lower than expected and never exceeded 0.24 nodes of damage. In 2008, over 0.60 nodes of damage occurred on isoline maize roots. The mean weight and head capsule width of larvae and adults recovered from MIR604 and isoline maize were generally not significantly different. Results are discussed in relation to insect resistance management of western corn rootworm.

  9. Historical and contemporary population genetics of the invasive western corn rootworm (Coleoptera: Chrysomelidae) in Croatia.

    PubMed

    Lemic, D; Mikac, K M; Bažok, R

    2013-08-01

    Classical population genetic analyses were used to investigate populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, in Croatia in 1996 and 2009. The number of alleles was low in both 1996 and 2009; however, more alleles were found in the putative populations surveyed in 2009. Croatia had only 51% of the alleles recorded from the United States and 69% from Europe. However, 10 private (unique) alleles were found in Croatia, which were not found previously in Europe. Most populations were out of Hardy-Weinberg equilibrium, although no linkage disequilibrium was found. Low to no genetic differentiation was found between population pairwise comparisons in 1996, with a greater level of differentiation found between populations sampled in 2009. Using the program STRUCTURE, a single genetic cluster was found for populations sampled in 1996 and 2009. However, two genetic clusters were detected when the 1996 and 2009 data were combined, indicating significant temporal differentiation. Isolation by distance pattern of gene flow characterized populations sampled in 2009 only when the most distant population of Ogulin (the head of the expansion front) was included in the analysis. When Ogluin was excluded from the 2009 analysis no isolation by distance pattern was found. The possible impact that control practices have had on the population genetics of D. v. virgifera in Croatia from 1996 to 2009 are discussed in light of the temporal genetics differences found.

  10. 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

    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

  11. 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

  12. Impact of western corn rootworm (Coleoptera: Chrysomelidae) on sweet corn and evaluation of insecticidal and cultural control options.

    PubMed

    Hoffmann, M P; Kirkwyland, J J; Gardner, J

    2000-06-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte, is an important pest of corn, Zea mays L., causing yield losses from root damage, plant lodging, and silk feeding. Because little is known about its impact on sweet corn, we conducted research to evaluate the combined effects of insecticide, planting date, and cultivar on root damage, plant lodging, and yield in central New York sweet corn. We also examined the influence of planting date and cultivar on the emergence of adult western corn rootworms. The research was conducted in 1994 and again in 1995 by using a split-split plot experimental design with insecticide as main plot, planting date as subplot, and cultivar as sub-subplot. The effect of cultivar on beetle emergence was not significant. Root damage was not correlated with adult emergence in 1994 but was positively correlated in 1995. In 1994, there was no interaction of the main factors, and all factors had a significant impact on root damage. In 1995 there was an interaction of insecticide and planting date, and of cultivar and planting date. Generally, root damage was reduced by insecticide and later planting. Plant lodging was affected by the interaction of insecticide and planting date, and the interaction of cultivar and planting date, for both years of the study. As with root damage, lodging was reduced with insecticide treatment and later planting but also was dependent on cultivar. In 1994 and especially in 1995, silk clipping by adult western corn rootworms precluded much inference about how yield was influenced by larval feeding damage on roots. The number of emerging western corn rootworm adults was lower and later in later plantings. PMID:10902334

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

    PubMed

    Venkata, Bala Puchakayala; Lauter, Nick; Li, Xu; Chapple, Clint; Krupke, Christian; Johal, Gurmukh; Moose, Stephen

    2013-01-01

    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 of alternate hosts. Conversely, the corn foliage is largely neglected as a food source by WCR beetles, leading to a perception of a passive interaction between the two. We report here a novel recessive mutation of corn that was identified and named after its foliar susceptibility to corn rootworm beetles (crw1). The crw1 mutant under field conditions was exceptionally susceptible to foliar damage by WCR beetles in an age-specific manner. It exhibits pleiotropic defects on cell wall biochemistry, morphology of leaf epidermal cells and lower structural integrity via differential accumulation of cell wall bound phenolic acids. These findings indicate that crw1 is perturbed in a pathway that was not previously ascribed to WCR susceptibility, as well as implying the presence of an active mechanism(s) deterring WCR beetles from devouring corn foliage. The discovery and characterization of this mutant provides a unique opportunity for genetic analysis of interactions between maize and adult WCR beetles and identify new strategies to control the spread and invasion of this destructive pest.

  14. crw1 - A Novel Maize Mutant Highly Susceptible to Foliar Damage by the Western Corn Rootworm Beetle

    PubMed Central

    Venkata, Bala Puchakayala; Lauter, Nick; Li, Xu; Chapple, Clint; Krupke, Christian; Johal, Gurmukh; Moose, Stephen

    2013-01-01

    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 of alternate hosts. Conversely, the corn foliage is largely neglected as a food source by WCR beetles, leading to a perception of a passive interaction between the two. We report here a novel recessive mutation of corn that was identified and named after its foliar susceptibility to corn rootworm beetles (crw1). The crw1 mutant under field conditions was exceptionally susceptible to foliar damage by WCR beetles in an age-specific manner. It exhibits pleiotropic defects on cell wall biochemistry, morphology of leaf epidermal cells and lower structural integrity via differential accumulation of cell wall bound phenolic acids. These findings indicate that crw1 is perturbed in a pathway that was not previously ascribed to WCR susceptibility, as well as implying the presence of an active mechanism(s) deterring WCR beetles from devouring corn foliage. The discovery and characterization of this mutant provides a unique opportunity for genetic analysis of interactions between maize and adult WCR beetles and identify new strategies to control the spread and invasion of this destructive pest. PMID:23951124

  15. Analysis of the dynamics of adaptation to transgenic corn and crop rotation by western corn rootworm (Coleoptera: Chrysomelidae) using a daily time-step model.

    PubMed

    Crowder, D W; Onstad, D W; Cray, M E; Pierce, C M F; Hager, A G; Ratcliffe, S T; Steffey, K L

    2005-04-01

    Western corn rootworm, Diabrotica virgifera virgifera LeConte, has overcome crop rotation in several areas of the north central United States. The effectiveness of crop rotation for management of corn rootworm has begun to fail in many areas of the midwestern United States, thus new management strategies need to be developed to control rotation-resistant populations. Transgenic corn, Zea mays L., effective against western corn rootworm, may be the most effective new technology for control of this pest in areas with or without populations adapted to crop rotation. We expanded a simulation model of the population dynamics and genetics of the western corn rootworm for a landscape of corn; soybean, Glycine max (L.); and other crops to study the simultaneous development of resistance to both crop rotation and transgenic corn. Results indicate that planting transgenic corn to first-year cornfields is a robust strategy to prevent resistance to both crop rotation and transgenic corn in areas where rotation-resistant populations are currently a problem or may be a problem in the future. In these areas, planting transgenic corn only in continuous cornfields is not an effective strategy to prevent resistance to either trait. In areas without rotation-resistant populations, gene expression of the allele for resistance to transgenic corn, R, is the most important factor affecting the evolution of resistance. If R is recessive, resistance can be delayed longer than 15 yr. If R is dominant, resistance may be difficult to prevent. In a sensitivity analysis, results indicate that density dependence, rotational level in the landscape, and initial allele frequency are the three most important factors affecting the results.

  16. 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

  17. Selection for resistance to mCry3A-expressing transgenic corn in western corn rootworm.

    PubMed

    Meihls, Lisa N; Higdon, Matthew L; Ellersieck, Mark; Hibbard, Bruce E

    2011-06-01

    To investigate the development of resistance to mCry3A, a laboratory colony of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was established from field survivors of mCry3A-expressing (MIR604) corn, Zea mays L. Feral adults emerging from MIR604 (selected) and isoline (control) field plots were collected and returned to the laboratory. Progeny of each colony was reared one generation on isoline corn and then crossed reciprocally with a nondiapausing colony. The resulting nondiapausing progeny were then reared on greenhouse corn in accordance with the wild type parent's origin (on MIR604 or isoline corn). After four, seven, and 10 total generations of selection, the resistance ratio of the selected colony was 0.5, 4.3, and 15.4 in terms of lethal concentration (LC)50 values in toxicity assays, with the latter two LC50 values being significant. After seven generations of selection in total, selected and control colonies were screened on MIR604 and isoline corn under field conditions. There was a significant colony x corn pedigree interaction in terms of plant damage. There was no significant difference in damage between MIR604 and isoline corn, whereas this difference was significant for the control colony. After 14 generations of selection, a seedling bioassay was performed. Again, there was a significant colony x corn pedigree interaction, this time in terms of the number of larvae recovered. There was no significant difference in the number of larvae recovered from MIR604 and isoline corn for the selected colony, whereas this difference was significant for the control colony, although larval size was greater on isoline corn for both colonies. Resistance has developed in western corn rootworm laboratory colonies to all Bt proteins currently registered for corn rootworm management, which emphasizes the importance of adhering to resistance management plans for maintaining product efficacy.

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

    PubMed

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

    2013-07-16

    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.

  19. 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.

  20. Larval susceptibility of an insecticide-resistant western corn rootworm (Coleoptera: Chrysomelidae) population to soil insecticides: laboratory bioassays, assays of detoxification enzymes, and field performance.

    PubMed

    Wright, R J; Scharf, M E; Meinke, L J; Zhou, X; Siegfried, B D; Chandler, L D

    2000-02-01

    Soil insecticides were evaluated in laboratory and field studies against larvae of an insecticide resistant population (Phelps County, NE) of western corn rootworm, Diabrotica virgifera virgifera LeConte. Insecticide toxicity was evaluated by topical application of technical insecticides to 3rd instars from Saunders County, NE (susceptible) and Phelps County populations. Resistance ratios (LD50 Phelps County/LD50 Saunders County) for the insecticides methyl parathion, tefluthrin, carbofuran, terbufos, and chlorpyrifos were 28.0, 9.3, 8.7, 2.6 and 1.3, respectively. Biochemical investigation of suspected enzymatic resistance mechanisms in 3rd instars identified significant elevation of esterase activity (alpha and beta naphthyl acetate hydrolysis [3.8- and 3.9-fold]). Examination of 3rd instar esterases by native PAGE identified increased intensity of several isoenzymes in the resistant population. Assays of cytochrome P450 activity (4-CNMA demethylation and aldrin epoxidation) did not identify elevated activity in resistant 3rd instars. Granular soil insecticides were applied at planting to corn, Zea mays L., in replicated field trials in 1997 and 1998 at the same Phelps County site as the source of resistant rootworms for the laboratory studies. In 1997, planting time applications of Counter 20CR, Counter 15 G (terbufos), and Lorsban 15 G (chlorpyrifos) resulted in the lowest root injury ratings (1-6 Iowa scale); 2.50, 2.55, 2.65, respectively (untreated check root rating of 4.55). In 1998, all insecticides performed similarly against a lower rootworm density (untreated check root rating of 3.72). These studies suggest that resistance previously documented in adults also is present in 3rd instars, esterases are possibly involved as resistance mechanisms, and resistance to methyl parathion in adults is also evident in larvae, but does not confer cross-resistance in larvae to all organophosphate insecticides.

  1. Evaluation of corn hybrids expressing Cry34Ab1/Cry35Ab1 and Cry3BbL against the western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Prasifka, P L; Rule, D M; Storer, N P; Nolting, S P; Hendrix, W H

    2013-04-01

    Studies were conducted across nine U.S. states, over 5 yr, to characterize the efficacy of transgenic corn (Zea mays L.) hybrids producing insecticidal proteins derived from Bacillus thuringiensis (Bt) for control of western corn rootworm, Diabrotica virgifera virgifera Le Conte. Hybrids tested had the same genetic background, contained one of two single events (DAS-59122-7 expressing Cry34Ab1/Cry35Ab1 or MON 88017 expressing Cry3Bb1) or a pyramid consisting of both rootworm-active events (SmartStax traits) and were compared with a non-Bt near isoline. Frequency analyses of root feeding data showed that hybrids containing both events sustained less root damage (0-3 node injury scale) than hybrids containing either event alone. The levels of root protection provided by MON 88017 and DAS-59122-7 were not different from each other. Efficacy was also evaluated based on consistency of protection, based on the proportion of plants with root ratings of either < or = 0.25 or < 1.00 on the node injury scale. The combination of two modes of action in SmartStax provided greater product consistency over a single mode of action at the 0.25 level and all hybrids producing Bt proteins provided equally high consistency at the 1.00 level. Overall these data show single and multiple mode of action hybrids provided high, consistent protection over the past 5 yr across the trial geography; however, pyramiding the rootworm Bt events provided greater and more consistent root protection. These findings also support that pyramided traits like SmartStax (Cry3Bb1 + Cry34Ab1/Cry35Ab1) remain a viable strategy for delaying resistance to either trait.

  2. Patterns of differential gene expression in adult rotation-resistant and wild-type western corn rootworm digestive tracts.

    PubMed

    Chu, Chia-Ching; Zavala, Jorge A; Spencer, Joseph L; Curzi, Matías J; Fields, Christopher J; Drnevich, Jenny; Siegfried, Blair D; Seufferheld, Manfredo J

    2015-08-01

    The western corn rootworm (WCR,Diabrotica virgifera virgifera LeConte) is an important pest of corn. Annual crop rotation between corn and soybean disrupts the corn-dependent WCR life cycle and is widely adopted to manage this pest. This strategy selected for rotation-resistant (RR) WCR with reduced ovipositional fidelity to corn. Previous studies revealed that RR-WCR adults exhibit greater tolerance of soybean diets, different gut physiology, and host-microbe interactions compared to rotation-susceptible wild types (WT). To identify the genetic mechanisms underlying these phenotypic changes, a de novo assembly of the WCR adult gut transcriptome was constructed and used for RNA-sequencing analyses of RNA libraries from different WCR phenotypes fed with corn or soybean diets. Global gene expression profiles of WT- and RR-WCR were similar when feeding on corn diets, but different when feeding on soybean. Using network-based methods, we identified gene modules transcriptionally correlated with the RR phenotype. Gene ontology enrichment analyses indicated that the functions of these modules were related to metabolic processes, immune responses, biological adhesion, and other functions/processes that appear to correlate to documented traits in RR populations. These results suggest that gut transcriptomic divergence correlated with brief soybean feeding and other physiological traits may exist between RR- and WT-WCR adults. PMID:26240606

  3. Emergence and Abundance of Western Corn Rootworm (Coleoptera: Chrysomelidae) in Bt Cornfields With Structured and Seed Blend Refuges.

    PubMed

    Hughson, Sarah A; Spencer, Joseph L

    2015-02-01

    To slow evolution of western corn rootworm (Diabrotica virgifera virgifera LeConte) resistance to Bt (Bacillus thuringiensis Berliner) corn hybrids, non-Bt "refuges" must be planted within or adjacent to Bt cornfields, allowing susceptible insects to develop without exposure to Bt toxins. Bt-susceptible adults from refuges are expected to find and mate with resistant adults that have emerged from Bt corn, reducing the likelihood that Bt-resistant offspring are produced. The spatial and temporal distribution of adults in four refuge treatments (20, 5, and 0% structured refuges and 5% seed blend) and adjacent soybean fields was compared from 2010 to 2012. Adult emergence (adults/trap/day) from refuge corn in structured refuge treatments was greater than that from Bt corn, except during the post-pollination period of corn phenology when emergence from refuge and Bt plants was often the same. Abundance of free-moving adults was greatest in and near refuge rows in structured refuge treatments during vegetative and pollination periods. By post-pollination, adult abundance became evenly distributed. In contrast, adult abundance in 5% seed blends and 0% refuges was evenly distributed, or nearly so, across plots throughout the season. The persistent concentration of adults in refuge rows suggests that structured refuge configurations may not facilitate the expected mixing of adults from refuge and Bt corn. Seed blends produce uniform distributions of adults across the field that may facilitate mating between Bt and refuge adults and ultimately delay the evolution of Bt resistance. PMID:26470111

  4. Western corn rootworm (Coleoptera: Chrysomelidae) dispersal and adaptation to single-toxin transgenic corn deployed with block or blended refuge.

