The Experts below are selected from a list of 1023 Experts worldwide ranked by ideXlab platform
Blair D Siegfried - One of the best experts on this subject based on the ideXlab platform.
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sublethal effects of vatpase a and snf7 dsrnas on biology of southern corn rootworm diabrotica undecimpunctata howardi barber
Journal of Economic Entomology, 2017Co-Authors: Adriano E Pereira, Lance J Meinke, Ana Maria Velez, Blair D SiegfriedAbstract:RNA interference is a powerful tool against corn rootworm. Adults and neonates of southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae), were exposed to the LC50 of vATPase-A and Snf7 double-stranded RNAs (dsRNAs), and the effects on female fecundity, egg viability, male fitness as measured by sperm viability and mating capacity, larval recovery along with dry weight, and instar determination 10 d after exposure to dsRNA, were determined. Significant reductions were observed for a number of parameters in dsRNA-exposed Rootworms relative to control treatments. Female fecundity and larval recovery were significantly reduced after exposure to both dsRNAs. In addition, larval dry weight and recovery of 2nd and 3rd instars along with dry weight for 3rd instars were significantly reduced after neonate exposure to vATPase-A dsRNA. Neither dsRNA affected male capacity to mate or sperm viability after exposure to the respective LC50s. After 10 d of feeding on untreated corn roots, neonates that survived exposure for 2 d to the vATPase-A dsRNA LC50 exhibited lower dry weight than the control. There was significant gene knockdown in adult males and females after exposure for 5 d to LC50 of vATPase-A and Snf7 dsRNAs. The parameters are discussed in terms of fitness and possible outcomes after deployment of corn hybrids expressing dsRNAs.
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parameters for successful parental rnai as an insect pest management tool in western corn rootworm diabrotica virgifera virgifera
Genes, 2016Co-Authors: Ana Maria Velez, Kenneth E Narva, Nicholas P Storer, Elane Fishilevich, Natalie Matz, Blair D SiegfriedAbstract:Parental RNAi (pRNAi) is an RNA interference response where the gene knockdown phenotype is observed in the progeny of the treated organism. pRNAi has been demonstrated in female western corn Rootworms (WCR) via diet applications and has been described as a potential approach for rootworm pest management. However, it is not clear if plant-expressed pRNAi can provide effective control of next generation WCR larvae in the field. In this study, we evaluated parameters required to generate a successful pRNAi response in WCR for the genes brahma and hunchback. The parameters tested included a concentration response, duration of the dsRNA exposure, timing of the dsRNA exposure with respect to the mating status in WCR females, and the effects of pRNAi on males. Results indicate that all of the above parameters affect the strength of pRNAi phenotype in females. Results are interpreted in terms of how this technology will perform in the field and the potential role for pRNAi in pest and resistance management strategies. More broadly, the described approaches enable examination of the dynamics of RNAi response in insects beyond pRNAi and crop pests.
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knockdown of rna interference pathway genes in western corn Rootworms diabrotica virgifera virgifera le conte demonstrates a possible mechanism of resistance to lethal dsrna
PLOS ONE, 2016Co-Authors: Ana Maria Velez, Kenneth E Narva, Chitvan Khajuria, Haichuan Wang, Blair D SiegfriedAbstract: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.
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parental rna interference of genes involved in embryonic development of the western corn rootworm diabrotica virgifera virgifera leconte
Insect Biochemistry and Molecular Biology, 2015Co-Authors: Chitvan Khajuria, Kenneth E Narva, Ana Maria Velez, Murugesan Rangasamy, Haichuan Wang, Elane Fishilevich, Meghan Frey, Newton Portilho Carneiro, Premchand Gandra, Blair D SiegfriedAbstract: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.
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transgenic approaches to western corn rootworm control
Advances in Biochemical Engineering \ Biotechnology, 2013Co-Authors: Kenneth E Narva, Blair D Siegfried, Nicholas P StorerAbstract: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. Open image in new window Graphical Abstract
William Kitching - One of the best experts on this subject based on the ideXlab platform.
