Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 247

Full-Text Articles in Entire DC Network

Efficacy Of A Cry1ab Gene For Control Of Maruca Vitrata (Lepidoptera: Crambidae) In Cowpea (Fabales: Fabaceae), Prince C. Addae, Mohammad F. Ishiyaku, Jean-Batiste Tignegre, Malick N. Ba, Joseph B. Bationo, Ibrahim D. K. Atokple, Mumuni Abudulai, Clémentine L. Dabiré-Binso, Fousséni Traore, Mohammed Saba, Muhammed L. Umar, Gloria A. Adazebra, Francis N. Onyekachi, Margaret A. Nemeth, Joseph E. Huesing, Larry R. Beach, Thomas J. V. Higgins, Richard L. Hellmich, Barry R. Pittendrigh Jan 2020

Efficacy Of A Cry1ab Gene For Control Of Maruca Vitrata (Lepidoptera: Crambidae) In Cowpea (Fabales: Fabaceae), Prince C. Addae, Mohammad F. Ishiyaku, Jean-Batiste Tignegre, Malick N. Ba, Joseph B. Bationo, Ibrahim D. K. Atokple, Mumuni Abudulai, Clémentine L. Dabiré-Binso, Fousséni Traore, Mohammed Saba, Muhammed L. Umar, Gloria A. Adazebra, Francis N. Onyekachi, Margaret A. Nemeth, Joseph E. Huesing, Larry R. Beach, Thomas J. V. Higgins, Richard L. Hellmich, Barry R. Pittendrigh

Entomology Publications

Cowpea [Vigna unguiculata (L) Walp.] is an important staple legume in the diet of many households in sub-Saharan Africa. Its production, however, is negatively impacted by many insect pests including bean pod borer, Maruca vitrata F., which can cause 20–80% yield loss. Several genetically engineered cowpea events that contain a cry1Ab gene from Bacillus thuringiensis (Bt) for resistance against M. vitrata were evaluated in Nigeria, Burkina Faso, and Ghana (West Africa), where cowpea is commonly grown. As part of the regulatory safety package, these efficacy data were developed and evaluated by in-country scientists. The Bt-cowpea lines were planted in ...


Soybean Aphid Efficacy Screening Program, 2018, Erin W. Hodgson, Greg Vannostrand Jan 2019

Soybean Aphid Efficacy Screening Program, 2018, Erin W. Hodgson, Greg Vannostrand

Entomology Publications

Soybean aphid, Aphis glycines Matsumura, has drastically changed soybean pest management in the North Central region. To date, SBA can be successfully managed by timely scouting and foliar insecticides in Iowa, but pyrethroid resistance is an emerging issue in the North Central region. In 2018, we established plots at two Iowa State University Research Farms (Northeast and Northwest) on 22 May and 30 May, respectively. NK S24-K2 soybean variety was used for all plots. Plots were arranged in an RCB design with four replications. Each plot was six rows in width and 50 ft in length at the Northeast location ...


Toxicity Of Bacillus Thuringiensis-Derived Pesticidal Proteins Cry1ab And Cry1ba Against Asian Citrus Psyllid, Diaphorina Citri (Hemiptera), Maria Teresa Fernandez-Luna, Pavan Kumar, David G. Hall, Ashaki D. Mitchell, Michael B. Blackburn, Bryony C. Bonning Jan 2019

Toxicity Of Bacillus Thuringiensis-Derived Pesticidal Proteins Cry1ab And Cry1ba Against Asian Citrus Psyllid, Diaphorina Citri (Hemiptera), Maria Teresa Fernandez-Luna, Pavan Kumar, David G. Hall, Ashaki D. Mitchell, Michael B. Blackburn, Bryony C. Bonning

Entomology Publications

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera), is an important pest of citriculture. The ACP vectors a bacterium that causes huanglongbing (HLB), a devastating and incurable disease of citrus. The bacterium Bacillus thuringiensis (Bt) produces multiple toxins with activity against a diverse range of insects. In efforts to provide additional control methods for the ACP vector of HLB, we identified pesticidal proteins derived from Bt for toxicity against ACP. The trypsin proteolytic profiles of strain-derived toxins were characterized. Strain IBL-00200, one of six strains with toxins shown to have basal activity against ACP was selected for liquid chromatography-mass ...