    PubMed

    Pan, Zaiqi; Onstad, David W; Nowatzki, Timothy M; Stanley, Bruce H; Meinke, Lance J; Flexner, J Lindsey

    2011-08-01

    A simulation model of the temporal and spatial dynamics and population genetics of western corn rootworm, Diabrotica virgifera virgifera LeConte, was created to evaluate the use of block refuges and seed blends in the management of resistance to transgenic insecticidal corn (Zea mays L.). This Bt corn expresses one transgenic corn event, DAS-59122-7, that produces a binary insecticidal protein toxin (Cry34Ab1/Cry35Ab1) and provides host-plant resistance. The model incorporates the latest information about larval and adult behavior. Results of this modeling effort indicate that the seed-blend scenarios in many cases produced equal or greater durability than block refuges that were relocated each year. Resistance evolved in the most likely scenarios in 10-16 yr. Our standard analysis presumed complete adoption of 59122 corn by all farmers in our hypothetical region, no crop rotation, and 100% compliance with Insect Resistant Management (IRM) regulations. As compliance levels declined, resistance evolved faster when block refuges were deployed. Seed treatments that killed the pest when applied to all seeds in a seed blend or just to seeds in Bt corn blocks delayed evolution of resistance. Greater control of the pest population by the seed treatment facilitated longer durability of the transgenic trait. Therefore, data support the concept that pyramiding a transgenic insecticidal trait with a highly efficacious insecticidal seed treatment can delay evolution of resistance.

  5. Patterns of differential gene expression in adult rotation-resistant and wild-type western corn rootworm digestive tracts

    PubMed Central

    Chu, Chia-Ching; Zavala, Jorge A; Spencer, Joseph L; Curzi, Matías J; Fields, Christopher J; Drnevich, Jenny; Siegfried, Blair D; Seufferheld, Manfredo J

    2015-01-01

    The western corn rootworm (WCR,Diabrotica virgifera virgifera LeConte) is an important pest of corn. Annual crop rotation between corn and soybean disrupts the corn-dependent WCR life cycle and is widely adopted to manage this pest. This strategy selected for rotation-resistant (RR) WCR with reduced ovipositional fidelity to corn. Previous studies revealed that RR-WCR adults exhibit greater tolerance of soybean diets, different gut physiology, and host–microbe interactions compared to rotation-susceptible wild types (WT). To identify the genetic mechanisms underlying these phenotypic changes, a de novo assembly of the WCR adult gut transcriptome was constructed and used for RNA-sequencing analyses of RNA libraries from different WCR phenotypes fed with corn or soybean diets. Global gene expression profiles of WT- and RR-WCR were similar when feeding on corn diets, but different when feeding on soybean. Using network-based methods, we identified gene modules transcriptionally correlated with the RR phenotype. Gene ontology enrichment analyses indicated that the functions of these modules were related to metabolic processes, immune responses, biological adhesion, and other functions/processes that appear to correlate to documented traits in RR populations. These results suggest that gut transcriptomic divergence correlated with brief soybean feeding and other physiological traits may exist between RR- and WT-WCR adults. PMID:26240606

  6. Patterns of differential gene expression in adult rotation-resistant and wild-type western corn rootworm digestive tracts.

    PubMed

    Chu, Chia-Ching; Zavala, Jorge A; Spencer, Joseph L; Curzi, Matías J; Fields, Christopher J; Drnevich, Jenny; Siegfried, Blair D; Seufferheld, Manfredo J

    2015-08-01

    The western corn rootworm (WCR,Diabrotica virgifera virgifera LeConte) is an important pest of corn. Annual crop rotation between corn and soybean disrupts the corn-dependent WCR life cycle and is widely adopted to manage this pest. This strategy selected for rotation-resistant (RR) WCR with reduced ovipositional fidelity to corn. Previous studies revealed that RR-WCR adults exhibit greater tolerance of soybean diets, different gut physiology, and host-microbe interactions compared to rotation-susceptible wild types (WT). To identify the genetic mechanisms underlying these phenotypic changes, a de novo assembly of the WCR adult gut transcriptome was constructed and used for RNA-sequencing analyses of RNA libraries from different WCR phenotypes fed with corn or soybean diets. Global gene expression profiles of WT- and RR-WCR were similar when feeding on corn diets, but different when feeding on soybean. Using network-based methods, we identified gene modules transcriptionally correlated with the RR phenotype. Gene ontology enrichment analyses indicated that the functions of these modules were related to metabolic processes, immune responses, biological adhesion, and other functions/processes that appear to correlate to documented traits in RR populations. These results suggest that gut transcriptomic divergence correlated with brief soybean feeding and other physiological traits may exist between RR- and WT-WCR adults.

  7. Population patterns of Mexican corn rootworm (Coleoptera: Chrysomelidae) adults indicated by different sampling methods.

    PubMed

    Spurgeon, D W; Esquivel, J F; Suh, C P C

    2004-04-01

    The Mexican corn rootworm, Diabrotica virgifera zeae Krysan & Smith, is a serious pest of corn, Zea mays L., in several areas of Texas. Recent demonstrations of areawide adult control suggest this tactic has promise for rootworm management, but additional information regarding treatment thresholds and sampling methodology is needed. In 2000 and 2001 we examined the influence of distance into the field on rootworm captures by CRW and Pherocon AM traps, the fidelity of trap captures to population estimates from visual counts of beetles on plants (whole plant samples), and the seasonal population patterns indicated by each sampling method. Only the CRW trap consistently indicated reduced trap captures at the field margin compared with other distances. However, trends for the AM trap and whole plant samples suggested sampling on the field margin should be avoided. Population estimates at other distances into the field (2-30 m) were usually statistically similar. Thus, monitoring does not require trap placement far into the field. Both trap types indicated population peaks after flowering in corn, whereas plant samples indicated peak populations during tasseling and flowering. Both the CRW trap and plant samples showed the proportion of female beetles increased as the season progressed, but the CRW trap underestimated the proportion of females until after flowering. Regressions relating captures by traps to counts from plant samples indicated efficiency of both traps increased with increasing plant development. Our findings should increase acceptance of the CRW trap by producers and consultants and provide a rationale for development of improved, plant growth stage-specific treatment thresholds.

  8. Greenhouse-Selected Resistance to Cry3Bb1-Producing Corn in Three Western Corn Rootworm Populations

    PubMed Central

    Meihls, Lisa N.; Higdon, Matthew L.; Ellersieck, Mark R.; Tabashnik, Bruce E.; Hibbard, Bruce E.

    2012-01-01

    Transgenic corn producing the Bacillus thuringiensis (Bt) toxin Cry3Bb1 has been useful for controlling western corn rootworm, Diabrotica virgifera virgifera LeConte, one of the most economically important crop pests in the United States. However, rapid evolution of resistance by this beetle to Bt corn producing Cry3Bb1 has been reported previously from the laboratory, greenhouse, and field. Here we selected in the greenhouse for resistance to Cry3Bb1 corn in three colonies of WCR derived from Kansas, Minnesota, and Wisconsin, respectively. Three generations of rearing on Cry3Bb1 corn significantly increased larval survival on Cry3Bb1 corn, resulting in similar survival in the greenhouse for selected colonies on Cry3Bb1 corn and isoline corn that does not produce Bt toxin. After four to seven generations of rearing on Cry3Bb1 corn, survival in the field on Cry3Bb1 corn relative to isoline corn more than doubled for selected colonies (72%) compared with control colonies (33%). For both selected and control colonies, survival in the field was significantly lower on Cry3Bb1 corn than on isoline corn. On isoline corn, most fitness components were similar for selected colonies and control colonies. However, fecundity was significantly lower for selected colonies than control colonies, indicating a fitness cost associated with resistance. The rapid evolution of resistance by western corn rootworm to Bt corn reported here and previously underlines the importance of effective resistance management for this pest. PMID:23284656

  9. 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...

  10. 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

  11. Increased survival of western corn rootworm on transgenic corn within three generations of on-plant greenhouse selection

    PubMed Central

    Meihls, Lisa N.; Higdon, Matthew L.; Siegfried, Blair D.; Miller, Nicholas J.; Sappington, Thomas W.; Ellersieck, Mark R.; Spencer, Terence A.; Hibbard, Bruce E.

    2008-01-01

    To delay evolution of insect resistance to transgenic crops producing Bacillus thuringiensis (Bt) toxins, nearby “refuges” of host plants not producing Bt toxins are required in many regions. Such refuges are expected to be most effective in slowing resistance when the toxin concentration in Bt crops is high enough to kill all or nearly all insects heterozygous for resistance. However, Bt corn, Zea mays, introduced recently does not meet this “high-dose” criterion for control of western corn rootworm (WCR), Diabrotica virgifera virgifera. A greenhouse method of rearing WCR on transgenic corn expressing the Cry3Bb1 protein was used in which approximately 25% of previously unexposed larvae survived relative to isoline survival (compared to 1–4% in the field). After three generations of full larval rearing on Bt corn (Constant-exposure colony), WCR larval survival was equivalent on Bt corn and isoline corn in greenhouse trials, and the LC50 was 22-fold greater for the Constant-exposure colony than for the Control colony in diet bioassays with Cry3Bb1 protein on artificial diet. After six generations of greenhouse selection, the ratio of larval recovery on Bt corn to isoline corn in the field was 11.7-fold greater for the Constant-exposure colony than the Control colony. Removal from selection for six generations did not decrease survival on Bt corn in the greenhouse. The results suggest that rapid response to selection is possible in the absence of mating with unexposed beetles, emphasizing the importance of effective refuges for resistance management. PMID:19047626

  12. Interactions among Bt maize, entomopathogens, and rootworm species (Coleoptera: Chrysomelidae) in the field: effects on survival, yield and root injury

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two year field study was conducted to determine how a blend of entomopathogens interacts with Bt maize to affect survival of corn rootworm (Diabrotica spp.) species and performance of maize (Zea maize L.). The blend of entomopathogens included two entomopathogenic nematodes, Steinernema carpocaps...

  13. Dynamic precision phenotyping reveals mechanism of crop tolerance to herbivory

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  14. Transgenic corn for control of the European corn borer and corn rootworms: a survey of Midwestern farmers' practices and perceptions.

    PubMed

    Wilson, Ted A; Rice, Marlin E; Tollefson, Jon J; Pilcher, Clinton D

    2005-04-01

    In 2001, a self-administered questionnaire was sent to 1000 corn, Zea mays L., farmers in each of five states (Illinois, Indiana, Iowa, Minnesota, and Nebraska) to evaluate their perceptions of transgenic corn designed to control the European corn borer, Ostrinia nubilalis (Hübner), and corn rootworms, Diabrotica spp. Respondents returned 1,313 surveys (26.2%). Farmers with small acreages planted a greater portion of their corn (54.5%) with transgenic corn for control of European corn borer than farmers with large farms (39.2%). The majority (75.2%) of farmers use crop rotation to control the corn rootworm. Nine insecticides comprised 92.2% of the commercial soil insecticides used for control of corn rootworm larvae. More than one-third of the farmers in Illinois (33.5%) and Indiana (39.4%) treated first-year corn for corn rootworm, primarily due to western corn rootworm egg laying in soybean, Glycine max (L.). When asked whether they would plant transgenic corn protected against the corn rootworm, 35.0% of farmers responded they would, whereas 40.5% said they were unsure. The two greatest farmer concerns about transgenic corn were the ability to sell harvested grain (59.3%) and additional technology fees (54.8%). Respondents indicated that less farmer exposure to insecticide (69.9%) and less insecticide in the environment (68.5%) were the primary benefits of transgenic corn. Farmers who had no concerns about transgenic corn for rootworm control were more likely to purchase the product (46.8%). The most common refuge-planting options farmers favored were adjacent fields (30.9%) and split fields (29.9%). Farmers (21.1%) observed a yield increase (23.7 bu/ha [9.6 bu/acre]) when using transgenic corn for European corn borer control compared with non-transgenic corn. These data can help in understanding farmers' knowledge and concerns regarding transgenic corn. This information may be of value to guide researchers, extension specialists, and policy makers in designing

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  16. Diabrotica flight in time and space as monitored with a high capacity trap placed in Zea mays fields of Illinois, USA.

    PubMed

    Hummel, H E; Shaw, J T

    2006-01-01

    Monitoring of insects by trapping is one of the prime tools of field entomologists. The leaf beetle Diabrotica virgifera virgifera LeConte (Coleoptera:Chrysomelidae) is no exception. Since its numbers (and consequently its mass) in a field population can be enormous, tools must be adapted to hold this many insects for later counting, sexing, biomass determinations, and additional investigations to follow. Since counting the high numbers during the flight peak may not be feasible at all, weighing and extrapolating to numbers by the correlation factor 1g = 160 to 170 beetles of mixed female and male sex was the method of choice. Around the perimeter of a hybrid maize (Z. mays) field of 0.6 ha, 16 high capacity traps were established at elevations ranging from 0 to 2 m above ground level. Optimal trapping is possible between 0.5 to 2m which field entomologists intuitively knew from experience and tradition. Below and above that level, the number of beetles is not zero but significantly below the optimum. High capacity traps can be left in the field with one loading of lure for four to seven days. Lures were the D. v. virgifera beetle sex pheromone 8-methyl-decane-2-ol propanoate (0.1 mg, collecting mainly male beetles) and the plant kairomone 4-methoxy-trans-cinnamaldehyde (10 mg, collecting both male and female beetles). The specific kairomone action (being much weaker than the pheromone) can be increased by simultaneously offering a feeding arrestant powder (e.g. prepared from ground Cucurbita texana or C. okeechobeensis) which keeps the beetles attracted by the kairomone lure close to the trapping site. There they can be immobilized and knocked down by a tiny source of carbaryl or dichlorvos fixed inside or at the surface of a plastic pellet or sheet. The high capacity traps are commercially available and can be reused for several flight seasons.

  17. A novel interaction between plant-beneficial rhizobacteria and roots: colonization induces corn resistance against the root herbivore Diabrotica speciosa.

    PubMed

    Santos, Franciele; Peñaflor, Maria Fernanda G V; Paré, Paul W; Sanches, Patrícia A; Kamiya, Aline C; Tonelli, Mateus; Nardi, Cristiane; Bento, José Mauricio S

    2014-01-01

    A number of soil-borne microorganisms, such as mycorrhizal fungi and rhizobacteria, establish mutualistic interactions with plants, which can indirectly affect other organisms. Knowledge of the plant-mediated effects of mutualistic microorganisms is limited to aboveground insects, whereas there is little understanding of what role beneficial soil bacteria may play in plant defense against root herbivory. Here, we establish that colonization by the beneficial rhizobacterium Azospirillum brasilense affects the host selection and performance of the insect Diabrotica speciosa. Root larvae preferentially orient toward the roots of non-inoculated plants versus inoculated roots and gain less weight when feeding on inoculated plants. As inoculation by A. brasilense induces higher emissions of (E)-β-caryophyllene compared with non-inoculated plants, it is plausible that the non-preference of D. speciosa for inoculated plants is related to this sesquiterpene, which is well known to mediate belowground insect-plant interactions. To the best of our knowledge, this is the first study showing that a beneficial rhizobacterium inoculant indirectly alters belowground plant-insect interactions. The role of A. brasilense as part of an integrative pest management (IPM) program for the protection of corn against the South American corn rootworm, D. speciosa, is considered.

  18. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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....

  19. Volatile chemicals associated with host plants of the strawberry rootworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  20. Characterization of the spatial dispersion of corn root injury by corn rootworms (Coleoptera: Chrysomelidae).

    PubMed

    Park, Yong-Lak; Tollefson, Jon J

    2005-04-01

    The dispersion of root injury to Zea mays L. by corn rootworm, Diabrotica spp., larvae was characterized using geostatistics to determine the appropriate sampling distance to obtain independent estimates of root injury. We also investigated the effect of the root injury levels on the spatial dependence of root injury at three different spatial scales: large-scale study with 25-m sampling distance in three, 8-ha fields; moderate-scale study with 0.2-m sampling distance in six, 2-ha fields; and small-scale study with exhaustive sampling in eight, 12-m(2) plots within cornfields. In the large-scale study, a nugget model best fit the semivariograms, indicating the dispersion of root injury exhibited a random pattern. In the moderate-scale study, all the semivariograms were best fit with an exponential model, and 68 to 96% of the variability was explained by spatial dependence, suggesting a high degree of spatial aggregation of corn root larval injury. The ranges of semivariograms fell within < 4 m, except one field that had the range of 14.7 m. In the small-scale study, the Gaussian, exponential, or spherical models fit the semivariograms best and 50 to 89% of the variability was explained by spatial dependence, suggesting spatial aggregation of root injury. The ranges of semivariograms were from 0.35 to 1.04 m. In the small-scale study, the degree of spatial dependence increased significantly (P < 0.05) as the average root injury increased within the range of root injury observed in the study. These results suggest that the minimum distance between root samples in small-plot insecticide trials should be > 1 m within a row to obtain unbiased estimates of root injury.

  1. 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

  2. Native Resistance of Maize to Western Corn Rootworm Larval Feeding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The western corn rootworm (WCR) is a major insect pest in continuous corn production. By feeding on corn roots, WCR causes economic losses due to plant lodging and decreased nutrient uptake. Currently, insecticides and transgenic corn are only available options for its control under continuous cor...

