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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. 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...

  3. 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...

  4. Preliminary Mapping of the Western Corn Rootworm (Diabrotica virgifera virgifera) Genome and Quantitative Trait Locus (QTL) Interval Mapping for Growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Preliminary investigations into the organization of the western corn rootworm (Diabrotica virgifera virgifera; WCR) genome have resulted in low to moderate density gender-specific maps constructed from progeny of a backcrossed, short-diapause WCR family. Maps were based upon variation at microsatel...

  5. Genetics of United States Populations of Western Corn Rootworm ( Diabrotica virgifera virgifera) and Implications for Bacillus thuringiensis (Bt) Corn Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Western corn rootworm (Diabrotica virgifera virgifera; WCR) were sampled from across much of their US range for population genetic analyses. We assayed allelic variation at microsatellite loci, including markers within a cadherin-like gene, a locus shown to be correlated with resistance to Bacillus...

  6. 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 ...

  7. 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

  8. 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

  9. Molecular evolution of glycoside hydrolase genes in the Western corn rootworm (Diabrotica virgifera virgifera).

    PubMed

    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

  10. 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

  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. 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

  13. Validation of reference housekeeping genes for gene expression studies in western corn rootworm (Diabrotica virgifera virgifera).

    PubMed

    Rodrigues, Thaís Barros; 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

  14. 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

  15. Purification and kinetic analysis of acetylcholinesterase from western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

    PubMed

    Gao, J R; Rao, J V; Wilde, G E; Zhu, K Y

    1998-01-01

    Acetylcholinesterase (AChE, EC 3.1.1.7) was purified from western corn rootworm (WCR, Diabrotica virgifera virgifera) beetles by affinity chromatography. The purification factor reached over 20,000-fold with a specific activity of 169.5 mumol/min/mg and a yield of 23%. The Vmax values for hydrolyzing acetylthiocholine (ATC), acetyl-(beta-methyl) thiocholine (A beta MTC), propionylthiocholine (PTC), and S-butyrylthiocholine (BTC) were 184.8, 140.5, 150.2, and 18.8 mumol/min/mg, respectively, and K(m) values were 19.7, 18.5, 14.1, and 11.0 microM, respectively. The first three substrates showed significant inhibition to the AChE at higher concentrations, whereas BTC showed inhibition at the concentrations of 0.25-2 nM but activation at > 4 mM. AChE activity was almost completely inhibited by 1 microM eserine and BW284C15, respectively, but only 12% of AChE activity were inhibited by ethopropazine at the same concentration. These results suggested that the purified AChE from WCR was a typical insect AChE. Insecticides or their oxidative metabolites, chlorpyrifos-methyl oxon, carbofuran, carbaryl, malaoxon, and paraoxon, used in in vitro kinetic study exhibited high inhibition to AChE purified from WCR. However, chlorpyrifos-methyl oxon and carbofuran showed at least 36- and 4-fold, respectively, higher inhibitory potency than the remaining insecticides examined. Results from our in vitro inhibition of AChE agreed quite well with the previously published in vivo bioassay data. PMID:9880902

  16. 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. PMID:15294828

  17. Binary Toxins from Bacillus thuringiensis Active against the Western Corn Rootworm, Diabrotica virgifera virgifera LeConte

    PubMed Central

    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

    2004-01-01

    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. PMID:15294828

  18. 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

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

    PubMed

    Coates, B S; Alves, A P; Wang, H; Zhou, X; Nowatzki, T; Chen, H; Rangasamy, M; Robertson, H M; Whitfield, C W; Walden, K K; Kachman, S D; French, B W; Meinke, L J; Hawthorne, D; Abel, C A; Sappington, T W; Siegfried, B D; Miller, N J

    2016-02-01

    The western corn rootworm, Diabrotica virgifera virgifera, is an insect pest of corn and population suppression with chemical insecticides is an important management tool. Traits conferring organophosphate insecticide resistance have increased in frequency amongst D. v. virgifera populations, resulting in the reduced efficacy in many corn-growing regions of the USA. We used comparative functional genomic and quantitative trait locus (QTL) mapping approaches to investigate the genetic basis of D. v. virgifera resistance to the organophosphate methyl-parathion. RNA from adult methyl-parathion resistant and susceptible adults was hybridized to 8331 microarray probes. The results predicted that 11 transcripts were significantly up-regulated in resistant phenotypes, with the most significant (fold increases ≥ 2.43) being an α-esterase-like transcript. Differential expression was validated only for the α-esterase (ST020027A20C03), with 11- to 13-fold greater expression in methyl-parathion resistant adults (P < 0.05). Progeny with a segregating methyl-parathion resistance trait were obtained from a reciprocal backcross design. QTL analyses of high-throughput single nucleotide polymorphism genotype data predicted involvement of a single genome interval. These data suggest that a specific carboyxesterase may function in field-evolved corn rootworm resistance to organophosphates, even though direct linkage between the QTL and this locus could not be established. PMID:26566705

  20. Secondary contact and admixture between independently invading populations of the western corn rootworm, Diabrotica virgifera virgifera in Europe.

    PubMed

    Bermond, Gérald; Ciosi, Marc; Lombaert, Eric; Blin, Aurélie; Boriani, Marco; Furlan, Lorenzo; Toepfer, Stefan; Guillemaud, Thomas

    2012-01-01

    The western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae), is one of the most destructive pests of corn in North America and is currently invading Europe. The two major invasive outbreaks of rootworm in Europe have occurred, in North-West Italy and in Central and South-Eastern Europe. These two outbreaks originated from independent introductions from North America. Secondary contact probably occurred in North Italy between these two outbreaks, in 2008. We used 13 microsatellite markers to conduct a population genetics study, to demonstrate that this geographic contact resulted in a zone of admixture in the Italian region of Veneto. We show that i) genetic variation is greater in the contact zone than in the parental outbreaks; ii) several signs of admixture were detected in some Venetian samples, in a bayesian analysis of the population structure and in an approximate bayesian computation analysis of historical scenarios and, finally, iii) allelic frequency clines were observed at microsatellite loci. The contact between the invasive outbreaks in North-West Italy and Central and South-Eastern Europe resulted in a zone of admixture, with particular characteristics. The evolutionary implications of the existence of a zone of admixture in Northern Italy and their possible impact on the invasion success of the western corn rootworm are discussed. PMID:23189184

  1. 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...

  2. 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

  3. Western corn rootworm Diabrotica v. virgifera in Europe: status, and options for future management.

    PubMed

    Hummel, H E; Deuker, A

    2009-01-01

    Diabrotica virgifero virgifera (Col.: Chrysomelidae) (western corn rootworm, WCR) unfortunately is now a firmly established European maize pest without indigenous natural enemies. Twenty years after its first introduction into Europe by traffic and trade, eradication is wishful thinking and not longer a viable option. Instead, European legislation calls for toxicological emergency measures on a case by case basis where and when new infestations occur either by new invasions from the native Americas or by introductions from other European countries. It is unclear at which point in time such treatment systems will break down because of development of resistant strains or by other complications of this seemingly unstable situation. Rather than proceeding as usual, sustainable biological, biotechnical and cultural methods should be practiced. Prominent among them are trapping and survey with attractants in conjunction with traditional crop rotation and phytosanitation. PMID:20218535

  4. Ultrastructural changes caused by Snf7 RNAi in larval enterocytes of western corn rootworm (Diabrotica virgifera virgifera Le Conte).

    PubMed

    Koči, Juraj; Ramaseshadri, Parthasarathy; Bolognesi, Renata; Segers, Gerrit; Flannagan, Ronald; Park, Yoonseong

    2014-01-01

    The high sensitivity to oral RNA interference (RNAi) of western corn rootworm (WCR, Diabrotica virgifera virgifera Le Conte) provides a novel tool for pest control. Previous studies have shown that RNAi of DvSnf7, an essential cellular component of endosomal sorting complex required for transport (ESCRT), caused deficiencies in protein de-ubiquitination and autophagy, leading to WCR death. Here we investigated the detailed mechanism leading to larval death by analyzing the ultrastructural changes in midgut enterocytes of WCR treated with double-stranded RNA (ds-DvSnf7). The progressive phases of pathological symptoms caused by DvSnf7-RNAi in enterocytes include: 1) the appearance of irregularly shaped macroautophagic complexes consisting of relatively large lysosomes and multi-lamellar bodies, indicative of failure in autolysosome formation; 2) cell sloughing and loss of apical microvilli, and eventually, 3) massive loss of cellular contents indicating loss of membrane integrity. These data suggest that the critical functions of Snf7 in insect midgut cells demonstrated by the ultrastructural changes in DvSnf7 larval enterocytes underlies the conserved essential function of the ESCRT pathway in autophagy and membrane stability in other organisms. PMID:24409288

  5. Identification of sensilla involved in taste mediation in adult western corn rootworm (Diabrotica virgifera virgifera LeConte).

    PubMed

    Chyb, S; Eichenseer, H; Hollister, B; Mullin, C A; Frazier, J L

    1995-03-01

    A group of sensilla present on the maxillary galea of adult western corn rootworm,Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) beetles has been identified morphologically and physiologically to be involved in taste mediation. There are approximately 15 chemosensory hairs on each galea. Bilateral removal of these structures resulted in a significantly reduced consumption of a strongly phagostimulant triterpenoid, cucurbitacin B, and led to increased ingestion of a phagodeterrent alkaloid, strychnine. Electrophysiological responses obtained via tip-recording of galeal chemosensilla with submillimolar concentrations of host and nonhost plant compounds resulted in dose responses overlapping with the effective behavioral ranges. Cucurbitacin B was found to evoke chemosensory responses at levels as low as 0.1µM. Sinceγ-aminobutyric acid (GABA) is an agonist. (-)-β-hydrastine and strychnine are antagonists, and cucurbitacin B has been proposed to act at a separate modulatory site of classical synaptic GABA and glycine receptor-channel complexes, results reported here raise the possibility that there are peripheral chemosensory receptor sites that may resemble, functionally and structurally, synaptic receptor sites in the central nervous system. PMID:24234063

  6. 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...

  7. Monitoring western corn rootworm (Diabrotica v. virgifera) adults: situation in Romania 2008.

    PubMed

    Hummel, Hans E; Dinnesen, S; Nedelev, T; Grozea, I; Badea, A M; Ulrichs, Ch

    2009-01-01

    Romania is part of the southeast European expansion zone of the invasive rootworm species Diabrotica v. virgifera LeConte (Col.: Chrysomelidae) (WCR). The pest originated in North America and reached Belgrade airport with US foreign aid air shipments prior to 1992. Today, about 20 years after its introduction, WCR is a major maize pest which regionally causes economic damage to maize. However, it also can colonize secondary hosts which complicates IPM efforts. Basis for sound management is a reliable monitoring system. The easiest and cheapest way is to use Metcalf type monitoring traps for the mobile adults. Sex pheromones and plant kairomones for trapping are commercially available. Traps can be either bought or cheaply prepared. Metcalf traps with adhesive and lure cost about 15 cents per piece. So state-wide trapping is no longer a problem for less affluent countries. Results from two independent locations in 2008 report flight curves and attractively of secondary hosts like Sorghum spp. in relation to the principle host Zea mays. In addition, high capacity traps baited with pheromone are surprisingly effective, and, in combination with the chemically inert, absorptive silica powder AL 06, will be considered as future alternatives in cases where frequent monitoring is unfeasible and were a large holding capacity is indicated. PMID:20222584

  8. Behavior and Ecology of the Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    1. Western corn rootworm beetles (WCR) are historic pests with a legacy of resistance and behavioral plasticity. Current patterns of behavior and nutritional ecology are important and relevant to the history and the future of rootworm management. The success of the most effective and environmenta...

  9. 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...

  10. 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...

  11. 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

  12. 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

  13. Use of chromatin remodeling ATPases as RNAi targets for parental control of western corn rootworm (Diabrotica virgifera virgifera) and Neotropical brown stink bug (Euschistus heros).

    PubMed

    Fishilevich, Elane; Vélez, Ana M; Khajuria, Chitvan; Frey, Meghan L F; Hamm, Ronda L; Wang, Haichuan; Schulenberg, Greg A; Bowling, Andrew J; Pence, Heather E; Gandra, Premchand; Arora, Kanika; Storer, Nicholas P; Narva, Kenneth E; Siegfried, Blair D

    2016-04-01

    RNA interference (RNAi) is a gene silencing mechanism that is present in animals and plants and is triggered by double stranded RNA (dsRNA) or small interfering RNA (siRNA), depending on the organism. In the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), RNAi can be achieved by feeding rootworms dsRNA added to artificial diet or plant tissues transformed to express dsRNA. The effect of RNAi depends on the targeted gene function and can range from an absence of phenotypic response to readily apparent responses, including lethality. Furthermore, RNAi can directly affect individuals that consume dsRNA or the effect may be transferred to the next generation. Our previous work described the potential use of genes involved in embryonic development as a parental RNAi technology for the control of WCR. In this study, we describe the use of chromatin-remodeling ATPases as target genes to achieve parental gene silencing in two insect pests, a coleopteran, WCR, and a hemipteran, the Neotropical brown stink bug, Euschistus heros Fabricius (Hemiptera: Pentatomidae). Our results show that dsRNA targeting chromatin-remodeling ATPase transcripts, brahma, mi-2, and iswi strongly reduced the fecundity of the exposed females in both insect species. Additionally, knockdown of chd1 reduced the fecundity of E. heros. PMID:26873291

  14. cDNA cloning, biochemical characterization and inhibition by plant inhibitors of the alpha-amylases of the Western corn rootworm, Diabrotica virgifera virgifera.

    PubMed

    Titarenko, E; Chrispeels, M J

    2000-10-01

    We report the characterization and cDNA cloning of two alpha-amylase isozymes from larvae of the Western corn rootworm (Diabrotica virgifera virgifera LeConte). Larvae raised on artificial media have very low levels of amylase activity, and much higher levels are found in larvae raised on maize seedlings. At pH 5.7, the optimum pH for enzyme activity, the alpha-amylases are substantially but not completely inhibited by amylase inhibitors from the common bean (Phaseolus vulgaris) and from wheat (Triticum aestivum). Using the reverse transcriptase polymerase chain reaction (RT-PCR), we cloned two cDNAs with 83% amino acid identity that encode alpha-amylase-like polypeptides. Expression of one of the two cDNAs in insect cells with a baculovirus vector shows that this cDNA encodes an active amylase with a mobility that corresponds to that of one of the two isozymes present in larval extracts. The expressed enzyme is substantially inhibited by the same two inhibitors. We also show that expression in Arabidopsis of the cDNA that encodes the amylase inhibitor AI-1 of the common bean results in the accumulation of active inhibitor in the roots, and the results are discussed with reference to the possibility of using amylase inhibitors as a strategy to genetically engineer maize plants that are resistant to Western corn rootworm larvae. PMID:10899464

  15. Behavioral and electrophysiological dose-response relationships in adult western corn rootworm (Diabrotica virgifera virgifera LeConte) for host pollen amino acids.

    PubMed

    Hollister, Benedict; Mullin, Christopher A.

    1998-05-01

    A strong correlation is shown between taste cell inputs and phagostimulatory outputs with predominant dietary pollen amino acids for western corn rootworm, Diabrotica virgifera virgifera. Behavioral and electrophysiological dose-response profiles in adult beetles are presented for five major free amino acids in host pollens. Differential responses were found with strongest phagostimulation and sensory response elicited by L-alanine and L-serine, followed in order by L-proline and beta-alanine. gamma-Aminobutyric acid gave the weakest and most sporadic response. ED(50) values for phagostimulation and chemosensory input were 28.3nmol/disk and 13mM, respectively, for L-alanine and 17nmol/disk and 11mM, respectively, for serine. Threshold values for the responses were approximately 1-2mM. These behavioral and chemosensory dose-response ranges correspond closely to levels of free amino acids present in host plant pollens. Use of these response values in development of a pollen chemosensory code for western corn rootworm feeding is discussed. PMID:12770166

  16. Genes, Gene Flow and Adaptation of Diabrotica virgifera virgifera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genetics of the western corn rootworm, D. v. virgifera, is a relatively new field of study. Nevertheless, rapid progress has been made in recent years and this trend seems likely to continue. Much of the earliest work on Diabrotica genetics was concerned with phylogenetics and molecular species ...

  17. 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...

  18. 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

  19. Molecular cloning and functional characterization of an endogenous endoglucanase belonging to GHF45 from the western corn rootworm, Diabrotica virgifera virgifera.

    PubMed

    Valencia, Arnubio; Alves, Analiza P; Siegfried, Blair D

    2013-01-25

    A novel insect β-1,4-endoglucanase (DvvENGaseI) gene belonging to the glycoside hydrolase family (GHF) 45 was identified from the western corn rootworm, Diabrotica virgifera virgifera. The cDNA of the DvvENGaseI consisted of a 720 bp open reading frame encoding a 239 amino-acid protein. Analysis of the amino acid sequence revealed that DvvENGaseI exhibits 60% protein sequence identity when compared with an endoglucanase belonging to GHF45 from another beetle, Leptinotarsa decemlineata. Western blot analyses using a polyclonal antiserum developed from a partial peptide sequence revealed that DvvENGaseI expression coincided with body regions corresponding to the fore-, mid- and hindgut, although regions corresponding to the midgut and hindgut were the primary sites for DvvENGaseI expression. Functional analysis of the DvvENGaseI by RNA interference (RNAi) indicated that nearly complete knock-down of gene expression could be obtained by injection of dsRNA based on qRT-PCR and western blot analysis. However, suppression only resulted in slight developmental delays suggesting that this gene may be part of a larger system of cellulose degrading enzymes. PMID:23137634

  20. Physiological and cellular responses caused by RNAi- mediated suppression of Snf7 orthologue in western corn rootworm (Diabrotica virgifera virgifera) larvae.

    PubMed

    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

  1. Performance of a model for egg hatching of the western corn rootworm, Diabrotica virgifera virgifera LeConte, using measured and modelled soil temperatures as input

    NASA Astrophysics Data System (ADS)

    Schaafsma, A. W.; Fuentes, J. D.; Gillespie, T. J.; Whitfield, G. H.; Ellis, C. R.

    1993-03-01

    A model for egg hatching of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was tested at several locations in Ontario, Canada, during the 1989 and 1990 seasons. The model required soil temperatures as input and was tested using measured and modelled data. Modelled soil temperatures at 5 and 10 cm depths were obtained from empirically and physically based models. The physically based model provided better estimates of soil temperatues, but both models slightly underestimated the temperatures. Predicted egg hatching, using measured and modelled soil temperature at 5 and 10 cm depths for all locations, compared reasonably well with the observations of egg hatching. When using modelled soil temperatures, the egg developmental model performed better using soil temperatures from the physically based model. However, both soil temperature models provided sufficiently accurate temperature values for use in the egg developmental model. Unlike the empirically based model, the physically based model was not site-specific and its application to larger areas appeared feasible.

  2. A plant defensive cystatin (soyacystatin) targets cathepsin L-like digestive cysteine proteinases (DvCALs) in the larval midgut of western corn rootworm (Diabrotica virgifera virgifera).

    PubMed

    Koiwa, H; Shade, R E; Zhu-Salzman, K; D'Urzo, M P; Murdock, L L; Bressan, R A; Hasegawa, P M

    2000-04-01

    Feeding bioassay results established that the soybean cysteine proteinase inhibitor N (soyacystatin N, scN) substantially inhibits growth and development of western corn rootworm (WCR), by attenuating digestive proteolysis [Zhao, Y. et al. (1996) Plant Physiol. 111, 1299-1306]. Recombinant scN was more inhibitory than the potent and broad specificity cysteine proteinase inhibitor E-64. WCR digestive proteolytic activity was separated by mildly denaturing SDS-PAGE into two fractions and in-gel assays confirmed that the proteinase activities of each were largely scN-sensitive. Since binding affinity to the target proteinase [Koiwa, H. et al. (1998) Plant J. 14, 371-380] governs the effectiveness of scN as a proteinase inhibitor and an insecticide, five peptides (28-33 kDa) were isolated from WCR gut extracts by scN affinity chromatographic separation. Analysis of the N-terminal sequence of these peptides revealed similarity to a cathepsin L-like cysteine proteinase (DvCAL1, Diabrotica virgifera virgifera cathepsin L) encoded by a WCR cDNA. Our results indicate that cathepsin L orthologs are pivotal digestive proteinases of WCR larvae, and are targets of plant defensive cystatins (phytocystatins), like scN. PMID:10760514

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

    PubMed

    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

  4. 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

  5. Semiochemical attractants ofDiabrotica undecimpunctata howardi barber, southern corn rootworm, andDiabrotica virgifera virgifera leconte, the western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Lampman, R L; Metcalf, R L; Andersen, J F

    1987-04-01

    During the summers of 1984 and 1985, a variety of structurally related benzenoid compounds was evaluated in sweet corn plots as attractants for adult southern corn rootworms (SCR), western com rootworms (WCR), and northern corn rootworms (NCR). Field response to the volatiles was measured by beetle counts on baited cylindrical sticky traps placed inside the corn plots at a height of l m above ground level. SCR adults were attracted late in the season (last week of August through September, 1984 and 1985) to numerous aromatic compounds, including phenylacetaldehyde, benzyl acetone, phenethyl alcohol, phenyl acetate, indole, veratrole, methyl eugenol, methyl isoeugenol, eugenol, and isoeugenol. Although many compounds attracted SCR adults late in the season, only veratrole, phenylacetaldehyde, and chavicol were significantly active in early and middle August 1985. WCR adults were attracted to a different group of compounds, namely estragole,trans-anethole, and indole. Estragole (4-methoxy-1-allylbenzene) was an effective WCR attractant from corn tasseling in early August 1985, until the end of the trapping period in late September and early October 1985. Indole andtrans-anethole (4-methoxy-1-propenylbenzene) were less effective attractants than estragole and were most active at the beginning and/or end of the corn season. Traps baited with 100 mg of estragole caught an average of 20 times more WCR adults than unbaited control traps, and the females outnumbered the males in the baited traps. Estragole dosage tests were conducted in three sweet corn plots on different dates in 1985 and the minimum effective dose ranged between 5 and 30 mg/trap. Field tests with structural analogs revealed the importance of the site of unsaturation in the allylic side chain of estragole and the effect of different ring substituents on WCR response. The phenylpropanoids, eugenol and isoeugenol, significantly attracted NCR adults, even though these beetles were in low abundance in the

  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. PMID:26005118

  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. Likelihood of multiple mating in Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

    PubMed

    Kang, Jungkoo; Krupke, Christian H

    2009-12-01

    We evaluated the mating ability of male western corn rootworms, Diabrotica virgifera virgifera Leconte (Coleoptera: Chrysomelidae), for 20 d after initial mating, using a series of laboratory experiments. Males mated an average of 2.24 times within 10 d after their first mating and averaged 0.15 matings between days 11 and 20 after their first mating. Because estimating the mating frequency in Bt/refuge cornfields is critical to developing robust and reliable models predicting Bt resistance development in this pest, we discuss how these laboratory findings may influence development and evaluation of current and future insect resistance management plans. PMID:20069837

  9. Genome Scan of Diabrotica virgifera virgifera for Genetic Variation Associated with Crop Rotation Tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop rotation has been a valuable technique for control of the western corn rootworm, Diabrotica virgifera virgifera, for almost a century. However, during the last two decades, crop rotation has ceased to be effective in an expanding area of the United States Corn Belt. This failure appears to be d...

  10. Distribution of genes and repetitive elements in the Diabrotica virgifera virgifera genome estimated using BAC sequencing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Feeding damage caused by the corn rootworm, Diabrotica virgifera virgifera, is destructive to corn plants in North America and Europe where control remains challenging due to evolution of resistance traits that allow survival when exposed to chemical and transgenic toxins. Genome sequencing of an i...

  11. 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

  12. 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

  13. Characterizing the mechanism of action of double-stranded RNA activity against western corn rootworm (Diabrotica virgifera virgifera LeConte).

    PubMed

    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

  14. 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...

  15. Novel Bacillus thuringiensis Binary Insecticidal Crystal Proteins Active on Western Corn Rootworm, Diabrotica virgifera virgifera LeConte

    PubMed Central

    Ellis, R. Tracy; Stockhoff, Brian A.; Stamp, Lisa; Schnepf, H. Ernest; Schwab, George E.; Knuth, Mark; Russell, Josh; Cardineau, Guy A.; Narva, Kenneth E.

    2002-01-01

    A new family of insecticidal crystal proteins was discovered by screening sporulated Bacillus thuringiensis cultures for oral activity against western corn rootworm (WCR) larvae. B. thuringiensis isolates PS80JJ1, PS149B1, and PS167H2 have WCR insecticidal activity attributable to parasporal inclusion bodies containing proteins with molecular masses of ca. 14 and 44 kDa. The genes encoding these polypeptides reside in apparent operons, and the 14-kDa protein open reading frame (ORF) precedes the 44-kDa protein ORF. Mutagenesis of either gene in the apparent operons dramatically reduced insecticidal activity of the corresponding recombinant B. thuringiensis strain. Bioassays performed with separately expressed, biochemically purified 14- and 44-kDa polypeptides also demonstrated that both proteins are required for WCR mortality. Sequence comparisons with other known B. thuringiensis insecticidal proteins failed to reveal homology with previously described Cry, Cyt, or Vip proteins. However, there is evidence that the 44-kDa polypeptide and the 41.9- and 51.4-kDa binary dipteran insecticidal proteins from Bacillus sphaericus are evolutionarily related. The 14- and 44-kDa polypeptides from isolates PS80JJ1, PS149B1, and PS167H2 have been designated Cry34Aa1, Cry34Ab1, and Cry34Ac1, respectively, and the 44-kDa polypeptides from these isolates have been designated Cry35Aa1, Cry35Ab1, and Cry35Ac1, respectively. PMID:11872461

  16. Novel Bacillus thuringiensis binary insecticidal crystal proteins active on western corn rootworm, Diabrotica virgifera virgifera LeConte.

    PubMed

    Ellis, R Tracy; Stockhoff, Brian A; Stamp, Lisa; Schnepf, H Ernest; Schwab, George E; Knuth, Mark; Russell, Josh; Cardineau, Guy A; Narva, Kenneth E

    2002-03-01

    A new family of insecticidal crystal proteins was discovered by screening sporulated Bacillus thuringiensis cultures for oral activity against western corn rootworm (WCR) larvae. B. thuringiensis isolates PS80JJ1, PS149B1, and PS167H2 have WCR insecticidal activity attributable to parasporal inclusion bodies containing proteins with molecular masses of ca. 14 and 44 kDa. The genes encoding these polypeptides reside in apparent operons, and the 14-kDa protein open reading frame (ORF) precedes the 44-kDa protein ORF. Mutagenesis of either gene in the apparent operons dramatically reduced insecticidal activity of the corresponding recombinant B. thuringiensis strain. Bioassays performed with separately expressed, biochemically purified 14- and 44-kDa polypeptides also demonstrated that both proteins are required for WCR mortality. Sequence comparisons with other known B. thuringiensis insecticidal proteins failed to reveal homology with previously described Cry, Cyt, or Vip proteins. However, there is evidence that the 44-kDa polypeptide and the 41.9- and 51.4-kDa binary dipteran insecticidal proteins from Bacillus sphaericus are evolutionarily related. The 14- and 44-kDa polypeptides from isolates PS80JJ1, PS149B1, and PS167H2 have been designated Cry34Aa1, Cry34Ab1, and Cry34Ac1, respectively, and the 44-kDa polypeptides from these isolates have been designated Cry35Aa1, Cry35Ab1, and Cry35Ac1, respectively. PMID:11872461

  17. Diabrotica virgifera virgifera on South-Northern expansion drive?

    PubMed

    Hummel, H E; Wagner, L; Bertossa, M; Deuker, A; Leithold, G

    2012-01-01

    As Wudtke and colleagues predicted and Hummel and colleagues later confirmed, the Western corn rootworm Diabrotica v. virgifera LeConte (Coleoptera: Chrysomelidae) (WCR) had shown the ability to expand northward from South and Eastern into Central Europe. Decades earlier WCR had done the same in North America. Yet, European entomologists erroneously assumed they would be somehow magically protected from such aggressive moves of WCR. Meanwhile we know better: Southern Germany is infested, and also many East European countries are victims of these Northern and also Eastern advances. In Germany, neither speed nor extent of such advances is well defined. Jumping advances similar to earlier spreading episodes may be the rule, but they are not well predictable. In this report, we argue for a persistent northbound trend of WCR. PMID:23885424

  18. A monitoring trap for Diabrotica virgifera virgifera and D. barberi adults lured with a poisoned cucurbitacin bait.

    PubMed

    Shaw, J T; Hummel, H E

    2003-01-01

    A trap is described that uses as a simple natural ingredient a cucurbitacin mixture to capture and carbaryl insecticide to kill northern and western corn rootworm beetles (Diabrotica barberi Smith and Lawrence, and Diabrotica virgifera virgifera LeConte (D.v.v.), respectively). The trap is consistent in numbers of beetles captured per trap per day, and it should be useful in integrated pest management programs to monitor the population density of rootworm beetles in corn fields. Captures between 1981 and 1983 in Illinois showed that western corn rootworm adults that disperse into first-year cornfields were predominantly females. These traps are being utilized today (2003) by many researchers in the New World desiring to know more about rootworm beetle movement and activities. Entomologists in the Old World confronted with the alien invasive pest D.v.v. should profit likewise from increased knowledge and availability of these traps for Diabrotica management. PMID:15149093

  19. Characterisation of cysteine proteinases responsible for digestive proteolysis in guts of larval western corn rootworm (Diabrotica virgifera) by expression in the yeast Pichia pastoris.

    PubMed

    Bown, David P; Wilkinson, Hillary S; Jongsma, Maarten A; Gatehouse, John A

    2004-04-01

    Cysteine proteinases are the major class of enzymes responsible for digestive proteolysis in western corn rootworm (Diabrotica virgifera), a serious pest of maize. A larval gut extract hydrolysed typical cathepsin substrates, such as Z-phe-arg-AMC and Z-arg-arg-AMC, and hydrolysis was inhibited by Z-phe-tyr-DMK, specific for cathepsin L. A cDNA library representing larval gut tissue mRNA contained cysteine proteinase-encoding clones at high frequency. Sequence analysis of 11 cysteine proteinase cDNAs showed that 9 encoded cathepsin L-like enzymes, and 2 encoded cathepsin B-like enzymes. Three enzymes (two cathepsin L-like, DvRS5 and DvRS30, and one cathepsin B-like, DvRS40) were expressed as recombinant proteins in culture supernatants of the yeast Pichia pastoris. The cathepsin L-like enzymes were active proteinases, whereas the cathepsin B-like enzyme was inactive until treated with bovine trypsin. The amino acid residue in the S2 binding pocket, the major determinant of substrate specificity in cathepsin cysteine proteinases, predicted that the two cathepsin L-like enzymes, DvRS5 and DvRS30, should differ in substrate specificity, with the latter resembling cathepsin B in hydrolysing substrates with a positively charged residue at P2. This prediction was confirmed; DvRS5 only hydrolysed Z-phe-arg-AMC and not Z-arg-arg-AMC, whereas DvRS30 hydrolysed both substrates. The enzymes showed similar proteolytic activity towards peptide substrates. PMID:15041015

  20. Adult activity and oviposition of corn rootworms, Diabrotica spp. (Coleoptera: Chrysomelidae), in Miscanthus, corn, and switchgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of the biomass crop Miscanthus (Miscanthus × giganteus Greef and Deuter ex Hodkinson and Renvoize) to support larval development for both United States (U.S.) and European populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, suggests an avenue for potential i...

  1. 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 ...

  2. 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...

  3. 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...

  4. Expression and induction of three family 4 cytochrome P450 (CYP4)* genes identified from insecticide-resistant and susceptible western corn rootworms, Diabrotica virgifera virgifera.