Plant Essential Oils Synergize Various Pyrethroid Insecticides And Antagonize Malathion In Aedes Aegypti, E. J. Norris, A. D. Gross, L. C. Bartholomay, J. R. Coats Jan 2019

Plant Essential Oils Synergize Various Pyrethroid Insecticides And Antagonize Malathion In Aedes Aegypti, E. J. Norris, A. D. Gross, L. C. Bartholomay, J. R. Coats

Entomology Publications

Pyrethroid resistance is a significant threat to agricultural, urban and public health pest control activities. Because economic incentives for the production of novel active ingredients for the control of public health pests are lacking, this field is particularly affected by the potential failure of pyrethroid‐based insecticides brought about by increasing pyrethroid resistance. As a result, innovative approaches are desperately needed to overcome insecticide resistance, particularly in mosquitoes that transmit deadly and debilitating pathogens. Numerous studies have demonstrated the potential of plant essential oils to enhance the efficacy of pyrethroids. The toxicity of pyrethroids combined with plant oils is significantly ...


Menthol Acts As A Positive Allosteric Modulator On Nematode Levamisole Sensitive Nicotinic Acetylcholine Receptors, Shivani Choudhary, Djordje S. Marjianović, Colin R. Wong, Xiaoyu Zhang, Melanie Abongwa, Joel R. Coats, Saša M. Trailović, Richard J. Martin, Alan P. Robertson Dec 2018

Menthol Acts As A Positive Allosteric Modulator On Nematode Levamisole Sensitive Nicotinic Acetylcholine Receptors, Shivani Choudhary, Djordje S. Marjianović, Colin R. Wong, Xiaoyu Zhang, Melanie Abongwa, Joel R. Coats, Saša M. Trailović, Richard J. Martin, Alan P. Robertson

Entomology Publications

The ongoing and widespread emergence of resistance to the existing anti-nematodal pharmacopeia has made it imperative to develop new anthelminthic agents. Historically, plants have been important sources of therapeutic compounds and offer an alternative to synthetic drugs. Monoterpenoids are phytochemicals that have been shown to produce acute toxic effects in insects and nematodes. Previous studies have shown nicotinic acetylcholine receptors (nAChRs) to be possible targets for naturally occurring plant metabolites such as carvacrol and carveol. In this study we examined the effects of monoterpenoid compounds on a levamisole sensitive nAChR from Oesophagostomum dentatum and a nicotine sensitive nAChR from Ascaris ...


Monarch Butterflies Show Differential Utilization Of Nine Midwestern Milkweed Species, Victoria Marie Pocius, John M. Pleasants, Diane M. Debinski, Keith G. Bidne, Richard L. Hellmich, Steven P. Bradbury, Sue L. Blodgett Oct 2018

Monarch Butterflies Show Differential Utilization Of Nine Midwestern Milkweed Species, Victoria Marie Pocius, John M. Pleasants, Diane M. Debinski, Keith G. Bidne, Richard L. Hellmich, Steven P. Bradbury, Sue L. Blodgett

Entomology Publications

Monarch butterfly overwintering numbers have declined over the past 20 years. Restoring habitat that includes milkweeds, the only host plants for larval monarch butterflies, is necessary to increase monarch numbers within the breeding range. The value of different milkweed species for restoration will depend, in part, on the extent to which they are utilized by ovipositing females. The number of eggs laid on different species over a season will be a function of plant size and phenology as well as female preference. We examined seasonal egg deposition and females' oviposition choices by comparing the number of eggs laid by free-flying ...