  3. Composition of grain and forage from corn rootworm-protected corn event MON 863 is equivalent to that of conventional corn (Zea mays l.).

    PubMed

    George, Cherian; Ridley, William P; Obert, Janet C; Nemeth, Margaret A; Breeze, Matthew L; Astwood, James D

    2004-06-30

    Insect-protected corn hybrids containing event MON 863 protect corn plants against feeding damage from corn rootworm (Diabrotica), a major North American insect pest. Corn event MON 863 contains a gene that expresses an amino acid sequence variant of the wild-type Cry3Bb1 insecticidal protein from Bacillus thuringiensis. The purpose of this study was to compare the composition of corn containing event MON 863 with that of conventional nontransgenic corn. Compositional analyses were conducted to measure proximates, fiber, amino acids, fatty acids, minerals, folic acid, thiamin, riboflavin, vitamin E, antinutrients, and certain secondary metabolites in grain and proximates and fiber content in forage collected from a total of eight field sites in the U.S. and Argentina. Compositional analyses demonstrated that the grain and forage of event MON 863 are comparable in their nutritional content to the control corn hybrid and conventional corn. These comparisons, together with the history of the safe use of corn as a common component of animal feed and human food, support the conclusion that corn event MON 863 is compositionally equivalent to, and as safe and nutritious as, conventional corn hybrids grown commercially today.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  5. 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.

  6. Resistance to Bt maize by western corn rootworm: insights from the laboratory and the field.

    PubMed

    Gassmann, Aaron J

    2016-06-01

    Western corn rootworm is a serious pest of maize. Beginning in 2003, management of western corn rootworm included transgenic maize that produces insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). The first Bt maize hybrids produced Cry3Bb1, but additional Bt toxins have since been introduced, including eCry3.1Ab, mCry3A and Cry34/35Ab1. Laboratory selection experiments found that western corn rootworm could develop resistance to all types of Bt maize following three to seven generations of selection. By 2009 cases of field-evolved resistance to Cry3Bb1 maize had been identified, with populations also showing cross-resistance to mCry3A maize. Factors likely contributing to resistance were the lack of a high dose of Bt toxin for maize targeting rootworm and minimal fitness costs of resistance. PMID:27436740

  7. Winter annual cover crop has only minor effects on major corn arthropod pests.

    PubMed

    Davis, Holly N; Currie, Randall S; Klocke, Norman L; Buschman, Lawrent L

    2010-04-01

    We studied the effects of downy brome, Bromus tectorum L., winter cover crop on several corn, Zea mays L., pests in the summer crop after the cover crop. An experiment was conducted that consisted of two trials with two levels of irrigation, two levels of weed control, and two levels of downy brome. Corn was grown three consecutive years after the downy brome grown during the winter. Banks grass mites, Oligonychus pratensis (Banks), twospotted spider mites, Tetranychus urticae Koch, and predatory mites from the genus Neoseiulus were present in downy brome at the beginning of the growing season. They moved into corn, but their numbers did not differ significantly across the treatments. Larval western corn rootworm, Diabrotica virgifera virgifera LeConte, feeding on corn roots was evaluated the second and third years of corn, production. Irrigation and herbicide treatments had no significant effects on rootworm injury levels. In one trial, rootworm injury ratings were significantly greater in treatments with a history of high versus low brome, but this effect was not significant in the other trial. Rootworm injury seemed to be similar across plots with different surface soil moistures. This suggests that the use of a winter cover crop such as downy brome will not have a major negative impact the arthropods studied.

  8. Performance of marking techniques in the field and laboratory for Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A reliable marking technique was needed for a mark-release-recapture experiment with adults of Diabrotica speciosa (Germar). Four marking techniques, acrylic paint (spattered or brushed on the surface of the insect); and fluorescent pigments (dusted on surfaces or mixed with diet to produce an inges...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  11. Searching for Natural Resistance to the Northern Corn Rootworm at the USDA/ARS Lab in Brookings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms and their management costs US farmers over 1 billion dollars annually. In recent years companies have developed corn hybrids with resistance to corn rootworms by inserting bacterial genes into the corn genome. These hybrids are often called GMOs (genetically modified organisms) and a...

  12. Field-evolved resistance by western corn rootworm to multiple Bacillus thuringiensis toxins in transgenic maize.

    PubMed

    Gassmann, Aaron J; Petzold-Maxwell, Jennifer L; Clifton, Eric H; Dunbar, Mike W; Hoffmann, Amanda M; Ingber, David A; Keweshan, Ryan S

    2014-04-01

    The widespread planting of crops genetically engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) places intense selective pressure on pest populations to evolve resistance. Western corn rootworm is a key pest of maize, and in continuous maize fields it is often managed through planting of Bt maize. During 2009 and 2010, fields were identified in Iowa in which western corn rootworm imposed severe injury to maize producing Bt toxin Cry3Bb1. Subsequent bioassays revealed Cry3Bb1 resistance in these populations. Here, we report that, during 2011, injury to Bt maize in the field expanded to include mCry3A maize in addition to Cry3Bb1 maize and that laboratory analysis of western corn rootworm from these fields found resistance to Cry3Bb1 and mCry3A and cross-resistance between these toxins. Resistance to Bt maize has persisted in Iowa, with both the number of Bt fields identified with severe root injury and the ability western corn rootworm populations to survive on Cry3Bb1 maize increasing between 2009 and 2011. Additionally, Bt maize targeting western corn rootworm does not produce a high dose of Bt toxin, and the magnitude of resistance associated with feeding injury was less than that seen in a high-dose Bt crop. These first cases of resistance by western corn rootworm highlight the vulnerability of Bt maize to further evolution of resistance from this pest and, more broadly, point to the potential of insects to develop resistance rapidly when Bt crops do not achieve a high dose of Bt toxin.

  13. Field-evolved resistance by western corn rootworm to multiple Bacillus thuringiensis toxins in transgenic maize

    PubMed Central

    Gassmann, Aaron J.; Petzold-Maxwell, Jennifer L.; Clifton, Eric H.; Dunbar, Mike W.; Hoffmann, Amanda M.; Ingber, David A.; Keweshan, Ryan S.

    2014-01-01

    The widespread planting of crops genetically engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) places intense selective pressure on pest populations to evolve resistance. Western corn rootworm is a key pest of maize, and in continuous maize fields it is often managed through planting of Bt maize. During 2009 and 2010, fields were identified in Iowa in which western corn rootworm imposed severe injury to maize producing Bt toxin Cry3Bb1. Subsequent bioassays revealed Cry3Bb1 resistance in these populations. Here, we report that, during 2011, injury to Bt maize in the field expanded to include mCry3A maize in addition to Cry3Bb1 maize and that laboratory analysis of western corn rootworm from these fields found resistance to Cry3Bb1 and mCry3A and cross-resistance between these toxins. Resistance to Bt maize has persisted in Iowa, with both the number of Bt fields identified with severe root injury and the ability western corn rootworm populations to survive on Cry3Bb1 maize increasing between 2009 and 2011. Additionally, Bt maize targeting western corn rootworm does not produce a high dose of Bt toxin, and the magnitude of resistance associated with feeding injury was less than that seen in a high-dose Bt crop. These first cases of resistance by western corn rootworm highlight the vulnerability of Bt maize to further evolution of resistance from this pest and, more broadly, point to the potential of insects to develop resistance rapidly when Bt crops do not achieve a high dose of Bt toxin. PMID:24639498

  14. Microbial Symbionts in Insects Influence Down-Regulation of Defense Genes in Maize

    PubMed Central

    Barr, Kelli L.; Hearne, Leonard B.; Briesacher, Sandra; Clark, Thomas L.; Davis, Georgia E.

    2010-01-01

    Diabrotica virgifera virgifera larvae are root-feeding insects and significant pests to maize in North America and Europe. Little is known regarding how plants respond to insect attack of roots, thus complicating the selection for plant defense targets. Diabrotica virgifera virgifera is the most successful species in its genus and is the only Diabrotica beetle harboring an almost species-wide Wolbachia infection. Diabrotica virgifera virgifera are infected with Wolbachia and the typical gut flora found in soil-living, phytophagous insects. Diabrotica virgifera virgifera larvae cannot be reared aseptically and thus, it is not possible to observe the response of maize to effects of insect gut flora or other transient microbes. Because Wolbachia are heritable, it is possible to investigate whether Wolbachia infection affects the regulation of maize defenses. To answer if the success of Diabrotica virgifera virgifera is the result of microbial infection, Diabrotica virgifera virgifera were treated with antibiotics to eliminate Wolbachia and a microarray experiment was performed. Direct comparisons made between the response of maize root tissue to the feeding of antibiotic treated and untreated Diabrotica virgifera virgifera show down-regulation of plant defenses in the untreated insects compared to the antibiotic treated and control treatments. Results were confirmed via QRT-PCR. Biological and behavioral assays indicate that microbes have integrated into Diabrotica virgifera virgifera physiology without inducing negative effects and that antibiotic treatment did not affect the behavior or biology of the insect. The expression data and suggest that the pressure of microbes, which are most likely Wolbachia, mediate the down-regulation of many maize defenses via their insect hosts. This is the first report of a potential link between a microbial symbiont of an insect and a silencing effect in the insect host plant. This is also the first expression profile for a plant

  15. Evaluation of tag entanglement as a factor in harmonic radar studies of insect dispersal.

    PubMed

    Boiteau, G; Vincent, C; Meloche, F; Leskey, T C; Colpitts, B G

    2011-02-01

    The observation of insects and other small organisms entangled in the habitat after the addition of vertical or trailing electronic tags to their body has generated concerns on the suitability of harmonic radars to track the dispersal of insects. This study compared the walking behavior of adult Colorado potato beetle (Leptinotarsa decemlineata (Say) Chrysomelidae), plum curculio (Conotrachelus nenuphar (Herbst) Curculionidae), and western corn rootworm (Diabrotica virgifera virgifera (LeConte) Chrysomelidae) with and without vertical and or trailing tags in field plots or arenas. The frequency of the larger Colorado potato beetles crossing bare ground or grassy plots was unaffected by the presence of an 8 cm trailing harmonic radar tag. However, plum curculios and western corn rootworms, were either unable to walk with a 4 cm trailing tag (plum curculio) or displayed a reduced ability to successfully cross a bare ground arena. Our results revealed the significant impact of vegetation on successful insect dispersal, whether tagged or not. The vertical movement of these insects on stems, stalks, and tubes was also unaffected by the presence of vertical tags. Trailing tags had a significant negative effect on the vertical movement of the western corn rootworm. Results show that harmonic radar technology is a suitable method for studying the walking paths of the three insects with appropriate tag type and size. The nuisance factor generated by appropriately sized tags was small relative to that of vegetation. PMID:22182617

  16. Node-injury scale to evaluate root injury by corn rootworms (Coleoptera: Chrysomelidae).

    PubMed

    Oleson, James D; Park, Yong-Lak; Nowatzki, Timothy M; Tollefson, Jon J

    2005-02-01

    Corn rootworm larval feeding on corn roots can significantly reduce grain yield by interfering with photosynthetic rates, limiting the uptake of water and nutrients, and by increasing the plant's susceptibility to lodging. Of the techniques developed to measure the efficacy of corn rootworm larval control tactics, root damage ratings have generally been adopted as the standard because sampling roots is relatively efficient. Historically, the primary scales used for scoring root injury from corn rootworm larval feeding have been the 1-6 and 1-9 scales. A critical deficiency of those scales, however, is that each increase in a root-rating score does not reflect a linear increase in the actual amount of injury to the root system. This results in injury scores that are expressed qualitatively. We developed the node-injury scale to more accurately quantify corn rootworm larval injury based on the proportion of nodal roots that contain feeding injury. With the node-injury scale, the relationship between the numerical scale and the amount of root injury is linear and intuitive. In this article, we describe the node-injury scale, discuss sampling issues to consider when using the scale, and suggest the minimum node-injury score that causes economic damage under varying degrees of environmental stress.

  17. Screening of botanical extracts for repellence against western corn rootworm larvae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. Genetic markers for western corn rootworm resistance to Bt toxin.

    PubMed

    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

    2015-03-01

    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.

  19. Genetic markers for western corn rootworm resistance to Bt toxin.

    PubMed

    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

    2015-03-01

    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

  20. 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

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

    PubMed

    Creighton, C S; Fassuliotis, G

    1985-04-01

    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

  2. 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

  3. Tempo and mode of evolutionary radiation in Diabroticina beetles (genera Acalymma, Cerotoma, and Diabrotica)

    PubMed Central

    Eben, Astrid; Espinosa de los Monteros, Alejandro

    2013-01-01

    Abstract Adaptive radiation is an aspect of evolutionary biology encompassing microevolution and macroevolution, for explaining the principles of lineage divergence. There are intrinsic as well as extrinsic factors that can be postulated to explain that adaptive radiation has taken place in specific lineages. The Diabroticina beetles are a prominent example of differential diversity that could be examined in detail to explain the diverse paradigms of adaptive radiation. Macroevolutionary analyses must present the differential diversity patterns in a chronological framework. The current study reviews the processes that shaped the differential diversity of some Diabroticina lineages (i.e. genera Acalymma, Cerotoma, and Diabrotica). These diversity patterns and the putative processes that produced them are discussed within a statistically reliable estimate of time. This was achieved by performing phylogenetic and coalescent analyses for 44 species of chrysomelid beetles. The data set encompassed a total of 2,718 nucleotide positions from three mitochondrial and two nuclear loci. Pharmacophagy, host plant coevolution, competitive exclusion, and geomorphological complexity are discussed as putative factors that might have influenced the observed diversity patterns. The coalescent analysis concluded that the main radiation within Diabroticina beetles occurred between middle Oligocene and middle Miocene. Therefore, the radiation observed in these beetles is not recent (i.e. post-Panamanian uplift, 4 Mya). Only a few speciation events in the genus Diabrotica might be the result of the Pleistocene climatic oscillations. PMID:24163585

  4. 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.

  5. 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. PMID:26011006

  6. A novel method of demonstrating the molecular and functional equivalence between in vitro and plant-produced double-stranded RNA.

    PubMed

    Urquhart, William; Mueller, Geoffrey M; Carleton, Stephanie; Song, Zihong; Perez, Tim; Uffman, Joshua P; Jensen, Peter D; Levine, Steven L; Ward, Jason

    2015-11-01

    A biotechnology-derived corn variety, MON 87411, containing a suppression cassette that expresses an inverted repeat sequence that matches the sequence of western corn rootworm (WCR; Diabrotica virgifera virgifera) has been developed. The expression of the cassette results in the formation of a double-stranded RNA (dsRNA) transcript containing a 240 bp fragment of the WCR Snf7 gene (DvSnf7) that confers resistance to corn rootworm by suppressing levels of DvSnf7 mRNA in WCR after root feeding. Internationally accepted guidelines for the assessment of genetically modified crop products have been developed to ensure that these plants are as safe for food, feed, and environmental release as their non-modified counterparts (Codex, 2009). As part of these assessments MON 87411 must undergo an extensive environmental assessment that requires large quantities of DvSnf7 dsRNA that was produced by in vitro transcription (IVT). To determine if the IVT dsRNA is a suitable surrogate for the MON 87411-produced DvSnf7 dsRNA in regulatory studies, the nucleotide sequence, secondary structure, and functional activity of each were characterized and demonstrated to be comparable. This comprehensive characterization indicates that the IVT DvSnf7 dsRNA is equivalent to the MON 87411-produced DvSnf7 dsRNA and it is a suitable surrogate for regulatory studies. PMID:26361852

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

    PubMed Central

    Bachman, Pamela M.; Jensen, Peter D.; Mueller, Geoffrey M.; Uffman, Joshua P.; Meng, Chen; Song, Zihong; Richards, Kathy B.; Beevers, Michael H.

    2015-01-01

    Abstract 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. Environ Toxicol Chem 2016;35:287–294. © 2015 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC. PMID:26011006

  8. A novel method of demonstrating the molecular and functional equivalence between in vitro and plant-produced double-stranded RNA.

