Monday, March 7, 2011

Bt Corn Symposia at Minneapolis Entomology Meeting

The following eight symposia on Bt maize will be presented at the 66th Meeting of the Entomological Society of America's North Central Branch at the Radisson University Hotel, in Minneapolis on March 13-16, 2011:

1) Bt Adoption by Illinois Producers and Refuge Management: Cause for Concern?
Time: 8:55 am Wed  Location: University Ballroom B
Michael E. Gray, University of Illinois

This presentation will focus on survey data collected from Illinois producers regarding their use of Bt hybrids to achieve insect protection. Data have been collected for several years at the University of Illinois Extension sponsored Corn and Soybean Classics. Responses from producers to a variety of questions were obtained using hand-held clickers in which anonymous feedback could be collected. Because of the escalating use of Bt hybrids, concern is increasing regarding the potential for resistance development. The results to a number of questions will be discussed such as the level of refuge compliance, refuge type preference, and likelihood of soil insecticide use with Bt. The use of seed blends (refuge-in-a-bag) as a refuge strategy is likely to become the foundation of resistance management programs in the future. Producer perspectives concerning seed blends, based upon survey responses, also will be discussed.

2) Why Use Corn Rootworm Insecticides Over a Corn Rootworm Traited Corn?
Time: 9:55 am Wed  Location: University Ballroom B
Caydee Savinelli and Craig Abell, Syngenta Crop Protection; and Patti L. Prasifka, Dow AgroSciences

Corn rootworm is sometimes known as the “Billion Dollar Insect Pest” and corn growers have used many tactics over the years to control this pest. The introduction of corn rootworm traited corn has been a step change in the control of corn rootworm. However, as with any insect control measure, the level of control may depend on the population dynamics of the target pest as well as secondary pests. This talk will address why and when it makes sense to use soil insecticides over corn rootworm traited corn.

3) Corn Rootworm Adult Emergence Patterns as Affected by Bt-RW Corn and Crop Rotation
Time: 1:50 pm Tue  Location: Nolte
Bruce D. Potter, University of Minnesota; Kenneth R. Ostlie and Jared M. Goos, University of Minnesota

During the 2008-2010 growing seasons, effects of Bt-RW hybrids and their isolines on quantitative and temporal aspects of corn rootworm beetle emergence were monitored in continuous corn and corn rotated with soybean in Dakota and Redwood County, MN. We found evidence that the Bt-RW trait delayed emergence for both corn rootworm species and both corn rotations. The implications of these emergence delays in terms of rootworm survival on transgenic corn, rootworm behavior, and monitoring of Bt-RW performance will be discussed.

4) Evaluating Response of Northern and Western Corn Rootworm to Transgenic Bt Corn
Time: 10:11 am Mon  Location: University Ballroom B
Ryan S. Keweshan and Aaron J. Gassmann, Iowa State University; Graham P. Head, Monsanto Company

The northern corn rootworm Diabrotica barberi and the western corn rootworm Diabrotica virgifera virgifera are major pests of corn in the United States. Bt corn that targets corn rootworm has been adopted rapidly by growers, and this places selective pressure on corn rootworm to evolve resistance. The pattern of adult emergence from Bt and refuge plants is an important factor affecting the development of resistance. The goal of our research was to measure patterns of adult emergence from Bt and non-Bt corn, and to assess fitness of adults surviving as larvae on Bt corn in the field. A total of four treatments were evaluated: 1) a single-trait event with Cry3Bb1 (YieldGard VT Triple), 2) a stacked event with Cry3Bb1 and Cry34Ab1/35Ab1 (SmartStax), 3) a near isogenic hybrid that did not contain rootworm active Bt and 4) a stacked event with a blended non-Bt refuge. For each of these treatments, we collected data on the abundance of adult male and female northern and western corn rootworm emerging over the course of the summer, and the fitness of these individuals, as indexed by width of their head capsule.

5) Gene Expression Profiles of Bt-resistant and Susceptible European Corn Borer Larvae (Ostrinia nubilalis) After Ingestion of Transgenic Cry1Ab Corn Leaves
Time: 9:35 am Mon  Location: Nolte
Jianxiu Yao, Lawrent L. Buschman, and Kun Yan Zhu, Kansas State University

Transgenic corn expressing insecticidal Cry1Ab from Bacillus thuringiensis (Bt) is very effective in controlling European corn borer (ECB), Ostrinia nubilalis. However, it is necessary to understand how ECB gut genes respond to transgenic corn because there is a threat ECB could develop resistance to Cry toxins. In this study, we developed a cDNA microarray built upon the ECB gut-specific EST database. The cDNA microarray contains 15,000 cDNA elements representing 2,755 different genes. We used this microarray to construct the gene expression profiles for early fourth-instar ECB larvae of the lab-selected resistant (R) strain and the susceptible (S) strain. Both strains were exposed to transgenic Cry1Ab corn (MON810-event) for 6-hrs. We identified 398 genes from the S strain and 264 genes from the R strain with a significantly increased or decreased expression (≥2.0 fold; p-value≤0.05) in comparing with unexposed larvae. Among those genes, 154 in the S strain and 88 in the R strain had putative molecular functions based on gene ontology analysis. 48 differentially expressed genes were common between the R and S strains. Interestingly, two aminopeptidase genes were up-regulated in the R strain, and down-regulated in the S strain. The rest of the genes had similar regulation in both strains. Especially, 17 genes in the S strain and 9 genes in the R strain had differential expression, which are potentially involved in Bt toxicity or/and Bt resistance. This study is the first large-scale monitoring of ECB larvae gut transcripts under exposed or unexposed to transgenic corn expressed Cry toxins