Effects Of Endophytic Entomopathogenic Fungi On Soybean Aphid And Identification Of Metarhizium Isolates From Agricultural Fields, Eric H. Clifton, Stefan T, Jaronski, Brad S. Coates, Erin W. Hodgson, Aaron J. Gassmann Mar 2018

Effects Of Endophytic Entomopathogenic Fungi On Soybean Aphid And Identification Of Metarhizium Isolates From Agricultural Fields, Eric H. Clifton, Stefan T, Jaronski, Brad S. Coates, Erin W. Hodgson, Aaron J. Gassmann

Entomology Publications

Terrestrial plants can harbor endophytic fungi that may induce changes in plant physiology that in turn affect interactions with herbivorous insects. We evaluated whether the application of entomopathogenic fungi Beauveria bassiana and Metarhizium brunneum to soybean seeds could become endophytic and affect interactions with soybean aphid (Aphis glycinesMatsumura). It was found that A. glycines population sizes increased on plants with M. brunneum (strain F52) seed inoculum, but no significant effects were shown with analogous treatments with B. bassiana (strain GHA). Fungi recovered from soybean plant tissues indicate that endophytism was established, and that B. bassiana was more prevalent. Metarhizium ...


Colonization History Of The Western Corn Rootworm (Diabrotica Virgifera Virgifera) In North America: Insights From Random Forest Abc Using Microsatellite Data, Eric Lombaert, Marc Ciosi, Nicholas J. Miller, Thomas W. Sappington, Aurélie Blin, Thomas Guillemaud Mar 2018

Colonization History Of The Western Corn Rootworm (Diabrotica Virgifera Virgifera) In North America: Insights From Random Forest Abc Using Microsatellite Data, Eric Lombaert, Marc Ciosi, Nicholas J. Miller, Thomas W. Sappington, Aurélie Blin, Thomas Guillemaud

Entomology Publications

First described from western Kansas, USA, the western corn rootworm, Diabrotica virgifera virgifera, is one of the worst pests of maize. The species is generally thought to be of Mexican origin and to have incidentally followed the expansion of maize cultivation into North America thousands of years ago. However, this hypothesis has never been investigated formally. In this study, the genetic variability of samples collected throughout North America was analysed at 13 microsatellite marker loci to explore precisely the population genetic structure and colonization history of D. v. virgifera. In particular, we used up-to-date approximate Bayesian computation methods based on ...


Management Of Insecticide-Resistant Soybean Aphids In The Upper Midwest Of The United States, Robert L. Koch, Erin W. Hodgson, Janet J. Knodel, Adam J. Varenhorst, Bruce D. Potter Jan 2018

Management Of Insecticide-Resistant Soybean Aphids In The Upper Midwest Of The United States, Robert L. Koch, Erin W. Hodgson, Janet J. Knodel, Adam J. Varenhorst, Bruce D. Potter

Entomology Publications

Since the first observation of soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), in North America in 2000, it has become the most economically damaging insect of soybean in the Upper Midwest of the United States. For the last 17 yr, soybean aphid management has relied almost entirely on the use of foliar-applied broad-spectrum insecticides. However, in 2015 in Minnesota, failures of foliar-applied pyrethroid insecticides were reported and pyrethroid resistance was confirmed with laboratory bioassays using lambda-cyhalothrin and bifenthrin. In 2016 and 2017, further reports of failures of pyrethroid insecticides and/or laboratory confirmation of resistance occurred in Iowa, North Dakota ...


Soybean Aphid Efficacy Screening Program, 2017, Erin W. Hodgson, Greg Vannostrand Jan 2018

Soybean Aphid Efficacy Screening Program, 2017, Erin W. Hodgson, Greg Vannostrand

Entomology Publications

Soybean aphid, Aphis glycines Matsumura, has drastically changed soybean pest management in the North Central region. To date, SBA can be successfully managed by timely scouting and foliar insecticides in Iowa, but pyrethroid resistance is an emerging issue in the North Central region.