    PubMed

    Urquhart, William; Mueller, Geoffrey M; Carleton, Stephanie; Song, Zihong; Perez, Tim; Uffman, Joshua P; Jensen, Peter D; Levine, Steven L; Ward, Jason

    2015-11-01

    A biotechnology-derived corn variety, MON 87411, containing a suppression cassette that expresses an inverted repeat sequence that matches the sequence of western corn rootworm (WCR; Diabrotica virgifera virgifera) has been developed. The expression of the cassette results in the formation of a double-stranded RNA (dsRNA) transcript containing a 240 bp fragment of the WCR Snf7 gene (DvSnf7) that confers resistance to corn rootworm by suppressing levels of DvSnf7 mRNA in WCR after root feeding. Internationally accepted guidelines for the assessment of genetically modified crop products have been developed to ensure that these plants are as safe for food, feed, and environmental release as their non-modified counterparts (Codex, 2009). As part of these assessments MON 87411 must undergo an extensive environmental assessment that requires large quantities of DvSnf7 dsRNA that was produced by in vitro transcription (IVT). To determine if the IVT dsRNA is a suitable surrogate for the MON 87411-produced DvSnf7 dsRNA in regulatory studies, the nucleotide sequence, secondary structure, and functional activity of each were characterized and demonstrated to be comparable. This comprehensive characterization indicates that the IVT DvSnf7 dsRNA is equivalent to the MON 87411-produced DvSnf7 dsRNA and it is a suitable surrogate for regulatory studies.

  9. 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.

  10. Results of a 90-day safety assurance study with rats fed grain from corn rootworm-protected corn.

    PubMed

    Hammond, B; Lemen, J; Dudek, R; Ward, D; Jiang, C; Nemeth, M; Burns, J

    2006-02-01

    The results of a 90-day rat feeding study with YieldGard (YieldGard Rootworm Corn is a registered trademark of Monsanto Technology, LLC.) Rootworm corn (MON 863) grain that is protected against feeding damage caused by corn rootworm larvae are presented. Corn rootworm-protection was accomplished through the introduction of a cry3Bb1 coding sequence into the corn genome for in planta production of a modified Cry3Bb1 protein from Bacillus thuringiensis. Grain from MON 863 and its near isogenic control were separately formulated into rodent diets at levels of 11% and 33% (w/w) by Purina Mills, Inc. Additionally, six groups of rats were fed diets containing grain from different conventional (non-biotechnology-derived) reference varieties. The responses of rats fed diets containing MON 863 were compared to those of rats fed grain from conventional corn varieties. All diets were nutritionally balanced and conformed to Purina Mills, Inc. specifications for Certified LabDiet 5002. There were a total of 400 rats in the study divided into 10 groups of 20 rats/sex/group. Overall health, body weight gain, food consumption, clinical pathology parameters (hematology, blood chemistry, urinalysis), organ weights, gross and microscopic appearance of tissues were comparable between groups fed diets containing MON 863 and conventional corn varieties. This study complements extensive agronomic, compositional and farm animal feeding studies with MON 863 grain, confirming that it is as safe and nutritious as existing conventional corn varieties.

  11. Discovery of midgut genes for the RNA interference control of corn rootworm.

    PubMed

    Hu, Xu; Richtman, Nina M; Zhao, Jian-Zhou; Duncan, Keith E; Niu, Xiping; Procyk, Lisa A; Oneal, Meghan A; Kernodle, Bliss M; Steimel, Joseph P; Crane, Virginia C; Sandahl, Gary; Ritland, Julie L; Howard, Richard J; Presnail, James K; Lu, Albert L; Wu, Gusui

    2016-01-01

    RNA interference (RNAi) is a promising new technology for corn rootworm control. This paper presents the discovery of new gene targets - dvssj1 and dvssj2, in western corn rootworm (WCR). Dvssj1 and dvssj2 are orthologs of the Drosophila genes snakeskin (ssk) and mesh, respectively. These genes encode membrane proteins associated with smooth septate junctions (SSJ) which are required for intestinal barrier function. Based on bioinformatics analysis, dvssj1 appears to be an arthropod-specific gene. Diet based insect feeding assays using double-stranded RNA (dsRNA) targeting dvssj1 and dvssj2 demonstrate targeted mRNA suppression, larval growth inhibition, and mortality. In RNAi treated WCR, injury to the midgut was manifested by "blebbing" of the midgut epithelium into the gut lumen. Ultrastructural examination of midgut epithelial cells revealed apoptosis and regenerative activities. Transgenic plants expressing dsRNA targeting dvssj1 show insecticidal activity and significant plant protection from WCR damage. The data indicate that dvssj1 and dvssj2 are effective gene targets for the control of WCR using RNAi technology, by apparent suppression of production of their respective smooth septate junction membrane proteins located within the intestinal lining, leading to growth inhibition and mortality. PMID:27464714

  12. Discovery of midgut genes for the RNA interference control of corn rootworm

    PubMed Central

    Hu, Xu; Richtman, Nina M.; Zhao, Jian-Zhou; Duncan, Keith E.; Niu, Xiping; Procyk, Lisa A.; Oneal, Meghan A.; Kernodle, Bliss M.; Steimel, Joseph P.; Crane, Virginia C.; Sandahl, Gary; Ritland, Julie L.; Howard, Richard J.; Presnail, James K.; Lu, Albert L.; Wu, Gusui

    2016-01-01

    RNA interference (RNAi) is a promising new technology for corn rootworm control. This paper presents the discovery of new gene targets - dvssj1 and dvssj2, in western corn rootworm (WCR). Dvssj1 and dvssj2 are orthologs of the Drosophila genes snakeskin (ssk) and mesh, respectively. These genes encode membrane proteins associated with smooth septate junctions (SSJ) which are required for intestinal barrier function. Based on bioinformatics analysis, dvssj1 appears to be an arthropod-specific gene. Diet based insect feeding assays using double-stranded RNA (dsRNA) targeting dvssj1 and dvssj2 demonstrate targeted mRNA suppression, larval growth inhibition, and mortality. In RNAi treated WCR, injury to the midgut was manifested by “blebbing” of the midgut epithelium into the gut lumen. Ultrastructural examination of midgut epithelial cells revealed apoptosis and regenerative activities. Transgenic plants expressing dsRNA targeting dvssj1 show insecticidal activity and significant plant protection from WCR damage. The data indicate that dvssj1 and dvssj2 are effective gene targets for the control of WCR using RNAi technology, by apparent suppression of production of their respective smooth septate junction membrane proteins located within the intestinal lining, leading to growth inhibition and mortality. PMID:27464714

  13. Monitoring of Maize Damage Caused by Western Corn Rootworm by Remote Sensing

    NASA Astrophysics Data System (ADS)

    Nádor, G.; Fényes, D.; Vasas, L.; Surek, G.

    2009-04-01

    The gradual dispersion of western corn rootworm (WCR) is becoming a serious maize pest in Europe, and all over the world. In 2008 using remote sensing data, the Remote Sensing Centre of Institute of Geodesy, Cartography and Remote Sensing (FÖMI RSC) carried out this project to identify WCR larval damage. Our goal with the present project is to assess and identify the disorder and structural changes caused by WCR larvae using optical (IRS-P6 AWiFS, IRS-P6 LISS, SPOT4 and SPOT5) and polarimetic radar (ALOS PALSAR) satellite images. We used 3 different individual features (Mono-maize feature, Optical feature, Radar feature) derived from remote sensing data to accomplish this goal. Findings were tested against on-the-spot ground assessments. Using radar polarimetry increased the accuracy significantly. The final results have implications for plant protection strategy, farming practices, pesticide producers, state authorities and research institutes.

  14. Nontarget organism effects tests on eCry3.1Ab and their application to the ecological risk assessment for cultivation of Event 5307 maize.

    PubMed

    Burns, Andrea; Raybould, Alan

    2014-12-01

    Event 5307 transgenic maize produces the novel insecticidal protein eCry3.1Ab, which is active against certain coleopteran pests such as Western corn rootworm (Diabrotica virgifera virgifera). Laboratory tests with representative nontarget organisms (NTOs) were conducted to test the hypothesis of no adverse ecological effects of cultivating Event 5307 maize. Estimates of environmental eCry3.1Ab concentrations for each NTO were calculated from the concentrations of eCry3.1Ab produced by 5307 maize in relevant plant tissues. Nontarget organisms were exposed to diets containing eCry3.1Ab or diets comprising Event 5307 maize tissue and evaluated for effects compared to control groups. No statistically significant differences in survival were observed between the control group and the group exposed to eCry3.1Ab in any organism tested. Measured eCry3.1Ab concentrations in the laboratory studies were equal to or greater than the most conservative estimates of environmental exposure. The laboratory studies corroborate the hypothesis of negligible ecological risk from the cultivation of 5307 maize.

  15. Intraplant communication in maize contributes to defense against insects.

    PubMed

    Varsani, Suresh; Basu, Saumik; Williams, W Paul; Felton, Gary W; Luthe, Dawn S; Louis, Joe

    2016-08-01

    The vasculature of plants act as a channel for transport of signal(s) that facilitate long-distance intraplant communication. In maize, Maize insect resistance1-Cysteine Protease (Mir1-CP), which has homology to papain-like proteases, provides defense to different feeding guilds of insect pests. Furthermore, accumulation of Mir1-CP in the vasculature suggests that Mir1-CP can potentially function as a phloem-mobile protein. In a recent study, we provided evidence that Mir1-CP can curtail the growth of phloem-sap sucking insect, corn leaf aphid (CLA; Rhopalosiphum maidis). Our current study further examined whether aboveground feeding by CLA can induce resistance to subsequent herbivory by belowground feeding western corn rootworm (WCR; Diabrotica virgifera virgifera). Aboveground feeding by CLA systemically induced the accumulation of Mir1-CP in the roots. Furthermore, foliage feeding by CLA provided enhanced resistance to subsequent herbivory by belowground feeding of WCR. Taken together, our previous findings and results presented here indicate that long-distance transport of Mir1-CP is critical for providing enhanced resistance to insect attack in maize. PMID:27467304

  16. Dynamic Precision Phenotyping Reveals Mechanism of Crop Tolerance to Root Herbivory[OPEN

    PubMed Central

    Robert, Christelle A.M.; Erb, Matthias; Hibbard, Bruce E.; Paven, Maxim; Gleede, Tassilo; Riehl, Barbara; Kersting, Lena; Cankaya, Aylin S.; Kunert, Anna T.; Xu, Youwen; Schueller, Michael J.; Alexoff, David; Lee, So Jeong; Fowler, Joanna S.

    2016-01-01

    The western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) is a major pest of maize (Zea mays) that is well adapted to most crop management strategies. Breeding for tolerance is a promising alternative to combat WCR but is currently constrained by a lack of physiological understanding and phenotyping tools. We developed dynamic precision phenotyping approaches using 11C with positron emission tomography, root autoradiography, and radiometabolite flux analysis to understand maize tolerance to WCR. Our results reveal that WCR attack induces specific patterns of lateral root growth that are associated with a shift in auxin biosynthesis from indole-3-pyruvic acid to indole-3-acetonitrile. WCR attack also increases transport of newly synthesized amino acids to the roots, including the accumulation of Gln. Finally, the regrowth zones of WCR-attacked roots show an increase in Gln turnover, which strongly correlates with the induction of indole-3-acetonitrile-dependent auxin biosynthesis. In summary, our findings identify local changes in the auxin biosynthesis flux network as a promising marker for induced WCR tolerance. PMID:27406166

  17. Anthropogenic increase in carbon dioxide compromises plant defense against invasive insects

    SciTech Connect

    Zavala, J.; Casteel, C.; DeLucia, E.; Berenbaum, M.

    2008-04-01

    Elevated levels of atmospheric carbon dioxide (CO{sub 2}), a consequence of anthropogenic global change, can profoundly affect the interactions between crop plants and insect pests and may promote yet another form of global change: the rapid establishment of invasive species. Elevated CO{sub 2} increased the susceptibility of soybean plants grown under field conditions to the invasive Japanese beetle (Popillia japonica) and to a variant of western corn rootworm (Diabrotica virgifera virgifera) resistant to crop rotation by down-regulating gene expression related to defense signaling [lipoxygenase 7 (lox7), lipoxygenase 8 (lox8), and 1-aminocyclopropane-1-carboxylate synthase (acc-s)]. The down-regulation of these genes, in turn, reduced the production of cysteine proteinase inhibitors (CystPIs), which are specific deterrents to coleopteran herbivores. Beetle herbivory increased CystPI activity to a greater degree in plants grown under ambient than under elevated CO{sub 2}. Gut cysteine proteinase activity was higher in beetles consuming foliage of soybeans grown under elevated CO{sub 2} than in beetles consuming soybeans grown in ambient CO{sub 2}, consistent with enhanced growth and development of these beetles on plants grown in elevated CO{sub 2}. These findings suggest that predicted increases in soybean productivity under projected elevated CO{sub 2} levels may be reduced by increased susceptibility to invasive crop pests.

  18. Intraplant communication in maize contributes to defense against insects.

    PubMed

    Varsani, Suresh; Basu, Saumik; Williams, W Paul; Felton, Gary W; Luthe, Dawn S; Louis, Joe

    2016-08-01

    The vasculature of plants act as a channel for transport of signal(s) that facilitate long-distance intraplant communication. In maize, Maize insect resistance1-Cysteine Protease (Mir1-CP), which has homology to papain-like proteases, provides defense to different feeding guilds of insect pests. Furthermore, accumulation of Mir1-CP in the vasculature suggests that Mir1-CP can potentially function as a phloem-mobile protein. In a recent study, we provided evidence that Mir1-CP can curtail the growth of phloem-sap sucking insect, corn leaf aphid (CLA; Rhopalosiphum maidis). Our current study further examined whether aboveground feeding by CLA can induce resistance to subsequent herbivory by belowground feeding western corn rootworm (WCR; Diabrotica virgifera virgifera). Aboveground feeding by CLA systemically induced the accumulation of Mir1-CP in the roots. Furthermore, foliage feeding by CLA provided enhanced resistance to subsequent herbivory by belowground feeding of WCR. Taken together, our previous findings and results presented here indicate that long-distance transport of Mir1-CP is critical for providing enhanced resistance to insect attack in maize.

  19. Microbial Communities Associated with the Larval Gut and Eggs of the Western Corn Rootworm

    PubMed Central

    Dematheis, Flavia; Kurtz, Benedikt; Vidal, Stefan; Smalla, Kornelia

    2012-01-01

    Background The western corn rootworm (WCR) is one of the economically most important pests of maize. A better understanding of microbial communities associated with guts and eggs of the WCR is required in order to develop new pest control strategies, and to assess the potential role of the WCR in the dissemination of microorganisms, e.g., mycotoxin-producing fungi. Methodology/Principal Findings Total community (TC) DNA was extracted from maize rhizosphere, WCR eggs, and guts of larvae feeding on maize roots grown in three different soil types. Denaturing gradient gel electrophoresis (DGGE) and sequencing of 16S rRNA gene and ITS fragments, PCR-amplified from TC DNA, were used to investigate the fungal and bacterial communities, respectively. Microorganisms in the WCR gut were not influenced by the soil type. Dominant fungal populations in the gut were affiliated to Fusarium spp., while Wolbachia was the most abundant bacterial genus. Identical ribosomal sequences from gut and egg samples confirmed a transovarial transmission of Wolbachia sp. Betaproteobacterial DGGE indicated a stable association of Herbaspirillum sp. with the WCR gut. Dominant egg-associated microorganisms were the bacterium Wolbachia sp. and the fungus Mortierella gamsii. Conclusion/Significance The soil type-independent composition of the microbial communities in the WCR gut and the dominance of only a few microbial populations suggested either a highly selective environment in the gut lumen or a high abundance of intracellular microorganisms in the gut epithelium. The dominance of Fusarium species in the guts indicated WCR larvae as vectors of mycotoxin-producing fungi. The stable association of Herbaspirillum sp. with WCR gut systems and the absence of corresponding sequences in WCR eggs suggested that this bacterium was postnatally acquired from the environment. The present study provided new insights into the microbial communities associated with larval guts and eggs of the WCR. However

  20. Quantification of transgene-derived double-stranded RNA in plants using the QuantiGene nucleic acid detection platform.