    PubMed

    Scharf, M E; Parimi, S; Meinke, L J; Chandler, L D; Siegfried, B D

    2001-04-01

    We have previously determined that cytochrome P450-based oxidation is involved in resistance to the insecticides methyl parathion and carbaryl in geographically distinct Nebraska western corn rootworm populations. Three new family 4 cytochrome P450 (CYP4) gene fragments (CYP4AJ1, CYP4G18 and CYP4AK1) were cloned and sequenced from insecticide-resistant and -susceptible western corn rootworms. Insecticide bioassays indicated the resistant population employed in this study was significantly resistant to the insecticides methyl parathion and carbaryl. CYP4AJ1 and CYP4G18 were cloned from both genomic PCR and RT-PCR products, although only CYP4AJ1 contains an intronic region. Alignments of inferred amino acid sequences with other homologous insect CYP4 genes indicates a high degree of similarity. Northern analysis concurrently employing mixed probes representing each of the three rootworm CYP4 fragments identified increased mRNA transcript signals (i) in resistant rootworms and (ii) following induction by the P450 inducer pentamethyl benzene. These results support our previous documentation of P450-based insecticide resistance and suggest increased CYP4 transcript abundance can serve as a molecular resistance-associated marker. PMID:11422509

  5. 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...

  6. 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...

  7. Natural enemies in control of invasive species Diabrotica virgifera Virgifera from maize crops.

    PubMed

    Grozea, Ioana; Carabet, Alin; Chirita, Ramona; Badea, Ana Maria

    2008-01-01

    The invasive Diabrotico virgifera virgifera Le Conte (western corn rootworm) species has become a very important pest of maize growing areas from Europe. Incidence of this pest in Europe and Romania attract the specialist's attention and European organisms regarding substantial changes which save the yield. Current trends in control regard the using natural enemies' because non-pollutants effects. In this way it follows protection of useful scale from agroecosystems and their exploitation in control of invasive population. It were take the soil and surface samples for establish the presence of control biological agents. The maximum appearance period of invasive species (July, August) is very important in establishing the analogy with appearance of predator's species. From natural enemies of Diabrotica virgifera can be notice follow species: Speira diademata, Argiope bruennichi, Theridion impressum (Arachnida: Araneae), Coccinella sp., Pseudophomus rufipes (Insecta: Coleoptera). The spider species Argiope bruennichi (Araneae: Araneidae) and Theridion impressum (Araneae: Theriidae) are able to diminish significantly population of adults, especially in appearance of maize silk. The aim of the theme we approach is to find solutions to the issues created by invasive species Diabrotica virgifera virgifera using an ecological alternative of the chemical methods, as an-polluting biological methods. In a period when easily apply to chemical substances we consider that is absolutely necessary the introduction of these biological methods. PMID:19226790

  8. Distribution and antifeedant associations of sesquiterpene lactones in cultivated sunflower (Helianthus annuus L.) on western corn rootworm (Diabrotica virgifera virgifera LeConte).

    PubMed

    Chou, J C; Mullin, C A

    1993-07-01

    Seven antifeedant sesquiterpene lactones (STLs), 4,5-dihydroniveusin A, argophyllin B, argophyllin A, 15-hydroxy-3-dehydrodesoxytifruticin, niveusin B, 1,2-anhydridoniveusin A, and an unidentified epoxide, in cultivated sunflower (Helianthus annuus L.) have been quantified by a highperformance thin-layer chromatography and UV-reflectance scanning densitometry analysis. Age-related expression of STL content in sunflower reveals a heretofore undescribed pattern in which nonpolar STLs such as 15-hydroxy-3-dehydrodesoxytifruticin predominate up to an age of three weeks, but are subsequently displaced by polar STLs, especially argophyllin A, through later foliar stages and anthesis. This leaf pattern of STL ontogeny is maintained in three widely differentH. annuus cultivars (Giant Gray Stripe, Royal Hybrid 2141, Hybrid 7111), which in turn had similar total contents of STLs. Antifeedant activity for western corn rootworm was positively correlated with STL content, particularly with argophyllin A and its isomer argophyllin B, in respective tissue extracts. Enhanced amounts of highly antifeedant argophyllins, especially in newly grown leaf and floral tissues yielding sunflower progeny, strongly suggest that these epoxy-STLs are a chemical defense against insect herbivory. PMID:24249174

  9. Impact of cysteine proteinase inhibition in midgut fluid and oral secretion on fecundity and pollen consumption of western corn rootworm (Diabrotica virgifera virgifera).

    PubMed

    Kim, Jae Hak; Mullin, Christopher A

    2003-03-01

    Cysteine proteinases predominate in the midgut fluid (MF) and oral secretion (OS) of adult western corn rootworm (WCR) based on their mild acidic pH optima (pH 6.0), enhanced activities after treatment with thiol reducing agents, and inhibition by selective cysteine proteinase inhibitors (PIs). Four cysteine PIs including E-64, calpeptin, calpain inhibitor II, and leupeptin (also a serine PI) strongly inhibited azocaseinolytic activity in a dose-dependent manner in both the MF and OS. The most significant effect on adult female WCR of cysteine PI consumption with corn pollen was the reduction in fecundity, but female survival was not apparently affected. Mean fresh weights for all PI-fed females were also lower than control groups. All PI-fed groups [E-64, calpain inhibitor I (Cal I) and leupeptin] had a significantly lower daily egg production than respective corn pollen-fed controls. E-64 was more potent than leupeptin and Cal I on inhibiting fecundity, which correlates with their relative anti-proteinase potency in vitro. E-64, Cal I, and leupeptin at 1.5-2 nmol/beetle/day reduced fecundity down to 25-45% of control values. Reduced egg production by PI-fed beetles results from a combination of the direct inhibition of protein digestion and a post-ingestive negative feedback mechanism, which reduces food intake. The supplement of ten essential amino acids into the E-64-treated pollen enhanced up to 3.7-fold the number of eggs laid compared to the E-64-fed group without these amino acids, suggesting that egg production is dependent on the supply of essential amino acids from corn pollen proteolysis. PMID:12587142

  10. Tolerance of eCry3.1Ab in reciprocal cross offspring of eCry3.1Ab-selected and control colonies of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two reciprocal cross colonies were created by separating virgin western corn rootworm, Diabrotica virgifera virgifera LeConte, males and females from both a selected laboratory colony that was being reared on eCry3.1Ab-expressing corn (Zea mays L.) and a control colony reared on its near isoline. F...

  11. Distribution of Genes and Repetitive Elements in the Diabrotica virgifera virgifera Genome Estimated Using BAC Sequencing

    PubMed Central

    Coates, Brad S.; Alves, Analiza P.; Wang, Haichuan; Walden, Kimberly K. O.; French, B. Wade; Miller, Nicholas J.; Abel, Craig A.; Robertson, Hugh M.; Sappington, Thomas W.; Siegfried, Blair D.

    2012-01-01

    Feeding damage caused by the western corn rootworm, Diabrotica virgifera virgifera, is destructive to corn plants in North America and Europe where control remains challenging due to evolution of resistance to chemical and transgenic toxins. A BAC library, DvvBAC1, containing 109,486 clones with 104 ± 34.5 kb inserts was created, which has an ~4.56X genome coverage based upon a 2.58 Gb (2.80 pg) flow cytometry-estimated haploid genome size. Paired end sequencing of 1037 BAC inserts produced 1.17 Mb of data (~0.05% genome coverage) and indicated ~9.4 and 16.0% of reads encode, respectively, endogenous genes and transposable elements (TEs). Sequencing genes within BAC full inserts demonstrated that TE densities are high within intergenic and intron regions and contribute to the increased gene size. Comparison of homologous genome regions cloned within different BAC clones indicated that TE movement may cause haplotype variation within the inbred strain. The data presented here indicate that the D. virgifera virgifera genome is large in size and contains a high proportion of repetitive sequence. These BAC sequencing methods that are applicable for characterization of genomes prior to sequencing may likely be valuable resources for genome annotation as well as scaffolding. PMID:22919272

  12. Distribution of genes and repetitive elements in the Diabrotica virgifera virgifera genome estimated using BAC sequencing.

    PubMed

    Coates, Brad S; Alves, Analiza P; Wang, Haichuan; Walden, Kimberly K O; French, B Wade; Miller, Nicholas J; Abel, Craig A; Robertson, Hugh M; Sappington, Thomas W; Siegfried, Blair D

    2012-01-01

    Feeding damage caused by the western corn rootworm, Diabrotica virgifera virgifera, is destructive to corn plants in North America and Europe where control remains challenging due to evolution of resistance to chemical and transgenic toxins. A BAC library, DvvBAC1, containing 109,486 clones with 104 ± 34.5 kb inserts was created, which has an ~4.56X genome coverage based upon a 2.58 Gb (2.80 pg) flow cytometry-estimated haploid genome size. Paired end sequencing of 1037 BAC inserts produced 1.17 Mb of data (~0.05% genome coverage) and indicated ~9.4 and 16.0% of reads encode, respectively, endogenous genes and transposable elements (TEs). Sequencing genes within BAC full inserts demonstrated that TE densities are high within intergenic and intron regions and contribute to the increased gene size. Comparison of homologous genome regions cloned within different BAC clones indicated that TE movement may cause haplotype variation within the inbred strain. The data presented here indicate that the D. virgifera virgifera genome is large in size and contains a high proportion of repetitive sequence. These BAC sequencing methods that are applicable for characterization of genomes prior to sequencing may likely be valuable resources for genome annotation as well as scaffolding. PMID:22919272

  13. Response ofDiabrotica virgifera virgifera, D. v. Zeae, andD. porracea to stereoisomers of 8-methyl-2-decyl propanoate.

    PubMed

    Guss, P L; Sonnet, P E; Carney, R L; Branson, T F; Tumlinson, J H

    1984-07-01

    The four stereoisomers of 8-methyl-2-decyl propanoate were tested in the United States and Mexico for attractiveness toDiabrotica virgifera virgifera LeConte, the western corn rootworm,D. v. zeae Krysan and Smith, the Mexican corn rootworm, andD. porracea Harold. Males ofD. v. virgifera andD. v. zeae responded strongly to the (2R,8R)-isomer and secondarily to (2S,8R), whileD. ponacea responded exclusively to the (2S,8R)-isomer. The (2S,8S)- and (2R,8S)-isomers were inactive in all tests. Synergism or inhibition was not detected when various mixtures of the isomers were tested withD. v. virgifera. These phenomena were not tested withD. v. zeae andD. ponacea. PMID:24318854

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 (GM) Bt-maize offers an additional means of control against W...

  15. 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.

  16. 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. PMID:24498652

  17. 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. PMID:24513336

  18. A Multifaceted Hemolymph Defense Against Predation in Diabrotica virgifera virgifera Larvae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Defensive chemistry mitigates the strength of trophic interactions between an herbivore and its diverse assemblage of predators. Diabrotica virgifera virgifera is a chrysomelid beetle whose subterranean larvae are a notorious pest of maize production, although they succumb a number of generalist pre...

  19. 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. PMID:23448029

  20. 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

  1. No Clear Effect of Admixture between Two European Invading Outbreaks of Diabrotica virgifera virgifera in Natura

    PubMed Central

    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

  2. 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...

  3. Spatial Distribution and Areawide Management of Diabrotica virgifera virgifera LeConte in South Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabrotica v. virgifera is an economically important pest of maize in the U.S. Corn Belt. The areawide management program was conducted from 1997 – 2001 in five states. The location in South Dakota encompassed 41.4 km2 and was dominated by corn and soybean fields. An IPM approach was used to suppres...

  4. Response of larvae of invasive maize pest Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae) to carbon/nitrogen ratio and phytosterol content of European maize varieties.

    PubMed

    Moeser, J; Vidal, S

    2004-08-01

    We studied the performance of larvae of Diabrotica virgifera virgifera LeConte (Chrysomelidae, Galerucinae) on 17 different maize, Zea mays L., varieties from six European countries. Food conversion efficiency studies were performed using a newly established method. The growth of D. v. virgifera (western corn rootworm) larvae and the amount of ingested food was measured and the food conversion efficiency was calculated. In addition, we analyzed the carbon/nitrogen ratio and the phytosterol content of the different varieties. Significant differences between the maize varieties with regard to larval weight gain, amount of ingested food, and food conversion efficiency were encountered. The efficiency of D. v. virgifera in converting root biomass into insect biomass was positively related to the amount of nitrogen in the plant tissue. Furthermore the root phytosterol content influenced the larval weight gain and the amount of ingested food. It was possible to group the varieties into suitable and unsuitable cultivars with regard to D. v. virgifera larval performance on the basis of the phytosterol content. Our results provide the first evidence of the high variability among European maize varieties with respect to D. v. virgifera nutrition. The use of less suitable maize varieties is discussed with respect to integrated pest management strategies. PMID:15384346

  5. 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...

  6. A novel Bacillus thuringiensis (PS149B1) containing a Cry34Ab1/Cry35Ab1 binary toxin specific for the western corn rootworm Diabrotica virgifera virgifera LeConte forms ion channels in lipid membranes.

    PubMed

    Masson, Luke; Schwab, George; Mazza, Alberto; Brousseau, Roland; Potvin, Lena; Schwartz, Jean-Louis

    2004-09-28

    The binary Bacillus thuringiensis PS149B1 insecticidal crystal (Cry) protein is comprised of two components, Cry34Ab1, a 14-kDa protein, and Cry35Ab1, a 44-kDa protein, the combination of which forms a novel binary toxin active on western corn rootworm larvae. The permeabilizing behavior of the native binary toxin and its two individual components expressed as recombinant proteins was studied using calcein efflux determination in liposomes and by ion channel activity measurements in planar lipid bilayers (PLBs). Data obtained with solubilized native PS149B1 binary protein revealed it to be a pore-forming toxin that can permeabilize liposomes and form ion channels ( approximately 300-900 pS) in PLBs at pH 5.5 but not pH 9.0. The 14-kDa component of the toxin also formed ion channels ( approximately 15-300 pS) at pH 5.5 but did not insert easily in PLBs. While the 44-kDa moiety did seldomly form resolvable ion channels ( approximately 15-750 pS) in PLBs, it did destabilize the membranes. It showed pH-dependent truncation to a stable 40-kDa protein. The purified 40-kDa truncated product formed channels ( approximately 10-450 pS) in PLBs at pH 5.5. At that same pH, while a 3:1 molar mixture (14:44 kDa) of the individual components of the toxin induced channel activity that resembled that of the 14-kDa component alone, the 3:1 molar mixture of the 14-kDa component and 40-kDa truncated product induced channel activity ( approximately 20-800 pS) similar to that of PS149B1 in planar lipid bilayers. We conclude that the overall membrane permeabilization process of Cry34Ab1/Cry35Ab1 is a result of ion channel formation. PMID:15379574

  7. Within and Between Field Dispersal of Diabrotica barberi and D. virgifera virgifera in the South Dakota Areawide Management Site

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dispersal is a means by which organisms search for food, shelter, mates, oviposition sites, etc., and can ultimately result in gene flow among populations. We investigated the within and between field movement of Diabrotica barberi Smith and Lawrence and D. virgifera virgifera LeConte (Coleoptera: C...

  8. Within and Between Field Movement of Diabrotica barberi and D. virgifera virgifera in the South Dakota Areawide Management Site

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dispersal is a way insects search for food, shelter, mates, oviposition sites, etc., and can ultimately result in gene flow among populations. We investigated the within and between field movement of Diabrotica barberi Smith and Lawrence and D. virgifera virgifera LeConte (Coleoptera: Chrysomelidae)...

  9. Spatial clustering of Diabrotica virgifera virgifera and Agriotes ustulatus in small-scale maize fields without topographic relief drift

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The soil living larvae of Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) and Agriotes ustulatus Schaller (Elateridae) can cause economic damage to maize roots. This study investigated the spatial clustering of both pests in four small-scale maize fields in southern Hungary, wher...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The proliferation of retrotransposons within a genome can contribute to increased sizes 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 root...

  11. MULTIPLE STRAIN WOLBACHIA INFECTION OF NORTHERN CORN ROOTWORM (DIABROTICA BARBERI)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Northern corn rootworm (Diabrotica barberi)(NCR) populations in the USA are infected with at least 3 strains of the endosymbiont, Wolbachia. NCR from central Illinois appears to be singly infected with a strain wBar2. NCR from eastern Illinois to Pennsylvania appear to harbor at least 2 differen...

  12. Comparative Performance of Single Nucleotide Polymorphism (SNP) and Microsatellite Markers for the Detection of Population Differentiation in Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Putative single nucleotide polymorphisms (SNPs) were identified from contiguous sequences assembled from Diabrotica virgifera virgifera midgut expressed sequence tags (ESTs). Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP)-based assays confirmed variation at 20 biallel...

  13. Effects of the Training Dataset Characteristics on the Performance of Nine Species Distribution Models: Application to Diabrotica virgifera virgifera

    PubMed Central

    Dupin, Maxime; Reynaud, Philippe; Jarošík, Vojtěch; Baker, Richard; Brunel, Sarah; Eyre, Dominic; Pergl, Jan; Makowski, David

    2011-01-01

    Many distribution models developed to predict the presence/absence of invasive alien species need to be fitted to a training dataset before practical use. The training dataset is characterized by the number of recorded presences/absences and by their geographical locations. The aim of this paper is to study the effect of the training dataset characteristics on model performance and to compare the relative importance of three factors influencing model predictive capability; size of training dataset, stage of the biological invasion, and choice of input variables. Nine models were assessed for their ability to predict the distribution of the western corn rootworm, Diabrotica virgifera virgifera, a major pest of corn in North America that has recently invaded Europe. Twenty-six training datasets of various sizes (from 10 to 428 presence records) corresponding to two different stages of invasion (1955 and 1980) and three sets of input bioclimatic variables (19 variables, six variables selected using information on insect biology, and three linear combinations of 19 variables derived from Principal Component Analysis) were considered. The models were fitted to each training dataset in turn and their performance was assessed using independent data from North America and Europe. The models were ranked according to the area under the Receiver Operating Characteristic curve and the likelihood ratio. Model performance was highly sensitive to the geographical area used for calibration; most of the models performed poorly when fitted to a restricted area corresponding to an early stage of the invasion. Our results also showed that Principal Component Analysis was useful in reducing the number of model input variables for the models that performed poorly with 19 input variables. DOMAIN, Environmental Distance, MAXENT, and Envelope Score were the most accurate models but all the models tested in this study led to a substantial rate of mis-classification. PMID:21701579

  14. 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

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

    PubMed

    Wang, H; Coates, B S; Chen, H; Sappington, T W; Guillemaud, T; Siegfried, B D

    2013-10-01

    The western corn rootworm, Diabrotica virgifera virgifera, is a damaging pest of cultivated corn that was controlled by applications of cyclodiene insecticides from the late 1940s until resistance evolved ∼10 years later. Range expansion from the western plains into eastern USA coincides with resistance development. 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. We found that the non-synonymous single nucleotide polymorphism (SNP) G/T at the GABA receptor cDNA position 838 (G/T(838)) of D. v. virgifera resulted in the alanine to serine change, and the codominant SNP allele T(838) was genetically linked to survival of beetles in aldrin bioassays. A phenotypic gradient of decreasing susceptibility from west to east was correlated with higher frequencies of the resistance-conferring T(838) allele in the eastern-most populations. This pattern exists in opposition to perceived selective pressures since the more eastern and most resistant populations probably experienced reduced exposure. The reasons for the observed distribution are uncertain, but historical records of the range expansion combined with the distribution of susceptible and resistant phenotypes and genotypes provide an opportunity to better understand factors affecting the species' range expansion. PMID:23841833

  16. Effects of a potato cysteine proteinase inhibitor on midgut proteolytic enzyme activity and growth of the southern corn rootworm, Diabrotica undecimpunctata howardi (Coleoptera: Chrysomelidae).

    PubMed

    Fabrick, J; Behnke, C; Czapla, T; Bala, K; Rao, A G; Kramer, K J; Reeck, G R

    2002-04-01

    The major proteinase activity in extracts of larval midguts from the southern corn rootworm (SCR), Diabrotica undecimpunctata howardi, was identified as a cysteine proteinase that prefers substrates containing an arginine residue in the P1 position. Gelatin-zymogram analysis of the midgut proteinases indicated that the artificial diet-fed SCR, corn root-fed SCR, and root-fed western corn rootworms (Diabrotica virgifera virgifera) possess a single major proteinase with an apparent molecular mass of 25kDa and several minor proteinases. Similar proteinase activity pH profiles were exhibited by root-fed and diet-fed rootworms with the optimal activity being slightly acidic. Rootworm larvae reared on corn roots exhibited significantly less caseinolytic activity than those reared on the artificial diet. Midgut proteolytic activity from SCR was most sensitive to inhibition by inhibitors of cysteine proteinases. Furthermore, rootworm proteinase activity was particularly sensitive to inhibition by a commercial protein preparation from potato tubers (PIN-II). One of the proteins, potato cysteine proteinase inhibitor-10', PCPI-10', obtained from PIN-II by ion-exchange chromatography, was the major source of inhibitory activity against rootworm proteinase activity. PCPI-10' and E-64 were of comparable potency as inhibitors of southern corn rootworm proteinase activity (IC(50) =31 and 35nM, respectively) and substantially more effective than chicken egg white cystatin (IC(50) =121nM). Incorporation of PCPI-10' into the diet of SCR larvae in feeding trials resulted in a significant increase in mortality and growth inhibition. We suggest that expression of inhibitors such as PCPI-10' by transgenic corn plants in the field is a potentially attractive method of host plant resistance to these Diabrotica species. PMID:11886775

  17. 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...

  18. Parasitism of Northern Corn Rootworms (Chrysomelidae: Diabrotica barberi) by Celatoria diabroticae (Tachinidae) in South Dakota: New Geographic Record

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms (Coleoptera: Chrysomelidae) are devastating pests of maize (Zea mays L.). Recently, there has been increased interest in biological control of rootworms, and one group of parasitoids under investigation for their potential as natural enemies of Diabrotica spp. are Celatoria (Diptera: ...

  19. 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). ...

  20. Basic biology and small-scale rearing of Celatoria compressa(Diptera: Tachinidae), a parasitoid of Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae).

    PubMed

    Zhang, F; Toepfer, S; Kuhlmann, U

    2003-12-01

    The tachinid Celatoria compressa Wulp has been evaluated as a candidate biological control agent for the western corn rootworm, Diabrotica virgifera virgiferaLeConte, in Europe, where it is an invasive alien pest of maize. Special emphasis has been placed on understanding aspects of the parasitoid basic biology and on developing a rearing technique for a small-scale production of C. compressapuparia. The age of C. compressa adults was found to be the most crucial factor in achieving mating. Only newly emerged, 1-h-old females, mated successfully with 2- to 5-day-old males, achieving a success rate of 74%. After mating, a prelarviposition period of 4 days occurred. The 5-day-old C. compressa females inserted their eggs containing fully-developed first instars directly into adults of D. v. virgifera. Total larval and pupal developmental time, including a pre-larviposition period of 4 days, was 29 days under quarantine laboratory conditions (25 degrees C daytime, 15 degrees C at night, L:D 14:10, 50% +/- 10% r.h). Females of C. compressa were capable of producing on average 30 puparia throughout a female's mean larviposition period of 15 days. A large number of host attacks by C. compressa were unsuccessful, resulting in a mean larviposition success rate of 24% per female. Parasitoid females appear to have difficulties inserting the egg through the intersegmental sutures or membranes around leg openings of the host adults. Although the small-scale rearing technique of C. compressa presented is both time and labour intensive, C. compressa has been reared successfully for at least 20 successive generations without shifting the 1 male : 1 female sex ratio using a non-diapause strain of D. v. virgifera. PMID:14704104

  1. 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...

  2. 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...

  3. Antixenosis in maize reduces feeding by western corn rootworm larvae (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The first known example of a naturally-occurring maize genotype with behavioral resistance to western corn rootworm larval feeding was discovered in tests with SUM2162. Behavioral responses of neonate western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae were evaluated in laboratory...

  4. Maize Phenology Affects Establishment, Damage, and Development of the Western Corn Rootworm (Coleoptera:Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of maize (Zea mays L.) phenology on establishment and adult emergence of the western corn rootworm (Diabrotica virgifera virgifera LeConte) as well as plant damage to maize was evaluated in the greenhouse and in field trials in 2001 and 2002. Although neonate western corn rootworm larva...

  5. 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...

  6. 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 ...

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

    PubMed

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

    2003-01-01

    increased from 16.0 to 63.9%. To successfully decrease the size and intensity of attacks of the Diabrotica v. virgifera population under conditions of applying insecticides or not, it is necessary to use maize hybrids of the earliest possible maturity group and to plant the seed on the earliest date possible in the first year of growing maize, if maize is to be followed by maize in the next year. PMID:15149095

  8. Corn volatiles as attractants for northern and western corn rootworm beetles (Coleoptera: Chrysomelidae:Diabrotica spp.).

    PubMed

    Hammack, L

    1996-07-01

    Synthetic corn volatiles and selected analogs were tested in commercial corn fields for attractiveness to feral northern (NCR,Diabrotica barberi) and western corn rootworm beetles (WCR,D. virgifera virgifera). Two new attractants, geranylacetone and α-terpineol, were identified among corn terpenes and compared at four stages in crop development with the phenylpropanoid standards cinnamyl alcohol and 4-methoxy-cinnamaldehyde, with each component at 30 mg/trap. Dose-response relationships (0.1-100 mg/trap) and efficacy of two-component blends (30 mg/component) were also examined. More beetles were captured on traps baited with (+)- than (-)-α-terpineol, but the difference was statistically significant only for WCR. Captures with geranylacetone or (+)-α-terpineol were directly proportional to the logarithm of the attractant dose. WCR females were attracted to as little as 0.1 mg of either compound. WCR males required ≥ 1.0 mg of (+)-α-terpineol and were not attracted to geranylacetone at any dose. NCR required ≥0.3 mg of either attractant and showed less marked response differences between the sexes than did WCR. Geranylacetone and cinnamyl alcohol were equally effective attractants, whereas (+)-α-terpineol was significantly less attractive to WCR but more attractive to NCR than was 4-methoxycinnamaldehyde. Corn terpenes and phenylpropanoid standards produced similar seasonal response patterns in that captures tended to rise in each case as the season progressed, except during silking when no compound was attractive. Mixing corn terpenes or phenylpropanoid standards synergized responses of WCR females, but (+)-α-terpineol suppressed attraction of NCR females to geranylacetone. PMID:24226082

  9. 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...

  10. 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

  11. Identification of a female-produced sex pheromone of the western corn rootworm.

    PubMed

    Guss, P L; Tumlinson, J H; Sonnet, P E; Proveaux, A T

    1982-02-01

    A sex pheromone has been isolated and identified from virgin females of the western corn rootworm (WCR),Diabrotica virgifera virgifera LeConte. The synthesized compound, racemic 8-methyl-2-decanol propanoate, was equal in attraction to the natural pheromone when tested in the field as a trap bait against three taxa ofDiabrotica known to respond to pheromone extracts from female WCR. Five taxa (D. virgifera virgifera; D. virgifera zeae Krysan and Smith, Mexican corn rootworm;D. longicornis barberi Smith and Lawrence, northern corn rootworm;D. longicornis longicornis (Say); andD. porracea Harold) were attracted to traps baited with 8-methyl-2-decanol propanoate. The response of male northern corn rootworms (NCR) in the field peaked at a relatively low concentration of 8-methyl-2-decanol propanoate and then was severely reduced at the higher concentrations tested. Conversely, the response of male WCR in the field continued to increase up to the highest dose tested. PMID:24414965

  12. Wolbachia MLST marker diversity from multiply infected northern corn rootworm (Diabrotica barberi) populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The northern corn rootworm (NCR, Diabrotica barberi) in eastern and central North America exhibits at least three distinct populations with respect to Wolbachia infection: uninfected; singly infected; multiply infected. The infected states are associated with different mtDNA haplotypes and reduced m...

  13. Impact of corn variety on potential predators of larval corn rootworms (Coleoptera: Diabrotica spp.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms (Coleoptera: Diabrotica spp.) are serious pests of maize around the world. Larvae feed on corn roots, which reduces uptake of water and nutrients and lowers plant yield. Current control practices rely on soil insecticides or genetically modified corn varieties. Although some researche...

  14. Northern corn rootworm (Diabrotica barberi) populations infected by at least 5 Wolbachia strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wolbachia infections are present in northern corn rootworm (Diabrotica barberi) populations from east of the Mississippi River. The boundary between infected and uninfected populations is in central Illinois. DNA sequencing of Wolbachia ftsZ and wsp segments indicates that east central Illinois popu...

  15. Density-Dependent and Density-Independent Mortality of the Western Corn Rootworm: Impact on Dose Calculations of Rootworm-Resistant Bt Corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The percent of viable eggs of the western corn rootworm, Diabrotica virgifera virgifera LeConte, which survived to the adult stage was evaluated for the effect of egg density in 2005 and 2007 in Central Missouri. In 2005, each plot was 2.44 m × 3.05 m and contained 64 maize, Zea mays L., plants. I...

  16. Adaptation and Invasiveness of Western Corn Rootworm: Intensifying Research on a Worsening Pest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The western corn rootworm, Diabrotica virgifera virgifera LeConte, is an established insect pest of maize (Zea mays L.) in North America. The rotation of maize with another crop, principally soybeans, Glycine max (L.), was the primary management strategy utilized by North American producers and rema...

  17. 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...

  18. 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...

  19. Field-based assessment of resistance to Bt Corn by Western Corn Rootworm

    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 ...

  20. 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...

  1. Developing genomics tools for the western corn rootworm - Progress and promise

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cooperative efforts among a number of interested scientists and institutions in the U.S. and Europe are being undertaken to expand genomics resources for the western corn rootworm (Diabrotica virgifera virgifera). Such resources include development of hundreds of single nucleotide polymorphism (SNP...

  2. 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...

  3. 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-...

  4. Fitness costs of resistance to Cry3Bb1 maize by Western Corn Rootworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crops producing toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage insect pests, including western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), a significant pest of maize. The evolution of resistance would diminish the ef...

  5. Mortality impact of MON863 transgenic maize roots on western corn rootworm larvae in the field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mortality of western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae due to feeding on MON863 transgenic maize (Zea mays L.) expressing the Cry3Bb1 protein relative to survivorship on maize with the same genetic background without the gene (isoline maize) was evaluated at three Missour...

  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. The Nutritive Value of Dying Maize and Setaria Faberi Roots for Western Corn Rootworm Development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The timing that senescing root tissues of Setaria faberi R.A.W. Herrm. and maize, Zea mays L., no longer support growth and development of neonate and 2nd instar western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae was evaluated under greenhouse conditions. Three separate experimen...

  8. 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...

  9. Localized Search Cues in Corn Roots for Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Host-recognition cues that elicit a unique “tight-turning” behavior by larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte, were extracted from living corn roots with acetone. In behavioral bioassays, an acetone extract of corn roots had activity in the tight-turning bioassa...

  10. Dynamic precision phenotyping reveals mechanism of crop tolerance to herbivory by the western corn rootworm

    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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In previous crop rotation research, adult emergence traps placed in plots planted to Cuphea PSR-23 (a selected cross of C. viscossisma and C. lanceolata) caught high numbers of adult western corn rootworms, Diabrotica virgifera virgifera LeConte, suggesting that larvae may have completed development...

  12. Genetic Diversity in Laboratory Colonies of Western Corn Rootworm (Coleoptera: Chrysomelidae) including a Nondiapause Colony

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Laboratory-reared western corn rootworms, Diabrotica virgifera virgifera, from colonies maintained at the North Central Agricultural Research Laboratory (NCARL) in Brookings, SD, are used extensively by many researchers in studies of the biology, ecology, behavior, and genetics of this major insect ...

  13. LARVAL SAMPLING AND INSTAR DETERMINATION IN FIELD POPULATIONS OF NORTHERN AND WESTERN CORN ROOTWORM (COLEOPTERA: CHRYSOMELIDAE).

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Head capsule width was measured for northern (Diabrotica barberi Smith & Lawrence) and western corn rootworm (D. virgifera virgifera LeConte) larvae recovered primarily from maize root systems but also from large soil cores each centered around a root system. Larvae for measurement derived from fie...

