Performing Department
Entomology
Non Technical Summary
Over 80 million acres of field corn (Zea mays) and 600,000 acres of sweet corn, worth about $65 billion and $1 billion respectively, are grown in the U.S. each year. The European corn borer (ECB) (Ostrinia nubilalis) and western corn rootworm (WCR) (Diabrotica virgifera virgifera) account for over $1 billion each in control costs and grain losses annually. Rootworms are particularly problematic because of their propensity to evolve resistance to management tactics, including crop rotation (Gray et al. 2009), insecticides (Meinke et al. 1998), and now Bt toxins (Gassmann et al. 2011, 2014).Since the commercial release of Bt transgenic corn against ECB in 1996 and against rootworms in 2004, a revolution in corn insect pest management has occurred. Seed companies continue to develop genetically-modified (GM) crops for pest protection. New GM corn hybrids have resistance to a broader range of lepidopteran pests, some have resistance to coleopteran pests, and most current GM hybrids have genes targeting both Lepidoptera and Coleoptera. This technology often eliminates the need to store and handle insecticides and it increases the efficiency of grower operations and pest control (Rice 2004, Sappington 2014). However, the development of resistance by WCR to some Bt toxins is threatening to reverse these gains. Keeping abreast of these changes with timely and relevant research over an area as large and diverse as the U.S. Corn Belt lends itself to a coordinated, committee approach.Bt corn acreage in the U.S. has increased from 8% in 1997 to 80% in 2014. At this level of adoption, the potential for resistance increases. Research conducted by this committee was used to develop models predicting the rates of resistance evolution and efficacy of refuge in preventing resistance. This led to the IRM approach that used a 20% independent refuge planting; however, as GM technology has evolved, so has IRM. Recently deployed GM corn hybrids use multiple genes that target ECB and WCR. The IRM plan for these hybrids requires a smaller refuge, and seed mixtures (Bt and non-BT) are now being deployed. The models supporting these IRM modifications were constructed using the best information available, but a number of assumptions had to be made. These assumptions must be tested and research conducted to move them from assumptions to quantified variables. Furthermore, information is needed on the economics of this evolving technology at the field, farm, and regional levels. Addressing these knowledge gaps forms the basis for several objectives of the project. The long-term goal of our research is to develop sustainable ways to manage the corn insect pest complex. This is a high regional priority, and in the context of demonstrating sustainable practices, it also is an important national priority.
Animal Health Component
0%
Research Effort Categories
Basic
20%
Applied
80%
Developmental
(N/A)
Goals / Objectives <b> Investigate the relationship between pest management technologies and the agricultural environment.</b> <p> 1a. Assess the need, efficacy and pest management window of seed treatment insecticides, primarily neonicotinoids, to control secondary below-ground insect pests.<p> 1b. Evaluate possible effects of insecticidal seed coatings on non-target beneficial insects.
<b> Investigate the ecology, biology, evolution, genetics, and behavior of corn arthropods.</b> <p> 2a. In cooperation with international community, develop genomics tools for key corn pests, including assembled and annotated genome and transcriptome sequences, genetic markers, and physical and QTL maps of important traits.<p> 2b. Characterize races of corn pests, including ecology of races in sympatry.<p> 2c. Assess effects of seed blend refuge in Bt corn on biology, development, and behavior of multiple lepidopteran pest species.<p> 2d. Examine the potential role of microbial associates on important pest traits, including insecticide resistance, behaviors relevant to pest status, and insect-plant interactions.<p> 2e. Characterize dispersal of adult WCR and lepidopteran pests, and assess its implications for IPM and for resistance development, spread, and mitigation.