    PubMed

    Armstrong, Toni A; Chen, Hao; Ziegler, Todd E; Iyadurai, Kelly R; Gao, Ai-Guo; Wang, Yongcheng; Song, Zihong; Tian, Qing; Zhang, Qiang; Ward, Jason M; Segers, Gerrit C; Heck, Gregory R; Staub, Jeffrey M

    2013-12-26

    The expanding use of RNA interference (RNAi) in agricultural biotechnology necessitates tools for characterizing and quantifying double-stranded RNA (dsRNA)-containing transcripts that are expressed in transgenic plants. We sought to detect and quantify such transcripts in transgenic maize lines engineered to control western corn rootworm (Diabrotica virgifera virgifera LeConte) via overexpression of an inverted repeat sequence bearing a portion of the putative corn rootworm orthologue of yeast Snf7 (DvSnf7), an essential component of insect cell receptor sorting. A quantitative assay was developed to detect DvSnf7 sense strand-containing dsRNA transcripts that is based on the QuantiGene Plex 2.0 RNA assay platform from Affymetrix. The QuantiGene assay utilizes cooperative binding of multiple oligonucleotide probes with specificity for the target sequence resulting in exceptionally high assay specificity. Successful implementation of this assay required heat denaturation in the presence of the oligonucleotide probes prior to hybridization, presumably to dissociate primary transcripts carrying the duplex dsRNA structure. The dsRNA assay was validated using a strategy analogous to the rigorous enzyme-linked immunosorbent assay evaluations that are typically performed for foreign proteins expressed in transgenic plants. Validation studies indicated that the assay is sensitive (to 10 pg of dsRNA/g of fresh tissue), highly reproducible, and linear over ∼2.5 logs. The assay was validated using purified RNA from multiple maize tissue types, and studies indicate that the assay is also quantitative in crude tissue lysates. To the best of our knowledge, this is the first report of a non-polymerase chain reaction-based quantitative assay for dsRNA-containing transcripts, based on the use of the QuantiGene technology platform, and will broadly facilitate characterization of dsRNA in biological and environmental samples.

  1. Formulations of Melia azedarach to Control Diabrotica speciosa (Germar) (Coleoptera: Chrysomelidae) Larvae in Corn and Plant Enhancement.

    PubMed

    Souza, B H S; Costa, E N; Forim, M R; Costa, E S; Boiça Júnior, A L

    2015-04-01

    We evaluated oil and powder formulations of Melia azedarach for controlling larvae of Diabrotica speciosa (Germar) in corn and plant enhancement. Five concentrations of each formulation were evaluated and compared to fipronil (negative control) and distilled water (positive control). After treatment, the number of surviving insects (larvae, pupae, and adults), the adult body weight, the sex ratio, and the longevity were recorded, while the height, dry weight of aerial part and roots, and number of leaves of plants were measured. The oil formulation at 4.0 mL reduced the larvae population of D. speciosa similarly to the insecticide fipronil, which resulted in greater height, dry weight of the root system, and number of leaves. Powder formulation at concentrations of 40, 80, and 160 mg caused larval mortality above 80%; however, these concentrations did not prevent reduction of plant height and dry weight of aerial part. Further studies assessing the residual period of M. azedarach control against D. speciosa larvae and its phytotoxicity, which are common traits associated with azadirachtin application, are necessary to subsidize the next steps of this alternative control strategy. PMID:26013136

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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....

  3. Results of a 13-week safety assurance study with rats fed grain from corn rootworm-protected, glyphosate-tolerant MON 88017 corn.

    PubMed

    Healy, C; Hammond, B; Kirkpatrick, J

    2008-07-01

    Presented are the results of a 13-week rat feeding study with grain from MON 88017 corn (brand name YieldGard VT Rootworm/RR2), protected from feeding damage caused by corn rootworm and tolerant to glyphosate, the active ingredient in Roundup agricultural herbicides. Corn rootworm protection is accomplished through the introduction of cryBb1 coding sequence from Bacillus thuringiensis into the corn genome for in planta production of a bioactive form of Cry3Bb1 protein. Also included in the genome is the coding sequence for the CP4 EPSPS protein from Agrobacterium sp. strain CP4 that confers glyphosate herbicidal tolerance. MON 88017 was formulated into rodent diets at 11 or 33% (w/w) levels with its near isogenic control at a level of 33% (w/w). Additionally, six diets containing grain from different conventional (non-biotechnology-derived), reference hybrids were formulated, each at 33% (w/w) levels of one of six reference grains. All diets were nutritionally balanced and conformed to PMI specifications for Certified LabDiet 5002 (PMI Certified LabDiet 5002 is a registered trademark of Purina Mills, Inc.). The responses of rats fed diets containing MON 88017 were comparable to those of rats fed a diet containing grain from its near isogenic control. This study complements extensive agronomic, compositional, and farm animal feeding studies with MON 88017 grain, confirming that it is as safe and nutritious as grain from existing commercial corn hybrids.

  4. Relevance of traditional integrated pest management (IPM) strategies for commercial corn producers in a transgenic agroecosystem: a bygone era?

    PubMed

    Gray, Michael E

    2011-06-01

    The use of transgenic Bt maize hybrids continues to increase significantly across the Corn Belt of the United States. In 2009, 59% of all maize planted in Illinois was characterized as a "stacked" gene variety. This is a 40% increase since 2006. Stacked hybrids typically express one Cry protein for corn rootworm control and one Cry protein for control of several lepidopteran pests; they also feature herbicide tolerance (to either glyphosate or glufosinate). Slightly more than 50 years has passed since Vernon Stern and his University of California entomology colleagues published (1959) their seminal paper on the integrated control concept, laying the foundation for modern pest management (IPM) programs. To assess the relevance of traditional IPM concepts within a transgenic agroecosystem, commercial maize producers were surveyed at a series of meetings in 2009 and 2010 regarding their perceptions on their use of Bt hybrids and resistance management. Special attention was devoted to two insect pests of corn, the European corn borer and the western corn rootworm. A high percentage of producers who participated in these meetings planted Bt hybrids in 2008 and 2009, 97 and 96.7%, respectively. Refuge compliance in 2008 and 2009, as mandated by the U.S. Environmental Protection Agency (EPA), was 82 and 75.7%, respectively, for those producers surveyed. A large majority of producers (79 and 73.3% in 2009 and 2010, respectively) revealed that they would, or had, used a Bt hybrid for corn rootworm (Diabrotica virgifera virgifera LeConte) or European corn borer (Ostrinia nubilalis Hübner) control even when anticipated densities were low. Currently, the EPA is evaluating the long-term use of seed blends (Bt and non-Bt) as a resistance management strategy. In 2010, a large percentage of producers, 80.4%, indicated they would be willing to use this approach. The current lack of integration of management tactics for insect pests of maize in the U.S. Corn Belt, due primarily to

  5. Modeling larval survival and movement to evaluate seed mixtures of transgenic corn for control of western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Onstad, D W

    2006-08-01

    I expanded the population dynamics and genetics model published in 2005 by Crowder and Onstad to include larval survival and movement to evaluate the role of mixtures of transgenic and nontransgenic corn, Zea mays L., seed for resistance management of western corn rootworm. I studied both density-independent and density-dependent toxin survival. In all but the worst-case scenarios, resistance did not evolve within 30 yr when the resistance allele, R, was recessive. The standard model with density-independent toxin survival based on the expression of a medium dose of toxin indicated that 50% R allele frequency will be reached by years 5 and 7, respectively, with dominant and partially recessive expression and 20% nontransgenic seed. The standard model with density-dependent toxin survival indicates that resistance will occur in year 5 under the same conditions. These results are similar to the published results of Crowder and Onstad who studied a model with adjacent block refuges and mostly nonrandom mating in the landscape (random only within each block). Results depended on the heterozygote advantage (differential survival between SS and RS) and the degree of random mating provided by the seed mixture.

  6. Multitrophic interactions among Western Corn Rootworm, Glomus intraradices and microbial communities in the rhizosphere and endorhiza of maize.

    PubMed

    Dematheis, Flavia; Kurtz, Benedikt; Vidal, Stefan; Smalla, Kornelia

    2013-01-01

    The complex interactions among the maize pest Western Corn Rootworm (WCR), Glomus intraradices (GI-recently renamed Rhizophagus intraradices) and the microbial communities in both rhizosphere and endorhiza of maize have been investigated in view of new pest control strategies. In a greenhouse experiment, different maize treatments were established: C (control plants), W (plants inoculated with WCR), G (plants inoculated with GI), GW (plants inoculated with GI and WCR). After 20 days of WCR root feeding, larval fitness was measured. Dominant arbuscular mycorrhizal fungi (AMF) in soil and maize endorhiza were analyzed by cloning of 18S rRNA gene fragments of AMF, restriction fragment length polymorphism and sequencing. Bacterial and fungal communities in the rhizosphere and endorhiza were investigated by denaturing gradient gel electrophoresis of 16S rRNA gene and ITS fragments, PCR amplified from total community DNA, respectively. GI reduced significantly WCR larval development and affected the naturally occurring endorhiza AMF and bacteria. WCR root feeding influenced the endorhiza bacteria as well. GI can be used in integrated pest management programs, rendering WCR larvae more susceptible to predation by natural enemies. The mechanisms behind the interaction between GI and WCR remain unknown. However, our data suggested that GI might act indirectly via plant-mediated mechanisms influencing the endorhiza microbial communities.

  7. Multitrophic interactions among Western Corn Rootworm, Glomus intraradices and microbial communities in the rhizosphere and endorhiza of maize

    PubMed Central

    Dematheis, Flavia; Kurtz, Benedikt; Vidal, Stefan; Smalla, Kornelia

    2013-01-01

    The complex interactions among the maize pest Western Corn Rootworm (WCR), Glomus intraradices (GI—recently renamed Rhizophagus intraradices) and the microbial communities in both rhizosphere and endorhiza of maize have been investigated in view of new pest control strategies. In a greenhouse experiment, different maize treatments were established: C (control plants), W (plants inoculated with WCR), G (plants inoculated with GI), GW (plants inoculated with GI and WCR). After 20 days of WCR root feeding, larval fitness was measured. Dominant arbuscular mycorrhizal fungi (AMF) in soil and maize endorhiza were analyzed by cloning of 18S rRNA gene fragments of AMF, restriction fragment length polymorphism and sequencing. Bacterial and fungal communities in the rhizosphere and endorhiza were investigated by denaturing gradient gel electrophoresis of 16S rRNA gene and ITS fragments, PCR amplified from total community DNA, respectively. GI reduced significantly WCR larval development and affected the naturally occurring endorhiza AMF and bacteria. WCR root feeding influenced the endorhiza bacteria as well. GI can be used in integrated pest management programs, rendering WCR larvae more susceptible to predation by natural enemies. The mechanisms behind the interaction between GI and WCR remain unknown. However, our data suggested that GI might act indirectly via plant-mediated mechanisms influencing the endorhiza microbial communities. PMID:24376437

  8. Using a generational time-step model to simulate dynamics of adaptation to transgenic corn and crop rotation by western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Crowder, D W; Onstad, D W

    2005-04-01

    We expanded a simulation model of the population dynamics and genetics of the western corn rootworm for a landscape of corn, soybean, and other crops to study the simultaneous development of resistance to both crop rotation and transgenic corn. Transgenic corn effective against corn rootworm was recently approved in 2003 and may be a very effective new technology for control of western corn rootworm in areas with or without the rotation-resistant variant. In simulations of areas with rotation-resistant populations, planting transgenic corn to only rotated cornfields was a robust strategy to prevent resistance to both traits. In these areas, planting transgenic corn to only continuous fields was not an effective strategy for preventing adaptation to crop rotation or transgenic corn. In areas without rotation-resistant phenotypes, gene expression of the allele for resistance to transgenic corn was the most important factor affecting the development of resistance to transgenic corn. If the allele for resistance to transgenic corn is recessive, resistance can be delayed longer than 15 yr, but if the resistant allele is dominant then resistance usually developed within 15 yr. In a sensitivity analysis, among the parameters investigated, initial allele frequency and density dependence were the two most important factors affecting the evolution of resistance. We compared the results of this simulation model with a more complicated model and results between the two were similar. This indicates that results from a simpler model with a generational time-step can compare favorably with a more complex model with a daily time-step.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  10. Multitrophic Interaction in the Rhizosphere of Maize: Root Feeding of Western Corn Rootworm Larvae Alters the Microbial Community Composition

    PubMed Central

    Dematheis, Flavia; Zimmerling, Ute; Flocco, Cecilia; Kurtz, Benedikt; Vidal, Stefan; Kropf, Siegfried; Smalla, Kornelia

    2012-01-01

    Background Larvae of the Western Corn Rootworm (WCR) feeding on maize roots cause heavy economical losses in the US and in Europe. New or adapted pest management strategies urgently require a better understanding of the multitrophic interaction in the rhizosphere. This study aimed to investigate the effect of WCR root feeding on the microbial communities colonizing the maize rhizosphere. Methodology/Principal Findings In a greenhouse experiment, maize lines KWS13, KWS14, KWS15 and MON88017 were grown in three different soil types in presence and in absence of WCR larvae. Bacterial and fungal community structures were analyzed by denaturing gradient gel electrophoresis (DGGE) of the16S rRNA gene and ITS fragments, PCR amplified from the total rhizosphere community DNA. DGGE bands with increased intensity were excised from the gel, cloned and sequenced in order to identify specific bacteria responding to WCR larval feeding. DGGE fingerprints showed that the soil type and the maize line influenced the fungal and bacterial communities inhabiting the maize rhizosphere. WCR larval feeding affected the rhiyosphere microbial populations in a soil type and maize line dependent manner. DGGE band sequencing revealed an increased abundance of Acinetobacter calcoaceticus in the rhizosphere of several maize lines in all soil types upon WCR larval feeding. Conclusion/Significance The effects of both rhizosphere and WCR larval feeding seemed to be stronger on bacterial communities than on fungi. Bacterial and fungal community shifts in response to larval feeding were most likely due to changes of root exudation patterns. The increased abundance of A. calcoaceticus suggested that phenolic compounds were released upon WCR wounding. PMID:22629377

  11. 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

  12. 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

  13. Refuge or Reservoir? The Potential Impacts of the Biofuel Crop Miscanthus x giganteus on a Major Pest of Maize

    PubMed Central

    Spencer, Joseph L.; Raghu, S.

    2009-01-01

    Background Interest in the cultivation of biomass crops like the C4 grass Miscanthus x giganteus (Miscanthus) is increasing as global demand for biofuel grows. In the US, Miscanthus is promoted as a crop well-suited to the Corn Belt where it could be cultivated on marginal land interposed with maize and soybean. Interactions (direct and indirect) of Miscanthus, maize, and the major Corn Belt pest of maize, the western corn rootworm, (Diabrotica virgifera virgifera LeConte, WCR) are unknown. Adding a perennial grass/biomass crop to this system is concerning since WCR is adapted to the continuous availability of its grass host, maize (Zea mays). Methodology/Principal Findings In a greenhouse and field study, we investigated WCR development and oviposition on Miscanthus. The suitability of Miscanthus for WCR development varied across different WCR populations. Data trends indicate that WCR populations that express behavioural resistance to crop rotation performed as well on Miscanthus as on maize. Over the entire study, total adult WCR emergence from Miscanthus (212 WCR) was 29.6% of that from maize (717 WCR). Adult dry weight was 75–80% that of WCR from maize; female emergence patterns on Miscanthus were similar to females developing on maize. There was no difference in the mean no. of WCR eggs laid at the base of Miscanthus and maize in the field. Conclusions/Significance Field oviposition and significant WCR emergence from Miscanthus raises many questions about the nature of likely interactions between Miscanthus, maize and WCR and the potential for Miscanthus to act as a refuge or reservoir for Corn Belt WCR. Responsible consideration of the benefits and risks associated with Corn Belt Miscanthus are critical to protecting an agroecosystem that we depend on for food, feed, and increasingly, fuel. Implications for European agroecosystems in which Miscanthus is being proposed are also discussed in light of the WCR's recent invasion into Europe. PMID:20016814

  14. Structural and biophysical characterization of Bacillus thuringiensis insecticidal proteins Cry34Ab1 and Cry35Ab1.

    PubMed

    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.

  15. Novel Three-Step Pseudo-Absence Selection Technique for Improved Species Distribution Modelling

    PubMed Central

    Senay, Senait D.; Worner, Susan P.; Ikeda, Takayoshi

    2013-01-01

    potential distribution of the Asian tiger mosquito (Aedes albopictus) and the Western corn rootworm (Diabrotica virgifera virgifera). PMID:23967167

  16. Linkages between FAO agroclimatic data resources and the development of GIS models for control of vector-borne diseases.

    PubMed

    Bernardi, M

    2001-04-27

    The Food and Agriculture Organization (FAO) of the United Nations is the largest specialized UN Agency dealing with agriculture, forestry and fishery, particularly in the developing countries. One of its technical services, placed under the Sustainable Development Department, has the responsibility to provide information on environment and natural resources as related to food and agriculture. It includes, among others, expertise in remote sensing, geographic information systems and agrometeorology, production of global environmental digital datasets, meteorological and remote sensing data collection and analysis at near real-time, development of methodologies, models and tools for data standardization, collection, spatialization, analysis and dissemination, networking and information sharing, development of integrated information management systems. Some experience has also been gained in the use of climatic digital datasets for spatial modeling of crop pests and diseases. The description of mapping the distribution of the Western Corn rootworm (Diabrotica virgifera) in Europe as a function of environmental conditions is presented as well as the global assessment of environmental potential constraints based on processing of digital datasets. A simple spatial interpolation routine is briefly explained.