  14. Environmental and Genotypic Effects for Western Corn Rootworm Tolerance Traits in American and European Maize Trials

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The western corn rootworm (Diabrotica virgifera virgifera LeConte) (WCR) is the most destructive pest of maize in North America currently causing considerable economic losses also in Central and Southeast Europe. Developing and releasing of commercial hybrids with higher level of native (host-plant)...

  15. Conventional Screening Overlooks Resistance Sources: Rootworm Damage of Diverse Inbred Lines and Their B73 Hybrids is Unrelated

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte) is a major pest of maize in the USA and Europe, and is likely to increase in importance as the trend towards continuous corn favors larger WCR populations. Although current transgenic approaches are effective, native resistance...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. Isolation and characterization of host recognition cues in corn roots for larvae of the western corn rootworm (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Behavioral bioassays were used to isolate compounds from germinating corn roots that elicit a host recognition response (tight-turning behavior) by neonate larvae of the western corn rootworm Diabrotica virgifera virgifera LeConte. When a behaviorally-active extract of germinating corn roots was sep...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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, size, and sex ratio of D. virg...

  2. 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...

  3. 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...

  4. 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 ...

  5. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. The Impact of MON863 Transgenic Roots is Equivalent on Western Corn Rootworm Larvae for a Wide Range of Maize Phenologies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of maize (Zea mays L.) phenology on establishment, damage, and adult emergence of the western corn rootworm (Diabrotica virgifera virgifera LeConte) to MON863 transgenic maize expressing the Cry3Bb1 protein and its isoline was evaluated in field trials in 2002 and 2003. As expected, pla...

  8. Development of resistance to eCry3.1Ab-expressing transgenic maize in a laboratory-selected population of western corn rootworm (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A laboratory colony of western corn rootworm, Diabrotica virgifera virgifera LeConte, was selected for resistance to transgenic maize expressing the eCry3.1ab protein. The selected colony was developed by rearing larvae on non-elite, non-commercial Bt maize expressing the eCry3.1Ab protein. After ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  10. Introduction of Diabrotica virgifera virgifera into the Old World and its consequences: a recently acquired invasive alien pest species on Zea mays from North America.

    PubMed

    Hummel, H E

    2003-01-01

    Diabrotica v. virgifera LeConte (Coleoptera: Chrysomelidae), (in short D.v.v.), with common name western corn rootworm, is endemic to the New World. Originating in the regions from South America to Mexico where it was in biological equilibrium with its natural enemies, predators and pathogens, it moved north with its food plants. Probably due to human agricultural farm practices with preference for monoculture of maize, the insect found open niches for expanding to the midwestern US where LeConte first described the species in Nebraska in 1867. Cyclodiene insecticide resistance, discovered in 1961, accelerated its spread and movement across the Great Plaines to the Atlantic Coast where it arrived around 1980. D.v.v. is a costly adversary to maize, to cucurbit, and, because of recent hostshifts, a threat to soybean production. Booming air travel and shipments of goods by air provided opportunities for D.v.v., without its natural enemies, to invade Europe where the insect was first described by F. Baca in 1993 near Belgrade airport (Baca 1993, Camprag & Baca 1995). From this focal point, D.v.v. expanded its range in all directions. Ten years later, in 2002, most of southeastern Europe has D.v.v. populations, some of them reaching economic damage levels such as those in Serbia, Croatia, and Hungary. New spot infestations in Northern Italy (Veneto, Lombardy, Piemonte) and in the Ticino region of Southern Switzerland, but also in Austria, Slovakia, Czechia, the Ukraine, even France, signal the final arrival of D.v.v. in Central Europe. The Alps, formerlyconsidered a natural barrier, might be circumvented or trespassed via air and road traffic. Model calculations by Baufeld and Enzian (2003) show that climatic and survival conditions are favorable for D.v.v. in all of Central Europe. Yet, in spite of well known annual losses of one billion dollars in the US, an effective and sustainable European strategy for keeping D.v.v. in check is still missing. PMID:15149091

  11. 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 ...

  12. 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

  13. Parasitism of Western Corn Rootworm Larvae and Pupae by Steinernema carpocapsae.

    PubMed

    Jackson, J J; Brooks, M A

    1995-03-01

    Virulence and development of the insect-parasitic nematode, Steinernema carpocapsae (Weiser) (Mexican strain), were evaluated for the immature stages of the western corn rootworm, Diabrotica virgifera virgifera LeConte. Third instar rootworm larvae were five times more susceptible to nematode infection than second instar larvae and 75 times more susceptible than first instar larvae and pupae, based on laboratory bioassays. Rootworm eggs were not susceptible. Nematode development was observed in all susceptible rootworm stages, but a complete life cycle was observed only in second and third instar larvae and pupae. Nematode size was affected by rootworm stage; the smallest infective-stage nematodes were recovered from second instar rootworm larvae. Results of this study suggest that S. carpocapsae should be applied when second and third instar rootworm larvae are predominant in the field. PMID:19277256

  14. Wolbachia wsp gene hypervariable region specific PCR primers detect multiple strain infections in northern corn rootworm (Diabrotica barberi)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The northern corn rootworm (Diabrotica barberi)(Coleoptera: Chrysomelidae) in eastern and central North America exhibits at least three distinct populations with respect to Wolbachia infection: uninfected; singly-infected; multi-infected. The infected states are associated with different mtDNA haplo...

  15. Sequences of Wolbachia wsp genes reveal multiple infection of individual northern corn rootworms (Diabrotica barberi) by several Wolbachia strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Northern corn rootworm (Diabrotica barberi)(NCR) populations in the USA are infected with at least 4 strains of the endosymbiont, Wolbachia. NCR from eastern Illinois to Pennsylvania appear to harbor at least 4 different strains designated wBar1, wBar3, wBar4, and wBar5. NCR from central Illinois ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  17. Insecticidal proteins from Bacillus thuringiensis protect corn from corn rootworms.

    PubMed

    Moellenbeck, D J; Peters, M L; Bing, J W; Rouse, J R; Higgins, L S; Sims, L; Nevshemal, T; Marshall, L; Ellis, R T; Bystrak, P G; Lang, B A; Stewart, J L; Kouba, K; Sondag, V; Gustafson, V; Nour, K; Xu, D; Swenson, J; Zhang, J; Czapla, T; Schwab, G; Jayne, S; Stockhoff, B A; Narva, K; Schnepf, H E; Stelman, S J; Poutre, C; Koziel, M; Duck, N

    2001-07-01

    Field tests of corn co-expressing two new delta-endotoxins from Bacillus thuringiensis (Bt) have demonstrated protection from root damage by western corn rootworm (Diabrotica virgifera virgifera LeConte). The level of protection exceeds that provided by chemical insecticides. In the bacterium, these proteins form crystals during the sporulation phase of the growth cycle, are encoded by a single operon, and have molecular masses of 14 kDa and 44 kDa. Corn rootworm larvae fed on corn roots expressing the proteins showed histopathological symptoms in the midgut epithelium. PMID:11433280

  18. 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...

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

    PubMed

    Wennemann, Ludger; Hummel, Hans E

    2002-01-01

    High wheel tractor applications of 4-methoxycinnamaldehyde (MCA)-coated corn granules ('grits') were conducted in Ruski Krstur (Serbia) in summer 2001 in a 5 ha corn field. Grits are a by-product after corn is harvested and separated from the cob and used as a carrier medium to disseminate MCA into the corn field. MCA is a kairomone mimic derived form Cucurbita maxima (Duchesne) used to disrupt orientation of Diabrotica virgifera virgifera LeConte towards different MCA and pheromone baited traps. The ultimate goal is to investigate the use of MCA as a mating disruptant. MCA was dissolved in an organic solvent and mixed in a cement machine with the grits. Grits were applied at rates of 17.39, 17.1 and 12.45 kg/ha on July 4th, July 19th and August 3rd. Before the impact of MCA as a disruptant can be addressed, the distribution patterns of MCA coated grits have to be thoroughly investigated. They were evaluated by counting girts deposited in 16 or 20 plastic dishes of 30-cm diameter positioned along 2 rows through the field directly after the grit application by tractor. Additionally, grits deposited on corn plant surface such as leaves, leaf axils and corn cobs were counted. Total number of grits collected in plastic dishes revealed even application rates at the first and second application but not on the third application date. Number of grits collected on plant surfaces were significantly different from each other regarding each application date. Altogether, grit distribution in the dishes as well as on the plant surface was variable. However, distribution patterns achieved so far hold promise to disseminate MCA coated grits into corn fields for orientation disruption or mating disruption of D. virgifera virgifera. PMID:12696417

  20. Protein profiling and tps23 induction in different maize lines in response to methyl jasmonate treatment and Diabrotica virgifera infestation.

    PubMed

    Capra, Emanuele; Colombi, Cinzia; De Poli, Pamela; Nocito, Fabio Francesco; Cocucci, Maurizio; Vecchietti, Alberto; Marocco, Adriano; Stile, Maria Rosaria; Rossini, Laura

    2015-03-01

    Plant responses to herbivore insects involve direct and indirect defense with the production of signal molecules including jasmonic acid (JA) and its derivatives (e.g. methyl jasmonate, MeJA). In maize (Zea mays), root feeding by Diabrotica virgifera larvae activates an indirect defense mechanism, through enthomopathogenic nematodes that are recruited after Terpene Synthase 23 (tps23) upregulation and (E)-β-caryophyllene root emission. In order to gain insight into the correlation between JA signaling and response to Diabrotica attack, we analyzed tps23 expression and protein profiles in maize roots in response to MeJA treatment and insect infestation. Similar to herbivore feeding, MeJA treatment was found to increase tps23 transcript accumulation, with consistent variations for both treatments in maize lines differing in (E)-β-caryophyllene production. Analysis of root protein profiles showed specific alterations leading to the identification of three proteins that were induced by MeJA treatment. We focused on a peroxidase-like protein (Px-like) showing that the corresponding transcripts accumulated in all tested lines. Results show that exogenous application of MeJA upregulates tps23 expression and specifically alters protein patterns in maize roots. Parallel effects on tps23 transcript accumulation were observed upon hormone exposure and insect infestation in different maize lines. In contrast, Px-like transcript profiling showed differences between treatments. These results support the possible involvement of MeJA in mediating the upregulation of tps23 in response to Diabrotica attack. PMID:25506768

  1. 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...

  2. Influence of western corn rootworm (Coleoptera: Chrysomelidae) larval injury on yield of different types of maize.

    PubMed

    Urías-López, M A; Meinke, L J

    2001-02-01

    Two field experiments were conducted in 1995-1996 to determine if there are common yield responses among maize hybrids to larval western corn rootworm, Diabrotica virgifera virgifera LeConte injury. Three yellow dent hybrids, five white food grade dent hybrids, and a popcorn hybrid were included in the study. The minimum level of rootworm injury as measured by root damage ratings (3.2-4.2) that significantly reduced yield was similar across the hybrids included in the study. However, the pattern of yield response to different rootworm injury levels varied among hybrids. This suggests that maize hybrids may inherently differ in their ability to tolerate rootworm injury and partition biomass in response to injury and other stresses. The complex interaction among hybrid, level of injury, and other stresses suggests that a common western corn rootworm injury-yield relationship may not exist within maize. PMID:11233098

  3. Evolution of diabroticite rootworm beetle (Chrysomelidae) receptors for Cucurbita blossom volatiles.

    PubMed

    Metcalf, R L; Lampman, R L

    1991-03-01

    The diabroticite rootworm beetles coevolved with plants of the family Cucurbitaceae as demonstrated by their feeding dependence on the tetracyclic triterpenoid cucurbitacins. These beetles also exhibit strong attraction to phenylpropanoid volatile components of Cucurbita blossoms. A mixture of 1,2,4-trimethoxybenzene, indole, and (E)-cinnamaldehyde, all blossom components, is highly attractive to the several species of diabroticite cucumber beetles and corn rootworms and is considered a simplified Cucurbita blossom kairomone odor. The evolutionary divergence in antennal receptor complementarity is best understood by comparing the species-specific responses of several Diabrotica to structural analogues of (E)-cinnamaldehyde, the major attractant for Diabrotica undecimpunctata howardi. Cinnamyl alcohol is a strong attractant for Diabrotica barberi, and 4-methoxycinnamaldehyde is an exceptional attractant for Diabrotica virgifera. The very closely related species D. barberi and Diabrotica cristata are most strongly attracted to 4-methoxyphenethanol, which is unattractive to the other species studied. PMID:11607158

  4. Evolution of diabroticite rootworm beetle (Chrysomelidae) receptors for Cucurbita blossom volatiles.

    PubMed Central

    Metcalf, R L; Lampman, R L

    1991-01-01

    The diabroticite rootworm beetles coevolved with plants of the family Cucurbitaceae as demonstrated by their feeding dependence on the tetracyclic triterpenoid cucurbitacins. These beetles also exhibit strong attraction to phenylpropanoid volatile components of Cucurbita blossoms. A mixture of 1,2,4-trimethoxybenzene, indole, and (E)-cinnamaldehyde, all blossom components, is highly attractive to the several species of diabroticite cucumber beetles and corn rootworms and is considered a simplified Cucurbita blossom kairomone odor. The evolutionary divergence in antennal receptor complementarity is best understood by comparing the species-specific responses of several Diabrotica to structural analogues of (E)-cinnamaldehyde, the major attractant for Diabrotica undecimpunctata howardi. Cinnamyl alcohol is a strong attractant for Diabrotica barberi, and 4-methoxycinnamaldehyde is an exceptional attractant for Diabrotica virgifera. The very closely related species D. barberi and Diabrotica cristata are most strongly attracted to 4-methoxyphenethanol, which is unattractive to the other species studied. PMID:11607158

  5. Multiplex polymerase chain reaction method for differentiating western and northern corn rootworm larvae (Coleoptera: Chrysomelidae).

    PubMed

    Roehrdanz, Richard L

    2003-06-01

    Western corn rootworm, Diabrotica virgifera virgifera LeConte, and northern corn rootworm, D. barberi Smith and Lawrence, are sympatric species and serious pests of corn cultivation in North America. Comparison of nucleotide sequence of mitochondrial cytochrome oxidase I and II was used to design polymerase chain reaction (PCR) primers that discriminate immature stages of the two species based on differences in amplicon size. Multiplex PCR can be used to give a positive test for each species in a single amplification reaction. This provides a method to identify field caught larvae and facilitates investigations of larval interaction and competition between the species. PMID:12852603

  6. 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. PMID:23604211

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

    PubMed

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

    2005-01-01

    Environmentally compatible and sustainable plant protection requires novel approaches to pest management characterized by minimal emphasis on toxicants. Classical toxicants traditionally dominated economic entomology for half a century. But worldwide problems with environmental pollution and with increasing resistance levels in all major pesticide classes and in many key insect species including Diabrotica virgifera virgifera (D.v.v.) strongly advocate a rethinking and a change in management paradigms used. Soft, minimally invasive, biological, biotechnical and cultural approaches should replace hard pesticides which are in favor up to now. Fortunately, pheromones, kairomones, plant attractants, better traps, new plant varieties and cultural methods like crop rotation, in short more sophisticated methods are now available as pressure for finding and exploring novel strategies increases. Facing this situation, a new biotechnical approach of population reduction of D.v.v., called "MSD" technique, is introduced. MSD is characterized as an approach combining mass trapping, shielding and deflecting of adult insects along an invisible odor barrier of synthetic kairomone which diminishes the flux of insects across a high capacity trap line baited with kairomone, thus reducing both the population fluctuation and number and its reproductive success within the shielded area. In the case of D.v.v. in Zea mays fields, effects realized by the MSD technique have been measured simultaneously by a number of independent criteria during the summers of 2003 and 2004 at 2 different locations in Illinois maize fields of up to one half hectare size. Results observed are statistically significant and cannot be explained by mass trapping alone. There is also an additional shielding and deflection, in short "diversion" effect whose basic sensory and behavioral mechanisms call for future exploration. PMID:16628896

  8. 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

  9. Identification of a female-produced sex pheromone from the southern corn rootworm,Diabrotica undecimpunctata howardi Barber.

    PubMed

    Guss, P L; Tumlinson, J H; Sonnet, P E; McLaughlin, J R

    1983-09-01

    A sex pheromone has been isolated and identified from virgin females of the southern corn rootworm (SCR),Diabrotica undecimpunctata howardi Barber. The synthesized compound, 10-methyl-2-tridecanone was shown to be attractive to males of the SCR, and also to males ofD. u. undecimpunctata Mannerheim, the western spotted cucumber beetle (WSCB), and ofD. u. duodecimnotata in Mexico. Males of both the SCR and the WSCB strongly preferred theR over theS enantiomer. The resolved enantiomers were not tested againstD. u. duodecimnotata. PMID:24407866

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

    PubMed

    Petzold-Maxwell, Jennifer L; Jaronski, Stefan T; Clifton, Eric H; Dunbar, Mike W; Jackson, Mark A; Gassmann, Aaron J

    2013-04-01

    A 2 yr field study was conducted to determine how a blend of entomopathogens interacted with Bt maize to affect mortality of Diabrotica spp. (Coleoptera: Chrysomelidae), root injury to maize (Zea maize L.) and yield. The blend of entomopathogens included two entomopathogenic nematodes, Steinernema carpocapsae Weiser and Heterorhabditis bacteriophora Poinar, and one entomopathogenic fungus, Metarhizium brunneum (Metschnikoff) Sorokin. Bt maize (event DAS59122-7, which produces Bt toxin Cry34/35Ab1) decreased root injury and survival of western corn rootworm (Diabrotica virgifera virgifera LeConte) and northern corn rootworm (Diabrotica barberi Smith & Lawrence) but did not affect yield. During year 1 of the study, when rootworm abundance was high, entomopathogens in combination with Bt maize led to a significant reduction in root injury. In year 2 of the study, when rootworm abundance was lower, entomopathogens significantly decreased injury to non-Bt maize roots, but had no effect on Bt maize roots. Yield was significantly increased by the addition of entomopathogens to the soil. Entomopathogens did not decrease survival of corn rootworm species. The results suggest that soil-borne entomopathogens can complement Bt maize by protecting roots from feeding injury from corn rootworm when pest abundance is high, and can decrease root injury to non-Bt maize when rootworm abundance is low. In addition, this study also showed that the addition of entomopathogens to soil contributed to an overall increase in yield. PMID:23786047

  11. MITOCHONDRIAL DNA AND ITS1 DIFFERENTIATION IN GEOGRAPHICAL POPULATIONS OF NORTHERN CORN ROOTWORM, DIABROTICA BARBERI (COLEOPTERA: CHRYSOMELIDAE): IDENTIFICATION OF DISTINCT GENETIC POPULATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic variation of mitochondrial DNA (mtDNA) and the nuclear ribosomal spacer, ITS1, in local and dispersed geographical populations of northern corn rootworm, Diabrotica barberi Smith and Lawrence was examined. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was use...

  12. Tracking the Extent of Multi-Strain Infection of Individual Northern Corn Rootworms (Diabrotica barberi) Using Specific Primers for Different wsp Hypervariable Regions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The northern corn rootworm (Diabrotica barberi) in eastern and central North America exhibits at least three distinct populations with respect to Wolbachia infection: uninfected; singly-infected; multi-infected. The infected states are associated with different mtDNA haplotypes and reduced mt variab...

  13. MITOCHONDRIAL DNA AND ITS1 DIFFERENTIATION IN GEOGRAPHICAL POPULATIONS OF NORTHERN CORN ROOTWORM, DIABROTICA BARBERI (COLEOPTERA: CHRYSOMELIDAE): IDENTIFICATION OF DISTINCT GENETIC POPULATIONS [SEE ABSTRACT FOR ACCESSION NOS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic variation of mitochondrial DNA (mtDNA) and the nuclear ribosomal spacer, ITS1, in local and dispersed geographical populations of northern corn rootworm, Diabrotica barberi Smith and Lawrence was examined. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was use...

  14. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  16. Lipid, polyamide, and flavonol phagostimulants for adult western corn rootworm from sunflower (Helianthus annuus L.) pollen.

    PubMed

    Lin, S; Mullin, C A

    1999-03-01

    Adult Diabroticites including western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, consume pollen of corn, squash, sunflower, and other species. Short-chain neutral amino acids in methanol-water extracts of pollen have been previously identified in our laboratory as strong phagostimulants for Diabrotica. Bioassay-driven fractionation was used to characterize the interacting lipid and midpolarity phagostimulants for adult WCR in Giant Gray Stripe sunflower, Helianthus annuus L., pollen. Lipids rich in omega3-linolenic acid including triglycerides, free fatty acids, phosphatidylethanolamines, phosphatidic acids, and phosphatidylcholines were highly phagostimulatory. Other important phagostimulatory components included a hydroxycinnamic acid-polyamine amide, N(1),N(5),N(10)-tri[(E)-p-coumaroyl]spermidine, and a flavonol, quercetin beta-3-O-glucoside. The structural characteristics of these phagoactive compounds and their role in the pollinivory specialization of rootworm beetles are discussed. PMID:10552441

  17. Behavioral responses of western corn rootworm larvae to volatile semiochemicals from corn seedlings.

    PubMed

    Hibbard, B E; Bjostad, L B

    1988-06-01

    Corn seedling volatiles collected cryogenically are highly attractive to western corn rootworm larvae,Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), in a laboratory bioassay. Carbon dioxide is known as an attractant for western corn rootworm larvae, and the amount of carbon dioxide in the cryogenic collections was measured with an infrared gas analyzer. In a choice test between a source containing carbon dioxide alone and a source containing corn seedling volatiles with an equal amount of carbon dioxide (verified by infrared gas analysis), western corn rootworm larvae chose the corn volatile source significantly more often than the side with carbon dioxide alone. This indicates that carbon dioxide is only one of the volatiles from corn seedlings that is behaviorally important and that other compounds of behavioral importance are present as well. PMID:24276403

  18. Diagnostic assays based on esterase-mediated resistance mechanisms in western corn rootworms (Coleoptera: Chrysomelidae).

    PubMed

    Zhou, Xuguo; Scharf, Michael E; Parimi, Srinivas; Meinke, Lance J; Wright, Robert J; Chandler, Laurence D; Siegfried, Blair D

    2002-12-01

    Resistance to methyl-parathion among Nebraska western corn rootworm, Diabrotica virgifera virgifera LeConte, populations is associated with increased hydrolytic metabolism of an organophosphate insecticide substrate. An electrophoretic method to identify resistant individuals based on the staining intensity of esterase isozymes on nondenaturing polyacrylamide gels was developed. Three groups of esterases (I, II, and III) were visible on the gels, but only group II esterase isozymes were intensified in resistant populations. A total of 26 and 31 field populations of western corn rootworms from Nebraska (in 1998 and 1999, respectively) were assessed with nondenaturing polyacrylamide gel electrophoresis (PAGE) assays and diagnostic concentration bioassays. Significant correlations were observed between the two diagnostic assays. Group II esterase isozymes provide a reliable biochemical marker for detection of methyl-parathion resistance in individual western corn rootworms and a tool for monitoring the frequency of resistant individuals in field populations. PMID:12539840

  19. 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

  20. Ovarian development and ovipositional preference of the western corn rootworm (Coleoptera: Chrysomelidae) variant in east central Illinois.

    PubMed

    Rondon, Silvia I; Gray, Michael E

    2004-04-01

    The rotation of maize, Zea mays L., and soybean, Glycine max (L.) Merr., has been the traditional cultural tactic to manage the western corn rootworm, Diabrotica virgifera virgifera LeConte, in the Corn Belt. The reduced effectiveness of this rotation as a pest management tool in east central Illinois, northern Indiana, and southern Michigan can be explained by the shift in the ovipositional behavior of the new variant of western corn rootworm. The objective of this study was to evaluate the influence of maize, soybean, oat, Avena sativa L., stubble, and alfalfa, Medicago sativa L., on the ovarian development and ovipositional preferences of the variant western corn rootworm. Field research was conducted near Urbana, IL, during 1998-2000. Gravid females were present throughout the season in all crops, and due to the prolonged period in which western corn rootworm females can lay eggs, none of the crops were immune from oviposition. Results indicated that the western corn rootworm variant oviposits in maize, soybean, oat stubble, and alfalfa In 1998 and 1999, maize was the preferred oviposition site among crops; however, in 2000, maize, soybean, and oat stubble treatments had similar densities of western corn rootworm eggs. Lack of oviposition preference of the western corn rootworm variant demonstrated in this experiment represents a reasonable explanation of why the effectiveness of the rotation strategy to control western corn rootworm has diminished. PMID:15154460

  1. Screening Maize Germplasm for Resistance to Western and Northern Corn Rootworms (Chrysomelidae: Diabrotica spp.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms (Coleoptera: Chrysomelidae) are devastating pests of maize (Zea mays L.), with a subterranean larval stage that consumes root tissue. To lessen reliance on soil insecticides and provide alternatives for genetically modified maize hybrids, researchers have developed novel maize germpla...

  2. 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...

  3. Comparison of adult corn rootworm (Coleoptera: Chrysomelidae) sampling methods.

    PubMed

    Whitworth, R J; Wilde, G E; Shufran, R A; Milliken, G A

    2002-02-01

    Studies were conducted in Kansas corn and soybean fields during 1997 to compare various sampling methods, traps, and trap components for capturing three species of adult corn rootworms: western (Diabrotica virgifera virgifera Leconte), southern (D. undecimpunctata howardi Barber), and northern (D. barberi Smith & Lawrence). Lure constituents affected the species of beetle attracted to the trap. Traps with a lure containing 4-methoxycinnamaldehyde attracted more western corn rootworms, those with a lure containing eugenol were more attractive to northern corn rootworms, and those containing trans-cinnamaldehyde were most attractive to southern corn rootworms. Multigard sticky traps caught more beetles than did Pherocon AM sticky traps. In corn, a newly designed lure trap caught more beetles than did sticky traps on most occasions. Also, lure-baited sticky traps caught more beetles than did nonbaited sticky traps. Varying the color of the lure trap bottom did not affect the number caught. In soybeans, the new lure traps captured more beetles than did the nonbaited Multigard or Pherocon AM sticky traps. Results of this study suggest the new lure trap may provide a more accurate assessment of corn rootworm populations than traditional monitoring techniques and may be more esthetically pleasing to growers and consultants. PMID:11942770

  4. Post-establishment movement of western corn rootworm larvae (Coleoptera: Chrysomelidae) in Central Missouri corn.

    PubMed

    Hibbard, Bruce E; Duran, Daniel P; Ellersieck, Mark R; Ellsbury, Michael M

    2003-06-01

    If registered, transgenic corn, Zea mays L., with corn rootworm resistance will offer a viable alternative to insecticides for managing Diabrotica spp. corn rootworms. Resistance management to maintain susceptibility is in the interest of growers, the Environmental Protection Agency, and industry, but little is known about many aspects of corn rootworm biology required for an effective resistance management program. The extent of larval movement by the western corn rootworm, Diabrotica virgifera virgifera LeConte, that occurs from plant-to-plant or row-to-row after initial establishment was evaluated in 1998 and 1999 in a Central Missouri cornfield. Post-establishment movement by western corn rootworm larvae was clearly documented in two of four treatment combinations in 1999 where larvae moved up to three plants down the row and across a 0.46-m row. Larvae did not significantly cross a 0.91-m row after initial host establishment in 1998 or 1999, whether or not the soil had been compacted by a tractor and planter. In the current experiment, western corn rootworm larvae moved from highly damaged, infested plants to nearby plants with little to no previous root damage. Our data do not provide significant insight into how larvae might disperse after initial establishment when all plants in an area are heavily damaged or when only moderate damage occurs on an infested plant. A similar situation might also occur if a seed mixture of transgenic and isoline plants were used and if transgenic plants with rootworm resistance are not repellent to corn rootworm larvae. PMID:12852594

  5. A spatially explicit model simulating western corn rootworm (Coleoptera: Chrysomelidae) adaptation to insect-resistant maize.

    PubMed

    Storer, Nicholas P

    2003-10-01

    A stochastic spatially explicit computer model is described that simulates the adaptation by western corn rootworm, Diabrotica virgifera virgifera LeConte, to rootworm-resistance traits in maize. The model reflects the ecology of the rootworm in much of the corn belt of the United States. It includes functions for crop development, egg and larval mortality, adult emergence, mating, egg laying, mortality and dispersal, and alternative methods of rootworm control, to simulate the population dynamics of the rootworm. Adaptation to the resistance trait is assumed to be controlled by a monogenic diallelic locus, whereby the allele for adaptation varies from incompletely recessive to incompletely dominant, depending on the efficacy of the resistance trait. The model was used to compare the rate at which the adaptation allele spread through the population under different nonresistant maize refuge deployment scenarios, and under different levels of crop resistance. For a given refuge size, the model indicated that placing the nonresistant refuge in a block within a rootworm-resistant field would be likely to delay rootworm adaptation rather longer than planting the refuge in separate fields in varying locations. If a portion of the refuge were to be planted in the same fields or in-field blocks each year, rootworm adaptation would be delayed substantially. Rootworm adaptation rates are also predicted to be greatly affected by the level of crop resistance, because of the expectation of dependence of functional dominance on dose. If the dose of the insecticidal protein in the maize is sufficiently high to kill >90% of heterozygotes and approximately 100% of susceptible homozygotes, the trait is predicted to be much more durable than if the dose is lower. A partial sensitivity analysis showed that parameters relating to adult dispersal affected the rate of pest adaptation. Partial validation of the model was achieved by comparing output of the model with field data on

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

    PubMed

    Wangila, David S; Gassmann, Aaron J; Petzold-Maxwell, Jennifer L; French, B Wade; Meinke, Lance J

    2015-04-01

    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 2013 to characterize the susceptibility of western corn rootworm populations to the rootworm-active proteins Cry3Bb1, mCry3A, and Cry34/35Ab1. Results demonstrate that there are heritable differences in susceptibility of Nebraska western corn rootworm populations to rootworm-active Bt traits. Proportional survival and corrected survival data coupled with field histories collectively support the conclusion that a level of field resistance to Cry3Bb1 has evolved in some Nebraska populations in response to selection pressure and that cross-resistance exists between Cry3Bb1 and mCry3A. There was no apparent cross-resistance between Cry34/35Ab1 and either Cry3Bb1 or mCry3A. The potential implications of these results on current and future corn rootworm management strategies are discussed. PMID:26470186

  7. 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. PMID:22812111

  8. Attraction of Heterorhabditis sp. toward synthetic (E)-beta-cariophyllene, a plant SOS signal emitted by maize on feeding by larvae of Diabrotica virgifera virgifera.

    PubMed

    Anbesse, S; Ehlers, R U

    2010-01-01

    Most plants, when damaged by herbivore insects, synthesize and release various chemicals as indirect defence mechanism that attract parasitic or predatory insects that are natural enemies of the herbivores. When attacked by Western Corn Rootworms, the roots of many maize plant varieties emit (E)-beta-caryophyllene that attracts the neighbouring entomopathogenic nematodes to kill the feeding pest. Through plant genetics and biotechnology it was possible to manipulate this volatile compound in order to increase the effectiveness of entomopathogenic nematodes in reducing the damage of the pest. In order to further use this strategy to improve the effectiveness of Heterorhabditis bacteriophora by selective breeding, we invesa tigated the applicability of the strategy in different standard laboratory bioassays using three different sand and agar plate assays. The synthetic form of (E)-beta-caryophyllene and H. megidis (the strain, which in previous investigation, showed significant attraction to caryophyllene) were used in the study. In all bioassays no significant difference was observed in attraction of nematodes between the caryophyllene treatments and the controls. The results contradict results of previous investigations done by other investigators (Rasmann et al., 2005). Future investigations for the genetic improvement of the host finding ability of entomopathogenic nematodes can therefore not target attraction to caryophyllene. PMID:21539265

  9. Characterization of bacteria isolated from maize roots: emphasis on Serratia and infestation with corn rootworms (Chrysomelidae: Diabrotica)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Larval corn rootworms (Coleoptera: Chrysomelidae) are soil-dwelling insect pests that frequently cause economic damage to maize (Zea mays L.) by consuming root tissues, thus lowering grain yield. Little is known about interactions between rootworms and soil bacteria, including potential impacts of m...