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hydrolytic kinetic resolution of terminal mono and bis epoxides in the synthesis of insect pheromones routes to r and s 10 methyldodecyl acetate r 10 methyl 2 tridecanone r z undec 6 en 2 ol nostrenol 1r 7r 1 7 dimethylnonyl propanoate 6r 12r 6 12 dimethylpentadecan 2 one 2s 11s 2 11 diacetoxytridecane and 2s 12s 2 12 diacetoxytridecane
Tetrahedron-asymmetry, 2002Co-Authors: Sharon Chow, William KitchingAbstract:Hydrolytic kinetic resolution (HKR) of functionalised epoxides using (salen)Co(OAc) complexes provides enantiomerically enriched epoxides and diols, which have been transformed into important insect sex pheromones. In this general approach, (-)-(R)- and (+)-(S)-10-methyldodecyl acetates from the smaller tea tortrix moth were obtained, as was (-)-(R)-10-methyltridecan-2-one from the southern corn rootworm. The (S)-epoxide obtained from undec-1-en-6-yne was transformed to (-)-(R)-(Z)-undec-6-en-2-ol (Nostrenol) from ant-lions. HKR of appropriate bisepoxides was also investigated, and transformations of the resulting bisepoxides and epoxydiols provided (-)-(1R,7R)-1,7-dimethylnonylpropanoate from corn Rootworms, (-)-(6R,12R)-6,12-dimethylpentadecan-2-one from the female banded cucumber beetle, and (-)-(2S,11S)-2,11-diacetoxytridecane and (+)-(2S,12S)-2,12-diacetoxytridecane from female pea-midges. (C) 2002 Elsevier Science Ltd. All rights reserved.
Sharon Chow - One of the best experts on this subject based on the ideXlab platform.
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hydrolytic kinetic resolution of terminal mono and bis epoxides in the synthesis of insect pheromones routes to r and s 10 methyldodecyl acetate r 10 methyl 2 tridecanone r z undec 6 en 2 ol nostrenol 1r 7r 1 7 dimethylnonyl propanoate 6r 12r 6 12 dimethylpentadecan 2 one 2s 11s 2 11 diacetoxytridecane and 2s 12s 2 12 diacetoxytridecane
Tetrahedron-asymmetry, 2002Co-Authors: Sharon Chow, William KitchingAbstract:Hydrolytic kinetic resolution (HKR) of functionalised epoxides using (salen)Co(OAc) complexes provides enantiomerically enriched epoxides and diols, which have been transformed into important insect sex pheromones. In this general approach, (-)-(R)- and (+)-(S)-10-methyldodecyl acetates from the smaller tea tortrix moth were obtained, as was (-)-(R)-10-methyltridecan-2-one from the southern corn rootworm. The (S)-epoxide obtained from undec-1-en-6-yne was transformed to (-)-(R)-(Z)-undec-6-en-2-ol (Nostrenol) from ant-lions. HKR of appropriate bisepoxides was also investigated, and transformations of the resulting bisepoxides and epoxydiols provided (-)-(1R,7R)-1,7-dimethylnonylpropanoate from corn Rootworms, (-)-(6R,12R)-6,12-dimethylpentadecan-2-one from the female banded cucumber beetle, and (-)-(2S,11S)-2,11-diacetoxytridecane and (+)-(2S,12S)-2,12-diacetoxytridecane from female pea-midges. (C) 2002 Elsevier Science Ltd. All rights reserved.
Thomas W. Sappington - One of the best experts on this subject based on the ideXlab platform.
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Western corn rootworm ( Diabrotica virgifera virgifera LeConte) population dynamics
Agricultural and Forest Entomology, 2009Co-Authors: Lance J Meinke, Thomas W. Sappington, David W. Onstad, Thomas Guillemaud, Nicholas J. Miller, Judit Komáromi, Nora Levay, Lorenzo Furlan, Jozsef Kiss, Ferenc TothAbstract:1 The western corn rootworm Diabrotica virgifera virgifera LeConte is a major insect pest of field maize, Zea mays L. Larvae can cause substantial injury by feeding on maize roots. Larval feeding may destroy individual roots or root nodes, and reduce plant growth, stability, and yield. Costs associated with managing corn Rootworms in continuous maize are annually one of the largest expenditures for insect management in the United States Corn Belt. 2 Even though D. virgifera virgifera has been studied intensively for over 50 years, there is renewed interest in the biology, ecology, and genetics of this species because of its ability to rapidly adapt to management tactics, and its aggressive invasive nature. 3 This article provides a comprehensive review of D. virgifera virgifera population dynamics, specifically: diapause, larval and adult development, seasonality, spatial and temporal dynamics at local and landscape scales, invasiveness in North America and Europe, and non-trophic interactions with other arthropods. 4 Gaps in current knowledge are identified and discussed especially within the context of challenges that scientists in North America and Europe are currently facing regarding pest dynamics and the need to develop appropriate management strategies for each geographic area
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Polymorphic microsatellite loci from the western corn rootworm (Insecta: Coleoptera: Chrysomelidae) and cross-amplification with other Diabrotica spp
Molecular Ecology Notes, 2005Co-Authors: Kyung Seok Kim, Thomas W. SappingtonAbstract:Corn Rootworms (Diabrotica spp.) make up the major insect pest complex of corn in the US and Europe, and there is a need for molecular markers for genetics studies. We used an enrichment strategy to develop microsatellite markers from the western corn rootworm (Diabrotica virgifera virgifera). Of 54 loci isolated, 25 were polymorphic, and of these, 17 were surveyed for variability in 59 wild individuals. In addition, the potential for cross-amplification of these microsatellites was surveyed for Mexican, northern, and southern corn Rootworms. Nine microsatellite loci showed Mendelian inheritance and are likely to be useful in population genetics studies
Ana Maria Velez - One of the best experts on this subject based on the ideXlab platform.