  17. Monitoring of Western Corn Rootworm Damage in Maize Fields by Using Integrated Radar (ALOS PALSAR) and Optical (IRS LISS, AWiFS) Satellite Data

    NASA Astrophysics Data System (ADS)

    Nador, Gizella; Fenyes, Diana; Surek, Gyorgy; Vasas, Laszlo

    2008-11-01

    The gradual dispersion of western corn rootworm (WCR) is becoming a serious maize pest in Europe, and all over the world. In 2008 using remote sensing data, the Remote Sensing Centre of Institute of Geodesy, Cartography and Remote Sensing (FÖMI RSC) carried out this project to identify WCR larval damage. Our goal with the present project is to assess and identify the disorder and structural changes caused by WCR larvae using optical (IRS-P6 AWiFS, IRS-P6 LISS, SPOT4 and SPOT5) and polarimetic radar (ALOS PALSAR) satellite images. The project aims to identify the extent of WCR damaged cornfields using both polarimetic radar images and optical satellite data time series. Findings were tested against on-the-spot ground assessments. Using radar polarimetry increased the accuracy significantly. The final results have implications for plant protection strategy, farming practices, pesticide producers, state authorities and research institutes.

  18. Assessment of Potential Risks of Dietary RNAi to a Soil Micro-arthropod, Sinella curviseta Brook (Collembola: Entomobryidae).

    PubMed

    Pan, Huipeng; Xu, Linghua; Noland, Jeffrey E; Li, Hu; Siegfried, Blair D; Zhou, Xuguo

    2016-01-01

    RNAi-based genetically engineered (GE) crops for the management of insect pests are likely to be commercialized by the end of this decade. Without a workable framework for conducting the ecological risk assessment (ERA) and a standardized ERA protocol, however, the utility of RNAi transgenic crops in pest management remains uncertain. The overall goal of this study is to assess the risks of RNAi-based GE crops on a non-target soil micro-arthropod, Sinella curviseta, which could be exposed to plant-protected dsRNAs deposited in crop residues. Based on the preliminary research, we hypothesized that insecticidal dsRNAs targeting at the western corn rootworm, Diabrotica virgifera virgifera, a billion-dollar insect pest, has no adverse impacts on S. curviseta, a soil decomposer. Following a tiered approach, we tested this risk hypothesis using a well-designed dietary RNAi toxicity assay. To create the worst-case scenario, the full-length cDNA of v-ATPase subunit A from S. curviseta were cloned and a 400 bp fragment representing the highest sequence similarity between target pest and non-target arthropods was selected as the template to synthesize insecticidal dsRNAs. Specifically, 10-days-old S. curviseta larvae were subjected to artificial diets containing v-ATPase A dsRNAs from both D. v. virgifera (dsDVV) and S. curviseta (dsSC), respectively, a dsRNA control, β-glucuronidase, from plant (dsGUS), and a vehicle control, H2O. The endpoint measurements included gene expression profiles, survival, and life history traits, such as developmental time, fecundity, hatching rate, and body length. Although, S. curviseta larvae developed significantly faster under the treatments of dsDVV and dsSC than the vehicle control, the combined results from both temporal RNAi effect study and dietary RNAi toxicity assay support the risk hypothesis, suggesting that the impacts of ingested arthropod-active dsRNAs on this representative soil decomposer are negligible. PMID:27471512

  19. Assessment of Potential Risks of Dietary RNAi to a Soil Micro-arthropod, Sinella curviseta Brook (Collembola: Entomobryidae)

    PubMed Central

    Pan, Huipeng; Xu, Linghua; Noland, Jeffrey E.; Li, Hu; Siegfried, Blair D.; Zhou, Xuguo

    2016-01-01

    RNAi-based genetically engineered (GE) crops for the management of insect pests are likely to be commercialized by the end of this decade. Without a workable framework for conducting the ecological risk assessment (ERA) and a standardized ERA protocol, however, the utility of RNAi transgenic crops in pest management remains uncertain. The overall goal of this study is to assess the risks of RNAi-based GE crops on a non-target soil micro-arthropod, Sinella curviseta, which could be exposed to plant-protected dsRNAs deposited in crop residues. Based on the preliminary research, we hypothesized that insecticidal dsRNAs targeting at the western corn rootworm, Diabrotica virgifera virgifera, a billion-dollar insect pest, has no adverse impacts on S. curviseta, a soil decomposer. Following a tiered approach, we tested this risk hypothesis using a well-designed dietary RNAi toxicity assay. To create the worst-case scenario, the full-length cDNA of v-ATPase subunit A from S. curviseta were cloned and a 400 bp fragment representing the highest sequence similarity between target pest and non-target arthropods was selected as the template to synthesize insecticidal dsRNAs. Specifically, 10-days-old S. curviseta larvae were subjected to artificial diets containing v-ATPase A dsRNAs from both D. v. virgifera (dsDVV) and S. curviseta (dsSC), respectively, a dsRNA control, β-glucuronidase, from plant (dsGUS), and a vehicle control, H2O. The endpoint measurements included gene expression profiles, survival, and life history traits, such as developmental time, fecundity, hatching rate, and body length. Although, S. curviseta larvae developed significantly faster under the treatments of dsDVV and dsSC than the vehicle control, the combined results from both temporal RNAi effect study and dietary RNAi toxicity assay support the risk hypothesis, suggesting that the impacts of ingested arthropod-active dsRNAs on this representative soil decomposer are negligible. PMID:27471512

  20. [Medical and biological safety assessment of genetically modified maize strain MIR604].

    PubMed

    Tutel'ian, V A; Gapparov, M M G; Avren'eva, L I; Aksiuk, I N; Guseva, G V; Kravchenko, L V; L'vova, L S; Saprykin, V P; Tyshko, N V; Chernysheva, O N

    2009-01-01

    The results of toxicologo-hygienic examinations, which were conducted within the framework of integrated medical and biological assessment of genetically modified rootworm Diabrotica spp.-protected maize event MIR604, are presented. Analysis of morphological, hematological, biochemical parameters and system (sensitive) biomarkers has not confirmed any toxic effect of maize event MIR604.

  1. [Medical and biological safety assessment of genetically modified maize event MON 88017. Report 1. Toxicologo-hygienic examinations].

    PubMed

    Tutel'ian, V A; Gapparov, M M; Avren'eva, L I; Aksiuk, I N; Guseva, G V; kravchenko, L V; L'vova, L S; Saprykin, V P; Tyshko, N V; Chernysheva, O N

    2008-01-01

    The results of toxicologo-hygienic examinations, which were conducted within the framework of integrated medical and biological assessment of genetically modified rootworm Diabrotica spp.--protected and glyphosate tolerant maize event MON 88017, are presented. Analysis of morphological, hematological, biochemical parameters and system (sensitive) biomarkers has not confirmed any toxic effect of maize event MON 88017.

  2. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  3. 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.

  4. 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. PMID:25764285

  5. 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

  6. A Physiological and Behavioral Mechanism for Leaf Herbivore-Induced Systemic Root Resistance.

    PubMed

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

    2015-12-01

    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

  7. A Physiological and Behavioral Mechanism for Leaf Herbivore-Induced Systemic Root Resistance.

    PubMed

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

    2015-12-01

    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.

  8. [Medical and biological safety assessment of genetically modified maize event MON 88017. Report 2. Genotoxicologic, immunologic and allergologic examinations].

    PubMed

    Tyshko, N V; Britsina, M V; Gmoshinskiĭ, I V; Zhanataev, A K; Zakharova, N S; Zorin, S N; Mazo, V K; Semenov, B F

    2008-01-01

    There are presented the results of genotoxicologic, immunologic and allergologic examinations which were conducted within the framework of integrated medical and biological assessment of genetically modified rootworm Diabrotica spp.--protected and glyphosate tolerant maize event MON 88017. Analysis of damages of DNA and structural chromosome aberrations, assessment of the allergenic potential and immunoreactive properties has not confirmed any genotoxic, allergenic and immunotoxic effect of maize event MON 88017.

  9. [Medical and biological safety assessment of genetically modified maize event MIR604].

    PubMed

    Tyshko, N V; Britsina, M V; Gmoshinskiĭ, I V; Zhanataev, A K; Zakharova, N S; Zorin, S N; Mazo, V K; Ozeretskovskaia, M N; Semenov, B F

    2009-01-01

    There are presented the results of genotoxicologic, immunologic and allergologic examinations which were conducted within the framework of integrated medical and biological assessment of genetically modified rootworm Diabrotica spp.-protected maize event MIR604. Analysis of damages of DNA and structural chromosome aberrations, assessment of the allergenic potential and immunoreactive properties has not confirmed any genotoxic, allergenic and immunotoxic effect of maize event MIR604.

  10. EXPLOITING CHEMICAL ECOLOGY FOR LIVELIHOOD IMPROVEMENT OF SMALL HOLDER FARMERS IN KENYA.

    PubMed

    Winter, E; Midega, C; Bruce, T; Hummel, H E; Langner, S S; Leithold, G; Khan, Z; Pickett, J

    2014-01-01

    study is needed. A second approach made use of species-specific insect monitoring traps baited with highly specific female sex pheromones for attracting and monitoring destructive insect pests. The female sex pheromone (8-methyl-decane-2-ol propanoate) of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) (Western Corn Rootworm) is readily available as bait in the "Metcalf sticky cup trap" for trapping males, an extraordinarily sensitive technique for monitoring the presence or absence of male beetles in a given area. Li et al. (2006) had argued for the likelihood of easy immigration of this cosmopolitan maize pest into East Africa. Our results, however, so far indicate the absence of a local population in the area of Mbita, while not excluding its presence at Nairobi or Mombasa. Both investigations contribute to different aspects of Kenyan economic development and may be seen as two independent but complementary contributions towards livelihood improvement of small holder farmers in Kenya. PMID:26084106

  11. EXPLOITING CHEMICAL ECOLOGY FOR LIVELIHOOD IMPROVEMENT OF SMALL HOLDER FARMERS IN KENYA.

    PubMed

    Winter, E; Midega, C; Bruce, T; Hummel, H E; Langner, S S; Leithold, G; Khan, Z; Pickett, J

    2014-01-01

    study is needed. A second approach made use of species-specific insect monitoring traps baited with highly specific female sex pheromones for attracting and monitoring destructive insect pests. The female sex pheromone (8-methyl-decane-2-ol propanoate) of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) (Western Corn Rootworm) is readily available as bait in the "Metcalf sticky cup trap" for trapping males, an extraordinarily sensitive technique for monitoring the presence or absence of male beetles in a given area. Li et al. (2006) had argued for the likelihood of easy immigration of this cosmopolitan maize pest into East Africa. Our results, however, so far indicate the absence of a local population in the area of Mbita, while not excluding its presence at Nairobi or Mombasa. Both investigations contribute to different aspects of Kenyan economic development and may be seen as two independent but complementary contributions towards livelihood improvement of small holder farmers in Kenya.

  12. A specialist root herbivore exploits defensive metabolites to locate nutritious tissues

    SciTech Connect

    Erb M.; Babst B.; Robert, C.A.M.; Veyrat, N.; Glauser, G.; Marti, G.; Doyen, G.R.; Villard, N.; Gaillard, M.D.P.; Koellner, T.G.; Giron, D.; Body, M.; Babst, B.A.; Turlings, T.C.J.; Erb, 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 deterred 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.

  13. 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.

  14. The role of abscisic acid and water stress in root herbivore-induced leaf resistance.

    PubMed

    Erb, Matthias; Köllner, Tobias G; Degenhardt, Jörg; Zwahlen, Claudia; Hibbard, Bruce E; Turlings, Ted C J

    2011-01-01

    • Herbivore-induced systemic resistance occurs in many plants and is commonly assumed to be adaptive. The mechanisms triggered by leaf-herbivores that lead to systemic resistance are largely understood, but it remains unknown how and why root herbivory also increases resistance in leaves. • To resolve this, we investigated the mechanism by which the root herbivore Diabrotica virgifera induces resistance against lepidopteran herbivores in the leaves of Zea mays. • Diabrotica virgifera infested plants suffered less aboveground herbivory in the field and showed reduced growth of Spodoptera littoralis caterpillars in the laboratory. Root herbivory did not lead to a jasmonate-dependent response in the leaves, but specifically triggered water loss and abscisic acid (ABA) accumulation. The induction of ABA by itself was partly responsible for the induction of leaf defenses, but not for the resistance against S. littoralis. Root-herbivore induced hydraulic changes in the leaves, however, were crucial for the increase in insect resistance. • We conclude that the induced leaf resistance after root feeding is the result of hydraulic changes, which reduce the quality of the leaves for chewing herbivores. This finding calls into question whether root-herbivore induced leaf-resistance is an evolved response.

  15. Effects of [3H]-BIDN, a novel bicyclic dinitrile radioligand for GABA-gated chloride channels of insects and vertebrates

    PubMed Central

    Rauh, James J; Benner, Eric; Schnee, Michael E; Cordova, Daniel; Holyoke, Caleb W; Howard, Michael H; Bai, Donglin; Buckingham, Steven D; Hutton, Michael L; Hamon, Alain; Roush, Richard T; Sattelle, David B

    1997-01-01

    The radiolabelled bicyclic dinitrile, [3H]-3,3-bis-trifluoromethyl-bicyclo[2.2.1]heptane-2,2-dicarbonitrile ([3H]-BIDN), exhibited, specific binding of high affinity to membranes of the southern corn rootworm (Diabrotica undecimpunctata howardi) and other insects. A variety of γ-aminobutyric acid (GABA) receptor convulsants, including the insecticides heptachlor (IC50, 35±3 nM) and dieldrin (IC50, 93±7 nM), displaced [3H]-BIDN from rootworm membranes. When tested at 100 μM, 1-(4-ethynylphenyl)-4-n-propyl-2,6,7-trioxabicyclo[2.2.2]octane(EBOB), 4-t-butyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-1-thione (TBPS), 1-phenyl-4-t-butyl-2,6,7-trioxabicyclo[2.2.2]octane (TBOB) and picrotoxin failed to displace 50% of [3H]-BIDN binding to rootworm membranes indicating that the bicyclic dinitrile radioligand probes a site distinct from those identified by other convulsant radioligands. Dissociation studies showed that dieldrin, ketoendrin, toxaphene, heptachlor epoxide and α and β endosulphan displace bound [3H]-BIDN from rootworm membranes by a competitive mechanism. Rat brain membranes were also shown to possess a population of saturable, specific [3H]-BIDN binding sites, though of lower affinity than in rootworm and with a different pharmacological profile. Of the insecticidal GABAergic convulsants that displaced [3H]-BIDN from rootworm, cockroach (Periplaneta americana) and rat brain membranes, many were more effective in rootworm. Functional GABA-gated chloride channels of rootworm nervous system and of cockroach nerve and muscle were blocked by BIDN, whereas cockroach neuronal GABAB receptors were unaffected. Expression in Xenopus oocytes of either rat brain mRNA, or cDNA-derived RNA encoding a GABA receptor subunit (Rdl) that is expressed widely in the nervous system of Drosophila melanogaster resulted in functional, homo-oligomeric GABA receptors that were blocked by BIDN. Thus, BIDN probes a novel site on GABA-gated Cl− channels to which a number of

  16. A Maize (E)-β-Caryophyllene Synthase Implicated in Indirect Defense Responses against Herbivores Is Not Expressed in Most American Maize Varieties[W][OA

    PubMed Central

    Köllner, Tobias G.; Held, Matthias; Lenk, Claudia; Hiltpold, Ivan; Turlings, Ted C.J.; Gershenzon, Jonathan; Degenhardt, Jörg

    2008-01-01

    The sesquiterpene (E)-β-caryophyllene is emitted by maize (Zea mays) leaves in response to attack by lepidopteran larvae like Spodoptera littoralis and released from roots after damage by larvae of the coleopteran Diabrotica virgifera virgifera. We identified a maize terpene synthase, Terpene Synthase 23 (TPS23), that produces (E)-β-caryophyllene from farnesyl diphosphate. The expression of TPS23 is controlled at the transcript level and induced independently by D. v. virgifera damage in roots and S. littoralis damage in leaves. We demonstrate that (E)-β-caryophyllene can attract natural enemies of both herbivores: entomopathogenic nematodes below ground and parasitic wasps, after an initial learning experience, above ground. The biochemical properties of TPS23 are similar to those of (E)-β-caryophyllene synthases from dicotyledons but are the result of repeated evolution. The sequence of TPS23 is maintained by positive selection in maize and its closest wild relatives, teosinte (Zea sp) species. The gene encoding TPS23 is active in teosinte species and European maize lines, but decreased transcription in most North American lines resulted in the loss of (E)-β-caryophyllene production. We argue that the (E)-β-caryophyllene defense signal was lost during breeding of the North American lines and that its restoration might help to increase the resistance of these lines against agronomically important pests. PMID:18296628

  17. A coleopteran cadherin fragment synergizes toxicity of Bacillus thuringiensis toxins Cry3Aa, Cry3Bb, and Cry8Ca against lesser mealworm, Alphitobius diaperinus (Coleoptera: Tenebrionidae).