Monarch Butterflies Do Not Place All Of Their Eggs In One Basket: Oviposition On Nine Midwestern Milkweed Species, Victoria M. Pocius, Diane M. Debinski, John M. Pleasants, Keith G. Bidne, Richard L. Hellmich Jan 2018

Monarch Butterflies Do Not Place All Of Their Eggs In One Basket: Oviposition On Nine Midwestern Milkweed Species, Victoria M. Pocius, Diane M. Debinski, John M. Pleasants, Keith G. Bidne, Richard L. Hellmich

Entomology Publications

Over the past two decades, the population of monarch butterflies east of the Rocky Mountains has experienced a significant decline in overwintering numbers. Habitat restoration that includes planting milkweeds is essential to boost monarch numbers within the breeding range. Milkweeds are the only host plants for larval monarch butterflies, but female oviposition preference for different milkweed species, especially those with overlapping ranges, is not well documented. We examined the relative inclination to lay eggs on nine milkweed species native to Iowa (no choice), and oviposition preference (choice) among the four most commonly occurring Iowa species (Asclepias incarnata, Asclepias syriaca, Asclepias ...


Assessing A Reciprocal International Student Travel Exchange: The Iowa State University And University Of Costa Rica Intercambio, Mark L. Gleason, Amy Wang Wong, Donald R. Lewis, Luis Felipe Arauz Cavallini, Barbara Clawson, Kevin R. Duerfeldt, Hayley M. Nelson, Gaile R. Nonnecke Oct 2017

Assessing A Reciprocal International Student Travel Exchange: The Iowa State University And University Of Costa Rica Intercambio, Mark L. Gleason, Amy Wang Wong, Donald R. Lewis, Luis Felipe Arauz Cavallini, Barbara Clawson, Kevin R. Duerfeldt, Hayley M. Nelson, Gaile R. Nonnecke

Entomology Publications

The creation and educational impact of a reciprocal travel exchange program for student groups in horticulture and allied sciences between Iowa State University (ISU) and the University of Costa Rica (UCR) are described. The program, called the “Intercambio,” (“exchange,” in English), has facilitated group travel for 10- to 12-day periods to farms and agricultural research centers in the host country annually since 1999. The article explores how the Intercambio began and factors that have helped to sustain it, to provide ideas for educators interested in initiating similar exchanges. Analysis of responses to a 2015 written survey of student participants indicated ...


Population Projection And Development Of The Mythimna Loreyi (Lepidoptera: Noctuidae) As Affected By Temperature: Application Of An Age-Stage, Two-Sex Life Table, Jianyang Qin, Lei Zhang, Yueqiu Liu, Thomas W. Sappington, Yunxia Cheng, Lizhi Luo, Xingfu Jiang Aug 2017

Population Projection And Development Of The Mythimna Loreyi (Lepidoptera: Noctuidae) As Affected By Temperature: Application Of An Age-Stage, Two-Sex Life Table, Jianyang Qin, Lei Zhang, Yueqiu Liu, Thomas W. Sappington, Yunxia Cheng, Lizhi Luo, Xingfu Jiang

Entomology Publications

The Mythimna (=Leucania) loreyi (Duponchel) has recently emerged as a major pest of grain crops in China. Little is known about its basic biology and ecology, making it difficult to predict its population dynamics. An age-stage, two-sex life table was constructed for this insect when reared on maize in the laboratory at five constant temperatures (18, 21, 24, 27, and 30 °C). Both the intrinsic rate of increase (r) and finite rate increase (λ) increased as temperature significantly increased and mean generation time (T) decreased significantly with increasing temperature. The highest values for net reproductive rate (R0) and fecundity ...


Farmers’ Perspectives On Resistance In Western Corn Rootworm To Crw-Bt Corn In Midwest Usa, David A. Andow, Robert J. Wright, Erin W. Hodgson, Thomas E. Hunt, Kenneth R. Ostlie Mar 2017

Farmers’ Perspectives On Resistance In Western Corn Rootworm To Crw-Bt Corn In Midwest Usa, David A. Andow, Robert J. Wright, Erin W. Hodgson, Thomas E. Hunt, Kenneth R. Ostlie

Entomology Publications

Resistance in western corn rootworm to transgenic corn hybrids was first confirmed in 2011 in Midwestern USA, and threatens their continued use. Farmers are often the first line of resistance detection, so their understanding and attitudes toward this issue are critical for improving resistance management. We conducted telephone focus groups during 2013 with farmers who had experienced rootworm resistance. There were four stages in dealing with unexpected rootworm injury: Awareness of a problem, diagnosis, confirmation, and recommendations. Most farmers discovered the problem themselves, but this usually happened too late in the growing season to limit yield loss. Once aware of ...