  10. 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

  11. Identification of a volatile attractant for Diabrotica and Acalymma spp. from blossoms of Cucurbita maxima duchesne.

    PubMed

    Andersen, J F; Metcalf, R L

    1986-03-01

    Fractionation of headspace volatiles from Cucurbita maxima blossoms by high-performance liquid chromatography resulted in the isolation of a single component which was highly active in an electroantennogram bioassay on Diabrotica undecimpunctata howardi antennae. This compound was identified as indole by gas chromatography-mass spectrometry. Field-trapping bioassays were conducted which indicated that indole is a potent attractant of the western corn rootworm,D. virgifera virgifera, and the striped cucumber beetle,Acalymma vittatum. The southern corn rootworm,D. u. howardi, did not respond, despite its strong EAG response. The sex ratio ofD. v. virgifera found in indole-baited traps varied seasonally. Males were trapped in abundance in late July and later September, 1983, while females were more abundant August and early September. The effectiveness of indole as aD. v. virgifera attractant also varied seasonally. A prolonged period of depressed trap catches occurred in early August 1983, during the silking and tasseling period of the corn in the field where trapping was carried out. PMID:24306908

  12. Effect of Bt maize and soil insecticides on yield, injury, and rootworm survival: implications for resistance management.

    PubMed

    Petzold-Maxwell, Jennifer L; Meinke, Lance J; Gray, Michael E; Estes, Ronald E; Gassmann, Aaron J

    2013-10-01

    A 2-yr field experiment was conducted to determine the effects on Diabrotica spp. (Coleoptera: Chrysomelidae) of an insecticidal seed treatment (Poncho 1250, (AI)/clothianidin) and a granular insecticide (Aztec 2.1G, (AI)/tebupirimphos and cyfluthrin) alone and in combination with maize producing the insectidical toxin Cry3Bb1 derived from the bacterium Bacillus thuringiensis (Bt). Yields for Bt maize plots were significantly greater than for non-Bt maize; however, insecticides did not significantly affect yield. Insecticides significantly decreased root injury in non-Bt maize plots, but there were no significant differences in root injury between Bt maize with or without either insecticide. Maize producing the Bt toxin Cry3Bb1 and the soil-applied insecticide Aztec significantly decreased survival of western corn rootworm (Diabrotica virgifera virgifera LeConte), while only Bt maize significantly decreased survival of the northern corn rootworm (Diabrotica barberi Smith & Lawrence). For both species, Bt maize and each of the insecticides delayed emergence. In the absence of density-dependent mortality, Bt maize imposed 71 and 80% reduction in survival on the western corn rootworm and the northern corn rootworm, respectively. The data from this study do not support combining insecticide with Bt maize because the addition of insecticide did not increase yield or reduce root injury for Bt maize, and the level of rootworm mortality achieved with conventional insecticide was likely too low to delay the evolution of Bt resistance. In addition, delays in emergence from Bt maize combined with insecticides could promote assortative mating among Bt-selected individuals, which may hasten resistance evolution. PMID:24224233

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

    PubMed

    Zukoff, Sarah N; Zukoff, Anthony L; Geisert, Ryan W; Hibbard, Bruce E

    2016-08-01

    Corn fields planted with plant-incorporated Bacillus thuringiensis (Bt) proteins must have a portion of the field planted with non-Bt, isoline, plants that 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 two or more toxins targeted toward the western corn rootworm, Diabrotica virgifera virgifera LeConte. Syngenta's corn hybrid, Agrisure Duracade, containing the eCry3.1Ab (event 5307) and mCry3a (event MIR604) rootworm-targeted toxins were registered as a seed blend in 2014. Western corn rootworm larval movement between the refuge plants and the Duracade plants was assessed to determine western corn rootworm survival and amount of root damage on these plants when planted in all possible seed blend scenarios. In this study, western corn rootworm larvae moved between isoline and Bt plants and adult survival was greater on Bt plants if movement from a neighboring infested isoline plant had occurred. However, root damage to these Bt plants did not reach economic levels. The low numbers of western corn rootworm larvae that did move from an infested Bt plant to an isoline plant could potentially select for resistance if they survived to adulthood. PMID:27190042

  14. Diabrotica egg separation from soil: an efficient and fast procedure for monitoring egg stages of corn rootworm populations.

    PubMed

    Shaw, J T; Hummel, H E

    2003-01-01

    Maize growers repeatedly are confronted with the need to make predictions and decisions about which of their fields are likely to develop corn rootworm populations above the economic threshold and are in need of treatment. One of the best parameters that can help as a basis for these decisions are corn rootworm egg counts in the soil. The Western corn rootworms have one generation each year. Females oviposit eggs in the soil in corn fields from late July through early September. These eggs overwinter in the soil and almost all hatch the following June. An apparatus is described that utilizes water, MgSO4 solution and differing screen sieves for extracting the rootworm eggs from the soil samples collected from the field after deciding on an acceptable sampling procedure. Samples may be a composite of subsamples or a number of individual samples taken at various locations in a field. The Illinois machine and the final separation of eggs, using flotation in 2 molar MgSO4 solution, are highly efficient, and recoveries of 97% of rootworm eggs manually placed in samples of soil have repeatedly been achieved. Thus, this would be a useful tool in integrated pest management programs that monitor the density of corn rootworm eggs in corn fields. PMID:15149094

  15. MOLECULAR PHYLOGENETIC RELATIONSHIPS AMONG DIABROTICA SPECIES (ACCESSION NO. AF195196)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms of the genus Diabrotica (Coleoptera: Chrysomelidae) are the most serious pest of corn in midwestern United States. Despite their economic importance, phylogenetic relationships within the genus remain unclear. Phylogenetic analysis of five Diabrotica was undertaken using DNA sequences...

  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. Interaction of insecticides, entomopathogenic nematodes, and larvae of the western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Nishimatsu, T; Jackson, J J

    1998-04-01

    Chemical insecticides and entomopathogenic nematodes have been independently used to suppress corn rootworm damage in maize. We report on the mortality response of larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte, to the combined treatment with 1 of 3 insecticides (terbufos, fonofos, and tefluthrin) and the entomopathogenic nematode Steinernema carpocapsae Weiser (Mexican strain). Corn rootworm mortality with combinations of the insecticides terbufos or fonofos and S. carpocapsae was typically additive for the 2 agents. Evidence of antagonism between these agents was sometimes observed. The combination of tefluthrin with S. carpocapsae frequently resulted in a synergistic response and a 24% average increase in expected mortality. The influence of the tefluthrin appears to be isolated to an effect on the rootworm larvae. Synergism also was observed when tefluthrin was combined with the nematode Heterorhabditis bacteriophora Poinar (Lewiston strain). The combined use of tefluthrin with an entomopathogenic nematode may offer an integrated approach to increase the efficacy of entomopathogenic nematodes for insect control. PMID:9589627

  18. Field capture of northern and western corn rootworm beetles relative to attractant structure and volatility.

    PubMed

    Hammack, Leslie; Petroski, Richard J

    2004-09-01

    We used field assays to study attraction of feral northern and western corn rootworm beetles (Diabrotica barberi and D. virgifera virgifera) to a series of mostly nitrogenous and benzenoid synthetic compounds allied with host plant and floral aromas. Vaporization rates were obtained for most field-tested compounds and selected additional lures under both ideal and field-representative, but constant, conditions. Although many test compounds showed at least trace activity for one or both species, methyl benzoate and some of its derivatives, notably methyl anthranilate and methyl 4-methoxybenzoate, merited emphasis as effective new lures for females. Structural alteration of methyl benzoate had consistently negative effects on northern corn rootworm captures despite variable effects on release rate, whereas western corn rootworm was more strongly attracted to methyl anthranilate and methyl 4-methoxybenzoate than to the considerably more volatile parent compound. Phenylacetaldoxime was attractive to females of both species, but no more so than syn-benzaldoxime, included as reference. Release rate was disproportionately low for benzaldoxime, as well as other nitrogenous lures, under field compared with ideal conditions. The attractiveness of salicylaldoxime to northern corn rootworm, despite its low field release rate, and the unattractiveness of methyl salicylate, having a methyl ester in place of the oxime group, similarly highlighted importance of the oxime moiety for reactivity of this species. PMID:15586676

  19. 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. PMID:22537837

  20. The role of Wolbachia bacteria in reproductive incompatibilities and hybrid zones of Diabrotica beetles and Gryllus crickets.

    PubMed

    Giordano, R; Jackson, J J; Robertson, H M

    1997-10-14

    A rickettsial bacterium in the genus Wolbachia is the cause of a unidirectional reproductive incompatibility observed between two major beetle pests of maize, the western corn rootworm, Diabrotica virgifera virgifera, and the Mexican corn rootworm, D. v. zeae. These subspecies are allopatric except for two known regions of sympatry in Texas and Mexico. We demonstrate that populations of D. v. virgifera, with the exception of two populations in southern Arizona, are infected with a strain of Wolbachia. Populations of D. v. zeae are not infected. Treatment of D. v. virgifera with tetracycline eliminated the Wolbachia and removed the reproductive incompatibility. Similar patterns of reproductive incompatibility exist among taxa of the cricket genus Gryllus. Gryllus assimilis, G. integer, G. ovisopis, G. pennsylvanicus, and G. rubens are infected with Wolbachia whereas G. firmus is usually not. Populations of G. rubens and G. ovisopis carry the same Wolbachia strain, which is distinct from that of G. integer. G. pennsylvanicus is infected with two Wolbachia strains, that found in G. rubens and one unique to G. pennsylvanicus. Moreover, a proportion of G. pennsylvanicus individuals harbors both strains. Wolbachia may have influenced speciation in some members of the genus Gryllus by affecting the degree of hybridization between species. Given that Wolbachia infections are relatively common in insects, it is likely that other insect hybrid zones may be influenced by infections with Wolbachia. PMID:9326628

  1. The role of Wolbachia bacteria in reproductive incompatibilities and hybrid zones of Diabrotica beetles and Gryllus crickets

    PubMed Central

    Giordano, Rosanna; Jackson, Jan J.; Robertson, Hugh M.

    1997-01-01

    A rickettsial bacterium in the genus Wolbachia is the cause of a unidirectional reproductive incompatibility observed between two major beetle pests of maize, the western corn rootworm, Diabrotica virgifera virgifera, and the Mexican corn rootworm, D. v. zeae. These subspecies are allopatric except for two known regions of sympatry in Texas and Mexico. We demonstrate that populations of D. v. virgifera, with the exception of two populations in southern Arizona, are infected with a strain of Wolbachia. Populations of D. v. zeae are not infected. Treatment of D. v. virgifera with tetracycline eliminated the Wolbachia and removed the reproductive incompatibility. Similar patterns of reproductive incompatibility exist among taxa of the cricket genus Gryllus. Gryllus assimilis, G. integer, G. ovisopis, G. pennsylvanicus, and G. rubens are infected with Wolbachia whereas G. firmus is usually not. Populations of G. rubens and G. ovisopis carry the same Wolbachia strain, which is distinct from that of G. integer. G. pennsylvanicus is infected with two Wolbachia strains, that found in G. rubens and one unique to G. pennsylvanicus. Moreover, a proportion of G. pennsylvanicus individuals harbors both strains. Wolbachia may have influenced speciation in some members of the genus Gryllus by affecting the degree of hybridization between species. Given that Wolbachia infections are relatively common in insects, it is likely that other insect hybrid zones may be influenced by infections with Wolbachia. PMID:9326628

  2. SEXUAL DIMORPHISM OF BASITARSI IN DIABROTICA AND CEROTOMA SPP. (COLEOPTERA: CHRYSOMELIDAE)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sexual dimorphism in basitarsal pad morphology is described for prothoracic and mesothoracic legs of Diabrotica virgifera virgifera LeConte, Diabrotica barberi Smith and Lawrence, and Diabrotica undecimpunctata howardi Barber and for prothoracic legs of Cerotoma trifucata (Forster). On the indicate...

  3. Adaptation by western corn rootworm (Coleoptera: Chrysomelidae) to Bt maize: inheritance, fitness costs, and feeding preference.

    PubMed

    Petzold-Maxwell, Jennifer L; Cibils-Stewart, Ximena; French, B Wade; Gassmann, Aaron J

    2012-08-01

    We examined inheritance of resistance, feeding behavior, and fitness costs for a laboratory-selected strain of western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), with resistance to maize (Zea maize L.) producing the Bacillus thuringiensis Berliner (Bt) toxin Cry3Bb1. The resistant strain developed faster and had increased survival on Bt maize relative to a susceptible strain. Results from reciprocal crosses of the resistant and susceptible strains indicated that inheritance of resistance was nonrecessive. No fitness costs were associated with resistance alleles in the presence of two entomopathogenic nematode species, Steinernema carpocapsae Weiser and Heterorhabditis bacteriophora Poinar. Larval feeding studies indicated that the susceptible and resistant strains did not differ in preference for Bt and non-Bt root tissue in choice assays. PMID:22928323

  4. TWO DIFFERENT WOLBACHIA TYPES CREATE A BREEDING BARRIER BETWEEN POPULATIONS OF NORTHERN CORN ROOTWORM (DIABROTICA BARBERI) IN ILLINOIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wolbachia sp. are endosymbiotic bacteria that are widespread in Arthropods and are often associated with reproductive incompatibilities between infected and uninfected individuals. 16S rDNA primers detected Wolbachia in northern corn rootworms (NCR) from the eastern portion of their range with a W...

  5. Predicting western corn rootworm (Coleoptera: Chrysomelidae) larval injury to rotated corn with Pherocon AM traps in soybeans.

    PubMed

    O'Neal, M E; Gray, M E; Ratcliffe, S; Steffey, K L

    2001-02-01

    Crop rotation for portions of east central Illinois and northern Indiana no longer adequately protects corn (Zea mays L.) roots from western corn rootworm, Diabrotica virgifera virgifera LeConte. Seventeen growers in east central Illinois monitored western corn rootworm adults in soybean (Glycine max L.) fields with unbaited Pherocon AM traps during 1996 and 1997. In the following years (1997 and 1998), growers left untreated strips (no insecticide applied) when these fields were planted with corn. Damage to rotated corn by rootworms was more severe in untreated than in treated strips of rotated corn, ranging from minor root scarring to a full node of roots pruned. Densities of western corn rootworms in soybean fields from 1996 were significantly correlated with root injury to rotated corn the following season. Adult densities from 1997 were not significantly correlated with root injury in 1998, due to heavy precipitation throughout the spring of 1998 and extensive larval mortality. Twenty-eight additional growers volunteered in 1998 to monitor rootworm adults in soybean fields with Pherocon AM traps based on recommendations that resulted from our research efforts in 1996 and 1997. In 1999, these 28 fields were rotated to corn, and rootworm larval injury was measured in untreated strips. Based on 1996-1997 and 1998-1999 data, a regression analysis revealed that 27% of the variation in root injury to rotated corn could be explained by adult density in soybeans the previous season. We propose a sampling plan for soybean fields and a threshold for predicting western corn rootworm larval injury to rotated corn. PMID:11233140

  6. Evidence of Resistance to Cry34/35Ab1 Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae): Root Injury in the Field and Larval Survival in Plant-Based Bioassays.

    PubMed

    Gassmann, Aaron J; Shrestha, Ram B; Jakka, Siva R K; Dunbar, Mike W; Clifton, Eric H; Paolino, Aubrey R; Ingber, David A; French, B Wade; Masloski, Kenneth E; Dounda, John W; St Clair, Coy R

    2016-08-01

    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 corn and mCry3A corn were found in Iowa and elsewhere. To date, western corn rootworm populations have remained susceptible to corn producing Bt toxin Cry34/35Ab1. In this study, we used single-plant bioassays to test field populations of western corn rootworm for resistance to Cry34/35Ab1 corn, Cry3Bb1 corn, and mCry3A corn. Bioassays included nine rootworm populations collected from fields where severe injury to Bt corn had been observed and six control populations that had never been exposed to Bt corn. We found incomplete resistance to Cry34/35Ab1 corn among field populations collected from fields where severe injury to corn producing Cry34/35Ab1, either singly or as a pyramid, had been observed. Additionally, resistance to Cry3Bb1 corn and mCry3A corn was found among the majority of populations tested. These first cases of resistance to Cry34/35Ab1 corn, and the presence of resistance to multiple Bt toxins by western corn rootworm, highlight the potential vulnerability of Bt corn to the evolution of resistance by western corn rootworm. The use of more diversified management practices, in addition to insect resistance management, likely will be essential to sustain the viability of Bt corn for management of western corn rootworm. PMID:27329619

  7. Long-chain free fatty acids: Semiochemicals for host location by western corn rootworm larvae.

    PubMed

    Hibbard, B E; Bernklau, E J; Bjostad, L B

    1994-12-01

    A bioassay-driven sequential fractionation scheme was used to isolate fractions of a crude dichloromethane maize seedling extract behaviorally active to larvae of the western corn rootworm,Diabrotica virgifera virgifera LeConte. (Z,Z)-9,12-Octadecadienoic (linoleic) acid, (Z)-9-octadecenoic (oleic) acid, and octadecanoic (stearic) acid were identified from a purified fraction of maize extract that was attractive to western corn rootworm larvae in choice tests with equal levels of carbon dioxide on both sides of the choice. When synthetic linoleic, oleic, and stearic acids were tested together in the amounts and proportions found in the attractive fraction (1000, 800, and 300 ng of linoleic, oleic, and stearic acids, respectively), significantly more western corn rootworm larvae were found on the side with synthetic free fatty acids plus carbon dioxide than on the side with carbon dioxide alone. Results of the choice-test bioassays were not significantly different when the synthetic blend of free fatty acids was substituted for the purified maize fraction. Neither the purified extract nor the synthetic blend was behaviorally active in preliminary single-choice experiments without carbon dioxide. Linoleic, oleic, and stearic acids were also tested individually in the choice test bioassay with carbon dioxide on both sides of the choice to determine a dose-response curve. Linoleic and oleic acid each had one dose that was significantly attractive in conjunction with carbon dioxide on both sides of the choice, but stearic acid was not active in the doses tested. PMID:24241996

  8. In-field labeling of western corn rootworm adults (Coleoptera: Chrysomelidae) with rubidium.

    PubMed

    Nowatzki, Timothy M; Niimi, Bradly; Warren, Kelli J; Putnam, Sean; Meinke, Lance J; Gosselin, David C; Harvey, F Edwin; Hunt, Thomas E; Siegfried, Blair D

    2003-12-01

    Field and laboratory studies were conducted in 2000 and 2001 to determine the feasibility of mass marking western corn rootworm adults, Diabrotica virgifera virgifera LeConte, with RbCl in the field. Results showed that application of rubidium (Rb) in solution to both the soil (1 g Rb/plant) and whorl (1 g Rb/plant) of corn plants was optimal for labeling western corn rootworm adults during larval development. Development of larvae on Rb-enriched corn with this technique did not significantly influence adult dry weight or survival. Rb was also highly mobile in the plant. Application of Rb to both the soil and the whorl resulted in median Rb concentrations in the roots (5,860 ppm) that were 150-fold greater than concentrations in untreated roots (38 ppm) 5 wk after treatment. Additionally, at least 90% of the beetles that emerged during the first 3 wk were labeled above the baseline Rb concentration (5 ppm dry weight) determined from untreated beetles. Because emergence was 72% complete at this time, a significant proportion of the population had been labeled. Results from laboratory experiments showed that labeled beetles remained distinguishable from unlabeled beetles for up to 4 d postemergence. The ability to efficiently label large numbers of beetles under field conditions and for a defined period with virtually no disruption of the population provides an unparalleled opportunity to conduct mark-recapture experiments for quantifying the short-range, intrafield movement of adult corn rootworms. PMID:14977112

  9. 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

  10. 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

  11. Captures of western corn rootworm (Coleoptera: Chrysomelidae) adults with Pherocon AM and vial traps in four crops in east central Illinois.

    PubMed

    Rondon, Silvia I; Gray, Michael E

    2003-06-01

    It is hypothesized that the long-term rotation of maize (Zea mays L.) and soybean (Glycine max L.) in east central Illinois has caused a significant change in the ovipositional behavior of the western corn rootworm, Diabrotica virgifera virgifera LeConte. Since the mid 1990s in east central Illinois, western corn rootworm adults have been observed feeding on soybean foliage and also now use soybean fields as egg laying sites. This behavioral adaptation has greatly decreased the effectiveness of rotation as a pest management tactic. By using Pherocon AM and vial traps, we evaluated the influence of maize, soybean, oat stubble (Avena sativa L.), and alfalfa (Medicago sativa L.) on male and female adult western corn rootworm densities from April 1998 through September 2000 near Urbana, IL. Our results indicated that western corn rootworm adults are common inhabitants of maize, soybean, oat stubble, and alfalfa. Trapping efforts with both Pherocon AM (attractive) and vial traps (passive) revealed that initial densities of both male and female western corn rootworm adults were greater in maize. Soon after emergence, densities of females began to decline within maize and increase in other crops (soybean, oat stubble, and alfalfa). Results from this experiment support the hypothesis that variant western corn rootworm females in east central Illinois are colonizing crops other than maize at densities of potential economic importance. Those producers who choose to rotate maize with soybean or alfalfa may remain at risk to economic larval injury to maize roots. Potentially, oat stubble also may support levels of western corn rootworm females resulting in sufficient oviposition to cause economic losses to rotated maize the following season. PMID:12852611

  12. 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. PMID:24690224

  13. Western corn rootworm and Bt maize: challenges of pest resistance in the field.

    PubMed

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

    2012-01-01

    Crops genetically engineered to produce insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) manage many key insect pests while reducing the use of conventional insecticides. One of the primary pests targeted by Bt maize in the United States is the western corn rootworm, Diabrotica virgifera virgifera LeConte. Beginning in 2009, populations of western corn rootworm were identified in Iowa, USA that imposed severe root injury to Cry3Bb1 maize. Subsequent laboratory bioassays revealed that these populations were resistant to Cry3Bb1 maize, with survival on Cry3Bb1 maize that was three times higher than populations not associated with such injury. Here we report the results of research that began in 2010 when western corn rootworm were sampled from 14 fields in Iowa, half of which had root injury to Cry3Bb1 maize of greater than 1 node. Of these samples, sufficient eggs were collected to conduct bioassays on seven populations. Laboratory bioassays revealed that these 2010 populations had survival on Cry3Bb1 maize that was 11 times higher and significantly greater than that of control populations, which were brought into the laboratory prior to the commercialization of Bt maize for control of corn rootworm. Additionally, the developmental delays observed for control populations on Cry3Bb1 maize were greatly diminished for 2010 populations. All 2010 populations evaluated in bioassays came from fields with a history of continuous maize production and between 3 and 7 y of Cry3Bb1 maize cultivation. Resistance to Cry34/35Ab1 maize was not detected and there was no correlation between survival on Cry3Bb1 maize and Cry34/35Ab1 maize, suggesting a lack of cross resistance between these Bt toxins. Effectively dealing with the challenge of field-evolved resistance to Bt maize by western corn rootworm will require better adherence to the principles of integrated pest management. PMID:22688688

  14. Larval sampling and instar determination in field populations of northern and western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Hammack, Leslie; Ellsbury, Michael M; Roehrdanz, Richard L; Pikul, Joseph L

    2003-08-01

    Abundance and head capsule width were measured for northern (Diabrotica barberi Smith & Lawrence) and western corn rootworm (D. virgifera virgifera LeConte) larvae recovered primarily from maize root systems but also from large soil cores each centered around a root system. Larvae for measurement derived from field populations under infestation and rotation regimes that allowed most specimens to be assigned to species. A frequency distribution of head capsule widths indicated three separate peaks for western corn rootworm, presumably representing frequency of the three larval instars, with no larvae measuring 280 or 420 microm in the valleys between peaks. Multiple normal curves fit to similar but partially overlapping peaks generated by northern corn rootworm suggested that division of first to second and second to third instar can best be made for this species at 267 and 406 microm, respectively (270 and 410 when measurements are made to the nearest 20 microm). These results implied that instar of individuals from mixed northern and western corn rootworm populations can be accurately judged from head capsule width without having to determine species. The relative abundance of western corn rootworm instars was similar in root systems removed from the center of 19-cm diameter x 19-cm deep soil cores and in soil cores from which the root systems were removed. Furthermore, the number of larvae from root systems correlated significantly with that from the surrounding soil. These results indicated that the former and much more convenient sampling unit can be used to estimate population developmental stage and possibly density, at least early in the season when these tests were done and young larvae predominated. PMID:14503586

  15. Inheritance and Fitness Costs of Resistance to Cry3Bb1 Corn by Western Corn Rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Ingber, David A; Gassmann, Aaron J

    2015-10-01

    Transgenic crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage pest insects. One of the primary pests targeted by Bt corn in the United States is western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae). Cry3Bb1 corn for management of western corn rootworm was commercialized in 2003, and beginning in 2009, populations of western corn rootworm with field-evolved resistance to Cry3Bb1 corn were found in Iowa. Here we quantify the magnitude, inheritance, and fitness costs of resistance to Cry3Bb1 corn in two strains (Hopkinton and Cresco) derived from field populations that evolved resistance to Cry3Bb1 corn. For Hopkinton, we found evidence for complete resistance to Cry3Bb1 corn and nonrecessive inheritance. Additionally, no fitness costs of Cry3Bb1 resistance were detected for Hopkinton. For Cresco, resistance was incomplete and recessive, and we detected fitness costs affecting developmental rate, survival to adulthood, and fecundity. These results suggest that variation may exist among field populations in both the inheritance and accompanying fitness costs of resistance. To the extent that field populations exhibit nonrecessive inheritance and a lack of fitness cost, this will favor more rapid evolution of resistance than would be expected when resistance is functionally recessive and is accompanied by fitness costs. PMID:26453731

  16. 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

  17. Monogalactosyldiacylglycerols as Host Recognition Cues for Western Corn Rootworm Larvae (Coleoptera: Chrysomelidae).

    PubMed

    Bernklau, E J; Hibbard, B E; Dick, D L; Rithner, C D; Bjostad, L B

    2015-04-01

    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-driven approach. When analyzed with LC-MS (positive ion scanning), the assay-active spot was found to contain four different MGDG species: 18:3-18:3 (1,2-dilinolenoyl), 18:2-18:3 (1-linoleoyl, 2-linolenoyl), 18:2-18:2 (1,2-dilinoleoyl), and 18:2-16:0 (1-linoleoyl, 2-palmitoyl). A polar fraction was also needed for activity. When combined with a polar fraction containing a blend of sugars (glucose:fructose:sucrose:myoinositol), the isolated MGDG elicited a unique tight-turning behavior by neonate western corn rootworm larvae that is indicative of host recognition. In behavioral bioassays where disks treated with the active blend were exposed to successive sets of rootworm larvae, the activity of MGDG increased over four exposures, suggesting that larvae may be responding to compounds produced after enzymatic breakdown of MGDG. In subsequent tests with synthetic blends composed of theoretical MGDG-breakdown products, larval responses to four synthetic blends were not significantly different (P<0.5) than the response to isolated MGDG. GC-MS analysis showed modest increases in the amounts of the 16:0, 18:0, and 18:3 free fatty acids released from MGDG after a 30-min exposure to rootworm larvae, which is consistent with the enzymatic breakdown hypothesis. PMID:26470164

  18. Western corn rootworm larval movement in SmartStax seed blend scenarios.

    PubMed

    Zukoff, Sarah N; Bailey, Wayne C; Ellersieck, Mark R; Hibbard, Bruce E

    2012-08-01

    Insect resistance management (IRM) can extend the lifetime of management options, but depends on extensive knowledge of the biology of the pest species involved for an optimal plan. Recently, the Environmental Protection Agency (EPA) registered seed blends refuge for two of the transgenic Bacillus thuringiensis (Bt) corn products targeting the western corn rootworm, Diabrotica virgifera virgifera LeConte. Larval movement between Bt and isoline plants can be detrimental to resistance management for high dose Bt products because the larger larvae can be more tolerant of the Bt toxins. We assessed movement of western corn rootworm larvae among four spatial arrangements of SmartStax corn (expressing both the Cry34/35Ab1 and Cry3Bb1 proteins) and isoline plants by infesting specific plants with wild type western corn rootworm eggs. Significantly fewer western corn rootworm larvae, on average, were recovered from infested SmartStax plants than infested isoline plants, and the SmartStax plants were significantly less damaged than corresponding isoline plants. However, when two infested isoline plants surrounded a SmartStax plant, a significant number of larvae moved onto the SmartStax plant late in the season. These larvae caused significant damage both years and produced significantly more beetles than any other plant configuration in the study (including isoline plants) in the first year of the study. This plant configuration would occur rarely in a 5% seed blend refuge and may produce beetles of a susceptible genotype because much of their initial larval development was on isoline plants. Results are discussed in terms of their potential effects on resistance management. PMID:22928304

  19. 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

  20. Geographic information systems in corn rootworm management

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  1. 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...

  2. Susceptibility of Northern Corn Rootworm Diabrotica barberi Smith (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. The Temporal and Spatial Invasion Genetics of the Western Corn Rootworm (Coleoptera: Chrysomelidae) in Southern Europe

    PubMed Central

    Lemic, Darija; Mikac, Katarina M.; Ivkosic, Stephanie A.; Bažok, Renata

    2015-01-01

    This study describes the genetics of the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte in southern Europe during the introduction (1996–2001) and establishment/spread (2002–2011) phases of its invasion. The Diabrotica microsatellite core-set was used to perform traditional population genetics analyses. Our results indicated that during the introduction phase genetic diversity and population genetic structure were lower overall as compared to the establishment/spread phase. Unusually high genetic differentiation was found between the Italy and southern Europe comparisons, including high differentiation between Italian populations separated by a short distance during the establishment/spread phase. STRUCTURE analysis revealed two genetic clusters during the introduction phase and two genetic clusters during the establishment/spread phase. However, bottlenecked populations were only detected during the invasion phase. A small but significant isolation by distance effect was noted in both phases. Serbia was the geographic source of WCR to Croatia and Hungary in the introduction phase, while the United States of America was the possible source of WCR to Italy in 2001. These introductory populations were the subsequent source of individuals sampled during the establishment/spread phase. Repeated introductions and admixture events in southern Europe may have resulted in genetically diverse WCR populations that have attained 83% of all known alleles worldwide. PMID:26406466

  4. The Temporal and Spatial Invasion Genetics of the Western Corn Rootworm (Coleoptera: Chrysomelidae) in Southern Europe.

    PubMed

    Lemic, Darija; Mikac, Katarina M; Ivkosic, Stephanie A; Bažok, Renata

    2015-01-01

    This study describes the genetics of the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte in southern Europe during the introduction (1996-2001) and establishment/spread (2002-2011) phases of its invasion. The Diabrotica microsatellite core-set was used to perform traditional population genetics analyses. Our results indicated that during the introduction phase genetic diversity and population genetic structure were lower overall as compared to the establishment/spread phase. Unusually high genetic differentiation was found between the Italy and southern Europe comparisons, including high differentiation between Italian populations separated by a short distance during the establishment/spread phase. STRUCTURE analysis revealed two genetic clusters during the introduction phase and two genetic clusters during the establishment/spread phase. However, bottlenecked populations were only detected during the invasion phase. A small but significant isolation by distance effect was noted in both phases. Serbia was the geographic source of WCR to Croatia and Hungary in the introduction phase, while the United States of America was the possible source of WCR to Italy in 2001. These introductory populations were the subsequent source of individuals sampled during the establishment/spread phase. Repeated introductions and admixture events in southern Europe may have resulted in genetically diverse WCR populations that have attained 83% of all known alleles worldwide. PMID:26406466

  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. 6-Methoxy-2-benzoxazolinone: A semiochemical for host location by western corn rootworm larvae.