    PubMed

    Park, Youngjin; Hua, Gang; Taylor, Milton D; Adang, Michael J

    2014-11-01

    The lesser mealworm, Alphitobius diaperinus, is a serious cosmopolitan pest of commercial poultry facilities because of its involvement in structural damage to poultry houses, reduction in feed conversion efficiency, and transfer of avian and human pathogens. Cry3Aa, Cry3Bb, and Cry8Ca insecticidal proteins of Bacillus thuringiensis are used to control coleopteran larvae. Cadherins localized in the midgut epithelium function as receptors for Cry toxins in lepidopteran, coleopteran, and dipteran insects. Previously, we demonstrated that the truncated cadherin (DvCad1) from Diabrotica virgifera virgifera, which consists of the C-terminal cadherin repeats (CR) 8-10 and expressed in Escherichia coli, enhanced Cry3Aa and Cry3Bb toxicity against several coleopteran species. Here we report that the DvCad1-CR8-10 enhances Cry3Aa, Cry3Bb, and Cry8Ca toxicity to lesser mealworm. Previously, by an enzyme linked immunosorbent microplate assay, we demonstrated that the DvCad1-CR8-10 binds activated-Cry3Aa (11.8 nM), -Cry3Bb (1.4nM), and now report that CR8-10 binds activated-Cry8Ca (5.7 nM) toxin. The extent of Cry toxins enhancement by DvCad1-CR8-10, which ranged from 3.30- to 5.93-fold, may have practical application for lesser mealworm control in preventing avian and human pathogen transfer in poultry facilities.

  18. Characteristics of tomato plants treated with leaf extracts of neem (Azadirachta indica A. Juss. (L.)) and mata-raton (Gliricidia sepium (Jacquin)): a greenhouse experiment.

    PubMed

    Montes-Molina, Joaquín Adolfo; Nuricumbo-Zarate, Ibis Harumy; Hernández-Díaz, Javier; Gutiérrez-Miceli, Federico Antonio; Dendooven, Luc; Ruíz-Valdiviezo, Víctor Manuel

    2014-09-01

    Extracts of neem (Azadirachta indica A.) and mata-raton (Gliricidia sepium) leaves were used as insect repellent during organic cultivation of tomato plants (Solanum lycopersicum) and were compared with untreated plants or plants treated with lambda-cyhalothrin (chemical treatment). The best developed tomato plants were found in the Gliricidia treatment, while difference between other treatments were small. The number of different species of macrofauna found on tomato plants were similar in different treatments, except for corn rootworm (Diabrotica spp.) found in the Gliricidia treatment, but not in other treatments. It was found that leaf extract of G. sepium stimulated tomato growth and altered the leaf and fruit characteristics. This was most likely due to its action as a growth regulator and/or an inductor of changes in the tomato growth regulation, but not due to its action as an insect repellent. Consequently, leaf extract of G. sepium could be used to stimulate tomato development.

  19. Characteristics of tomato plants treated with leaf extracts of neem (Azadirachta indica A. Juss. (L.)) and mata-raton (Gliricidia sepium (Jacquin)): a greenhouse experiment.

    PubMed

    Montes-Molina, Joaquín Adolfo; Nuricumbo-Zarate, Ibis Harumy; Hernández-Díaz, Javier; Gutiérrez-Miceli, Federico Antonio; Dendooven, Luc; Ruíz-Valdiviezo, Víctor Manuel

    2014-09-01

    Extracts of neem (Azadirachta indica A.) and mata-raton (Gliricidia sepium) leaves were used as insect repellent during organic cultivation of tomato plants (Solanum lycopersicum) and were compared with untreated plants or plants treated with lambda-cyhalothrin (chemical treatment). The best developed tomato plants were found in the Gliricidia treatment, while difference between other treatments were small. The number of different species of macrofauna found on tomato plants were similar in different treatments, except for corn rootworm (Diabrotica spp.) found in the Gliricidia treatment, but not in other treatments. It was found that leaf extract of G. sepium stimulated tomato growth and altered the leaf and fruit characteristics. This was most likely due to its action as a growth regulator and/or an inductor of changes in the tomato growth regulation, but not due to its action as an insect repellent. Consequently, leaf extract of G. sepium could be used to stimulate tomato development. PMID:25204070

  20. 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. PMID:25163650

  1. A wind-oriented sticky trap for evaluating the behavioural response of diabrotica speciosa (germar) to bitter cucurbit extracts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbitacins attract many species of Luperini leaf beetles, for which they have been studied and applied in traps and toxic baits. Males and females feed avidly on these compounds, but field trials reveal that males are far more attracted to them than females. A wind oriented baited sticky trap was...

  2. Membrane-permeabilizing activities of Bacillus thuringiensis coleopteran-active toxin CryIIIB2 and CryIIIB2 domain I peptide.

    PubMed Central

    Von Tersch, M A; Slatin, S L; Kulesza, C A; English, L H

    1994-01-01

    Bacillus thuringiensis toxin CryIIIB2 exhibits activity against two agriculturally important pests, the Colorado potato beetle, Leptinotarsa decemlineata, and the Southern corn rootworm, Diabrotica undecimpunctata. CryIIIB2 shows significant structural similarity to Colorado potato beetle-active toxin CryIIIA, whose crystal structure has been determined elsewhere [J. Li, J. Carrol, and D. J. Ellar, Nature (London) 353:815-821, 1991]. A clone limited to the putative 7-alpha-helical bundle domain I peptide of CryIIIB2 was constructed by PCR. The truncated protein was expressed at high levels in Escherichia coli. Domain I peptide was isolated and compared with native CryIIIB2 toxin in promoting ion efflux from synthetic phospholipid vesicles and formation of ion channels in black lipid membranes. The results showed that CryIIIB2 domain I peptide is sufficient for ion channel formation and promotes ion efflux. Both native CryIIIB2 toxin and domain I peptide were inefficient channel-forming proteins that produced noisy ion channels of various conductance states. In ion efflux assays, native toxin promoted greater ion efflux from synthetic vesicles than did the truncated peptide. Images PMID:7527203

  3. Potential of mass trapping for long-term pest management and eradication of invasive species.

    PubMed

    El-Sayed, A M; Suckling, D M; Wearing, C H; Byers, J A

    2006-10-01

    Semiochemical-based pest management programs comprise three major approaches that are being used to provide environmentally friendly control methods of insect pests: mass trapping, "lure and kill," and mating disruption. In this article, we review the potential of mass trapping in long-term pest management as well as in the eradication of invasive species. We discuss similarities and differences between mass trapping and other two main approaches of semiochemical-based pest management programs. We highlight several study cases where mass trapping has been used either in long-term pest management [e.g., codling moth, Cydia pomonella (L.); pink bollworm, Pectinophora gossypiella (Saunders); bark beetles, palm weevils, corn rootworms (Diabrotica spp.); and fruit flies] or in eradication of invasive species [e.g., gypsy moth, Lymantria dispar (L.); and boll weevil, Anthonomus grandis grandis Boheman). We list the critical issues that affect the efficacy of mass trapping and compare these with previously published models developed to investigate mass trapping efficacy in pest control. We conclude that mass trapping has good potential to suppress or eradicate low-density, isolated pest populations; however, its full potential in pest management has not been adequately realized and therefore encourages further research and development of this technology. PMID:17066782

  4. Tritrophic interactions among Bt maize, an insect pest and entomopathogens: effects on development and survival of western corn rootworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural systems often provide a model for testing ecological hypotheses, while ecological theory can enable more effective pest management. One of the best examples of this is the interaction between host-plant resistance and natural enemies. With the advent of crops that are genetically modifi...

  5. Harmonic radar: assessing the impact of tag weight on walking behavior of Colorado potato beetle, plum curculio and corn rootworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The impact of electronic dipole tags on the walking behavior of three insects was determined using video tracking software. Results varied within and between the three species studied. The mean horizontal speed of the Colorado potato beetle, Leptinotarsa decemlineata (Say), was reduced by 8 percen...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  7. Western Corn Rootworm (Coleoptera: Chrysomelidae)Larval Movement in eCry3.1Ab+mCry3A Seed Blend Scenarios

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn fields planted with plant-incorporated Bacillus thuringiensis (Bt) proteins must have a portion of the field planted with non-Bt, isoline, plants which serve as a refuge for susceptible insects. In the Corn Belt, refuge seeds are now blended in the bag with Bt seeds for corn hybrids containing ...

  8. 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).

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  10. Environmental Fate of Double-Stranded RNA in Agricultural Soils

    PubMed Central

    Dubelman, Samuel; Fischer, Joshua; Zapata, Fatima; Huizinga, Kristin; Jiang, Changjian; Uffman, Joshua; Levine, Steven; Carson, David

    2014-01-01

    A laboratory soil degradation study was conducted to determine the biodegradation potential of a DvSnf7 dsRNA transcript derived from a Monsanto genetically modified (GM) maize product that confers resistance to corn rootworm (CRW; Diabrotica spp.). This study provides new information to improve the environmental assessment of dsRNAs that become pesticidal through an RNAi process. Three agricultural soils differing in their physicochemical characteristics were obtained from the U.S., Illinois (IL; silt loam), Missouri (MO; loamy sand) and North Dakota (ND; clay loam), and exposed to the target dsRNA by incorporating insect-protected maize biomass and purified (in vitro-transcribed) DvSnf7 RNA into soil. The GM and control (non-GM maize) materials were added to each soil and incubated at ca. 22°C for 48 hours (h). Samples were collected at 12 time intervals during the incubation period, extracted, and analyzed using QuantiGene molecular analysis and insect bioassay methods. The DT50 (half-life) values for DvSnf7 RNA in IL, MO, and ND soils were 19, 28, and 15 h based on QuantiGene, and 18, 29, and 14 h based on insect bioassay, respectively. Furthermore, the DT90 (time to 90% degradation) values for DvSnf7 RNA in all three soils were <35 h. These results indicate that DvSnf7 RNA was degraded and biological activity was undetectable within approximately 2 days after application to soil, regardless of texture, pH, clay content and other soil differences. Furthermore, soil-incorporated DvSnf7 RNA was non-detectable in soil after 48 h, as measured by QuantiGene, at levels ranging more than two orders of magnitude (0.3, 1.5, 7.5 and 37.5 µg RNA/g soil). Results from this study indicate that the DvSnf7 dsRNA is unlikely to persist or accumulate in the environment. Furthermore, the rapid degradation of DvSnf7 dsRNA provides a basis to define relevant exposure scenarios for future RNA-based agricultural products. PMID:24676387

  11. 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

  12. 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

  13. 77 FR 69838 - MON 87410 and MON 87411 Pesticide-Incorporated Protectant Corn Events: Pesticide Experimental Use...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-21

    ... double stranded RNA (dsRNA) transcript comprising a Dv49 inverted repeat sequence derived from Diabrotica... stranded RNA (dsRNA) transcript comprising a Dv49 inverted repeat sequence derived from Diabrotica... stranded RNA (dsRNA) transcript suppression cassette with an inverted repeat sequence, Dv49, obtained...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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,...

  15. 78 FR 48672 - FIFRA Scientific Advisory Panel; Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... of chemical substances under the Federal Food, Drug, and Cosmetic Act (FFDCA) and FIFRA. Since other..., Insect Resistance Management, Corn rootworm biology and ecology, Population sampling, Bioassay techniques... Office of Chemical Safety and Pollution Prevention (OCSPP) and is structured to provide scientific...

  16. Studies of Corn Stover Decomposition Using the Litter Bag Technique

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Decomposition rates of residue from three genetically-modified corn hybrids expressing one or more Bt endotoxins were compared to that of residue from a near isogenic, unmodified hybrid. The corn hybrids were (i) DKC60-16 (Yieldguard Corn Borer), (ii) DKC60-12 (Yieldguard Corn Rootworm), (iii) DKC60...

  17. Corn insect pests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. 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.

  19. 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.

  20. Characterization of Cry34Ab1 and Cry35Ab1 insecticidal crystal proteins expressed in transgenic corn plants and Pseudomonas fluorescens.

    PubMed

    Gao, Yong; Schafer, Barry W; Collins, Randy A; Herman, Rod A; Xu, Xiaoping; Gilbert, Jeffrey R; Ni, Weiting; Langer, Vickie L; Tagliani, Laura A

    2004-12-29

    Cry34Ab1 and Cry35Ab1 proteins, identified from Bacillus thuringiensis strain PS149B1, act together to control corn rootworms. Transgenic corn lines coexpressing the two proteins were developed to protect corn against rootworm damage. Large quantities of the two proteins were needed to conduct studies required for assessing the safety of this transgenic corn crop. Because it was technically infeasible to obtain sufficient quantities of high purity Cry34Ab1 and Cry35Ab1 proteins from the transgenic corn plants, the proteins were produced using a recombinant Pseudomonas fluorescens (Pf) production system. The two proteins from both the transgenic corn and the Pf were purified and characterized. The proteins from each host had the expected molecular mass and were immunoreactive to specific antibodies in enzyme-linked immunosorbent assay and Western blot analysis. Data from N-terminal sequencing, tryptic peptide mass fingerprinting, internal peptide sequencing, and biological activity provided direct evidence that the Cry34Ab1 and Cry35Ab1 proteins produced in Pf and transgenic corn were, respectively, comparable or equivalent molecules. In addition, neither protein had detectable glycosylation regardless of the host.

  1. Impact of Location, Cropping History, Tillage, and Chlorpyrifos on Soil Arthropods in Peanut.

    PubMed

    Cardoza, Yasmin J; Drake, Wendy L; Jordan, David L; Schroeder-Moreno, Michelle S; Arellano, Consuelo; Brandenburg, Rick L

    2015-08-01

    Demand for agricultural production systems that are both economically viable and environmentally conscious continues to increase. In recent years, reduced tillage systems, and grass and pasture rotations have been investigated to help maintain or improve soil quality, increase crop yield, and decrease labor requirements for production. However, documentation of the effects of reduced tillage, fescue rotation systems as well as other management practices, including pesticides, on pest damage and soil arthropod activity in peanut production for the Mid-Atlantic US region is still limited. Therefore, this project was implemented to assess impacts of fescue-based rotation systems on pests and other soil organisms when compared with cash crop rotation systems over four locations in eastern North Carolina. In addition, the effects of tillage (strip vs. conventional) and soil chlorpyrifos application on pod damage and soil-dwelling organisms were also evaluated. Soil arthropod populations were assessed by deploying pitfall traps containing 50% ethanol in each of the sampled plots. Results from the present study provide evidence that location significantly impacts pest damage and soil arthropod diversity in peanut fields. Cropping history also influenced arthropod diversity, with higher diversity in fescue compared with cash crop fields. Corn rootworm damage to pods was higher at one of our locations (Rocky Mount) compared with all others. Cropping history (fescue vs. cash crop) did not have an effect on rootworm damage, but increased numbers of hymenopterans, acarina, heteropterans, and collembolans in fescue compared with cash crop fields. Interestingly, there was an overall tendency for higher number of soil arthropods in traps placed in chlorpyrifos-treated plots compared with nontreated controls. PMID:26314040

  2. Impact of Location, Cropping History, Tillage, and Chlorpyrifos on Soil Arthropods in Peanut.

    PubMed

    Cardoza, Yasmin J; Drake, Wendy L; Jordan, David L; Schroeder-Moreno, Michelle S; Arellano, Consuelo; Brandenburg, Rick L

    2015-08-01

    Demand for agricultural production systems that are both economically viable and environmentally conscious continues to increase. In recent years, reduced tillage systems, and grass and pasture rotations have been investigated to help maintain or improve soil quality, increase crop yield, and decrease labor requirements for production. However, documentation of the effects of reduced tillage, fescue rotation systems as well as other management practices, including pesticides, on pest damage and soil arthropod activity in peanut production for the Mid-Atlantic US region is still limited. Therefore, this project was implemented to assess impacts of fescue-based rotation systems on pests and other soil organisms when compared with cash crop rotation systems over four locations in eastern North Carolina. In addition, the effects of tillage (strip vs. conventional) and soil chlorpyrifos application on pod damage and soil-dwelling organisms were also evaluated. Soil arthropod populations were assessed by deploying pitfall traps containing 50% ethanol in each of the sampled plots. Results from the present study provide evidence that location significantly impacts pest damage and soil arthropod diversity in peanut fields. Cropping history also influenced arthropod diversity, with higher diversity in fescue compared with cash crop fields. Corn rootworm damage to pods was higher at one of our locations (Rocky Mount) compared with all others. Cropping history (fescue vs. cash crop) did not have an effect on rootworm damage, but increased numbers of hymenopterans, acarina, heteropterans, and collembolans in fescue compared with cash crop fields. Interestingly, there was an overall tendency for higher number of soil arthropods in traps placed in chlorpyrifos-treated plots compared with nontreated controls.