Fitness Costs Associated With Cry1f Resistance In The European Corn Borer, J. L. Petzold-Maxwell, B. D. Siegfried, R. L. Hellmich, C. A. Abel, B. S. Coates, T. A. Spencer, R. J. Horikoshi, A. J. Gassmann Feb 2017

Fitness Costs Associated With Cry1f Resistance In The European Corn Borer, J. L. Petzold-Maxwell, B. D. Siegfried, R. L. Hellmich, C. A. Abel, B. S. Coates, T. A. Spencer, R. J. Horikoshi, A. J. Gassmann

Entomology Publications

Crops producing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely planted to manage insect pests. Bt crops can provide an effective tool for pest management; however, the evolution of Bt resistance can diminish this benefit. The European corn borer, Ostrinia nubilalis Hübner, is a significant pest of maize and is widely managed with Bt maize in the Midwest of the United States. When Bt crops are grown in conjunction with non-Bt refuges, fitness costs of Bt resistance can delay the evolution of resistance. Importantly, fitness costs often vary with ecological factors, including host-plant genotype and diapause. In ...


Dietary Risk Assessment Of V-Atpase A Dsrnas On Monarch Butterfly Larvae, Huipeng Pan, Xiaowei Yang, Keith G. Bidne, Richard L. Hellmich, Blair D. Siegfried, Xuguo Zhou Feb 2017

Dietary Risk Assessment Of V-Atpase A Dsrnas On Monarch Butterfly Larvae, Huipeng Pan, Xiaowei Yang, Keith G. Bidne, Richard L. Hellmich, Blair D. Siegfried, Xuguo Zhou

Entomology Publications

By suppressing the expression of genes with essential biological functions, in planta RNAi can negatively affect the development and survival of target pests. As a part of a concerted effort to assess the risks of RNAi transgenic crops on non-target organisms, we developed an in vivo toxicity assay to examine the impacts of ingested dsRNAs incurred to the monarch butterfly, Danaus plexippus (L.), an iconic eco-indicator in North America. To create the worst case scenario, the full-length v-ATPase A cDNAs from the target pest, western corn rootworm, Diabrotica virgifera virgifera, and the non-target D. plexippus were respectively cloned. A 400 ...


Phytoecdysteroids As Antifeedants Towards Several Beetles That Include Polyphagous And Monophagous Feeding Guilds, Russell A. Jurenka, Kathryn Russell, Matthew E. O'Neal Jan 2017

Phytoecdysteroids As Antifeedants Towards Several Beetles That Include Polyphagous And Monophagous Feeding Guilds, Russell A. Jurenka, Kathryn Russell, Matthew E. O'Neal

Entomology Publications

BACKGROUND

Plants are thought to produce ecdysteroids as a means of protection from insect herbivores. Some insects will not feed on plants containing high amounts of phytoecdysteroids, and this response could be limited to monophagous and oligophagous insects. The aim of this study was to determine whether phytoecdysteroids could inhibit feeding in several species of beetles that range from monophagous to polyphagous.

RESULTS

Here we demonstrate that phytoecdysteroids, including 20-hydroxyecdysone, prevent several beetle species from feeding on preferred host plants, including the polyphagous Japanese beetle Popillia japonica (Scarabaeidae). Phytoecdysteroids prevented feeding damage when sprayed onto soybean plants in no-choice and ...