<b>Develop and assess IPM and IRM systems for the arthropod complex in corn.</b> <p> 3a. Characterize and monitor for resistance of lepidopteran pests to Bt corn and conventional insecticides, and assess possible IRM and mitigation strategies.<p> 3b. Characterize geographic extent and nature of resistance of <i>Diabrotica</i> spp. to Cry toxins, pyrethroids, and other insecticides, and develop appropriate IPM and IRM strategies for problem areas.<p> 3c. Work toward improving an artificial diet for WCR rearing and more sensitive bioassays of toxins.<p> 3d. Develop strategies to manage the ear-feeding pest complex and model implications for IRM and IPM.<p> 3e. Develop <i>Helicoverpa armigera</i> early detection and mitigation network.<p> 3f. Develop region-specific bioeconomic models to assess refuge and IPM strategies for managing lepidopteran and coleopteran pest resistance to Bt corn expressing stacked and pyramided toxins.<p> 3g. Assess the extent to which limited farmer access to Bt corn varieties targeting only coleopteran or only lepidopteran pests affects the risk of resistance when the economic importance of each pest varies regionally.
<b>Employ diverse delivery methods to disseminate information related to sustainable management of corn arthropod pests.</b> <p> 4a. Establish an NC-205 video library website with permanent high quality versions of IPM videos for open online access and download to computer and portable electronic devices.<p> 4b. Produce and deploy a comprehensive IPM system for cost-effective prevention, early detection, rapid diagnosis, and mitigation of new and emerging corn pests that links all stakeholders who have common interests in pest detection and management.<p> 4c. Develop an array of IPM and IRM distance education workshops.
Project Methods
Krupke will be focused on these two objectives:Obj. 1. Investigate the relationship between pest management technologies and the agricultural environment. 1a. Assess the need, efficacy and pest management window of seed treatment insecticides, primarily neonicotinoids, to control secondary below-ground insect pests.IN will coordinate an effort to survey fields across the Corn Belt to quantify the population densities of key pests, and characterize the protection offered by neonicotinoid seed treatments by quantifying the levels of insecticide present in treated seeds and seedlings at various points throughout the season, using established LC-tandem mass spectrometry. The results will be used to determine the degree of overlap between populations of early season pests in the region and the window of efficacy afforded by neonicotinoid seed treatments.1b. Evaluate possible effects of insecticidal seed coatings on non-target beneficial insects.IN and PA will lead U.S. efforts to evaluate the effects of seed treatment upon a range of beneficial insects, including pollinators, important predators and species that are particularly charismatic and/or imperiled. Abundance and diversity studies of non-target insects using a combination of survey techniques will be conducted. Candidates for further study may be subjected to more detailed dose/response studies in laboratory settings that include estimates of sublethal effects.Obj. 3. Develop and assess IPM and IRM systems for the arthropod complex in corn. 3a. Characterize and monitor for resistance of lepidopteran pests to Bt corn and conventional insecticides, and assess possible IRM and mitigation strategies.NE and IA will coordinate target pest population collections from across Corn Belt and diagnostic bioassays will be conducted annually to assess susceptibility of target pest species (e.g. ECB and fall armyworm) using established methodology (Marcon et al. 1999, Marcon et al. 2000, Siegfried et al. 2007). Inheritance experiments will involve reciprocal crosses of resistant and susceptible parental populations to establish an F1 generation and dominance determined based on the response curve of the heterozygous individuals. Backcross of the F1 heterozygotes to one of the parental strains will be used to estimate the number of genetic factors that contribute to resistance. A variety of biochemical, molecular and genomic tools will be used to assess mechanisms of resistance (Coates et al. 2011, Crespo et al. 2011).3b. Characterize geographic extent and nature of resistance of Diabrotica spp. to Cry toxins, pyrethroids, and other insecticides, and develop appropriate IPM and IRM strategies for problem areas.IA, IL, MN, NE, and Ontario will conduct field visits to identify suspected cases of Bt resistance. Fields will be visited in response to concerns by farmers and crop consultants of possible resistance to Bt corn. A gene check will be used to confirm the type of Bt corn planted in the field, roots will be sampled to evaluate feeding injury, and a sample of WCR collected to generate eggs for bioassays. Single-plant bioassay, following Gassmann et al. 2014, along with other bioassay methods, such as Nowatzki et. al (2008), will be applied to measure the level of resistance to various Bt events. NE and KS will make field collections of WCR in areas with pyrethroid use histories and/or reduced pyrethroid efficacy. Both adult diagnostic and dose response topical assays with pyrethroid active ingredients will be conducted to determine relative susceptibility level and geographic distribution of resistance.