6) Incidence of Mycotoxins in Bt and Conventional Corn Hybrids in Relation to Insect Pest Abundance
Time: 9:59 am Mon  Location: Nolte
Rosemary Gutierrez, Billy W. Fuller, and Bradley L. McManus, South Dakota State University

Mycotoxins are fungal metabolites that can contaminate foods and feeds causing toxic effects in higher organisms that consume these products. The more common mycotoxins in corn are fumonisin, aflatoxin and deoxynivalenol (DON), and they are known to cause health issues in humans and animals (Hussein, 2001). Dry weather early in the season followed by wet weather during silking stage combined with insect damage on corn ears may increase the amount of fungal infection (Munkvold, 1999). Conventional and Bt corn plots were located in Aurora, South Dakota during 2009 year. Carbaryl was applied at 1.12 Kg[AI]/ha in half the plots to eliminate beneficial arthropods and thus trigger later-season pest resurgence contaminants. Sap beetles in the sprayed Bt plots were 50-fold greater in numbers than that observed in untreated-Bt plots. Corn rootworms were over 3-fold greater in conventional corn plots compared to that found in Bt treatments. Corn leaf aphid numbers were highest in sprayed-Bt plots compared to all treatments. Mycotoxins levels showed no significant differences between hybrids and insecticide treatments. Zearalenone was the only mycotoxin that showed significant differences comparing with fumonisin, aflotoxin anddeoxynivalenol (DON) in both hybrids. Zearalenone, aflotoxin, fumonisin nor DON levels were not significantly correlated with the percent of ears with visibly moldy insect-damaged kernels. Based on the levels of mycotoxins results conventional and Bt corn hybrids did not exceed the tolerated mycotoxin levels of human and animal consumption.

7) Interactions Among an Entomopathogenic Fungus, an Insect Predator, Mallada signatus (Neuroptera: Chrysopidae), and the Host, Helicoverpa armigera (Lepidoptera: Noctuidae), on Bt Cotton
Time: 10:11 am Mon  Location: Nolte
Md. H. Bahar, Alice Del Socorro, John N. Stanley, Peter C. Gregg, and David Backhouse, University of New England (Australia); Robert Mensah, Australian Cotton Research Institute

Greenhouse experiments were conducted to examine the interactions among Helicoverpa armigera, two of its natural enemies (green lacewing, Mallada signatus & an entomopathogenic fungus*) and transgenic Bt cotton. Fifty H. armigera neonates were placed on different locations of each whole potted cotton plant in a greenhouse. Two green lacewings were released and/or 50 ml fungal spore suspension was sprayed on each plant. After 96 hours both Bt cotton plant and green lacewing significantly reduced the survival of H. armigera larvae. The combined effect of green lacewing and Bt toxin on reducing H. armigera larvae was synergistic. The fungus did not affect the activities of either green lacewing or Bt cotton. In can be concluded that the predatory insect green lacewing and the entomopathogenic fungus are compatible with transgenic Bt cotton. * Due to commercial-in-confidence reasons, the name of the fungus can not be revealed.

8) Potential for Diabrotica Population Suppression with Area-Wide Adoption of Bt Corn
Time: 10:50 am Wed  Location: University Ballroom B
Nicholas P. Storer and Kevin L. Steffey, Dow AgroSciences; William D. Hutchison, University of Minnesota

Area-wide adoption of insect protected Bt corn and Bt cotton crops has led to significant reductions in certain target pest populations. Here we examine the potential for pyramided corn rootworm-active Bt traits to suppress populations of western corn rootworm in North America and Europe.

In addition, the meeting will feature an Insect Photo Salon, a hands-on photography workshop for entomologists, and symposia on bed bugs, biocontrol of invasive species, potato entomology, trends in corn IPM/IRM research, Diabrotica populations and control tactics, soybean aphid management, and insect biodiversity in urban environments.

For more information, including the full program schedule and instructions on how to register, please visit: Contact information can be found at

The Entomological Society of America (ESA) is the largest organization in the world dedicated to the science, magic, and mystery of the world’s most abundant life form -- insects. With more than 6,000 active members, the ESA helps to promote understanding of insects and solve world problems associated with them, including world hunger, disease prevention, and urban pest control. ESA is a 501c(3) not-for-profit membership society headquartered in Lanham, MD.