Application Of Kin Theory To Long-Standing Problem In Nematode Production For Biocontrol, Thomas W. Sappington, Ruth A. Hufbauer Jan 2017

Application Of Kin Theory To Long-Standing Problem In Nematode Production For Biocontrol, Thomas W. Sappington, Ruth A. Hufbauer

Entomology Publications

Much research effort has been extended toward developing systems for managing soil inhabiting insect pests of crops with entomopathogenic nematodes as biocontrol agents. Although small plot or laboratory experiments may suggest a particular insect pest is vulnerable to management in this way, it is often difficult to scale-up nematode production for application at the field- and farm scale to make such a tactic viable. Part of the problem is that entomopathogenic nematode strains must be propagated by serial passage in vivo, because storage by freezing decreases fitness. At the same time, serial propagation results in loss of virulence (ability to ...


Soybean Aphid Efficacy Screening Program, 2016, Erin W. Hodgson, Greg Vannostrand Jan 2017

Soybean Aphid Efficacy Screening Program, 2016, Erin W. Hodgson, Greg Vannostrand

Entomology Publications

Soybean aphid, Aphis glycines Matsumura, has drastically changed soybean pest management in the North Central region. To date, SBA can be successfully managed by timely scouting and foliar insecticides. Host plant resistance is the newest soybean aphid management tool and is complementary to existing chemical control.


Performance Of Early Instar Monarch Butterflies (Danaus Plexippus L.) On Nine Milkweed Species Native To Iowa, Victoria M. Pocius, Diane M. Debinski, Keith G. Bidne, Richard L. Hellmich, Frances K. Hunter Jan 2017

Performance Of Early Instar Monarch Butterflies (Danaus Plexippus L.) On Nine Milkweed Species Native To Iowa, Victoria M. Pocius, Diane M. Debinski, Keith G. Bidne, Richard L. Hellmich, Frances K. Hunter

Entomology Publications

Over the past two decades, the population of monarch butterflies east of the Rocky Mountains has experienced a significant decline. Habitat restoration that includes milkweed plants is crucial to boost population numbers in the breeding range. Monarch butterfly larvae use milkweeds as their only host plant, but larval performance on different milkweed species is not well documented. We examined early instar survival and growth on nine milkweed species native to Iowa. These included Asclepias exaltata (poke milkweed), A. hirtella (tall green milkweed), A. incarnata (swamp milkweed), A. speciosa (showy milkweed), A. sullivantii (prairie milkweed), A. syriaca (common milkweed), A. tuberosa ...


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, Aaron J. Gassmann, Ram B. Shrestha, Siva R. K. Jakka, Mike W. Dunbar, Eric H. Clifton, Aubrey R. Paolino, David A. Ingber, B. Wade French, Kenneth E. Masloski, John W. Dounda, Coy R. St. Clair Aug 2016

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

Entomology Publications

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 ...


Dynamic Role And Importance Of Surrogate Species For Assessing Potential Adverse Environmental Impacts Of Genetically Engineered Insect-Resistant Plants On Non-Target Organisms, Michael Wach, Richard L. Hellmich, Raymond Layton, Jörg Romeis, Patricia G. Gadaleta Aug 2016

Dynamic Role And Importance Of Surrogate Species For Assessing Potential Adverse Environmental Impacts Of Genetically Engineered Insect-Resistant Plants On Non-Target Organisms, Michael Wach, Richard L. Hellmich, Raymond Layton, Jörg Romeis, Patricia G. Gadaleta

Entomology Publications

Surrogate species have a long history of use in research and regulatory settings to understand the potentially harmful effects of toxic substances including pesticides. More recently, surrogate species have been used to evaluate the potential effects of proteins contained in genetically engineered insect resistant (GEIR) crops. Species commonly used in GEIR crop testing include beneficial organisms such as honeybees, arthropod predators, and parasitoids. The choice of appropriate surrogates is influenced by scientific factors such as the knowledge of the mode of action and the spectrum of activity as well as societal factors such as protection goals that assign value to ...