    PubMed

    Bjostad, L B; Hibbard, B E

    1992-07-01

    A bioassay-driven sequential fractionation scheme was used to isolate all portions of a crude dichloromethane corn seedling extract behaviorally active to larvae of the western corn rootworm,Diabrotica virgifera virgifera LeConte. 6-Methoxy-2-benzoxazolinone (MBOA) was identified as one of the most important components of an attractive crude corn extract. MBOA was found on or in the intact root tissues by injecting an extract of undamaged roots onto an HPLC immediately after extraction. MBOA was demonstrated to be volatile and functions as a semiochemical in conjunction with carbon dioxide in host location by western corn rootworm larvae, which are oligophagous on the roots of maize and several other species of grasses. Because MBOA occurs almost exclusively in maize and other grasses, it offers a simple way for the larvae to distinguish possible hosts from non-hosts. MBOA has previously been reported as a chemical defense against other insect species. This is the first report in grasses of a secondary compound that is toxic or a deterrent to nonadapted insect herbivores but that is used as a semiochemical in host location by a specialist insect species. PMID:24254139

  7. Modeling the dynamics of adaptation to transgenic corn by western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Onstad, D W; Guse, C A; Spencer, J L; Levine, E; Gray, M E

    2001-04-01

    A simulation model of the population dynamics and genetics of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was created for a landscape of corn, soybean, and other crops. Although the model was created to study a 2-locus problem for beetles having genes for resistance to both crop rotation and transgenic corn, during this first phase of the project, the model was simulated to evaluate only resistance management plans for transgenic corn. Allele expression in the rootworm and toxin dose in the corn plant were the two most important factors affecting resistance development. A dominant resistance allele allowed quick evolution of resistance to transgenic corn, whereas a recessive allele delayed resistance >99 yr. With high dosages of toxin and additive expression, the time required to reach 3% resistance allele frequency ranged from 13 to >99 yr. With additive expression, lower dosages permitted the resistant allele frequency to reach 3% in 2-9 yr with refuges occupying 5-30% of the land. The results were sensitive to delays in emergence by susceptible adults and configuration of the refuge (row strips versus blocks). PMID:11332850

  8. Genetic variation in geographical populations of western and Mexican corn rootworm.

    PubMed

    Szalanski, A L; Roehrdanz, R L; Taylor, D B; Chandler, L

    1999-11-01

    Genetic variation in the nuclear rDNA ITS1 region of western corn rootworm, Diabrotica virgifera virgifera (WCR), and Mexican corn rootworm, D. v. zeae (MCR) was studied. Two sites were detected which differentiated WCR and MCR in the 642-base sequence. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the first internal transcribed spacer region (ITS1) sequence revealed no variation within or among the twelve WCR and two MCR populations. PCR-RFLP of 75% of the mitochondrial DNA genome detected one significant polymorphic site out of the approximately 190 restriction sizes observed in WCR. The polymorphism did not differentiate geographical populations of WCR and is not diagnostic for the subspecies. The low levels of variation observed in WCR suggests either high levels of gene flow or a recent geographical expansion from a relatively small base. Gene flow would facilitate the rapid spread of traits that could compromise control programmes, such as insecticide resistance or behavioural modifications. The minimal genetic differentiation between WCR and MCR raises questions about the evolutionary history of these subspecies and how the distinct phenotypes are maintained. PMID:10620046

  9. Responses of northern and western corn rootworms to semiochemical attractants in corn fields.

    PubMed

    Lance, D R

    1988-04-01

    Small plots (18 × 18 m) were treated with grids of cotton wicks that contained semiochemicals for adultDiabrotica barberi Smith and Lawrence, the northern corn rootworm (NCR). In plots treated with eugenol (350 g/hectare), NCR were attracted to point sources of the compound, but there were no significant changes in numbers of either NCR orD. virgifera virgifera LeConte, the western corn rootworm (WCR), found on plants in the plots. In plots treated with 12.5 mg/hectare of 8R-methyl-2R-decyl propanoate (2R,8R-MDP, the apparent female-produced sex pheromone of NCR and WCR), males of both species were attracted to point sources, but beetles did not congregate within treated plots. With racemic 2,8-MDP at 1.0 g/hectare, male WCR were attracted into plots, but NCR of both sexes were strongly repelled. In a separate study, capture of beetles at pheromone-baited traps declined when the surrounding area contained wicks that emitted racemic 2,8-MDP. In treated plots, male WCR were relatively inefficient at finding pheromone sources. With NCR, emigration from plots could account totally for the observed 3- to 10-fold reduction in catch at 0.01-1.0 g/hectare. PMID:24276203

  10. Impact of the Bt Corn Proteins Cry34/35Ab1 and Cry3Bb1, Alone or Pyramided, on Western Corn Rootworm (Coleoptera: Chrysomelidae) Beetle Emergence in the Field.

    PubMed

    Hitchon, A J; Smith, J L; French, B W; Schaafsma, A W

    2015-08-01

    Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a major pest of corn, Zea mays L. The effect of the Bt proteins Cry34/35Ab1 and Cry3Bb1, alone or pyramided in corn hybrids on D. v. virgifera adult emergence was evaluated in field experiments for 3 yr. Experiments were infested artificially with 2,500 viable D. v. virgifera eggs per row meter of corn. The reduction in beetle emergence compared with non-Bt controls, from Cry34/35Ab1, Cry3Bb1, and the pyramided hybrids ranged from 64.3 to 97.4%, 91.1 to 95.2%, and 98.1 to 99.6%, respectively. The sex ratio of emerged beetles was usually female-biased from the Cry3Bb1 and pyramided treatments, but not from Cry34/35Ab1 treatment alone. Emergence from all Bt hybrids was delayed compared with the control, with the delay longest from the pyramided hybrid. In 2013, three egg infestation levels were tested, with density-dependent mortality observed at 1,250 viable eggs per row meter. The effect of Bt proteins on the emergence timing and sex ratio of D. v. virgifera may impact the suitability of resistance management plans, specifically the effectiveness of the refuge strategy. Susceptible males emerging from refuge might not be synchronized to mate with potentially resistant females emerging later from Bt corn hybrids. PMID:26470344

  11. 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. PMID:23905746

  12. Effect of soybean varieties on survival and fecundity of western corn rootworm.

    PubMed

    Dunbar, Mike W; Gassmann, Aaron J

    2012-04-01

    The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of corn (Zea mays L.) in North America and has evolved resistance to crop rotation by ovipositing in alternate crops such as soybeans [Glycine max (L.) Merr.]. Through experiments with plants grown in the greenhouse and the field, we tested whether soybeans with resistance to the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), affected survival, fecundity, and consumption of soybean for D. v. virgifera. Soybean varieties tested included those types resistant to A. glycines (Rag1 and rag1/rag3) and a susceptible near isoline of the Rag1 variety. Females were provided with a diet of corn tissue for 4 d after which they were fed a diet of tissue from one of three soybean varieties for 4 d, starved for 4 d, or fed corn tissue. When fed greenhouse grown plants, strains differed significantly in survival and consumption, but consumption did not differ by variety of soybean. Diet treatment only affected fecundity; individuals fed corn continuously had greater fecundity than those individuals fed soybeans. In the experiment with plants grown in the field, leaf consumption differed among strains and individuals fed corn continuously had greater fecundity than the other treatments. Soybean varieties with Rag1 and rag1/rag3 resistance to A. glycines did not appear to affect the fitness of D. v. virgifera. Thus, planting of these A. glycines-resistant soybean varieties should not directly affect the spread of rotation-resistant D. v. virgifera. PMID:22606835

  13. Effects of entomopathogens on mortality of western corn rootworm (Coleoptera: Chrysomelidae) and fitness costs of resistance to Cry3Bb1 maize.

    PubMed

    Hoffmann, Amanda M; French, B Wade; Jaronski, Stefan T; Gassmann, Aaron J

    2014-02-01

    Fitness costs can delay pest resistance to crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt), and past research has found that entomopathogens impose fitness costs of Bt resistance. In addition, entomopathogens can be used for integrated pest management by providing biological control of pests. The western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of maize and is currently managed by planting of Bt maize. We tested whether entomopathogenic nematodes and fungi increased mortality of western corn rootworm and whether these entomopathogens increased fitness costs of resistance to Cry3Bb1 maize. We exposed western corn rootworm larvae to two species of nematodes, Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae) and Steinernemafeltiae Filipjev (Rhabditida: Steinernematidae), and to two species of fungi, Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae) (strain GHA) and Metarhizium brunneum (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) (strain F52) in two assay types, namely, seedling mat and small cup. Larval mortality increased with the concentration of H. bacteriophora and S. feltiae in the small cup assay, and with the exception of S. feltiae and B. bassiana in the seedling mat assay, mortality from entomopathogens was significantly greater than zero for the remaining entomopathogens in both assays. However, no fitness costs were observed in either assay type for any entomopathogen. Increased mortality of western corn rootworm larvae caused by these entomopathogens supports their potential use in biological control; however, the lack of fitness costs suggests that entomopathogens will not delay the evolution of Bt resistance in western corn rootworm. PMID:24665720

  14. 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

  15. Insecticidal activity of monoterpenoids to western corn rootworm (Coleoptera: Chrysomelidae), twospotted spider mite (Acari: Tetranychidae), and house fly (Diptera: Muscidae).

    PubMed

    Lee, S; Tsao, R; Peterson, C; Coats, J R

    1997-08-01

    Acute toxicities of 34 naturally occurring monoterpenoids were evaluated against 3 important arthropod pest species; the larva of the western corn rootworm, Diabrotica virgifera virgifera LeConte; the adult of the twospotted spider mite. Tetranychus urticae Koch; and the adult house fly. Musca domestica L. Potential larvicidal or acaricidal activities of each monoterpenoid were determined by topical application, leaf-dip method, soil bioassay, and greenhouse pot tests. Phytotoxicity was also tested on a corn plant. Citronellic acid and thymol were the most topically toxic against the house fly, and citronellol and thujone were the most effective on the western corn rootworm. Most of the monoterpenoids were lethal to the twospotted spider mite at high concentrations; carvomenthenol and terpinen-4-ol were especially effective. A wide range of monoterpenoids showed some larvicidal activity against the western corn rootworm in the soil bioassay. Perillaldehyde, the most toxic (LC50 = 3 micrograms/g) in soil, was only 1/3 as toxic as carbofuran, a commercial soil insecticide (LC50 = 1 microgram/g). Selected monoterpenoids also effectively protected corn roots from attack by the western corn rootworm larvae under greenhouse conditions. alpha-Terpineol was the best monoterpenoid in the greenhouse pot test. The acute toxicity of monoterpenoids was low relative to conventional insecticides. Some monoterpenoids were phytotoxic to corn roots and leaves. l-Carvone was the most phytotoxic, whereas pulegone was the safest. The results with thymyl ethyl ether, one of the synthetic derivatives of thymol, showed a potential of derivatization to reduce monoterpenoid phytotoxicity. PMID:9260540

  16. Evidence of evolving carbaryl resistance in western corn rootworm (Coleoptera: Chrysomelidae) in areawide-managed cornfields in north central Kansas.

    PubMed

    Zhu, K Y; Wilde, G E; Higgins, R A; Sloderbeck, P E; Buschman, L L; Shufran, R A; Whitworth, R J; Starkey, S R; He, F

    2001-08-01

    Susceptibility of adult populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, to carbaryl was determined by a survey in 1996 before the implementation of an areawide management program near Scandia in north central Kansas. Subsequently, the susceptibility of western corn rootworm adults to carbaryl has been monitored throughout the program from 1997 to 2000 in both control and managed areas. In 1996, adults were highly susceptible to carbaryl with a mean LC50 value of 0.64 microg/vial. This value was comparable to those for adults collected from other regions within Kansas. However, adult susceptibility to carbaryl decreased rapidly within the managed area, where the cucurbitacin- carbaryl-based bait SLAM has been used as the primary tool to control adults in this project since 1997. In 1999, adults collected from the managed area were 9- and 20-fold less susceptible to carbaryl at the LC50 and LC90 levels, respectively, than those evaluated in 1996. In contrast, adults collected from the control area were only 2- and 3-fold less susceptible to carbaryl at the LC50 and LC90 levels, respectively, than adults evaluated in 1996. Although field adult populations of western corn rootworm were relatively low in 2000, evaluations showed trends similar to those in 1999 regarding their carbaryl susceptibility in the managed and control areas. These results provide evidence that western corn rootworm has been evolving carbaryl resistance rapidly in response to the use of SLAM in areawide-managed cornfields near Scandia. PMID:11561854

  17. 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

  18. 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. PMID:23951124

  19. Soil application of an encapsulated CO2 source and its potential for management of western corn rootworm larvae.

    PubMed

    Schumann, M; Patel, A; Vidal, S

    2014-02-01

    Western corn rootworm (Diabrotica virgifera virgifera LeConte) larvae use carbon dioxide (CO2) to locate the roots of their hosts. This study investigated whether an encapsulated CO2 source (CO2-emitting capsules) is able to outcompete CO2 gradients established by corn root respiration in the soil. Furthermore, the following two management options with the capsules were tested in semifield experiments (0.5- to 1-m2 greenhouse plots): the disruption of host location and an "attract-and-kill" strategy in which larvae were lured to a soil insecticide (Tefluthrin) between the corn rows. The attract-and-kill strategy was compared with an application of Tefluthrin in the corn rows (conventional treatment) at 33 and 18% of the standard field application rate. Application of the CO2-emitting capsules 30 cm from the plant base increased CO2 levels near the application point for up to 20 d with a peak at day 10. Both the disruption of host location and an attract-and-kill strategy caused a slight but nonsignificant reduction in larval densities. The disruption of host location caused a 17% reduction in larval densities, whereas an attract-and-kill strategy with Tefluthrin added at 33 and 18% of the standard application rate caused a 24 and 27% reduction in larval densities, respectively. As presently formulated, the CO2-emitting capsules, either with or without insecticide, do not provide adequate control of western corn rootworm. PMID:24665706

  20. 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

  1. 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

  2. Evaluation of conventional resistance to European corn borer (Lepidoptera: Crambidae) and western corn rootworm (Coleoptera: Chrysomelidae) in experimental maize lines developed from a backcross breeding program.

    PubMed

    Abel, C A; Berhow, M A; Wilson, R L; Binder, B F; Hibbard, B E

    2000-12-01

    Plant resistance is a promising control method for the two most damaging insect pests of maize, Zea mays L.: the European corn borer, Ostrinia nubilalis (Hübner), and the western corn rootworm Diabrotica virgifera virgifera LeConte. Fifteen experimental lines of maize, derived from a backcross breeding program designed to introgress resistance to European corn borer from Peruvian maize into two U.S. Corn Belt adapted inbred lines, were evaluated for resistance to European corn borer and western corn rootwonrm. The experimental lines were in the second generation of backcrossing. All experimental lines were resistant to leaf blade feeding by European corn borer. These lines had low levels of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one, a chemical commonly associated with leaf blade feeding resistance, indicating that this was not the mechanism of resistance to leaf blade feeding in these lines. Eleven experimental lines were resistant to leaf sheath and collar feeding by European corn borer. Useful sources of European corn borer ovipositional nonpreference and root feeding resistance to western corn rootworm were not identified. Some of the lines evaluated in this study may provide useful sources of resistance to both leaf blade and leaf sheath and collar feeding by European corn borer. PMID:11142317

  3. Expression and characterization of a recombinant endoglucanase from western corn rootworm, in Pichia pastoris.

    PubMed

    Valencia Jiménez, Arnubio; Wang, Haichuan; Siegfried, Blair D

    2014-01-01

    The endoglucanase cDNA, Dvv-ENGase I, from western corn rootworm, Diabrotica virgifera virgifera LeConte was expressed using the GS115 methylotrophic strain of Pichia pastoris. The Dvv-ENGase I gene was cloned into the integrative plasmid pPICZαA under the control of AOX1, which is a methanol-inducible promoter. Positive clones were selected for their ability to produce the recombinant endoglucanase upon continuous methanol induction. The secreted recombinant insect endoglucanase Dvv-ENGase I has an apparent molecular mass of 29 kDa. The recombinant endo-1,4-β-glucanase (ENGase) was able to digest the substrates: hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), and Whatman No. 1 filter paper. A higher accumulation of reducing sugar was evident when the P. pastoris expression medium contained HEC (1%) instead of CMC (1%). An enzymatic activity band was detected after performing electrophoretic separation under nondenaturing conditions. The biological activity of the recombinant Dvv-ENGase I was influenced by the presence of protease inhibitors in the culture medium. PMID:25434035

  4. 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. PMID:23798396

  5. Inheritance of methyl-parathion resistance in Nebraska western corn rootworm populations (Coleoptera: Chrysomelidae).

    PubMed

    Parimi, Srinivas; Scharf, Michael E; Meinke, Lance J; Chandler, Laurence D; Siegfried, Blair D

    2003-02-01

    Field populations of western corn rootworm, Diabrotica virgifera virgifera LeConte, were collected from three different sites (York Co., Phelps Co., and Saunders Co.) in Nebraska during 1996. Adult bioassays of these three populations were conducted with different concentrations of methyl-parathion and at a diagnostic concentration (1.0 microg/ml) to determine resistance levels among these populations. Self and reciprocal crosses were made between the two resistant and one susceptible laboratory-reared populations. Dose-responses and dominance ratios calculated for the four reciprocal crosses indicated that resistance was incompletely dominant in both strains, although in one of the strains there was an indication of sex linkage. However, evaluation of native polyacrylamide gels stained for nonspecific esterases and nonspecific esterase activity of parents and F1 progeny of the crosses suggested that esterase inheritance was completely dominant and autosomal. The results of this study were inconclusive with regard to the precise nature of inheritance, because the bioassays and esterase assays could not discriminate between heterozygotes and homozygotes. However, they do provide insight into the potential for developing simple diagnostic assays to assess resistance frequencies. Based on the inheritance studies described in this investigation, we can begin to generate information on specific genetic factors that dictate the evolutionary divergence of discrete resistant populations and facilitate modeling efforts designed to approximate the movement of genes for resistance among populations. PMID:12650355

  6. 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. PMID:24020261

  7. Identification and quantification of hydroxamic acids in maize seedling root tissue and impact on western corn rootworm (Coleoptera: Chrysomelidae) larval development.

    PubMed

    Davis, C S; Ni, X; Quisenberry, S S; Foster, J E

    2000-06-01

    Hydroxamic acid content was analyzed in the root tissue of four maize, Zea mays L., lines using high-performance liquid chromatography (HPLC) and related to western corn rootworm, Diabrotica virgifera virgifera LeConte, larval development and survivorship. Maize lines evaluated included Mp710 (PI 596627), MpSWCB-4, (PI 550498), Sc213 (PI 548792), and Dk580 (DeKalb commercial hybrid). Maize plants from each line were grown in test tubes containing a transparent agarose gel medium in a growth chamber. After 8 d of growth, root tissue of each line was harvested and hydroxamic acid content analyzed using HPLC. Three hydroxamic acids, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), 6-methoxybenzoxazolinone (MBOA), and 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA), were identified in the maize roots tested. DIMBOA concentration was quantified and ranged from 246.37 +/- 70.53 micrograms to 91.84 +/- 49.82 micrograms DIMBOA per gram of root tissue. No significant difference was found among lines in D. v. virgifera larval development and survivorship. PMID:10902360

  8. Single and blended maize volatiles as attractants for diabroticite corn rootworm beetles.

    PubMed

    Hammack, L

    2001-07-01

    Synthetic maize volatiles and analogs dispensed singly and blended were tested for attractiveness to western (WCR, Diabrotica virgifera virgifera) and northern corn rootworm beetles (NCR, D. barberi) in maize fields. Newly identified attractants included syn-benzaldoxime, especially for NCR, and beta-caryophyllene for WCR females. (+/-)-Linalool was more effective than was (-)-linalool. Myrcene, (+)-beta-pinene, and (-)-beta-pinene were unattractive. Adding methyl salicylate to (+/-)-linalool, (+)-alpha-terpineol, or beta-ionone appeared to synergistically increase capture of WCR females, but dispensing the terpenes in binary blends did not. Dose-response data for methyl salicylate, (+/-)-linalool, and a blend of both compounds confirmed the synergy. beta-Caryophyllene, but not (-)-alpha-pinene, added to the latter blend produced a further synergistic increase in WCR female capture that did not vary with sesquiterpene dose from 1.0 to 100 mg. Indole addition to the same blend caused an increase in WCR female captures indicative of synergy, assuming that each did not individually lure different segments of the WCR female population. The green leaf volatiles (Z)-3-hexenyl acetate and (Z)-3-hexen-1-ol were unattractive alone and had no influence on efficacy of traps baited with 3.3 mg each of (+/-)-linalool, methyl salicylate, and beta-caryophyllene. The latter mixture captured about half as many WCR females as did 10 mg of 4-methoxycinnamaldehyde, a potent WCR attractant standard. Substituting beta-ionone for (+/-)-linalool yielded a ternary blend that captured more beetles than did the aldehyde and was unaffected by aldehyde addition. Olive oil, which has been used to sustain attractant volatilization, did not affect captures. The results show that the blending of maize volatiles has thepotential to greatly improve efficacy of lures having promising applications in corn rootworm population management. PMID:11504034

  9. 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. PMID:23786070

  10. 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. PMID:14658504

  11. Effectiveness of Corn Rootworm (Coleoptera: Chrysomelidae) Areawide Pest Management in South Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabrotica barberi Smith & Lawrence and D. v. virgifera virgifera LeConte are serious pests of maize (Zea mays L.). The U. S. Department of Agriculture, Agricultural Research Service implemented a five year (1997-2001) areawide pest management program in five geographic locations, including one in S...

  12. 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

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

    PubMed

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

    2005-01-01

    The American Chrysomelid beetle Diabrotica virgifera virgifera LeConte (D.v.v.), also called the western corn rootworm, spread from the location of its original introduction into Europe, Belgrade airport (BACA 1993), in all directions. Within a decade it occupied almost all countries of South-eastern and Central Europe. However, it reached Slovenia as late as 2003: Only 19 specimen were found in maize fields of the eastern and also western provinces. Already in the summer of 2004, their number had risen to 386 which were mainly found in the eastern provinces near the borders to Croatia, Austria and Hungary. For their monitoring, a simple trap is being described which can be acquired in high numbers at a very low price and can guaranty a most sensitive detection of beetles. The Metcalf cup trap which in Slovenia so far has been unknown performed the task of monitoring quite well at five locations. It will also facilitate the future search for new and increasing infestations. Comparing 2004 with the year 2003, D.v.v. expanded its range in eastern Slovenia by about 15 km. These new infestations will include territories in which fields of the regionally Important oil seed pumpkin Cucurbita pepo are located. With important traffic connections between South-eastern and Central Europe, Slovenia will occupy a bridgehead function in the preventive protection of maize from D.v.v. spreading into more northerly European regions including western Austria and southern Germany. PMID:16628904

  14. Isolation and characterization of host recognition cues in corn roots for larvae of the western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Bernklau, E J; Hibbard, B E; Bjostad, L B

    2013-12-01

    Behavioral bioassays were used to isolate compounds from germinating corn roots that elicit a host recognition response (tight-turning behavior) by neonate larvae of the western corn rootworm Diabrotica virgifera virgifera LeConte. When a behaviorally active extract of germinating corn roots was separated into an aqueous partition and a hexane partition, significantly more larvae (P < 0.05) responded to the recombined partitions than to either partition alone, demonstrating that the active material is a blend comprising both polar and nonpolar compounds. When the aqueous partition was separated with reverse-phase solid phase extraction, most of the behavioral activity was retained in the 100% water fraction (F-1). Gas chromatography-mass spectrometry analysis determined that F-1 contained a blend of small sugars, diacids, amino acids, and inorganic compounds. The nonpolar partition was separated on a silica column, and the resulting fractions were tested in combination with F-1 from the aqueous separation. More than 70% of larvae responded to the 100% acetone fraction (fraction B) in combination with F-1, and the response to this treatment was significantly higher than responses to the other nonpolar fractions or to F-1 alone. Methyl esterification of fraction B, followed by gas chromatographic fatty acid methyl ester analysis, confirmed that fraction B primarily consisted of lipids containing fatty acyl groups. PMID:24498734

  15. 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

  16. Characterization of general esterases from methyl parathion-resistant and -susceptible populations of western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Zhou, Xuguo; Scharf, Michael E; Meinke, Lance J; Chandler, Laurence D; Siegfried, Blair D

    2003-12-01

    A consistent correlation between elevated esterase activity and methyl parathion resistance among Nebraska western corn rootworm, Diabrotica virgifera virgifera LeConte, populations has previously been documented. Characterization of general esterase activity using naphtholic esters as model substrates indicated that differences between resistant and susceptible strains could be maximized by optimizing assay conditions. The optimal conditions identified here were similar to those reported for other insect species. The majority of general esterase activity was found in the cytosolic fractions of resistant populations, whereas the activity was more evenly distributed between cytosolic and mitochondrial/nuclear fractions in the susceptible population. General esterase activity was predominately located in the adult thorax and abdomen. Although there were significant differences in general esterase activities between resistant and susceptible populations, the differences exhibited in single beetle activity assays did not provide sufficient discrimination to identify resistant individuals. In contrast, single larva activity assays provided greater discrimination and could be considered as an alternative to traditional bioassay techniques. PMID:14977127

  17. Monitoring western corn rootworm (Coleoptera: Chrysomelidae) susceptibility to carbaryl and cucurbitacin baits in the areawide management pilot program.

    PubMed

    Siegfried, Blair D; Meinke, Lance J; Parimi, Srinivas; Scharf, Michael E; Nowatzki, Timothy J; Zhou, X; Chandler, Laurence D

    2004-10-01

    Areawide pest management involves the uniform application of a pest control strategy over wide geographic areas. Therefore, these programs are likely to impose intense selective pressures, and the risk for resistance development among pest species for which areawide management programs are implemented is likely to be high. Pilot studies for areawide management of western corn rootworm, Diabrotica virgifera virgifera LeConte, were conducted from 1996 to 2002 at four different sites across the Corn Belt. This program used cucurbitacin baits to deliver high doses of a traditional neurotoxic insecticide (carbaryl) to individual insects while reducing the overall rate of insecticide use. Because of the concern and potential for resistance evolution, annual assessments of susceptibility to the active ingredient carbaryl were conducted both within the managed area as well as from untreated control areas. Significantly reduced susceptibility to carbaryl based on survival at a diagnostic concentration was detected in three of the four management sites (Kansas, Iowa, and Illinois/Indiana), whereas susceptibility of beetles collected outside the managed areas remained unchanged. Additionally, significantly reduced responsiveness to cucurbitacin baits was observed in beetles collected from the managed area relative to the control area at the same three sites. These results suggest strongly that areawide management has the potential to select for resistance and that a strategy for managing resistance and reducing selective pressure should be proactively implemented. PMID:15568365

  18. 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

  19. 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

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

    PubMed

    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

  1. Applying an integrated refuge to manage western corn rootworm (Coleoptera: Chrysomelidae): effects on survival, fitness, and selection pressure.

    PubMed

    Petzold-Maxwell, Jennifer L; Alves, Analiza P; Estes, Ronald E; Gray, Michael E; Meinke, Lance J; Shields, Elson J; Thompson, Stephen D; Tinsley, Nicholas A; Gassmann, Aaron J

    2013-10-01

    The refuge strategy can delay resistance of insect pests to transgenic maize producing toxins from Bacillus thuringiensis (Bt). This is important for the western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), because of its history of adaptation to several management practices. A 2-yr study across four locations was conducted to measure the effects of integrated refuge (i.e., blended refuge) on western corn rootworm survival to adulthood, fitness characteristics, and susceptibility to Bt maize in the subsequent generation. The treatments tested in this study were as follows: a pure stand of Bt maize (event DAS-59122-7, which produces Bt toxins Cry34Ab1/Cry35Ab1), a pure stand of refuge (non-Bt maize), and two variations on an integrated refuge consisting of 94.4% Bt maize and 5.6% non-Bt maize. Within the two integrated refuge treatments, refuge seeds received a neonicotinoid insecticidal seed treatment of either 1.25 mg clothianidin per kernel or 0.25 mg thiamethoxam per kernel. Insects in the pure stand refuge treatment had greater survival to adulthood and earlier emergence than in all other treatments. Although fecundity, longevity, and head capsule width were reduced in treatments containing Bt maize for some site by year combinations, Bt maize did not have a significant effect on these factors when testing data across all sites and years. We found no differences in susceptibility of larval progeny to Bt maize in bioassays using progeny of adults collected from the four treatments. PMID:24224265

  2. Consumption of residue containing cucurbitacin feeding stimulant and reduced rates of carbaryl insecticide by western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Behle, R W

    2001-12-01

    Application of insecticide at a reduced rate with a cucurbitacin-based feeding stimulant is a viable alternative to a broadcast insecticide application for control of adult western corn rootworms, Diabrotica virgifera virgifera, LeConte. Because of the small amount of material applied, it is conceivable that a high density of beetles could consume all of the spray residue before economic control is achieved. A laboratory experiment was conducted to determine the amount of cucurbitacin-based spray residue consumed by beetles. Dried residue of four treatments were exposed to three groups of 10 rootworm beetles for 1 h each. Treatments consisted of a cucurbitacin-based adjuvant (Cidetrak CRW, Trécé, Salinas, CA) with carbaryl insecticide (Sevin XLR Plus, Rhone Poulenc, Research Triangle Park, NC) mixed at 0, 0.12, 1.2, and 12 g (AI)/liter. For the treatment with cucurbitacin adjuvant only (no insecticide), beetles consumed 0.029 mg beetle(-1) h(-1) of exposure. Approximately 54% of the beetles were recorded as feeding at any given time during the 60-min feeding period. However, when the spray residue contained carbaryl, no weight loss of treatment residue was measured, though the beetles were observed to feed from the residue during the first few minutes of exposure. When residue included insecticide, beetles quickly ceased feeding (within 20 min), and toxicity behavior was observed 30 min after initial exposure for up to 75% of the beetles, which were classified as moribund (unable to stand upright). Beetle mortality was recorded 24 h after exposure and demonstrated that male beetles (53% dead for three insecticide treatments) were more susceptible to carbaryl toxicity than female beetles (28% dead for three insecticide treatments). Regression analysis showed a significant positive relationship between mortality of female beetles and ovarian development. Based on the measurements of this experiment, it is unlikely that realistic beetle densities would consume

  3. Economics versus alleles: balancing integrated pest management and insect resistance management for rotation-resistant western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Onstad, D W; Crowder, D W; Mitchell, P D; Guse, C A; Spencer, J L; Levine, E; Gray, M E

    2003-12-01

    Western corn rootworm, Diabrotica virgifera virgifera LeConte, has overcome crop rotation in several areas of the central United States. We expanded a simple model of adult behavior and population genetics to explain how rotation resistance may have developed and to study ways to manage the western corn rootworm in a landscape of corn, soybean, and winter wheat where evolution of resistance may occur. We modeled six alternative management strategies over a 15-yr time horizon, as well as a strategy involving a 2-yr rotation of corn and soybean in 85% of the landscape, to investigate their effectiveness from both a biological and economic perspective. Generally, resistance to crop rotation evolves in fewer than 15 yr, and the rate of evolution increases as the level of rotated landscape (selection pressure) increases. When resistance is recessive, all six alternative strategies were effective at preventing evolution of rotation resistance. The two most successful strategies were the use of transgenic rotated corn in a 2-yr rotation and a 3-yr rotation of corn, soybean, and wheat with unattractive wheat (for oviposition) preceding corn. Results were most sensitive to increases in the initial allele frequency and modifications of the density-dependent survival function. Economically, three alternative strategies were robust solutions to the problem, if technology fees were not too high. Repellant soybean, attractive rotated corn, and transgenic rotated corn, all in 2-yr rotations, were economically valuable approaches. However, even the currently common 2-yr rotation was economical when resistance was recessive and the actual costs of resistance would not be paid until far in the future. PMID:14977129

  4. Flight behavior of methyl-parathion-resistant and -susceptible western corn rootworm (Coleoptera: Chrysomelidae) populations from Nebraska.