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sublethal effects of vatpase a and snf7 dsrnas on biology of southern corn rootworm diabrotica undecimpunctata howardi barber
Journal of Economic Entomology, 2017Co-Authors: Adriano E Pereira, Lance J Meinke, Ana Maria Velez, Blair D SiegfriedAbstract:RNA interference is a powerful tool against corn rootworm. Adults and neonates of southern corn rootworm, Diabrotica undecimpunctata howardi Barber (Coleoptera: Chrysomelidae), were exposed to the LC50 of vATPase-A and Snf7 double-stranded RNAs (dsRNAs), and the effects on female fecundity, egg viability, male fitness as measured by sperm viability and mating capacity, larval recovery along with dry weight, and instar determination 10 d after exposure to dsRNA, were determined. Significant reductions were observed for a number of parameters in dsRNA-exposed Rootworms relative to control treatments. Female fecundity and larval recovery were significantly reduced after exposure to both dsRNAs. In addition, larval dry weight and recovery of 2nd and 3rd instars along with dry weight for 3rd instars were significantly reduced after neonate exposure to vATPase-A dsRNA. Neither dsRNA affected male capacity to mate or sperm viability after exposure to the respective LC50s. After 10 d of feeding on untreated corn roots, neonates that survived exposure for 2 d to the vATPase-A dsRNA LC50 exhibited lower dry weight than the control. There was significant gene knockdown in adult males and females after exposure for 5 d to LC50 of vATPase-A and Snf7 dsRNAs. The parameters are discussed in terms of fitness and possible outcomes after deployment of corn hybrids expressing dsRNAs.
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parameters for successful parental rnai as an insect pest management tool in western corn rootworm diabrotica virgifera virgifera
Genes, 2016Co-Authors: Ana Maria Velez, Kenneth E Narva, Nicholas P Storer, Elane Fishilevich, Natalie Matz, Blair D SiegfriedAbstract:Parental RNAi (pRNAi) is an RNA interference response where the gene knockdown phenotype is observed in the progeny of the treated organism. pRNAi has been demonstrated in female western corn Rootworms (WCR) via diet applications and has been described as a potential approach for rootworm pest management. However, it is not clear if plant-expressed pRNAi can provide effective control of next generation WCR larvae in the field. In this study, we evaluated parameters required to generate a successful pRNAi response in WCR for the genes brahma and hunchback. The parameters tested included a concentration response, duration of the dsRNA exposure, timing of the dsRNA exposure with respect to the mating status in WCR females, and the effects of pRNAi on males. Results indicate that all of the above parameters affect the strength of pRNAi phenotype in females. Results are interpreted in terms of how this technology will perform in the field and the potential role for pRNAi in pest and resistance management strategies. More broadly, the described approaches enable examination of the dynamics of RNAi response in insects beyond pRNAi and crop pests.
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knockdown of rna interference pathway genes in western corn Rootworms diabrotica virgifera virgifera le conte demonstrates a possible mechanism of resistance to lethal dsrna
PLOS ONE, 2016Co-Authors: Ana Maria Velez, Kenneth E Narva, Chitvan Khajuria, Haichuan Wang, Blair D SiegfriedAbstract: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.
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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
Insect Biochemistry and Molecular Biology, 2016Co-Authors: Elane Fishilevich, Ana Maria Velez, Chitvan Khajuria, Haichuan Wang, Meghan Frey, Ronda Hamm, Greg Schulenberg, Andrew J Bowling, Heather E Pence, Premchand GandraAbstract: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.
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parental rna interference of genes involved in embryonic development of the western corn rootworm diabrotica virgifera virgifera leconte
Insect Biochemistry and Molecular Biology, 2015Co-Authors: Chitvan Khajuria, Kenneth E Narva, Ana Maria Velez, Murugesan Rangasamy, Haichuan Wang, Elane Fishilevich, Meghan Frey, Newton Portilho Carneiro, Premchand Gandra, Blair D SiegfriedAbstract: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.