  3. 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. PMID:25682510

  4. Partitioning Yield Loss on Yellow Squash into Nematode and Insect Components

    PubMed Central

    McSorley, R.; Waddill, V. H.

    1982-01-01

    The effect of a contplex of several insect and nematode pests on yield of yellow squash (Cucurbita pepo L.) was examined in two field tests in southern Florida. Applications of permethrin for insect control and oxamyl primarily for nematode control plus some insect control were made alone and in combination to achieve differential reduction of various insect and nematode components contributing to yield loss. The effect of these components on yield was further analyzed by multiple regression. Yield losses in weight of small fruit to nematode and insect pests together were estimated at 23.4% and 30.4% in each of the two tests, respectively. In the first test, this loss was attributed to the melonworm, Diaphania hyalinata, while in the second test, it was attributed to D. hyalinata and the nematodes Quinisulcius acutus and particularly Rotylenchulus reniforrnis. D. hyalinata accounted for further losses of 9.0% and 10.3%, respectively, from direct damage to the fruit. Despite the presence of low levels of Diabrotica balteata, Liriomyza sativae, and Myzus persicae, yields were little affected by these pests. Prediction of yield loss by multiple regression analysis was more accurate when both insect and nematode populations were present in the plots than when nematodes alone were present. PMID:19295683

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Bt-maize event MON 88017 expressing Cry3Bb1 does not cause harm to non-target organisms.

    PubMed

    Devos, Yann; De Schrijver, Adinda; De Clercq, Patrick; Kiss, József; Romeis, Jörg

    2012-12-01

    This review paper explores whether the cultivation of the genetically modified Bt-maize transformation event MON 88017, expressing the insecticidal Cry3Bb1 protein against corn rootworms (Coleoptera: Chrysomelidae), causes adverse effects to non-target organisms (NTOs) and the ecological and anthropocentric functions they provide. Available data do not reveal adverse effects of Cry3Bb1 on various NTOs that are representative of potentially exposed taxonomic and functional groups, confirming that the insecticidal activity of the Cry3Bb1 protein is limited to species belonging to the coleopteran family of Chrysomelidae. The potential risk to non-target chrysomelid larvae ingesting maize MON 88017 pollen deposited on host plants is minimal, as their abundance in maize fields and the likelihood of encountering harmful amounts of pollen in and around maize MON 88017 fields are low. Non-target adult chrysomelids, which may occasionally feed on maize MON 88017 plants, are not expected to be affected due to the low activity of the Cry3Bb1 protein on adults. Impacts on NTOs caused by potential unintended changes in maize MON 88017 are not expected to occur, as no differences in composition, phenotypic characteristics and plant-NTO interactions were observed between maize MON 88017 and its near-isogenic line. PMID:22576225

  10. Selection of entomopathogenic nematodes for enhanced responsiveness to a volatile root signal helps to control a major root pest.

    PubMed

    Hiltpold, Ivan; Baroni, Mariane; Toepfer, Stefan; Kuhlmann, Ulrich; Turlings, Ted C J

    2010-07-15

    The efficacy of natural enemies as biological control agents against insect pests can theoretically be enhanced by artificial selection for high responsiveness to foraging cues. The recent discovery that maize roots damaged by the western corn rootworm (WCR) emit a key attractant for insect-killing nematodes has opened the way to explore whether a selection strategy can improve the control of root pests. The compound in question, (E)-beta-caryophyllene, is only weakly attractive to Heterorhabditis bacteriophora, one of the most infectious nematodes against WCR. To overcome this drawback, we used a six-arm below-ground olfactometer to select for a strain of H. bacteriophora that is more readily attracted to (E)-beta-caryophyllene. After six generations of selection, the selected strain responded considerably better and moved twice as rapidly towards a (E)-beta-caryophyllene source than the original strain. There was a minor trade-off between this enhanced responsiveness and nematode infectiveness. Yet, in subsequent field tests, the selected strain was significantly more effective than the original strain in reducing WCR populations in plots with a maize variety that releases (E)-beta-caryophyllene, but not in plots with a maize variety that does not emit this root signal. These results illustrate the great potential of manipulating natural enemies of herbivores to improve biological pest control.

  11. Bt-maize event MON 88017 expressing Cry3Bb1 does not cause harm to non-target organisms.

    PubMed

    Devos, Yann; De Schrijver, Adinda; De Clercq, Patrick; Kiss, József; Romeis, Jörg

    2012-12-01

    This review paper explores whether the cultivation of the genetically modified Bt-maize transformation event MON 88017, expressing the insecticidal Cry3Bb1 protein against corn rootworms (Coleoptera: Chrysomelidae), causes adverse effects to non-target organisms (NTOs) and the ecological and anthropocentric functions they provide. Available data do not reveal adverse effects of Cry3Bb1 on various NTOs that are representative of potentially exposed taxonomic and functional groups, confirming that the insecticidal activity of the Cry3Bb1 protein is limited to species belonging to the coleopteran family of Chrysomelidae. The potential risk to non-target chrysomelid larvae ingesting maize MON 88017 pollen deposited on host plants is minimal, as their abundance in maize fields and the likelihood of encountering harmful amounts of pollen in and around maize MON 88017 fields are low. Non-target adult chrysomelids, which may occasionally feed on maize MON 88017 plants, are not expected to be affected due to the low activity of the Cry3Bb1 protein on adults. Impacts on NTOs caused by potential unintended changes in maize MON 88017 are not expected to occur, as no differences in composition, phenotypic characteristics and plant-NTO interactions were observed between maize MON 88017 and its near-isogenic line.

  12. 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.

  13. Effects of a killed-cover crop mulching system on sweetpotato production, soil pests, and insect predators in South Carolina.

    PubMed

    Jackson, D Michael; Harrison, Howard F

    2008-12-01

    Sweetpotatoes, Ipomoea batatas (L.) Lam. (Convolvulaceae), are typically grown on bare soil where weeds and erosion can be serious problems. Conservation tillage systems using cover crop residues as mulch can help reduce these problems, but little is known about how conservation tillage affects yield and quality of sweetpotato or how these systems impact populations of beneficial and pest insects. Therefore, field experiments were conducted at the U.S. Vegetable Laboratory, Charleston, SC, in 2002-2004 to evaluate production of sweetpotatoes in conventional tillage versus a conservation tillage system by using an oat (Avena sativa L. (Poaceae)-crimson clover (Trifolium incarnatum L.) (Fabaceae) killed-cover crop (KCC) mulch. The four main treatments were 1) conventional tillage, hand-weeded; 2) KCC, hand-weeded; 3) conventional tillage, weedy; and 4) KCC, weedy. Each main plot was divided into three subplots, whose treatments were sweetpotato genotypes: 'Ruddy', which is resistant to soil insect pests; and 'SC1149-19' and 'Beauregard', which are susceptible to soil insect pests. For both the KCC and conventional tillage systems, sweetpotato yields were higher in plots that received hand weeding than in weedy plots. Orthogonal contrasts revealed a significant effect of tillage treatment (conventional tillage versus KCC) on yield in two of the 3 yr. Ruddy remained resistant to injury by soil insect pests in both cropping systems; and it consistently had significantly higher percentages of clean roots and less damage by wireworm-Diabrotica-Systena complex, sweetpotato flea beetles, grubs, and sweetpotato weevils than the two susceptible genotypes. In general, injury to sweetpotato roots by soil insect pests was not significantly higher in the KCC plots than in the conventionally tilled plots. Also, more fire ants, rove beetles, and carabid beetle were captured by pitfall traps in the KCC plots than in the conventional tillage plots during at least 1 yr of the study

  14. 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

  15. 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. PMID:25627217

  16. Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes

    PubMed Central

    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

  17. Effects of 90-Day Feeding of Transgenic Maize BT799 on the Reproductive System in Male Wistar Rats.

    PubMed

    Guo, Qian-ying; He, Li-xia; Zhu, Han; Shang, Jun-li; Zhu, Ling-yan; Wang, Jun-bo; Li, Yong

    2015-12-01

    BT799 is a genetically modified (GM) maize plant that expresses the Cry1Ac gene from Bacillus thuringiensis (Bt). The Cry1Ac gene was introduced into maize line Zhen58 to encode the Bt crystal protein and thus produce insect-resistant maize BT799. Expression of Bt protein in planta confers resistance to Lepidopteran pests and corn rootworms. The present study was designed to investigate any potential effects of BT799 on the reproductive system of male rats and evaluate the nutritional value of diets containing BT799 maize grain in a 90-day subchronic rodent feeding study. Male Wistar rats were fed with diets containing BT799 maize flours or made from its near isogenic control (Zhen58) at a concentration of 84.7%, nutritionally equal to the standard AIN-93G diet. Another blank control group of male rats were treated with commercial AIN-93G diet. No significant differences in body weight, hematology and serum chemistry results were observed between rats fed with the diets containing transgenic BT799, Zhen58 and the control in this 13-week feeding study. Results of serum hormone levels, sperm parameters and relative organ/body weights indicated no treatment-related side effects on the reproductive system of male rats. In addition, no diet-related changes were found in necropsy and histopathology examinations. Based on results of the current study, we did not find any differences in the parameters tested in our study of the reproductive system of male rats between BT799 and Zhen58 or the control. PMID:26633453

  18. Effects of 90-Day Feeding of Transgenic Maize BT799 on the Reproductive System in Male Wistar Rats.

    PubMed

    Guo, Qian-ying; He, Li-xia; Zhu, Han; Shang, Jun-li; Zhu, Ling-yan; Wang, Jun-bo; Li, Yong

    2015-12-02

    BT799 is a genetically modified (GM) maize plant that expresses the Cry1Ac gene from Bacillus thuringiensis (Bt). The Cry1Ac gene was introduced into maize line Zhen58 to encode the Bt crystal protein and thus produce insect-resistant maize BT799. Expression of Bt protein in planta confers resistance to Lepidopteran pests and corn rootworms. The present study was designed to investigate any potential effects of BT799 on the reproductive system of male rats and evaluate the nutritional value of diets containing BT799 maize grain in a 90-day subchronic rodent feeding study. Male Wistar rats were fed with diets containing BT799 maize flours or made from its near isogenic control (Zhen58) at a concentration of 84.7%, nutritionally equal to the standard AIN-93G diet. Another blank control group of male rats were treated with commercial AIN-93G diet. No significant differences in body weight, hematology and serum chemistry results were observed between rats fed with the diets containing transgenic BT799, Zhen58 and the control in this 13-week feeding study. Results of serum hormone levels, sperm parameters and relative organ/body weights indicated no treatment-related side effects on the reproductive system of male rats. In addition, no diet-related changes were found in necropsy and histopathology examinations. Based on results of the current study, we did not find any differences in the parameters tested in our study of the reproductive system of male rats between BT799 and Zhen58 or the control.

  19. Effects of 90-Day Feeding of Transgenic Maize BT799 on the Reproductive System in Male Wistar Rats

    PubMed Central

    Guo, Qian-ying; He, Li-xia; Zhu, Han; Shang, Jun-li; Zhu, Ling-yan; Wang, Jun-bo; Li, Yong

    2015-01-01

    BT799 is a genetically modified (GM) maize plant that expresses the Cry1Ac gene from Bacillus thuringiensis (Bt). The Cry1Ac gene was introduced into maize line Zhen58 to encode the Bt crystal protein and thus produce insect-resistant maize BT799. Expression of Bt protein in planta confers resistance to Lepidopteran pests and corn rootworms. The present study was designed to investigate any potential effects of BT799 on the reproductive system of male rats and evaluate the nutritional value of diets containing BT799 maize grain in a 90-day subchronic rodent feeding study. Male Wistar rats were fed with diets containing BT799 maize flours or made from its near isogenic control (Zhen58) at a concentration of 84.7%, nutritionally equal to the standard AIN-93G diet. Another blank control group of male rats were treated with commercial AIN-93G diet. No significant differences in body weight, hematology and serum chemistry results were observed between rats fed with the diets containing transgenic BT799, Zhen58 and the control in this 13-week feeding study. Results of serum hormone levels, sperm parameters and relative organ/body weights indicated no treatment-related side effects on the reproductive system of male rats. In addition, no diet-related changes were found in necropsy and histopathology examinations. Based on results of the current study, we did not find any differences in the parameters tested in our study of the reproductive system of male rats between BT799 and Zhen58 or the control. PMID:26633453

  20. Stabilization of cucurbitacin E-glycoside, a feeding stimulant for diabroticite beetles, extracted from bitter Hawkesbury watermelon.

    PubMed

    Martin, Phyllis A W; Blackburn, Michael; Schroder, Robert F W; Matsuo, Koharto; Li, Betty W

    2002-01-01

    Cucurbitacins are feeding stimulants for diabroticite beetles, including corn rootworms and cucumber beetles, which can be added to a bait containing an insecticide thereby reducing the levels of other insecticide treatments needed to control these pests. One of them, cucurbitacin E-glycoside, is water soluble and easily processed from mutant bitter Hawkesbury watermelons (BHW) that express elevated levels of cucurbitacin. Storage of BHW extract at room temperature resulted in a 92% reduction of cucurbitacin E-glycoside over two months, while refrigeration or freezing resulted in a 60% loss of the active ingredient during this time. The loss of the active ingredient was correlated with an increase in BHW extract pH from 5 to greater than 9. The increase in pH of the BHW extracts at room temperature appeared to be due to the growth of certain bacteria, especially Bacillusspp. In refrigerated extracts, the pH remained relatively constant, and bacterial growth was dominated by bacteria such as Lactobacilli. An alternative to refrigeration is concentration of BHW extract. One means of concentration is spray drying, but the high sugar content of the BHW extract (20mg/ml glucose, 40mg/ml fructose) makes this technique impractical. Fermentation of the BHW extract by the yeast, Saccharomyces boulardii, eliminated the sugars and did not raise the pH nor alter the cucurbitacin E-glycoside content of the extract. Elimination of the sugars by fermentation produced an extract that could be successfully spray dried. BHW extract fermented by S. boulardii produced a higher level of feeding stimulation for spotted cucumber beetles in laboratory choice tests. When applied to cucumbers, there was no difference in control of spotted and striped cucumber beetles between baits of fresh or fermented juices combined with the same insecticide. PMID:15455053

  1. 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.

  2. Comparison of broiler performance when fed diets containing grain from second-generation insect-protected and glyphosate-tolerant, conventional control or commercial reference corn.

    PubMed

    Taylor, M; Hartnell, G; Nemeth, M; Lucas, D; Davis, S

    2007-09-01

    Two 42-d floor pen studies were conducted to compare broiler (Ross x Ross 308) performance and carcass measurements when broilers were fed diets containing grain from either second-generation lepidopteran insect-protected corn (MON 89034; study 1) or second-generation lepidopteran combined with second-generation corn rootworm-protected and glyphosate-tolerant corn (MON 89034 x MON 88017; study 2) with those of diets containing corn grain from the conventional control and 4 conventional corn hybrids. In both studies, broilers were fed starter diets (approximately 55%, wt/wt, corn grain) from d 0 to 21 and grower-finisher diets (approximately 59%, wt/wt, corn grain) from d 21 to 42. Each study used a randomized complete block design with 6 dietary treatments assigned randomly within 5 blocks of 12 pens each (6 male and 6 female) and 10 pens per treatment group (5 male and 5 female). In study 1 (MON 89034), no treatment differences were detected among dietary treatments for feed intake, weight gain, or any measured carcass parameter. A significant difference was noted for adjusted feed conversion between MON 89034 and control birds; however, no differences were detected in individual treatment comparisons between the MON 89034 and 3 of the 4 commercial corn diets. In study 2 (MON 89034 x MON 88017), no treatment differences were observed for feed intake and most carcass parameters. When significant treatment differences were detected, no differences were observed between MON 89034 x MON 88017, its control, and 2 or more of the commercial corn diets. In each study, comparison of all parameters measured showed no differences between birds fed the test diet and the population of birds fed the control and 4 commercial corn diets. In conclusion, the test diets were nutritionally equivalent to diets containing the control and corn grain from commercial hybrids.