    PubMed

    Stebbing, Jenny A; Meinke, Lance J; Naranjo, Steve E; Siegfried, Blair D; Wright, Robert J; Chandler, Laurence D

    2005-08-01

    Relative flight behavior of methyl-parathion-resistant and -susceptible western corn rootworm, Diabrotica virgifera virgifera LeConte populations, was studied as part of a larger effort to characterize the potential impact of insecticide resistance on adult life history traits and to understand the evolution and spread of resistance. A computer interfaced actograph was used to compare flight of resistant and susceptible individuals, and flight of resistant individuals with and without prior exposure to methyl-parathion. In each case, mean trivial and sustained flight durations were compared among treatments. In general, there were few differences in trivial or sustained flight characteristics as affected by beetle population, insecticide exposure, sex, or age and there were few significant interactions among variables. Tethered flight activity was highly variable and distributions of flight duration were skewed toward flights of short duration. Tethered flight activity was similar among resistant and susceptible beetles with the exception that susceptible beetles initiated more flights per beetle than resistant beetles. After sublethal exposure to methyl-parathion, total flight time, total trivial flight time, and mean number of flights per resistant beetle declined significantly. Because long-range flight was uncommon, short- to medium-duration flights may play an important role in determining gene flow and population spread of resistant D. v. virgifera. These results suggest that organophosphate-resistant beetles can readily move and colonize new areas, but localized selection pressure (e.g., management practices) and exposure to methyl-parathion may contribute to the small-scale differences in resistance intensity often seen in the field. PMID:16156583

  5. Cultural diabrotica containment strategy in Switzerland: until now a convincing success story.

    PubMed

    Bertossa, M; Hummel, Hans E

    2013-01-01

    Ever since 2000 Switzerland belongs to the 22 European countries where the quarantine pest Diabrotica virgifera virgifera LeConte, Western corn rootworm (WCR), has been detected. It is reported to be the most important maizepest worldwide with an economic damage reaching 1.5 billion US$. In Switzerland it is constantly present in the southern part of the Alps while only few beetles are sporadically found in the northern part. Observations from 2000 up to 2012 support the hypothesis that the populations in the southern part of the Alps are generated by yearly migrations from principal foci situated in neighbouring Italian areas of Lombardy. Neither the tight correlation between travel distance and time of first arrival at various points from South to North, nor the steady decline of population along the route can be explained otherwise. Control measures enacted by Swiss authorities were principally based on a tightly enforced crop rotation scheme without chemical inputs as usually practiced in parts of the European Union. The effectiveness of crop rotation has been tested in a 5 year field trial comparing a continuous maize cropping system with a croprotation system and a maximum of one year of maizewithin a two year period (1:1). Population density was measured using synthetic pheromone baited traps and observations of root damage. Results showed that no economically relevant population built up during this period in the crop rotation treatment, whereas in the statistical evaluation of continuous maizecropping root damages could be detected after 4 years. One to one (1:1) year crop rotations are a common practice since 2001 in Southern Switzerland and are well accepted by farmers. Consequently, not a gram of pesticide has been employed against WCR in Switzerland up to now. The low level population density also helped to avoid the introduction of WCR populations into Cantons north of the Alps and thus prevented further spreading towards the state territories of

  6. 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...

  7. Development of resistance to eCry3.1Ab-expressing transgenic maize in a laboratory-selected population of western corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Frank, Daniel L; Zukoff, Anthony; Barry, Julie; Higdon, Matthew L; Hibbard, Bruce E

    2013-12-01

    A laboratory colony of western corn rootworm, Diabrotica virgifera virgifera LeConte, was selected for resistance to transgenic maize expressing the eCry3.1Ab protein. The selected colony was developed by rearing larvae on nonelite noncommercial Bt maize expressing the eCry3.1Ab protein. After four generations, selected and control colonies were screened on eCry3.1Ab-expressing and isoline maize using greenhouse experiments. There was a significant colony x maize pedigree interaction in terms of the number of larvae recovered. There was no significant difference in the number of larvae recovered from eCry3.1Ab-expressing and isoline maize for the selected colony, whereas this difference was significant for the control colony. There was not a significant colony x maize pedigree interaction in terms of root damage, or the number of beetles recovered, but the effect of maize pedigree was significant. After four and eight generations of selection, seedling bioassays were performed. Again, there was a significant colony x maize pedigree interaction in terms of the number of larvae recovered. After 11 generations of selection, larvae from the selected colony had higher LC50 values than the control colony when exposed to increasing concentrations of the eCry3.1Ab protein. The resistance ratio of the selected colony was 2.58. These data provide necessary information for understanding the potential for Bt resistance by western corn rootworm and underscores the need for insect resistance management plans for this pest. PMID:24498752

  8. 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

  9. Disruption of host location of western corn rootworm larvae (Coleoptera: Chrysomelidae) with carbon dioxide.

    PubMed

    Bernklau, E J; Fromm, E A; Bjostad, L B

    2004-04-01

    Elevated concentrations of carbon dioxide (CO2) prevented neonate larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte, from locating the roots of growing corn in behavioral bioassays conducted in soil tubs. When CO2 was pumped into one end of a soil tub, significantly more larvae were recovered from soil at the treated end than from soil around a growing corn plant at the opposite end of the tub. In controls with ambient air pumped into one end of a soil tub, significantly more larvae were recovered from the soil around the corn plant than from soil on the treated side. Larvae were unable to locate the roots of corn seedlings when CO2-generating materials were mixed into the soil. CO2-concentrations in soil were measured by mass spectrometry with selected ion monitoring at m/z 44. Granules composed of baker's yeast, yeast nutrients, and an organic substrate were prepared as a CO2 source and were tested in larger soil tub bioassays. Significantly fewer larvae were recovered from corn roots in the soil tubs with yeast granules than from corn roots in control soil tubs. The CO2-generating granules produced soil CO2 concentrations between 15.8 and 18.5 mmol/mol (compared with 1.7-2.6 mmol/mol in control tubs), and this was sufficient to prevent larvae from locating corn roots. In field trials, organic and inorganic CO2- generating treatments resulted in root ratings that were significantly lower than for the control plants. PMID:15154452

  10. Spermatophore size in relation to body size and pairing duration in the Northern Corn Rootworm (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms (Diabrotica spp.) can inflict serious damage to maize (Zea mays L.) and have evolved resistance to cultural and chemical management methods. Currently genetically modified maize producing rootworm-toxic proteins derived from the bacterium, Bacillus thuringiensis Berliner, is extensive...

  11. Field resistance of two soybean germplasm lines, HC95-15MB and HC95-24MB, against bean leaf beetle (Coleoptera: Chrysomelidae), western corn rootworm (Coleoptera: Chrysomelidae), and Japanese beetles (Coleoptera: Scarabaidae).

    PubMed

    Hammond, R B; Bierman, P; Levine, E; Cooper, R L

    2001-12-01

    Two recently released, Mexican bean beetle, Epilachna varivestis, Mulsant, resistant soybean, Glycine max (L.) Merrill, germplasm lines, HC95-15MB and HC95-24MB, were examined for foliar and pod feeding resistance to adult bean leaf beetles, Cerotoma trifurcata (Forster), western corn rootworms, Diabrotica virgifera virgifera LeConte, and Japanese beetles, Popillia japonica Newman. Both lines were planted along with a susceptible control cultivar in 18 by 30-m plots and separate 0.8-ha size fields. Insects were sampled on a weekly basis with a sweep net. In late summer, defoliation ratings were recorded along with data on percentage pod feeding. Although a few significant differences in insect densities were obtained among the soybean lines on some sampling dates, no specific trends were observed in the ability of the resistant germplasm to reduce insect numbers. Insect population densities were similarly on all lines. However, both resistant lines were able to reduce defoliation during the growing season. Conversely, percentage pod feeding was similar among all the soybean lines, with no differences observed. The resistant germplasm lines appear able to lower levels of defoliation, and thus, offer a potential management tactic where leaf feeding, i.e., defoliation, is of concern. However, their ability to greatly reduce beetle population densities, and for the bean leaf beetle, to reduce pod feeding, appears limited. PMID:11777070

  12. 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

  13. Establishing an in vivo assay system to identify components involved in environmental RNA interference in the western corn rootworm.

    PubMed

    Miyata, Keita; Ramaseshadri, Parthasarathy; Zhang, Yuanji; Segers, Gerrit; Bolognesi, Renata; Tomoyasu, Yoshinori

    2014-01-01

    The discovery of environmental RNA interference (RNAi), in which gene expression is suppressed via feeding with double-stranded RNA (dsRNA) molecules, opened the door to the practical application of RNAi-based techniques in crop pest management. The western corn rootworm (WCR, Diabrotica virgifera virgifera) is one of the most devastating corn pests in North America. Interestingly, WCR displays a robust environmental RNAi response, raising the possibility of applying an RNAi-based pest management strategy to this pest. Understanding the molecular mechanisms involved in the WCR environmental RNAi process will allow for determining the rate limiting steps involved with dsRNA toxicity and potential dsRNA resistance mechanisms in WCR. In this study, we have established a two-step in vivo assay system, which allows us to evaluate the involvement of genes in environmental RNAi in WCR. We show that laccase 2 and ebony, critical cuticle pigmentation/tanning genes, can be used as marker genes in our assay system, with ebony being a more stable marker to monitor RNAi activity. In addition, we optimized the dsRNA dose and length for the assay, and confirmed that this assay system is sensitive to detect well-known RNAi components such as Dicer-2 and Argonaute-2. We also evaluated two WCR sid1- like (sil) genes with this assay system. This system will be useful to quickly survey candidate systemic RNAi genes in WCR, and also will be adaptable for a genome-wide RNAi screening to give us an unbiased view of the environmental/systemic RNAi pathway in WCR. PMID:25003334

  14. Role of egg density on establishment and plant-to-plant movement by western corn rootworm larvae (Coleoptera: Chrysomelidae).

    PubMed

    Hibbard, B E; Higdon, M L; Duran, D P; Schweikert, Y M; Ellersieck, M R

    2004-06-01

    The effect of egg density on establishment and dispersal of larvae of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was evaluated in a 3-yr field study. Implications of these data for resistance management plans for Bt crops are discussed. Viable egg levels of 100, 200, 400, 800, and 1600 eggs per infested plant were evaluated in 2000, 2001, and 2002. A 3200 viable egg level was also tested in 2001 and 2002. All eggs were infested on one plant per subplot in a field that was planted to soybean, Glycine max (L.), in the previous year. For each subplot, the infested plant, three plants down the row, the closest plant in the adjacent row of the plot, and a control plant at least 1.5 m from any infested plant (six plants total) were sampled. In 2000, there were five sample dates between egg hatch and pupation, and in 2001 and 2002, there were six sample dates. On each sample date, four replications of each egg density were sampled for both larval recovery and plant damage. Initial establishment on a corn plant seemed to not be density-dependent because a similar percentage of larvae was recovered from all infestation rates. Plant damage and, secondarily, subsequent postestablishment larval movement were density-dependent. Very little damage and postestablishment movement occurred at lower infestation levels, but significant damage and movement occurred at higher infestation rates. Movement generally occurred at a similar time as significant plant damage and not at initial establishment, so timing of movement seemed to be motivated by available food resources rather than crowding. At the highest infestation level in 2001, significant movement three plants down the row and across the 0.76 m row was detected, perhaps impacting refuge strategies for transgenic corn. PMID:15279266

  15. Effectiveness of glues used for harmonic radar tag attachment and impact on survival and behavior of three insect pests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of three cyanoacrylate glues to ensure a durable bond between the Colorado potato beetle, Leptinotarsa decemlineata (Say), the plum curculio, Conotrachelus nenuphar (Herbst) or the Corn Rootworms, (Western Corn Rootworm, Diabrotica virgifera virgifera LeConte and Northern Corn Rootworm, ...

  16. Prairie grasses as hosts of the northern corn rootworm (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated 27 prairie grass species thought to be among those domi-nant 200 years ago in the northern Midwest as larval hosts of the northern corn rootworm, Diabrotica barberi Smith and Lawrence. Maize (Zea mays L.), spring wheat (Tritcum aestivum L.), and sorghum (Sorghum bicolor L.) were includ...

  17. INCREASED INCIDENCE OF EXTENDED DIAPAUSE IN NORTHERN CORN ROOTWORM AS EVIDENCED BY GEOREFERENCED ADULT EMERGENCE DATA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Georeferenced grid samples for northern corn rootworm , Diabrotica barberi Smith and Lawrence (Coleoptera: Chrysomelidae) were taken over a 6-year period from two study sites in eastern South Dakota. A field in Moody County, SD was sampled in 1995, 1997 and 1999 and a second field in Brookings Co.,...

  18. Wolbachia multilocus sequence typing of singly infected and multiply infected populations of Northern Corn Rootworm (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The northern corn rootworm (Diabrotica barberi) in eastern and central North America exhibits at least three distinct populations with respect to Wolbachia infection: uninfected; singly-infected; multiply-infected. The infected states are associated with different mtDNA haplotypes and reduced mtDNA ...

  19. Multiple mating, fecundity and longevity in female Northern Corn Rootworm (Coleoptera: Chrysomelidae) in relation to body size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite a long history of cultural and chemical control strategies, Diabrotica spp. still can inflict serious damage to maize (Zea mays L.). Currently, genetically modified maize produce a rootworm-toxic protein derived from the soil bacterium, Bacillus thuringiensis Berliner. To slow the progressio...

  20. Molecular phylogeny of Diabrotica beetles (Coleoptera: Chrysomelidae) inferred from analysis of combined mitochondrial and nuclear DNA sequences.

    PubMed

    Clark, T L; Meinke, L J; Foster, J E

    2001-08-01

    The phylogenetic relationships of thirteen Diabrotica (representing virgifera and fucata species groups) and two outgroup Acalymma beetle species (Coleoptera: Chrysomelidae) were inferred from the phylogenetic analysis of a combined data set of 1323 bp of mitochondrial DNA (mtDNA) cytochrome oxidase subunit 1 (COI) and the entire second internal transcribed spacer region (ITS-2) of nuclear ribosomal DNA of 362 characters. Species investigated were D. adelpha, D. balteata, D. barberi, D. cristata, D. lemniscata, D. longicornis, D. porracea, D. speciosa, D. undecimpunctata howardi, D. u. undecimpunctata, D. virgifera virgifera, D. v. zeae, D. viridula, and outgroup A. blandulum and A. vittatum. Maximum parsimony (MP), minimum evolution (ME), and maximum likelihood (ML) analyses of combined COI and ITS-2 sequences clearly place species into their traditional morphological species groups with MP and ME analyses resulting in identical topologies. Results generally confer with a prior work based on allozyme data, but within the virgifera species group, D. barberi and D. longicornis strongly resolve as sister taxa as well as monophyletic with the neotropical species, D. viridula, D. cristata and D. lemniscata also resolve as sister taxa. Both relationships are not in congruence with the prior allozyme-based hypothesis. Within the fucata species group, D. speciosa and D. balteata resolve as sister taxa. Results also strongly supported the D. virgifera and D. undecimpunctata subspecies complexes. Our proposed phylogeny provides some insight into current hypotheses regarding distribution status and evolution of various life history traits for Diabrotica. PMID:11520353

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

    PubMed

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

    2012-08-01

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

  2. Wolbachia wsp gene clones detect the distribution of Wolbachia variants and wsp hypervariable regions among individuals of a multistrain infected population of Diabrotica barberi (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The northern corn rootworm (Diabrotica barberi) in eastern and central North America exhibits at least three distinct populations with respect to Wolbachia infection: uninfected; singly-infected; multi-infected. The infected states are associated with different mtDNA haplotypes and reduced mtDNA var...

  3. Corn rootworms and Bt resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  4. Factors influencing distribution ofDiabrotica spp. in blossoms of cultivatedCucurbita spp.

    PubMed

    Andersen, J F; Metcalf, R L

    1987-04-01

    Cultivars representing three species ofCucurbita were examined for blossom preference byDiabrotica spp.C. maxima cultivars were found to be preferred byD. undecimpunctata howardi over those ofC. pepo andC. moschata.D. virgifera virgifera preferredC. maxima and the "Connecticut Field" cultivar ofC. pepo.C. moschata and other cultivars ofC. pepo were not preferred. Cultivars were examined for differences in floral volatile release, blossom cucurbitacin content, and pollen content of male blossoms.C. maxima male blossoms released a larger quantity of volatiles thanC. pepo orC. moschata. Also, onlyC. maxima male blossoms contained cucurbitacins. Cultivars ofC. moschata contained the largest quantities of pollen, but all three species contained relatively large quantities. The data indicate a correspondence ofD. u. howardi distribution in the field with high volatile release rates and high cucurbitacin levels that are found inC. maxima blossoms.D. v. virgifera distribution appears to be somewhat independent of these factors since this species was abundant in blossoms of aC. pepo cultivar as well as cultivars ofC. maxima. PMID:24302038

  5. Diapause in northern corn rootworm (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabroticite corn rootworms are prominent pests of maize and have adapted to both cultural and chemical management methods. In response to a widely used corn-soybean crop rotation in the U.S. Corn Belt over several years, northern corn rootworm (NCR) populations adapted by increasing the proportion ...

  6. 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...

  7. Areawide Insect Management Plans for Corn Rootworm Using GIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms (Coleoptera: Chrysomelidae) are serious pests of maize in the United States and Europe. Historically, chemical pesticides and crop rotation have been used to control these pests, creating economic and environmental concerns. A five year corn rootworm areawide management program was es...

  8. A Novel Interaction between Plant-Beneficial Rhizobacteria and Roots: Colonization Induces Corn Resistance against the Root Herbivore Diabrotica speciosa

    PubMed Central

    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. PMID:25405495

  9. Assessing Larval Rootworm Behavior after Contacting Maize Roots: Impact of Germplasm, Rootworm Species, and Diapause Status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current methods of screening maize (Zea mays L.) germplasm for susceptibility or resistance to corn rootworms (Coleoptera: Chrysomelidae) rely primarily on information from large-scale field experiments. Due to labor and cost constraints associated with field trials, alternative evaluation methods a...

  10. 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....

  11. Mating behavior of Diabrotica speciosa (Coleoptera: Chrysomelidae).

    PubMed

    Nardi, C; Luvizotto, R A; Parra, J R P; Bento, J M S

    2012-06-01

    Diabrotica speciosa (Germar) is an economically important pest of Neotropical cultures and represents a quarantine risk for Neartic and Paleartic Regions. Despite its agricultural importance, few studies have been done on mating behavior and chemical communication, which has delayed the development of behavioral techniques for population management, such as the use of pheromone traps. In this study, we determined 1) the age at first mating; 2) diel rhythm of matings; 3) number of matings over 7 d; 4) the sequence of D. speciosa activities during premating, mating, and postmating; 5) the duration of each activity; and 6) response to male and female conspecific volatiles in Y-tube olfactometer. The first mating occurred between the third and seventh day after adult emergence and the majority of pairs mated on the fourth day after emergence. Pairs of D. speciosa showed a daily rhythm of mating with greater sexual activity between the end of the photophase and the first half of the scotophase. During the 7 d of observation, most pairs mated only once, although 30% mated two, three, or four times. In a Y-tube olfactometer, males were attracted by virgin females as well as by the volatile compounds emitted by females. Neither males nor their volatiles were attractive to either sex. Our observation provide information about mating behavior of D. speciosa, which will be useful in future research in chemical communication, such as identification of the pheromone and development of management techniques for this species using pheromone traps. PMID:22732614

  12. 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...

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

    PubMed

    Derunkov, A; Konstantinov, A

    2013-01-01

    The following new synonyms in Diabrotica Chevrolat 1836 are proposed: D.flaviventris Jacoby 1887 and D. tibialis Jacoby 1887 are synonyms of D. adelpha Harold 1875; D. peckii Bowditch 1911 is a synonym of D. bioculata Bowditch 1911; D. nummularis Harold 1877 is a synonym of D. circulata Harold 1875; D. linensis Bechyné 1956 is a synonym of D. trifurcata Jacoby 1887; D. brunneosignata Jacoby 1887 is a synonym of D. sinuata Olivier 1790; D. duplicata Jacoby 1887 is a synonym of D. viridifasciata Jacoby 1887. Diabrotica cyaneomaculata Jacoby 1887 does not share the synapomorphies of Diabrotica and is treated as incertae sedis. Diabrotica tripunctata (Fabricius) is removed from synonymy with D. sinuata Olivier and is considered to be a valid species. The original combination is restored for Diabroticafasciata Kirsch, the species being transferred from Paranapiacaba Bechyné back to Diabrotica. It was found that the type series of D. godmani Jacoby contains seven different taxa: one is D. godmani itself; one is D. championi Jacoby; one is D. quadricollis Jacoby; three are unidentified Diabrotica species, each different from the others; and one is not a Diabrotica. The type series of D. viridicollis Jacoby contains four different taxa, D. viridicollis Jacoby itself and three different unidentified Diabrotica species. PMID:26473221

  14. Utility of morphological and molecular techniques for determination of paternity in two subspecies of Diabrotica undecimpunctata (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An experiment was conducted to determine the paternity of F1 progeny using morphological and molecular methods in Diabrotica (Coleoptera: Chrysomelidae) subspecies: Diabrotica undecimpunctata howardi Barber, also known as spotted cucumber beetle and D. undecimpunctata undecimpunctata Mannerheim, als...

  15. 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

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

    PubMed

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

    2015-01-01

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

  17. Interactions of alternate hosts, post-emergence grass control, and rootworm-resistant transgenic corn on western corn rootworm (Coleoptera: Chrysomelidae) damage and adult emergence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field studies were conducted in 2003 and 2004 to determine the effects of grassy weeds, post-emergence grass control, transgenic rootworm-resistant corn expressing the Cry3Bb1 endotoxin and glyphosate herbicide tolerance (Bt corn), and the interactions of these factors on western corn rootworm, Diab...

  18. Use of transgenic plants to measure insect herbivore movement.

    PubMed

    Spencer, Joseph L; Mabry, Timothy R; Vaughn, Ty T

    2003-12-01

    Use of ingested transgenic corn tissue as a marker for measuring movement of adult Diabrotica virgifera virgifera (LeConte) (Coleoptera: Chrysomelidae; western corn rootworm) was investigated. Laboratory observations of beetles feeding on corn foliage, pollen, silks, or soybean foliage provided background on feeding patterns. The interval between food consumption and its appearance in feces (gut passage time) ranged from 102.7 +/- 11 min for soybean foliage to 56.7 +/- 2.9 min for corn silks. In a laboratory assay, protein expression tests identified the presence of Cry3Bb1 protein inside 50% of adult D. virgifera for up to 16 h after they had last consumed Cry3Bb1 protein-expressing corn silks from 'YieldGard Rootworm' corn plants (Monsanto Co.). Cry3Bb1 protein could not be detected by 32 h postfeeding. The proportion of Cry3Bb1 protein-positive beetles declined linearly with increasing time since feeding on 'YieldGard Rootworm' tissue. Approximately 20% of adult D. virgifera collected near 'YieldGard Rootworm' corn plots tested positive for Cry3Bb1 protein, indicating 'YieldGard Rootworm' tissue consumption within the last 16-32 h. Based on a 16- to 32-h postfeeding detection interval for Cry3Bb1 protein and the distance between 'YieldGard Rootworm' sources and sites where Cry3Bb1-positive insects were collected, 85.3% of males and females moved < or = 4.6-9.1 m/d through R2-R3 stage corn. Among Cry3Bb1-positive adults that left corn and were captured in an adjacent soybean field, 86.4% of males and 93.1% of females moved < or = 4.6-9.1 m/d through soybean. Detection of transgenic plant tissues in mobile insect herbivores is a novel application of biotechnology to the study of insect movement. PMID:14977111

  19. Azalea's Worst Nightmare: The Strawberry Rootworm, Paria fargariae Wilcox

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The strawberry rootworm (SRW), Paria fargariae Wilcox, is an emergent pest of azaleas in commercial production nurseries in the southeastern US. Larvae feed on roots but do minimal damage. Adults feed at night and make small holes in the foliage. Severe damage has been reported in many nurseries, es...

  20. 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...

  1. Biology and Genetics of the Strawberry Rootworm, Paria fragariae Wilcox

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The strawberry rootworm, Paria fragariae, is an emergent pest of ornamental nurseries in the southeastern US attacking a widening range of woody ornamentals. Conflicting observations regarding the biology and morphology of this insect have led us to believe that sub-species of Paria may exist in thi...

  2. Binary insecticidal crystal protein from Bacillus thuringiensis, strain PS149B1: effects of individual protein components and mixtures in laboratory bioassays.

    PubMed

    Herman, Rod A; Scherer, Peter N; Young, Debra L; Mihaliak, Charles A; Meade, Thomas; Woodsworth, Aaron T; Stockhoff, Brian A; Narva, Kenneth E

    2002-06-01

    A family of novel binary insecticidal crystal proteins, with activity against western corn rootworm, Diabrotica virgifera virgifera LeConte, was identified from Bacillus thuringiensis Berliner. A binary insecticidal crystal protein (bICP) from B. thuringiensis strain PS149B1 is composed of a 14-kDa protein (Cry34Abl) and a 44-kDaprotein (Cry35Ab1). These proteins have been co-expressed in transgenic maize plants, Zea mays L., and effectively control western corn rootworm larvae under field conditions. Laboratory experiments were conducted to better understand the contribution of each component protein to the in vivo activity of the bICP. The 14-kDa protein is active alone against southern corn rootworm, Diabrotica undecimpunctata howardi Barber, and was synergized by the 44-kDa protein. In mixtures, the concentration of the 14-kDa protein had a greater impact on efficacy than the 44-kDa component. Although both proteins are clearly required for maximal insecticidal activity, laboratory results did not support the formation of a stable, fixed-ratio complex of the two component proteins. PMID:12076012

  3. 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...

  4. Allozyme gene diversities in some leaf beetles (Coleoptera: Chrysomelidae).

    PubMed

    Krafsur, E S

    1999-08-01

    Gene diversity at allozyme loci was investigated in the bean leaf beetle, Ceratoma trifurcata Forster; the elm leaf beetle, Xanthogaleruca luteola (Muller); the cottonwood leaf beetle, Chrysomela scripta Fabricus; the western corn rootworm, Diabrotica virgifera virgifera LeConte; the southern corn rootworm, also called the spotted cucumber beetle, D. undecimpunctata howardi Baker; the northern corn rootworm, D. barberi Smith and Lawrence; and the Colorado potato beetle, Leptinotarsa decemlineata (Say). Six of these species are economically important pests of crops and display adaptive traits that may correlate with genetic diversity. Gene diversity H(E) in bean leaf beetles was 17.7 +/- 4.0% among 32 loci. In western corn rootworms, H(E) = 4.8 +/- 2.0% among 36 loci, and in spotted cucumber beetles, H(E) = 11.9 +/- 2.7% among 39 loci. Diversity among 27 loci was 10.5 +/- 4.3% in the Colorado potato beetle. The data were compared with gene diversity estimates from other leaf beetle species in which heterozygosities varied from 0.3 to 21% and no correlation was detected among heterozygosities, geographic ranges, or population densities. Distributions of single-locus heterozygosities were consistent with selective neutrality of alleles. PMID:10624512

  5. 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

  6. Initial Larval Feeding on an Alternate Host Enhances Western Corn Rootworm (Coleoptera: Chrysomelidae) Beetle Emergence on Cry3Bb1-Expressing Maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential for rootworm larvae to move between grassy weeds and transgenic maize may be important in resistance management of transgenic rootworm-resistant maize. To determine the impact of initial feeding of rootworm larvae on alternate hosts, followed by switching host to transgenic maize, on ...

  7. Rapid digestion of Cry34Ab1 and Cry35Ab1 in simulated gastric fluid.

    PubMed

    Herman, Rod A; Schafer, Barry W; Korjagin, Valerie A; Ernest, April D

    2003-11-01

    Two genes were identified in Bacillus thuringiensis Berliner (Bt) that code for the proteins that comprise a Cry34Ab1/Cry35Ab1 binary insecticidal crystal protein. Maize, Zea mays L., plants have been transformed to express the Cry34Ab1/Cry35Ab1 proteins, and as a result, these plants are resistant to attack by western corn rootworm, Diabrotica virgifera virgifera LeConte, a major pest in the Midwestern corn-growing area of the U.S.A. As part of the safety assessment for the proteins, digestibility studies were conducted. Digestion experiments with both proteins demonstrated rapid degradation in simulated gastric fluid, comparable to other registered plant-incorporated protectants. Quantitative and qualitative approaches for determining digestibility are illustrated. PMID:14582981

  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. Registration of the maize germplasm CRW3(S1)C6 with resistance to western corn rootworm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize germplasm CRW3(S1)C6 is a synthetic population developed with resistance to western corn rootworm (WCR) by the USDA-ARS Plant Genetics Research Unit in cooperation with the Missouri Agricultural Experiment Station at the University of Missouri-Columbia. The corn rootworm is one of the most se...

  13. Behavioral responses of western corn rootworm larvae to naturally occurring and synthetic hydroxamic acids.

    PubMed

    Xie, Y; Arnason, J T; Philogéne, B J; Atkinson, J; Morand, P

    1992-07-01

    Hydroxamic acids have been shown to be toxic to many pest insects and pathogens. In this study, the behavioral responses of western corn rootworm larvae to naturally occurring and synthetic hydroxamic acids were investigated. In a choice test between corn roots treated with hydroxamic acids and roots treated with distilled water (control), western corn rootworm larvae chose to burrow into the control roots significantly more often than compoundtreated roots. In addition, when corn roots were treated with different hydroxamic acids in a designed searching-behavior test, neonate larvae of western corn rootworm responded by significantly reducing the number of turns, while the area searched and locomotor rate significantly increased. The responses were dependent on the concentrations of the test compounds. These results suggested that hydroxamic acids were acting as behavior-modifying and possibly feeding-deterrent chemicals. PMID:24254140

  14. 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. PMID:24639498

  15. 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

  16. 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

  17. Convergent evolution of cucurbitacin feeding in spatially isolated rootworm taxa (Coleoptera: Chrysomelidae; Galerucinae, Luperini).

    PubMed

    Gillespie, Joseph J; Kjer, Karl M; Duckett, Catherine N; Tallamy, Douglas W

    2003-10-01

    Historically, chemical ecologists assumed that cucurbitacin feeding and sequestration in rootworm leaf beetles is a remnant of an ancient association between the Luperini (Coleoptera: Chrysomelidae; Galerucinae) and Cucurbitaceae (ancestral host hypothesis). Under this premise, rootworms that do not develop on cucurbits but undergo pharmacophagous forays for cucurbitacins are thought to do so to supplement novel host diets that lack these bitter compounds. The ancestral host hypothesis is supported from studies of pyrrolizidine alkaloid pharmacophagy in Lepidoptera but has not been subjected to phylogenetic analysis within the Luperini. New evidence that this feeding behavior is better correlated with an adult affinity for pollen than with larval host offers the possibility that Old and New World rootworm species with an affinity for cucurbitacins converged on this behavior through apomorphic taste receptor modifications (loose receptor hypothesis). Here we test the monophyly of cucurbitacin feeding within the Luperini by using nuclear and mitochondrial sequence data to infer phylogenetic relationships among 49 taxa representing tribes of the Galerucinae and subtribes of the Luperini. The resulting phylogenetic hypothesis is mostly concordant with existing tribal and subtribal delineations within the Subfamily Galerucinae sensu stricto (Galerucinae not including the flea beetles). The establishment of ancestry among the subtribes of the Luperini refutes the monophyly of cucurbitacin feeding and cucurbit specialization, with the New World Diabroticina being paraphyletic to the Old World Aulacophorina and cosmopolitan Luperina. These data unambiguously support the convergent evolution of cucurbitacin feeding in rootworms and are inconsistent with the ancestral host hypothesis. PMID:12967617

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  19. Screening of botanical compounds 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...