Soybean Aphid Efficacy Screening Program, 2015, Erin W. Hodgson, Greg Vannostrand Jul 2016

Soybean Aphid Efficacy Screening Program, 2015, Erin W. Hodgson, Greg Vannostrand

Entomology Publications

Soybean aphid, Aphis glycines Matsumura, has drastically changed soybean pest management in the North Central region. To date, SBA can be successfully managed by timely scouting and foliar insecticides. Host plant resistance is the newest soybean aphid management tool and is complementary to existing chemical control. In 2015, we established plots at two Iowa State University Research Farms (Northeast and Northwest) on 27 May and 27 May, respectively. NK S25-E5 soybean variety was used for all the soybean aphid-susceptible treatments, and 28ARC5 soybean variety was used for the Rag2 -containing treatments. Plots were arranged in an RCB design with four ...


Biocontrol Of The Oriental Armyworm, Mythimna Separata, By The Tachinid Fly Exorista Civilis Is Synergized By Cry1ab Protoxin, Xingfu Jiang, Lei Zhang, Haixia Yang, Thomas W. Sappington, Yunxia Cheng, Li Zhi Luo Jun 2016

Biocontrol Of The Oriental Armyworm, Mythimna Separata, By The Tachinid Fly Exorista Civilis Is Synergized By Cry1ab Protoxin, Xingfu Jiang, Lei Zhang, Haixia Yang, Thomas W. Sappington, Yunxia Cheng, Li Zhi Luo

Entomology Publications

Tritrophic interactions between Mythimna separata, its tachinid parasite Exorista civilis and the Cry1Ab were examined. Although 6th instar M. separata mortality increased with increasing Cry1Ab concentration, some tolerance was evident. Likewise, parasitization by E. civilis resulted in only 18% host mortality. However, combination of Cry1Ab and E. civilis parasitization resulted in a significant Cry1Ab dose-dependent increase in mortality over that of either alone, including a 50–56% synergistic increase in efficacy at the two concentrations tested. Pupal weight, adult emergence and lifetime fecundity of M. separata derived from larvae surviving both agents were negatively affected. The ability of E. civilis ...


Field-Based Assessment Of Resistance To Bt Corn By Western Corn Rootworm (Coleoptera: Chrysomelidae), Ram B. Shrestha, Sive R. K. Jakka, B. Wade French, Aaron J. Gassmann Jun 2016

Field-Based Assessment Of Resistance To Bt Corn By Western Corn Rootworm (Coleoptera: Chrysomelidae), Ram B. Shrestha, Sive R. K. Jakka, B. Wade French, Aaron J. Gassmann

Entomology Publications

Western corn rootworm, Diabrotica virgifera virgifera LeConte, is a serious pest of corn and is managed with corn that produces insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). Beginning in 2009, resistance to Cry3Bb1 corn, and severe injury to Cry3Bb1 corn in the field, was observed in Iowa. However, few data exist on how Cry3Bb1-resistant western corn rootworm interact with various management practices in the field. Using a field experiment, we measured adult emergence and feeding injury to corn roots for both Cry3Bb1-resistant and Cry3Bb1-susceptible populations of western corn rootworm when tested against various Bt corn hybrids and a ...


The Interaction Of Two-Spotted Spider Mites, Tetranychus Urticae Koch, With Cry Protein Production And Predation By Amblyseius Andersoni (Chant) In Cry1ac/Cry2ab Cotton And Cry1f Maize, Yan-Yan Guo, Jun-Ce Tian, Wang-Peng Shi, Xue-Hui Dong, Jörg Romeis, Steven E. Naranjo, Richard L. Hellmich, Anthony M. Shelton Feb 2016

The Interaction Of Two-Spotted Spider Mites, Tetranychus Urticae Koch, With Cry Protein Production And Predation By Amblyseius Andersoni (Chant) In Cry1ac/Cry2ab Cotton And Cry1f Maize, Yan-Yan Guo, Jun-Ce Tian, Wang-Peng Shi, Xue-Hui Dong, Jörg Romeis, Steven E. Naranjo, Richard L. Hellmich, Anthony M. Shelton

Entomology Publications

Crops producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuringiensis(Bt), are an important tool for managing lepidopteran pests on cotton and maize. However, the effects of these Bt crops on non-target organisms, especially natural enemies that provide biological control services, are required to be addressed in an environmental risk assessment. Amblyseius andersoni (Acari: Phytoseiidae) is a cosmopolitan predator of the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), a significant pest of cotton and maize. Tri-trophic studies were conducted to assess the potential effects of Cry1Ac/Cry2Ab cotton and Cry1F maize on life history parameters (survival rate, development time ...