  20. Tracking predation of subterranean pests: digestion of corn rootworm DNA by a generalist mite

    Technology Transfer Automated Retrieval System (TEKTRAN)

    qPCR is a useful tool for understanding predator-prey relationships. We investigated rootworm DNA digestion by male and female predatory mites. Males and females initially consumed comparable amounts of DNA, which was digested at similar rates. Field-collected mites need to be preserved quickly for ...

  1. 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

  2. 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

  3. Effects of Pesta-Pelletized Steinernema carpocapsae (All) on Western Corn Rootworms and Colorado Potato Beetles.

    PubMed

    Nickle, W R; Connick, W J; Cantelo, W W

    1994-06-01

    Pesta-pelletized Steinernema carpocapsae (All) nematodes were used in soil treatments in the greenhouse against larvae of Western corn rootworm and prepupae of Colorado potato beetle. The pesta-pellets delivered 100,000 living nematodes/g. Infective-stage nematodes and their associated bacteria survived the pesta-pellet process, emerged from the pellets in large numbers in the soil, and reduced adult emergence of both pest insects by more than 90%. PMID:19279889

  4. 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

  5. Inhibition of Diabrotica Larval Growth by Patatin, the Lipid Acyl Hydrolase from Potato Tubers.

    PubMed Central

    Strickland, J. A.; Orr, G. L.; Walsh, T. A.

    1995-01-01

    Patatin, the nonspecific lipid acyl hydrolase from potato (Solanum tuberosum L.) tubers, dose-dependently inhibits the growth of southern corn rootworm (SCR) and western corn rootworm when fed to them on artificial diet. The 50% growth reduction levels are somewhat cultivar dependent, ranging from 60 to 150 [mu]g/g diet for neonate SCR larvae. A single patatin isoform also inhibits larval growth. Neonate SCR continuously exposed to patatin are halted in larval development. Treatment with di-isopropylfluorophosphate essentially eliminates patatin's phospholipase, galactolipase, and acyl hydrolase activities. SCR growth inhibition is eliminated also, indicating that patatin's serine hydrolase activity is responsible for the observed activities. Patatin-mediated phospholipolysis is highly pH and cultivar dependent, with specific activities up to 300-fold less at pH 5.5 than at pH 8.5. Esterase or phospholipase activities do not correlate with insect growth inhibition. Galactolipase activity, being cultivar and pH independent, correlates significantly with SCR growth inhibition. Insect-growth inhibition of patatin is significantly reduced with increased dietary cholesterol levels. In conclusion, patatin represents a new class of insect-control proteins with a novel mode of action possibly involving lipid metabolism. PMID:12228621

  6. Inhibition of Diabrotica Larval Growth by Patatin, the Lipid Acyl Hydrolase from Potato Tubers.

    PubMed

    Strickland, J. A.; Orr, G. L.; Walsh, T. A.

    1995-10-01

    Patatin, the nonspecific lipid acyl hydrolase from potato (Solanum tuberosum L.) tubers, dose-dependently inhibits the growth of southern corn rootworm (SCR) and western corn rootworm when fed to them on artificial diet. The 50% growth reduction levels are somewhat cultivar dependent, ranging from 60 to 150 [mu]g/g diet for neonate SCR larvae. A single patatin isoform also inhibits larval growth. Neonate SCR continuously exposed to patatin are halted in larval development. Treatment with di-isopropylfluorophosphate essentially eliminates patatin's phospholipase, galactolipase, and acyl hydrolase activities. SCR growth inhibition is eliminated also, indicating that patatin's serine hydrolase activity is responsible for the observed activities. Patatin-mediated phospholipolysis is highly pH and cultivar dependent, with specific activities up to 300-fold less at pH 5.5 than at pH 8.5. Esterase or phospholipase activities do not correlate with insect growth inhibition. Galactolipase activity, being cultivar and pH independent, correlates significantly with SCR growth inhibition. Insect-growth inhibition of patatin is significantly reduced with increased dietary cholesterol levels. In conclusion, patatin represents a new class of insect-control proteins with a novel mode of action possibly involving lipid metabolism. PMID:12228621

  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. PMID:26361852

  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. PMID:26011006

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

    SciTech Connect

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

    1986-08-01

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

  11. Isolation of corn semiochemicals attractive and repellent to western corn rootworm larvae.

    PubMed

    Hibbard, B E; Bjostad, L B

    1990-12-01

    Dichloromethane extracts of germinating corn are significantly attractive to western corn rootworm larvae in choice tests with equal levels of carbon dioxide present on both sides of the choice. Two fractions that are significantly attractive and two fractions that are significantly repellent to larvae were isolated from these extracts of germinating corn by gas chromatography and silica gel chromatography. In a separate set of experiments, Porapak N was used to collect headspace volatiles from germinating corn; significantly more larvae were attracted to aliquots of these extracts in singlechoice tests without added carbon dioxide present than to solvent controls. PMID:24263439

  12. Female fecundity and longevity in Northern Corn Rootworm (Coleoptera: Chrysomelidae) in relation to multiple mating and body size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A single mating generally supplies female insects with enough sperm to fertilize a lifetime of eggs; however, many females mate repeatedly during their lifetime. It is believed that female northern corn rootworm mate only once in their lifetime. We paired combinations of large, small, and average si...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  14. MOVEMENT OF NORTHERN CORN ROOTWORMS IN RELATION TO SEX, SIZE, AND REPRODUCTIVE STATUS IN THE SOUTH DAKOTA AREAWIDE MANAGEMENT SITE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn rootworms are economically important pests of maize. Farmers may soon be able to plant Bt maize to reduce CRW populations. One concern is that resistance to the Bt toxin could quickly evolve. Gene flow among resistant and susceptible populations may reduce resistance evolution. Dispersal is...

  15. 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

  16. 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

  17. 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.

  18. Inhibition of seed germination by extracts of bitter Hawkesbury watermelon containing cucurbitacin, a feeding stimulant for corn rootworm (Coleoptera: Chrysomelidae).

    PubMed

    Martin, Phyllis A W; Blackburn, Michael

    2003-04-01

    Cucurbitacins are feeding stimulants for corn rootworm used in baits to control the adults of this insect pest. Corn rootworm larvae also feed compulsively on cucurbitacins. Cucurbitacins are reported to be gibberellin antagonists that may preclude their use as seed treatments for these soil-dwelling insects. The crude extract of a bitter Hawkesbury watermelon containing cucurbitacin E-glycoside significantly inhibited germination of watermelon, squash, and tomato seeds. Although the germination of corn seed was not significantly inhibited, root elongation was inhibited by crude extracts, but not by high-performance liquid chromatography-purified cucurbitacin E-glycoside. Therefore, the effects of the major components in the bitter watermelon extract (e.g., sugars) on seed germination and root elongation were determined. Pure sugars (glucose and fructose), at concentrations found in watermelon extract, mimicked the inhibition of seed germination and root elongation seen with the crude bitter Hawkesbury watermelon extract. Removal of these sugars may be necessary to use this extract as a bait for corn rootworm larvae as a seed or root treatment. PMID:14994812

  19. 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.

  20. Estimation of the dispersal of a major pest of maize by cline analysis of a temporary contact zone between two invasive outbreaks.

    PubMed

    Bermond, Gérald; Blin, Aurélie; Vercken, Elodie; Ravigné, Virginie; Rieux, Adrien; Mallez, Sophie; Morel-Journel, Thibaut; Guillemaud, Thomas

    2013-11-01

    Dispersal is a key factor in invasion and in the persistence and evolution of species. Despite the importance of estimates of dispersal distance, dispersal measurement remains a real methodological challenge. In this study, we characterized dispersal by exploiting a specific case of biological invasion, in which multiple introductions in disconnected areas lead to secondary contact between two differentiated expanding outbreaks. By applying cline theory to this ecological setting, we estimated σ, the standard deviation of the parent-offspring distance distribution, of the western corn rootworm, Diabrotica virgifera virgifera, one of the most destructive pests of maize. This species is currently invading Europe, and the two largest invasive outbreaks, in northern Italy and Central Europe, have recently formed a secondary contact zone in northern Italy. We identified vanishing clines at 12 microsatellite loci throughout the contact zone. By analysing both the rate of change of cline slope and the spatial variation of linkage disequilibrium at these markers, we obtained two σ estimates of about 20 km/generation(1/2). Simulations indicated that these estimates were robust to changes in dispersal kernels and differences in population density between the two outbreaks, despite a systematic weak bias. These estimates are consistent with the results of direct methods for measuring dispersal applied to the same species. We conclude that secondary contact resulting from multiple introductions is very useful for the inference of dispersal parameters and should be more widely used in other species. PMID:24118290

  1. 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. PMID:24407432

  2. Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms.

    PubMed

    Robert, Christelle A M; Ferrieri, Richard A; Schirmer, Stefanie; Babst, Benjamin A; Schueller, Michael J; Machado, Ricardo A R; Arce, Carla C M; Hibbard, Bruce E; Gershenzon, Jonathan; Turlings, Ted C J; Erb, Matthias

    2014-11-01

    Upon attack by leaf herbivores, many plants reallocate photoassimilates below ground. However, little is known about how plants respond when the roots themselves come under attack. We investigated induced resource allocation in maize plants that are infested by the larvae Western corn rootworm Diabrotica virgifera virgifera. Using radioactive (11) CO(2), we demonstrate that root-attacked maize plants allocate more new (11) C carbon from source leaves to stems, but not to roots. Reduced meristematic activity and reduced invertase activity in attacked maize root systems are identified as possible drivers of this shoot reallocation response. The increased allocation of photoassimilates to stems is shown to be associated with a marked thickening of these tissues and increased growth of stem-borne crown roots. A strong quantitative correlation between stem thickness and root regrowth across different watering levels suggests that retaining photoassimilates in the shoots may help root-attacked plants to compensate for the loss of belowground tissues. Taken together, our results indicate that induced tolerance may be an important strategy of plants to withstand belowground attack. Furthermore, root herbivore-induced carbon reallocation needs to be taken into account when studying plant-mediated interactions between herbivores. PMID:24762051

  3. 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

  4. 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. PMID:24328125

  5. 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

  6. 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....

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. Analysis of the Predator Community of a Subterranean Herbivorous Insect Based on Polymerase Chain Reaction

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using quantitative PCR and a novel pitfall trap design, we described the diel and seasonal activity patterns of the predator community in association with Diabrotica virgifera virgifera (WCR), generated a relative consumption index of WCR for the major predator operational taxonomic units (OTU), and...

  9. 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. PMID:18492601

  10. Synthesis of (6R,12R)-6,12-Dimethylpentadecan-2-one, the Female-Produced Sex Pheromone from Banded Cucumber Beetle Diabrotica balteata, Based on a Chiron Approach.

    PubMed

    Shen, Wei; Hao, Xiang; Shi, Yong; Tian, Wei-Sheng

    2015-12-01

    Herein we describe a synthesis of (6R,12R)-6,12-dimethylpentadecan-2-one (5), the female produced sex pheromone of banded cucumber beetle Diabrotica balteata Le Conte, from (R)-4-methyl-5-valerolactone, a methyl-branched chiron. PMID:26882689

  11. 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

  12. 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. PMID:24376437

  13. 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

  14. 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...

  15. 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

  16. Novel three-step pseudo-absence selection technique for improved species distribution modelling.

    PubMed

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

    2013-01-01

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

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

    PubMed

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

    2012-01-01

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

  18. Analysis of new aphid lethal paralysis virus (ALPV) isolates suggests evolution of two ALPV species.

    PubMed

    Liu, Sijun; Vijayendran, Diveena; Carrillo-Tripp, Jimena; Miller, W Allen; Bonning, Bryony C

    2014-12-01

    Aphid lethal paralysis virus (ALPV; family Dicistroviridae) was first isolated from the bird cherry-oat aphid, Rhopalosiphum padi. ALPV-like virus sequences have been reported from many insects and insect predators. We identified a new isolate of ALPV (ALPV-AP) from the pea aphid, Acyrthosiphon pisum, and a new isolate (ALPV-DvV) from western corn rootworm, Diabrotica virgifera virgifera. ALPV-AP has an ssRNA genome of 9940 nt. Based on phylogenetic analysis, ALPV-AP was closely related to ALPV-AM, an ALPV isolate from honeybees, Apis mellifera, in Spain and Brookings, SD, USA. The distinct evolutionary branches suggested the existence of two lineages of the ALPV virus. One consisted of ALPV-AP and ALPV-AM, whilst all other isolates of ALPV grouped into the other lineage. The similarity of ALPV-AP and ALPV-AM was up to 88 % at the RNA level, compared with 78-79 % between ALPV-AP and other ALPV isolates. The sequence identity of proteins between ALPV-AP and ALPV-AM was 98-99 % for both ORF1 and ORF2, whilst only 85-87 % for ORF1 and 91-92 % for ORF2 between ALPV-AP and other ALPV isolates. Sequencing of RACE (rapid amplification of cDNA ends) products and cDNA clones of the virus genome revealed sequence variation in the 5' UTRs and in ORF1, indicating that ALPV may be under strong selection pressure, which could have important biological implications for ALPV host range and infectivity. Our results indicated that ALPV-like viruses infect insects in the order Coleoptera, in addition to the orders Hemiptera and Hymenoptera, and we propose that ALPV isolates be classified as two separate viral species. PMID:25170050

  19. 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. PMID:25390338

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

    PubMed

    Wennemann, L; Hummel, H E

    2003-01-01

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

  1. 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

  2. Dissecting the mode of maize chlorotic mottle virus transmission (Tombusviridae: Machlomovirus) by Frankliniella williamsi (Thysanoptera: Thripidae).

    PubMed

    Cabanas, D; Watanabe, S; Higashi, C H V; Bressan, A

    2013-02-01

    Maize chlorotic mottle virus (MCMV) (Tombusviridae: Machlomovirus) has been recorded in Hawaii (Kauai Island) since the early 1990s and has since become one of the most widespread corn viruses in the Hawaiian Islands. In the United States Mainland, MCMV has been reported to be transmitted by six different species of chrysomelid beetles, including the western corn rootworm, Diabrotica virgifera virgifera LeConte. However, none of these beetle species have been reported in Hawaii where the corn thrips, Frankliniella williamsi Hood (Thysanoptera: Thripidae) has been identified to be the main vector. In this study, we developed leaf disk transmission assays and real time reverse transcription-polymerase chain reaction to examine the mode of MCMV transmission by the corn thrips. We showed that thrips transmitted the virus with no evidence for latent periods. Both larvae and adults transmitted the virus for up to 6 d after acquisition, with decreasing rates of transmission as time progressed. There was no evidence that adult thrips that acquired the virus as larvae were competent vectors. Real time reverse-transcription polomerase chain reaction assays showed that viral load was depleted from the vector's body after thrips had access to healthy plant tissue. Depletion of viral load was also observed when thrips matured from larvae to adults. Thrips were able to transmit MCMV after acquisition and inoculation access periods of 3 h. However, transmission efficiency increased with longer acquisition and inoculation access periods. Taken altogether our data suggests that corn thrips transmit MCMV in a semipersistent manner. To our knowledge, this is the first work reporting evidence of a plant virus transmitted semipersistently by thrips. PMID:23448010

  3. 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

  4. 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

  5. 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. PMID:11378139

  6. 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

  7. 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.

  8. 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

  9. 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

  10. Effect of corn hybrids expressing the coleopteran-specific cry3Bb1 protein for corn rootworm control on aboveground insect predators.

    PubMed

    Ahmad, Aqeel; Wilde, Gerald E; Whitworth, R Jeff; Zolnerowich, Gregory

    2006-08-01

    Field and laboratory studies were conducted to determine the effect of transgenic Bacillus thuringiensis (Bt) corn, Zea mays L. (YieldGard Rootworm), expressing the Cry3Bb1 protein on aboveground nontarget insect predators (minute pirate bug, ladybird beetles, and carabids). Visual counts of adult and immature Orius insidiosus (Say), Coleomegilla maculata (DeGeer), Hippodamia convergens Gurin-Meneville, and Scymnus spp. occurring in Bt corn and its non-Bt isoline were made at Manhattan, KS, in 2002 and at Manhattan and Scandia, KS, in 2003. No significant differences were found between the Bt corn and non-Bt isoline plots in the abundance (number per plant) of O. insidiosus, C. maculata, H. convergens, and Scymnus spp. Field predation on Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) egg masses was also observed during the silking stage of corn at Manhattan and Scandia in 2003. No significant differences were observed among treatments in predation rate for predators with chewing versus sucking mouthparts. Two laboratory studies determined the effect of Cry3Bb1 protein expressed in Bt corn pollen on C. maculata and carabids. The larvae of C. maculata were reared on Bt pollen, non-Bt pollen, or greenbugs, Schizaphis graminum (Rondani). The duration of larval and pupal stages, developmental time from egg hatch to adult emergence, percentage of survival, and elytra length were compared among treatments. There were no significant differences in developmental time of larvae fed pollen or greenbugs during their first two instars. However, significantly prolonged development of the third (1 d) and fourth instars (2 d) was observed for larvae fed greenbugs only. Total time for larval development was significantly longer for larvae that fed on greenbugs versus larvae fed on pollen. No significant differences were observed among treatments in the percentage of larvae that pupated or pupal stage duration. Larvae that fed on greenbugs had higher pupal and adult weights

  11. Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. Herbivore-induced plant volatiles mediate host selection by a root herbivore.

    PubMed

    Robert, Christelle A M; Erb, Matthias; Duployer, Marianne; Zwahlen, Claudia; Doyen, Gwladys R; Turlings, Ted C J

    2012-06-01

    In response to herbivore attack, plants mobilize chemical defenses and release distinct bouquets of volatiles. Aboveground herbivores are known to use changes in leaf volatile patterns to make foraging decisions, but it remains unclear whether belowground herbivores also use volatiles to select suitable host plants. We therefore investigated how above- and belowground infestation affects the performance of the root feeder Diabrotica virgifera virgifera, and whether the larvae of this specialized beetle are able to use volatile cues to assess from a distance whether a potential host plant is already under herbivore attack. Diabrotica virgifera larvae showed stronger growth on roots previously attacked by conspecific larvae, but performed more poorly on roots of plants whose leaves had been attacked by larvae of the moth Spodoptera littoralis. Fittingly, D. virgifera larvae were attracted to plants that were infested with conspecifics, whereas they avoided plants that were attacked by S. littoralis. We identified (E)-β-caryophyllene, which is induced by D. virgifera, and ethylene, which is suppressed by S. littoralis, as two signals used by D. virgifera larvae to locate plants that are most suitable for their development. Our study demonstrates that soil-dwelling insects can use herbivore-induced changes in root volatile emissions to identify suitable host plants. PMID:22486361

  13. A Review of the Natural Enemies of Beetles in the Subtribe Diabroticina (Coleoptera: Chrysomelidae): Implications for Sustainable Pest Management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabroticina is a speciose subtribe of New World Chrysomelidae (Subfamily Galerucinae: Tribe Luperini) that includes pests like corn rootworms, cucumber beetles and bean leaf beetles (e.g. Diabrotica, Acalymma, Cerotoma species). The evolution and spread of pesticide resistance, the European invasio...

  14. A comparison of the persistence in a clay loam of single and repeated annual applications of seven granular insecticides used for corn rootworm control.

    PubMed

    Harris, C R; Chapman, R A; Tolman, J H; Moy, P; Henning, K; Harris, C

    1988-02-01

    In May 1983, granular formulations of carbofuran, chlorpyrifos, disulfoton, fonofos, isofenphos, phorate, and terbufos were applied in incorporated bands to duplicate 2 m2 field plots of clay loam. Insecticide concentrations were determined in the bands at 0,1,2,3,4,6,8,10,12,16, and 20 wk. Following spring cultivation, the insecticides were applied to the same plots in 1984 and 1985. In addition, carbofuran was applied to previously untreated plots in 1984 and all 7 materials were applied to previously untreated plots in 1985. Sampling and analysis were carried out as in 1983. Persistence was assessed on the basis of the disappearance rates measured for the 1st 8 wk and of a calculated Effectiveness Potential (the ratio of the average residue in the upper 5 cm of the band at 8, 10 and 12 wk and the published LC95 for western corn rootworm in clay loam soil). Soils treated with carbofuran and isofenphos in 1984 and all soils treated in 1985 were tested for anti-insecticide activity. Soil cores from some carbofuran, chlorpyrifos and terbufos treated plots were sectioned vertically to establish the distribution of the insecticides during 1985. In addition, granular and pure chemical forms of isofenphos and carbofuran were applied at 10 ppm to anti-isofenphos and anti-carbofuran active and control soils (from field plots) maintained at 10 and 20% moisture in the laboratory to assess the effect of formulation and moisture on persistence in active soils. Insecticide concentrations were determined at 0,1,3,7, 10,14,21,28, and 35 days. The persistence of chlorpyrifos, terbufos and phorate was relatively constant over the 3 years and between plots receiving single and multiple treatments. Disulfoton and fonofos behavior was more variable and that of carbofuran and isofenphos was extremely variable. Anti-insecticide activity against carbofuran and isofenphos was detectable 2 wk after an initial application and was still present the following spring. Anti

  15. 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...

  16. Herbivory of maize by southern corn rootworm induces expression of the major intrinsic protein ZmNIP1;1 and leads to the discovery of a novel aquaporin ZmPIP2;8.

    PubMed

    Lawrence, Susan D; Novak, Nicole G; Xu, Hao; Cooke, Janice E K

    2013-08-01

    Aquaporins channel water and other neutral molecules through cell membranes. Aquaporin gene expression is subject to transcriptional control and can be modulated by factors affecting water balance such as salt, abscisic acid and drought. During infestation of maize by southern corn rootworm (SCR), an insect that chews into and significantly damages maize roots, three maize aquaporins were differentially expressed upon prolonged infestation. Using a brief infestation of maize roots ZmNIP1;1 transcript abundance again increased under infestation while expression of a new aquaporin, ZmPIP2;8 and ZmTIP2;2 expression did not change. Since ZmPIP2;8 has not been described previously, the deduced protein sequence was analyzed in silico and found to contain the hallmarks of plant aquaporins, with a predicted protein structure similar to other functionally characterized PIP2s. NIPs characterized to date have been implicated in facilitating the movement of a variety of small molecules, while TIPs and PIPs often have the capacity to facilitate trans-membrane movement of water. Functional assays (using heterologous expression in Xenopus laevis oocytes) of ZmTIP2;2 and ZmPIP2;8 confirmed that these aquaporins demonstrate water channel capacity. PMID:23673351

  17. 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

  18. 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

  19. 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

  20. Entomopathogenic nematodes in the European biocontrol market.

    PubMed

    Ehlers, R U

    2003-01-01

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

  1. 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

  2. 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.

  3. 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. PMID:26454117

  4. 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

  5. Indole as an olfactory synergist for volatile kairomones for diabroticite beetles.

    PubMed

    Metcalf, R L; Lampman, R L; Deem-Dickson, L

    1995-08-01

    Olfactory synergism, where combinations of plant volatile kairomones are quantitatively more attractive to insects than the sum of attraction of the individual components, is an important but little-studied phenomenon in host plant selection and feeding and in pollination ecology. Diabroticite beetles (Coleoptera: Chrysomelidae) are strongly attracted toCucurbita blossoms, and 2- to 3-fold olfactory synergism has been demonstrated in four species by combinations of the key blossom volatiles, 1,2,4-trimethoxybenzene, indole, and (E)-cinnamaldehyde. This TIC mixture represents an optimizedCurcurbita blossom volatile kairomone mixture useful in monitoring Diabroticite populations and in studying their behavior and ecology. Indole, which exhibits a spectrum of attraction to these beetles ranging from moderate forDiabrotica virgifera virgifera andAcalymma vittatum to very weak forD. barberi, is the primary synergistic component. Indole combined with 4-methoxycinnamaldehyde was significantly synergistic toD. v. virgifera at a ratio of 1:300 and produced 4-fold synergism at a ratio of 1:1. Indole combined with 4-methoxyphenethanol was less synergistic toD. barberi with 1.5- to 2-fold synergism at a 1:1 ratio. These consistent variations in diabroticite beetle olfactory responses presumably indicate evolutionary divergences in the numbers of relict indole antennal receptors. PMID:24234523

  6. Genetically engineered maize plants reveal distinct costs and benefits of constitutive volatile emissions in the field.

    PubMed

    Robert, Christelle Aurélie Maud; Erb, Matthias; Hiltpold, Ivan; Hibbard, Bruce Elliott; Gaillard, Mickaël David Philippe; Bilat, Julia; Degenhardt, Jörg; Cambet-Petit-Jean, Xavier; Turlings, Ted Christiaan Joannes; Zwahlen, Claudia

    2013-06-01

    Genetic manipulation of plant volatile emissions is a promising tool to enhance plant defences against herbivores. However, the potential costs associated with the manipulation of specific volatile synthase genes are unknown. Therefore, we investigated the physiological and ecological effects of transforming a maize line with a terpene synthase gene in field and laboratory assays, both above- and below ground. The transformation, which resulted in the constitutive emission of (E)-β-caryophyllene and α-humulene, was found to compromise seed germination, plant growth and yield. These physiological costs provide a possible explanation for the inducibility of an (E)-β-caryophyllene-synthase gene in wild and cultivated maize. The overexpression of the terpene synthase gene did not impair plant resistance nor volatile emission. However, constitutive terpenoid emission increased plant apparency to herbivores, including adults and larvae of the above ground pest Spodoptera frugiperda, resulting in an increase in leaf damage. Although terpenoid overproducing lines were also attractive to the specialist root herbivore Diabrotica virgifera virgifera below ground, they did not suffer more root damage in the field, possibly because of the enhanced attraction of entomopathogenic nematodes. Furthermore, fewer adults of the root herbivore Diabrotica undecimpunctata howardii were found to emerge near plants that emitted (E)-β-caryophyllene and α-humulene. Yet, overall, under the given field conditions, the costs of constitutive volatile production overshadowed its benefits. This study highlights the need for a thorough assessment of the physiological and ecological consequences of genetically engineering plant signals in the field to determine the potential of this approach for sustainable pest management strategies. PMID:23425633

  7. 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

  8. Belowground chemical signaling in maize: when simplicity rhymes with efficiency.

    PubMed

    Hiltpold, Ivan; Turlings, Ted C J

    2008-05-01

    Maize roots respond to feeding by larvae of the beetle Diabrotica virgifera virgifera by releasing (E)-beta-caryophyllene. This sesquiterpene, which is not found in healthy maize roots, attracts the entomopathogenic nematode Heterorhabditis megidis. In sharp contrast to the emission of virtually only this single compound by damaged roots, maize leaves emit a blend of numerous volatile organic compounds in response to herbivory. To try to explain this difference between roots and leaves, we studied the diffusion properties of various maize volatiles in sand and soil. The best diffusing compounds were found to be terpenes. Only one other sesquiterpene known for maize, alpha-copaene, diffused better than (E)-beta-caryophyllene, but biosynthesis of the former is far more costly for the plant than the latter. The diffusion of (E)-beta-caryophyllene occurs through the gaseous rather than the aqueous phase, as it was found to diffuse faster and further at low moisture level. However, a water layer is needed to prevent complete loss through vertical diffusion, as was found for totally dry sand. Hence, it appears that maize has adapted to emit a readily diffusing and cost-effective belowground signal from its insect-damaged roots. PMID:18443880

  9. Belowground ABA boosts aboveground production of DIMBOA and primes induction of chlorogenic acid in maize.

    PubMed

    Erb, Matthias; Gordon-Weeks, Ruth; Flors, Victor; Camañes, Gemma; Turlings, Ted C J; Ton, Jurriaan

    2009-07-01

    Plants are important mediators between above- and belowground herbivores. Consequently, interactions between root and shoot defenses can have far-reaching impacts on entire food webs. We recently reported that infestation of maize roots by larvae of the beetle Diabrotica virgifera virgifera induced shoot resistance against herbivores and pathogens. Root herbivory also enhanced aboveground DIMBOA and primed for enhanced induction of chlorogenic acid, two secondary metabolites that have been associated with plant stress resistance. Interestingly, the plant hormone abscisic acid (ABA) emerged as a putative long-distance signal in the regulation of these systemic defenses. In this addendum, we have investigated the role of root-derived ABA in aboveground regulation of DIMBOA and the phenolic compounds chlorogenic acid, caffeic and ferulic acid. Furthermore, we discuss the relevance of ABA in relation to defense against the leaf herbivore Spodoptera littoralis. Soil-drench treatment with ABA mimicked root herbivore-induced accumulation of DIMBOA in the leaves. Similarly, ABA mimicked aboveground priming of chlorogenic acid production, causing augmented induction of this compound after subsequent shoot attack by S. littoralis caterpillars. These findings confirm our notion that ABA acts as an important signal in the regulation of aboveground defenses during belowground herbivory. However, based on our previous finding that ABA alone is not sufficient to trigger aboveground resistance against S. littoralis caterpillars, our results also suggest that the ABA-inducible effects on DIMBOA and chlorogenic acid are not solely responsible for root herbivore-induced resistance against S. littoralis. PMID:19820311

  10. Utility of EST-derived SSRs as population genetics markers in a beetle.

    PubMed

    Kim, Kyung Seok; Ratcliffe, Susan T; French, B Wade; Liu, Lei; Sappington, Thomas W

    2008-01-01

    Microsatellite, or simple sequence repeat (SSR), loci can be identified by mining expressed sequence tag (EST) databases, and where these are available, marker development time and expense can be decreased considerably over conventional strategies of probing the entire genome. However, it is unclear whether they provide information on population structure similar to that generated by anonymous genomic SSRs. We performed comparative population genetic analyses between EST-derived SSRs (EST-SSRs) and anonymous SSRs developed from genomic DNA for the same set of populations of the insect Diabrotica virgifera, a beetle in the family Chrysomelidae. Compared with noncoding, nontranscribed regions, EST-SSRs were generally less polymorphic but had reduced occurrence of null alleles and greater cross-species amplification. Neutrality tests suggested the loci were not under positive selection. Across all populations and all loci, the genomic and EST-SSRs performed similarly in estimating genetic diversity, F(IS), F(ST), population assignment and exclusion tests, and detection of distinct populations. These findings, therefore, indicate that the EST-SSRs examined can be used with confidence in future genetic studies of Diabrotica populations and suggest that EST libraries can be added as a valuable source of markers for population genetics studies in insects and other animals. PMID:18222933

  11. The complete mitochondrial genome of Galeruca daurica (Joannis) (Coleoptera: Chrysomelidae).

    PubMed

    Zhou, Xiaorong; Han, Haibin; Pang, Baoping; Zhang, Pengfei

    2016-07-01

    Abstracts Galeruca daurica (Joannis) (Coleoptera: Chrysomelidae) is one of important pests in the Inner Mongolia grasslands. The complete mitochondrial genome was sequenced. The genome is 16 615 bp long, with an AT content of 78.1%, containing 37 typical animal mitochondrial genes and an AT-rich region. All 13 PCGs share the start codon ATN, and the usual termination codons (TAA and TAG) are found from 13 protein-coding genes, except for COI, COII, and ND4 (T). All the 22 typical animal tRNA genes are found in G. daurica mt-genome, and most of the tRNAs could be folded into the classic cloverleaf secondary structure except for tRNA-Ser (AGN), which lacks the dihydrouracil (DHU) stem. The sizes of the large ribosomal RNA genes are 1276 bp long and small ribosomal RNA genes are 747 bp long. The AT content of the AT-rich region is 79.0%. Phylogenetic analysis supports that the coleopteran insects from the same family cluster in the same group, and Chrysomelidae and Tenebrionidae are basal to the Cerambycidae. Galeruca daurica has a closest relationship with Diabrotica barberi and Diabrotica virgifera. PMID:26122336

  12. Effect of Cry3Bb transgenic corn and tefluthrin on the soil microbial community: biomass, activity, and diversity.

    PubMed

    Devare, M H; Jones, C M; Thies, J E

    2004-01-01

    Transgenic Bt corn expressing the Cry3Bb insecticidal protein active against corn rootworm (CRW) (Diabrotica spp.; Coleoptera: Chrysomelidae) was released for commercial use in 2003 and is expected to be widely adopted. Yet, the direct and indirect risks to soil microorganisms of growing this CRW-resistant Bt corn versus applying insecticides to control the rootworm have not been assessed under field conditions. The effects of CRW Bt corn and the insecticide tefluthrin [2,3,5,6-tetrafluoro-4-methylbenzyl (Z)-(1RS)-cis-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate] on soil microbial biomass, activity (N mineralization potential, short-term nitrification rate, and soil respiration), and bacterial community structure as determined by terminal restriction fragment length polymorphism (T-RFLP) analysis were assessed over two seasons in a field experiment. Bt corn had no deleterious effects on microbial activity or bacterial community measures compared with the non-transgenic isoline. The T-RFLP analysis indicated that amplifiable bacterial species composition and relative abundance differed substantially between years, but did not differ between rhizosphere and bulk soils. The application of tefluthrin also had no effect on any microbial measure except decreased soil respiration observed in tefluthrin-treated plots compared with Bt and non-transgenic isoline (NoBt) plots in 2002. Our results indicate that the release of CRW Bt corn poses little threat to the ecology of the soil microbial community based on parameters measured in this study. PMID:15224918

  13. Sexual Differences in the Basitarsae of Diabrotica and Cerotoma spp. (Coleoptera: Chrysomelidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabroticite beetles are economically important pests of North American agriculture. In the U. S., the most destructive of these beetles feed on maize, assorted cucurbits, and legumes. Many factors have contributed to renewed interest in their basic biology due to their invasiveness into new habitat...

  14. Survival and Growth of Diabrotica Balteata Larvae on Insect-Resistant Sweetpotato Genotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Production of sweetpotatoes is severely limited by several insect pests, and new pest management approaches for this crop are needed. A host plant resistance research program typically depends on reliable bioassay procedures to streamline evaluation of germplasm. Thus, a laboratory bioassay proced...

  15. 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. PMID:25218400

  16. Western corn rootworm larval movement in a SmartStax seed blend scenarios

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect resistance management (IRM) can extend the lifetime of management options, but depends on extensive knowledge of the biology of the pest species involved for an optimal plan. Recently, the Environmental Protection Agency (EPA) registered a seed blend refuge for two of the transgenic Bt corn ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  18. 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

  19. 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

  20. 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

  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. 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...

  3. Multiple mating, fecundity and longevity in female Northern Corn Rootworm (Coleoptera: Chrysomelidae) in relation to body size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In most insects, a single mating is usually sufficient to supply females with enough sperm to fertilize a lifetime production of eggs. Despite sufficient sperm, many female insects mate repeatedly in their lifetime. This may be due, in part, to having mated with a small male that did not supply enou...

  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. Rootworm Management with Genetically Modified Corn: Current Status, Potential for Resistance, and a Look Toward the Future

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 crop...

  6. Resistance to Bt corn by western corn rootworm (Coleoptera: Chrysomelidae) in the U.S. corn belt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Transgenic Bt corn hybrids that produce insecticidal proteins from the bacterium Bacillus thuringiensis Berliner have become the standard insect management tactic across the United States Corn Belt. Widespread planting of Bt corn creates intense selection pressure for target insects to develop resis...

  7. Effects of entomopathogens on mortality of western corn rootworm and fitness costs of resistance to Cry3Bb1 maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fitness costs can delay pest resistance to crops that produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) and past research has found that entomopathogens impose fitness costs of Bt resistance. Additionally, entomopathogens can be used for integrated pest management by...

  8. GROUND BEETLE OCCURRENCE IN ROTATED FIELDS OF BT CORN AND SOYBEAN IN THE SOUTH DAKOTA CORN ROOTWORM AREAWIDE SITE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground beetles are important generalist predators in agricultural landscapes. During 2000-2001 we placed 2 transects of pitfall traps in each of 4 fields of rotated lepidopteran Bt corn and soybean. Sampling was conducted on a weekly basis and traps remained open for a 2-day period. In 2000, we c...

  9. Microbial populations and enzyme activities in soil in situ under transgenic corn expressing cry proteins from Bacillus thuringiensis.

    PubMed

    Icoz, I; Saxena, D; Andow, D A; Zwahlen, C; Stotzky, G

    2008-01-01

    Transgenic Bt crops produce insecticidal Cry proteins that are released to soil in plant residues, root exudates, and pollen and that may affect soil microorganisms. As a continuation of studies in the laboratory and a plant-growth room, a field study was conducted at the Rosemount Experiment Station of the University of Minnesota. Three Bt corn varieties that express the Cry1Ab protein, which is toxic to the European corn borer (Ostrinia nubilalis Hübner), and one Bt corn variety that expresses the Cry3Bb1 protein, which is toxic to the corn rootworm complex (Diabrotica spp.), and their near-isogenic non-Bt varieties were evaluated for their effects on microbial diversity by classical dilution plating and molecular (polymerase chain reaction-denaturing gradient gel electrophoresis) techniques and for the activities of some enzymes (arylsulfatases, acid and alkaline phosphatases, dehydrogenases, and proteases) involved in the degradation of plant biomass. After 4 consecutive years of corn cultivation (2003-2006), there were, in general, no consistent statistically significant differences in the numbers of different groups of microorganisms, the activities of the enzymes, and the pH between soils planted with Bt and non-Bt corn. Numbers and types of microorganisms and enzyme activities differed with season and with the varieties of corn, but these differences were not related to the presence of the Cry proteins in soil. The Cry1Ab protein of Bt corn (events Bt11 and MON810) was detected in most soils during the 4 yr, whereas the Cry3Bb1 protein was not detected in soils of Bt corn (event MON863) expressing the cry3Bb1 gene. PMID:18396552

  10. Two novel strains of Bacillus thuringiensis toxic to coleopterans.

    PubMed Central

    Rupar, M J; Donovan, W P; Groat, R G; Slaney, A C; Mattison, J W; Johnson, T B; Charles, J F; Dumanoir, V C; de Barjac, H

    1991-01-01

    Two novel strains of Bacillus thuringiensis were isolated from native habitats by the use of genes coding for proteins toxic to coleopterans (cryIII genes) as hybridization probes. Strain EG2838 (isolated by the use of the cryIIIA probe) contained a cryIIIA-hybridizing plasmid of approximately 100 MDa and synthesized crystal proteins of approximately 200 (doublet), 74, 70, 32, and 28 kDa. Strain EG4961 (isolated by the use of a cryIIIA-related probe) contained a cryIIIA-hybridizing plasmid of approximately 95 MDa and synthesized crystal proteins of 74, 70, and 30 kDa. Structural relationships among the crystal proteins of strains EG2838 and EG4961 were detected; antibodies to the CryIIIA protein toxic to coleopterans reacted with the 74- and 70-kDa proteins of EG2838 and EG4961, antibodies to the 32-kDa plus 28-kDa proteins of EG2838 reacted with the 30-kDa protein of EG4961, and antibodies to the 200-kDa proteins of EG2838 reacted with the 28-kDa protein of EG2838. Experiments with B. thuringiensis flagella antibody reagents demonstrated that EG2838 belongs to H serotype 9 (reference strain B. thuringiensis subsp. tolworthi) and that EG4961 belongs to H serotype 18 (reference strain B. thuringiensis subsp. kumamotoensis). A mixture of spores plus crystal proteins of either EG2838 or EG4961 was toxic to the larvae of Colorado potato beetle (Leptinotarsa decemlineata), and significantly, the EG4961 mixture was also toxic to the larvae of southern corn rootworm (Diabrotica undecimpunctata howardi). DNA restriction blot analysis suggested that strains EG2838 and EG4961 each contained a unique gene coding for a protein toxic to coleopterans. Images PMID:1781691

  11. Two novel strains of Bacillus thuringiensis toxic to coleopterans.

    PubMed

    Rupar, M J; Donovan, W P; Groat, R G; Slaney, A C; Mattison, J W; Johnson, T B; Charles, J F; Dumanoir, V C; de Barjac, H

    1991-11-01

    Two novel strains of Bacillus thuringiensis were isolated from native habitats by the use of genes coding for proteins toxic to coleopterans (cryIII genes) as hybridization probes. Strain EG2838 (isolated by the use of the cryIIIA probe) contained a cryIIIA-hybridizing plasmid of approximately 100 MDa and synthesized crystal proteins of approximately 200 (doublet), 74, 70, 32, and 28 kDa. Strain EG4961 (isolated by the use of a cryIIIA-related probe) contained a cryIIIA-hybridizing plasmid of approximately 95 MDa and synthesized crystal proteins of 74, 70, and 30 kDa. Structural relationships among the crystal proteins of strains EG2838 and EG4961 were detected; antibodies to the CryIIIA protein toxic to coleopterans reacted with the 74- and 70-kDa proteins of EG2838 and EG4961, antibodies to the 32-kDa plus 28-kDa proteins of EG2838 reacted with the 30-kDa protein of EG4961, and antibodies to the 200-kDa proteins of EG2838 reacted with the 28-kDa protein of EG2838. Experiments with B. thuringiensis flagella antibody reagents demonstrated that EG2838 belongs to H serotype 9 (reference strain B. thuringiensis subsp. tolworthi) and that EG4961 belongs to H serotype 18 (reference strain B. thuringiensis subsp. kumamotoensis). A mixture of spores plus crystal proteins of either EG2838 or EG4961 was toxic to the larvae of Colorado potato beetle (Leptinotarsa decemlineata), and significantly, the EG4961 mixture was also toxic to the larvae of southern corn rootworm (Diabrotica undecimpunctata howardi). DNA restriction blot analysis suggested that strains EG2838 and EG4961 each contained a unique gene coding for a protein toxic to coleopterans. PMID:1781691

  12. 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...

  13. 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...

  14. 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).

  15. Western Corn Rootworm (Coleoptera: Chrysomelidae) Larval Movement in eCry3.1Ab1mCry3A 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 ...

  16. 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

  17. 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

  18. 78 FR 64211 - FIFRA Scientific Advisory Panel; Notice of Cancellation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-28

    ... Federal Register on August 9, 2013 (78 FR 48672, FRL-9394-3). This meeting will be rescheduled in the near... review scientific uncertainties associated with corn rootworm resistance monitoring for Bt corn...

  19. 78 FR 48672 - FIFRA Scientific Advisory Panel; Notice of Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-09

    ... meeting should have expertise in one or more of the following areas: Insect resistance to pesticides, Insect Resistance Management, Corn rootworm biology and ecology, Population sampling, Bioassay techniques (to assess insect susceptibility). Nominees should be scientists who have sufficient...

  20. Dichloromethane attracts diabroticite larvae in a laboratory behavioral bioassay.

    PubMed

    Jewett, D K; Bjostad, L B

    1996-07-01

    A two-choice laboratory behavioral bioassay was used to demonstrate that dichloromethane elicits the dose-dependent attraction of secondinstar western and southern corn rootworms. Preliminary data suggest that second-instar banded cucumber beetles are also attracted to dichloromethane. An eluotropic series of 10 materials, including distilled water, ethanol, methanol, acetone, ethyl dichloroacetate, dichloromethane, diethyl ether, benzene, hexadecane, and hexane, was tested for attraction of western corn rootworm larvae. Dichloromethane was the only one attractive at all doses tested, and orthogonal comparisons revealed a quadratic trend (convex) for responses of larvae to increasing dose. Benzene and hexadecane also attracted larvae, but significantly fewer than dichloromethane, and only at three doses and one dose, respectively. Orthogonal comparisons revealed no linear or quadratic trend for responses of larvae to increasing doses of either compound. Dichloromethane is the first organic compound demonstrated to attract western corn rootworm larvae in the absence of carbon dioxide. Carbon dioxide has previously been reported to attract western corn rootworm larvae either independently or when combined with other organic compounds, and the sensitivity of our bioassay was tested by demonstrating the dose-dependent attraction of western corn rootworm larvae to carbonated water as a carbon dioxide source. We have also demonstrated the attraction of southern corn rootworm larvae to carbon dioxide and propose that carbon dioxide and dichloromethane behave analogously when they interact with chemoreceptor sites on larvae. PMID:24226089

  1. 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,...

  2. 78 FR 68439 - FIFRA Scientific Advisory Panel; Notice of Rescheduled Public Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-14

    ... notice was published in the Federal Register on October 28, 2013 (78 FR 64211) (FRL-9902-06). All other information provided in the Federal Register on August 9, 2013 (78 FR 48672) (FRL-9394-3) remains unchanged...) to consider and review, Scientific Uncertainties Associated with Corn Rootworm Resistance...

  3. 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...

  4. Corn Insect Pests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Historically, the major corn insect pests have been corn rootworms (northern and western), European corn borer, and black cutworm. Bt-corn hybrids are effective against most of these pests. However, Bt-corn hybrids are not effective against corn leaf aphid, corn root aphid, sap beetles, corn rootwor...

  5. A critical evaluation of host ranges of parasitoids of the subtribe Diabroticina (Coleoptera: Chrysomelidae: Galerucinae: Luperini) using field and laboratory host records

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Diabroticina are a large group of American Chrysomelidae that include such pests as corn rootworms, cucumber beetles, and bean leaf beetles. Classical biocontrol has not been for these pests because they are mostly pests of crops under intensive pesticide use, and because they are native to thei...

  6. A new method for insect pest monitoring at the nursery

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The strawberry rootworm, Paria fragariae Wilcox (Coleoptera: Chrysomelidae), is a primary pest of azaleas and other containerized ornamental crops at production nurseries. The cryptic nature of all life stages of this pest can make detection and subsequent control a challenge. The intent of our re...

  7. Genetic Diversity Within and Between Nursery Populations of Paria Fragariae Species Complex and Implications for Insecticide Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The strawberry rootworm (SRW), Paria fragariae Wilcox, has been a growing pest of production nurseries in the southeastern United States since its introduction in the mid 1980's. The small beetle feeds nocturnally on evergreen azaleas and causes severe damage to the leaves which diminishes the marke...

  8. Restoring a maize root signal that attracts insect-killing nematodes to control a major pest

    PubMed Central

    Degenhardt, Jörg; Hiltpold, Ivan; Köllner, Tobias G.; Frey, Monika; Gierl, Alfons; Gershenzon, Jonathan; Hibbard, Bruce E.; Ellersieck, Mark R.; Turlings, Ted C. J.

    2009-01-01

    When attacked by herbivorous insects, plants emit volatile compounds that attract natural enemies of the insects. It has been proposed that these volatile signals can be manipulated to improve crop protection. Here, we demonstrate the full potential of this strategy by restoring the emission of a specific belowground signal emitted by insect-damaged maize roots. The western corn rootworm induces the roots of many maize varieties to emit (E)-β-caryophyllene, which attracts entomopathogenic nematodes that infect and kill the voracious root pest. However, most North American maize varieties have lost the ability to emit (E)-β-caryophyllene and may therefore receive little protection from the nematodes. To restore the signal, a nonemitting maize line was transformed with a (E)-β-caryophyllene synthase gene from oregano, resulting in constitutive emissions of this sesquiterpene. In rootworm-infested field plots in which nematodes were released, the (E)-β-caryophyllene-emitting plants suffered significantly less root damage and had 60% fewer adult beetles emerge than untransformed, nonemitting lines. This demonstration that plant volatile emissions can be manipulated to enhance the effectiveness of biological control agents opens the way for novel and ecologically sound strategies to fight a variety of insect pests. PMID:19666594

  9. 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. PMID:15612796

  10. Photorhabdus luminescens W-14 insecticidal activity consists of at least two similar but distinct proteins. Purification and characterization of toxin A and toxin B.

    PubMed

    Guo, L; Fatig, R O; Orr, G L; Schafer, B W; Strickland, J A; Sukhapinda, K; Woodsworth, A T; Petell, J K

    1999-04-01

    Both the bacterium Photorhabdus luminescens alone and its symbiotic Photorhabdus-nematode complex are known to be highly pathogenic to insects. The nature of the insecticidal activity of Photorhabdus bacteria was investigated for its potential application as an insect control agent. It was found that in the fermentation broth of P. luminescens strain W-14, at least two proteins, toxin A and toxin B, independently contributed to the oral insecticidal activity against Southern corn rootworm. Purified toxin A and toxin B exhibited single bands on native polyacrylamide gel electrophoresis and two peptides of 208 and 63 kDa on SDS-polyacrylamide gel electrophoresis. The native molecular weight of both the toxin A and toxin B was determined to be approximately 860 kDa, suggesting that they are tetrameric. NH2-terminal amino acid sequencing and Western analysis using monospecific antibodies to each toxin demonstrated that the two toxins were distinct but homologous. The oral potency (LD50) of toxin A and toxin B against Southern corn rootworm larvae was determined to be similar to that observed with highly potent Bt toxins against lepidopteran pests. In addition, it was found that the two peptides present in toxin B could be processed in vitro from a 281-kDa protoxin by endogenous P. luminescens proteases. Proteolytic processing was shown to enhance insecticidal activity. PMID:10092674

  11. Two wound-inducible soybean cysteine proteinase inhibitors have greater insect digestive proteinase inhibitory activities than a constitutive homolog.

    PubMed

    Zhao, Y; Botella, M A; Subramanian, L; Niu, X; Nielsen, S S; Bressan, R A; Hasegawa, P M

    1996-08-01

    Diverse functions for three soybean (Glycine max L. Merr.) cysteine proteinase inhibitors (CysPIs) are inferred from unique characteristics of differential regulation of gene expression and inhibitory activities against specific Cys proteinases. Based on northern blot analyses, we found that the expression in leaves of one soybean CysPI gene (L1) was constitutive and the other two (N2 and R1) were induced by wounding or methyl jasmonate treatment. Induction of N2 and R1 transcript levels in leaves occurred coincidentally with increased papain inhibitory activity. Analyses of kinetic data from bacterial recombinant CysPI proteins indicated that soybean CysPIs are noncompetitive inhibitors of papain. The inhibition constants against papain of the CysPIs encoded by the wound and methyl jasmonate-inducible genes (57 and 21 nM for N2 and R1, respectively) were 500 to 1000 times lower than the inhibition constant of L1 (19,000 nM). N2 and R1 had substantially greater inhibitory activities than L1 against gut cysteine proteinases of the third-instar larvae of western corn rootworm and Colorado potato beetle. Cysteine proteinases were the predominant digestive proteolytic enzymes in the guts of these insects at this developmental stage. N2 and R1 were more inhibitory than the epoxide trans-epoxysuccinyl-L-leucylamide-(4-guanidino)butane (E-64) against western corn rootworm gut proteinases (50% inhibition concentration = 50, 200, and 7000 nM for N2, R1, and E-64, respectively). However, N2 and R1 were less effective than E-64 against the gut proteinases of Colorado potato beetle. These results indicate that the wound-inducible soybean CysPIs, N2 and R1, function in host plant defense against insect predation, and that substantial variation in CysPI activity against insect digestive proteinases exists among plant CysPI proteins. PMID:8756506

  12. Two wound-inducible soybean cysteine proteinase inhibitors have greater insect digestive proteinase inhibitory activities than a constitutive homolog.

    PubMed Central

    Zhao, Y; Botella, M A; Subramanian, L; Niu, X; Nielsen, S S; Bressan, R A; Hasegawa, P M

    1996-01-01

    Diverse functions for three soybean (Glycine max L. Merr.) cysteine proteinase inhibitors (CysPIs) are inferred from unique characteristics of differential regulation of gene expression and inhibitory activities against specific Cys proteinases. Based on northern blot analyses, we found that the expression in leaves of one soybean CysPI gene (L1) was constitutive and the other two (N2 and R1) were induced by wounding or methyl jasmonate treatment. Induction of N2 and R1 transcript levels in leaves occurred coincidentally with increased papain inhibitory activity. Analyses of kinetic data from bacterial recombinant CysPI proteins indicated that soybean CysPIs are noncompetitive inhibitors of papain. The inhibition constants against papain of the CysPIs encoded by the wound and methyl jasmonate-inducible genes (57 and 21 nM for N2 and R1, respectively) were 500 to 1000 times lower than the inhibition constant of L1 (19,000 nM). N2 and R1 had substantially greater inhibitory activities than L1 against gut cysteine proteinases of the third-instar larvae of western corn rootworm and Colorado potato beetle. Cysteine proteinases were the predominant digestive proteolytic enzymes in the guts of these insects at this developmental stage. N2 and R1 were more inhibitory than the epoxide trans-epoxysuccinyl-L-leucylamide-(4-guanidino)butane (E-64) against western corn rootworm gut proteinases (50% inhibition concentration = 50, 200, and 7000 nM for N2, R1, and E-64, respectively). However, N2 and R1 were less effective than E-64 against the gut proteinases of Colorado potato beetle. These results indicate that the wound-inducible soybean CysPIs, N2 and R1, function in host plant defense against insect predation, and that substantial variation in CysPI activity against insect digestive proteinases exists among plant CysPI proteins. PMID:8756506

  13. 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

  14. 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

  15. Accumulation of terpenoid phytoalexins in maize roots is associated with drought tolerance.

    PubMed

    Vaughan, Martha M; Christensen, Shawn; Schmelz, Eric A; Huffaker, Alisa; McAuslane, Heather J; Alborn, Hans T; Romero, Maritza; Allen, Leon Hartwell; Teal, Peter E A

    2015-11-01

    Maize (Zea mays) production, which is of global agro-economic importance, is largely limited by herbivore pests, pathogens and environmental conditions, such as drought. Zealexins and kauralexins belong to two recently identified families of acidic terpenoid phytoalexins in maize that mediate defence against both pathogen and insect attacks in aboveground tissues. However, little is known about their function in belowground organs and their potential to counter abiotic stress. In this study, we show that zealexins and kauralexins accumulate in roots in response to both biotic and abiotic stress including, Diabrotica balteata herbivory, Fusarium verticillioides infection, drought and high salinity. We find that the quantity of drought-induced phytoalexins is positively correlated with the root-to-shoot ratio of different maize varieties, and further demonstrate that mutant an2 plants deficient in kauralexin production are more sensitive to drought. The induction of phytoalexins in response to drought is root specific and does not influence phytoalexin levels aboveground; however, the accumulation of phytoalexins in one tissue may influence the induction capacity of other tissues. PMID:25392907

  16. 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. PMID:21882695

  17. Cucurbitacins as kairomones for diabroticite beetles.

    PubMed

    Metcalf, R L; Metcalf, R A; Rhodes, A M

    1980-07-01

    The characteristic bitter substances of the Cucurbitaceae act as kairomones for a large group of diabroticite beetles (Chrysomelidae, Galerucinae, Luperini), promoting host selection and compulsive feeding behavior. These beetles (e.g., Diabrotica undecimpunctata howardi) respond to as little as 1 ng of cucurbitacin (Cuc) B on thin-layer plates by arrest and compulsive feeding. Six species of diabroticite beetles were about 10 times more responsive to Cuc B than to Cuc E and less responsive to Cuc D, I, and L. Chloroform extracts of 18 species of Cucurbita were developed on thin-layer chromatograms and exposed to diabroticite beetles. The feeding patterns showed pronounced beetle responses to three general Cuc distribution patterns: Cuc B and D as in Cucurbita andreana and C. ecuadorensis; Cuc E and I as in C. okeechobeensis and C. martinezii; and Cuc E glycoside in C. texana. All the diabroticites responded in exactly the same feeding patterns. The results demonstrate a coevolutionary association between the Cucurbitaceae and the Luperini, during which the intensely bitter and toxic Cucs that arose to repel herbivores and protect the plants from attack became specific kairomone feeding stimulants for the beetles. PMID:16592849

  18. Cucurbitacins as kairomones for diabroticite beetles

    PubMed Central

    Metcalf, Robert L.; Metcalf, Robert A.; Rhodes, A. M.

    1980-01-01

    The characteristic bitter substances of the Cucurbitaceae act as kairomones for a large group of diabroticite beetles (Chrysomelidae, Galerucinae, Luperini), promoting host selection and compulsive feeding behavior. These beetles (e.g., Diabrotica undecimpunctata howardi) respond to as little as 1 ng of cucurbitacin (Cuc) B on thin-layer plates by arrest and compulsive feeding. Six species of diabroticite beetles were about 10 times more responsive to Cuc B than to Cuc E and less responsive to Cuc D, I, and L. Chloroform extracts of 18 species of Cucurbita were developed on thin-layer chromatograms and exposed to diabroticite beetles. The feeding patterns showed pronounced beetle responses to three general Cuc distribution patterns: Cuc B and D as in Cucurbita andreana and C. ecuadorensis; Cuc E and I as in C. okeechobeensis and C. martinezii; and Cuc E glycoside in C. texana. All the diabroticites responded in exactly the same feeding patterns. The results demonstrate a coevolutionary association between the Cucurbitaceae and the Luperini, during which the intensely bitter and toxic Cucs that arose to repel herbivores and protect the plants from attack became specific kairomone feeding stimulants for the beetles. PMID:16592849

  19. 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

  20. Large scale production of Bacillus thuringiensis PS149B1 insecticidal proteins Cry34Ab1 and Cry35Ab1 from Pseudomonas fluorescens.

    PubMed

    Huang, Ke-Xue; Badger, Monty; Haney, Keith; Evans, Steve L

    2007-06-01

    The 14kDa (Cry34Ab1) and 44kDa (Cry35Ab1) binary insecticidal proteins are produced naturally by Bacillus thuringiensis PS149B1 as parasporal inclusion bodies. Here, we show production of these two insecticidal proteins in recombinant Pseudomonas fluorescens and their subsequent purification to near homogeneity to provide large quantities of protein for safety-assessment studies associated with the registration of transgenic corn plants. The gene sequence specific for each protein was expressed in P. fluorescens and fermented at the 75-L scale. For Cry34Ab1, the protein accumulated as insoluble inclusion bodies, and was purified by extraction directly from the cell pastes at pH 3.4 with a sodium acetate buffer, selective precipitation at pH 7.0, and differential centrifugation. For Cry35Ab1, the protein was extracted from the purified inclusion bodies with sodium acetate buffer (pH 3.5) containing 0.5M urea, followed by diafiltration. No chromatography steps were required to produce over 30g of lyophilized protein powder with purity greater than 98%, while retaining full insecticidal activity against Western corn rootworm larvae. The proteins were further characterized to assure identity and suitability for use in safety-assessment studies. PMID:17337206

  1. 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. PMID:17439144

  2. 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. PMID:23311749

  3. Relative densities of natural enemy and pest insects within California hedgerows.

    PubMed

    Gareau, Tara L Pisani; Letourneau, Deborah K; Shennan, Carol

    2013-08-01

    Research on hedgerow design for supporting communities of natural enemies for biological control lags behind farmer innovation in California, where assemblages of perennial plant species have been used on crop field margins in the last decade. We compared natural enemy to pest ratios between fields with hedgerows and fields with weedy margins by sampling beneficial insects and key pests of vegetables on sticky cards. We used biweekly vacuum samples to measure the distribution of key insect taxa among native perennial plant species with respect to the timing and intensity of bloom. Sticky cards indicated a trend that field margins with hedgerows support a higher ratio of natural enemies to pests compared with weedy borders. Hedgerow plant species hosted different relative densities of a generally overlapping insect community, and the timing and intensity of bloom only explained a small proportion of the variation in insect abundance at plant species and among hedgerows, with the exception of Orius spp. on Achillea millefolium L. and Baccharis pilularis De Candolle. Indicator Species Analysis showed an affinity of parasitic wasps, especially in the super-family Chalcidoidea, for B. pilularis whether or not it was in flower. A. millefolium was attractive to predatory and herbivorous homopterans; Heteromeles arbutifolia (Lindley) Roemer and B. pilularis to Diabrotica undecimpunctata undecimpunctata Mannerheim; and Rhamnus californica Eschsch to Hemerobiidae. Perennial hedgerows can be designed through species selection to support particular beneficial insect taxa, but plant resources beyond floral availability may be critical in providing structural refuges, alternative prey, and other attractive qualities that are often overlooked. PMID:23905731

  4. 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

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

    PubMed Central

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

    2015-01-01

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

  6. 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

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

    PubMed

    Rauschen, Stefan; Schaarschmidt, Frank; Gathmann, Achim

    2010-10-01

    Beetles (Coleoptera) are a diverse and ecologically important group of insects in agricultural systems. The Environmental Risk Assessment (ERA) of genetically modified Bt-crop varieties with insect resistances thus needs to consider and assess the potential negative impacts on non-target organisms belonging to this group. We analysed data gathered during 6 years of field-release experiments on the impact of two genetically modified Bt-maize varieties (Ostrinia-resistant MON810 and Diabrotica-resistant MON88017) on the occurrence and field densities of Coleoptera, especially the two families Coccinellidae and Chrysomelidae. Based on a statistical analysis aimed at establishing whether Bt-maize varieties are equivalent to their near-isogenic counterparts, we discuss the limitations of using field experiments to assess the effects of Bt-maize on these two beetle families. The densities of most of the beetle families recorded in the herb layer were very low in all growing seasons. Coccinellidae and Chrysomelidae were comparatively abundant and diverse, but still low in numbers. Based on their role as biological control agents, Coccinellidae should be a focus in the ERA of Bt-plants, but given the large natural variability in ladybird densities in the field, most questions need to be addressed in low-tier laboratory tests. Chrysomelidae should play a negligible role in the ERA of Bt-plants, since they occur on-crop as secondary pests only. Species occurring off-crop, however, can be addressed in a similar fashion as non-target Lepidoptera in Cry1Ab expressing Bt-maize. PMID:20012775

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

    PubMed Central

    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 Bacillus spp. 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

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

    PubMed

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

    2011-02-01

    Despite the rapid adoption of crops expressing the insecticidal Cry protein(s) from Bacillus thuringiensis (Bt), public concern continues to mount over the potential environmental impacts. Reduced residue decomposition rates and increased tissue lignin concentrations reported for some Bt corn hybrids have been highlighted recently as they may influence soil carbon dynamics. We assessed the effects of MON863 Bt corn, producing the Cry3Bb protein against the corn rootworm complex, on these aspects and associated decomposer communities by terminal restriction fragment length polymorphism (T-RFLP) analysis. Litterbags containing cobs, roots, or stalks plus leaves from Bt and unmodified corn with (non-Bt+I) or without (non-Bt) insecticide applied were placed on the soil surface and at a 10-cm depth in field plots planted with these crop treatments. The litterbags were recovered and analyzed after 3.5, 15.5, and 25 months. No significant effect of treatment (Bt, non-Bt, and non-Bt+I) was observed on initial tissue lignin concentrations, litter decomposition rate, or bacterial decomposer communities. The effect of treatment on fungal decomposer communities was minor, with only 1 of 16 comparisons yielding separation by treatment. Environmental factors (litterbag recovery year, litterbag placement, and plot history) led to significant differences for most measured variables. Combined, these results indicate that the differences detected were driven primarily by environmental factors rather than by any differences between the corn hybrids or the use of tefluthrin. We conclude that the Cry3Bb corn tested in this study is unlikely to affect carbon residence time or turnover in soils receiving these crop residues. PMID:21148693

  10. 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. PMID:16302741

  11. 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

  12. 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

  13. 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., Jr.; Skinner, Kenneth D.

    2012-01-01

    samples from all three study areas, but other pesticides were detected only in samples from Oahu, or only in samples from the Columbia Plateau and Snake River Plain. This is because some pesticides (such as atrazine) are broad-spectrum pesticides that are used on many crops in many different areas of the United States. Other pesticides (such as simazine, metribuzin, and metolachlor) are used on row crops (such as potatoes, barley, and alfalfa) grown in the Columbia Plateau and Snake River Plain, but not on pineapple or sugarcane grown in Oahu. Atrazine logistic-regression models indicate that areas with a high percentage of land in crops (such as potatoes or sugarcane), a low percentage of fallow land, and highly permeable soils with low amounts of organic matter are most likely to have atrazine detected in the groundwater. Areas where agricultural activities were absent had much lower probabilities of atrazine being detected. The Snake River Plain had a much higher probability of atrazine detections, with more than 50 percent of the land area having greater than a 50 percent probability of atrazine contamination. Oahu had a much lower probability of atrazine contamination, with only 24 percent of the land area having greater than a 50 percent probability of atrazine contamination. 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.