Early Detection And Mitigation Of Resistance To Bt Maize By Western Corn Rootworm (Coleoptera: Chrysomelidae), David A. Andow, Steven G. Pueppke, Arthur W. Schaafsma, Aaron J. Gassmann, Thomas W. Sappington, Lance J. Meinke, Paul D. Mitchell, Terrance M. Hurley, Richard L. Hellmich, R. Pat Porter Feb 2016

Early Detection And Mitigation Of Resistance To Bt Maize By Western Corn Rootworm (Coleoptera: Chrysomelidae), David A. Andow, Steven G. Pueppke, Arthur W. Schaafsma, Aaron J. Gassmann, Thomas W. Sappington, Lance J. Meinke, Paul D. Mitchell, Terrance M. Hurley, Richard L. Hellmich, R. Pat Porter

Entomology Publications

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 ...


The Effect Of An Interspersed Refuge On Aphis Glycines (Hemiptera: Aphididae), Their Natural Enemies, And Biological Control, A. J. Varenhorst, M. E. O'Neal Feb 2016

The Effect Of An Interspersed Refuge On Aphis Glycines (Hemiptera: Aphididae), Their Natural Enemies, And Biological Control, A. J. Varenhorst, M. E. O'Neal

Entomology Publications

Soybean production in the north central United States has relied heavily on the use of foliar and seed applied insecticides to manage Aphis glycines (Hemiptera: Aphididae). An additional management strategy is the use soybean cultivars containing A. glycines resistance genes ( Rag ). Previous research has demonstrated that Rag cultivars are capable of preventing yield loss equivalent to the use of foliar and seed-applied insecticides. However, the presence of virulent biotypes in North America has raised concern for the durability of Rag genes. A resistance management program that includes a refuge for avirulent biotypes could limit the frequency at which virulent biotypes ...


Broad-Spectrum Resistance To Bacillus Thuringiensis Toxins By Western Corn Rootworm (Diabrotica Virgifera Virgifera), Siva R. K. Jakka, Ram B. Shrestha, Aaron J. Gassmann Jan 2016

Broad-Spectrum Resistance To Bacillus Thuringiensis Toxins By Western Corn Rootworm (Diabrotica Virgifera Virgifera), Siva R. K. Jakka, Ram B. Shrestha, Aaron J. Gassmann

Entomology Publications

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 ...


Effects Of Refuges On The Evolution Of Resistance To Transgenic Corn By The Western Corn Rootworm, Diabrotica Virgifera Virgifera Leconte, Jennifer Deitloff, Mike W. Dunbar, David A. Ingber, Bruce E. Hibbard, Aaron J. Gassmann Jan 2016

Effects Of Refuges On The Evolution Of Resistance To Transgenic Corn By The Western Corn Rootworm, Diabrotica Virgifera Virgifera Leconte, Jennifer Deitloff, Mike W. Dunbar, David A. Ingber, Bruce E. Hibbard, Aaron J. Gassmann

Entomology Publications

BACKGROUND

Diabrotica virgifera virgifera LeConte is a major pest of corn and causes over a billion dollars of economic loss annually through yield reductions and management costs. Corn producing toxins derived from Bacillus thuringiensis (Bt) has been developed to help manage D. v. virgifera. However, previous studies have demonstrated the ability of this species to evolve resistance to Bt toxins in both laboratory and field settings.

RESULTS

We used an experimental evolution approach to test the refuge strategies for delaying resistance of D. v. virgifera to corn producing Bt toxin Cry34/35Ab1. In the absence of refuges, D. v. virgifera ...