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United States Department of Agriculture

Agricultural Research Service

Research Project: Ecologically-Based Management of Insect Pests of Corn, with Emphasis on Corn Borers, Rootworms, and Cutworms

Location: Corn Insects and Crop Genetics Research

Project Number: 5030-22000-017-00
Project Type: Appropriated

Start Date: Oct 01, 2010
End Date: Sep 30, 2015

Objective:
1) Improve knowledge of the ecology, genetics, and behavior of corn pests such as corn borer, corn rootworm, and western bean cutworm in relation to pest abundance and insect resistance to transgenic corn; 2) Determine the nature and degree of potential impacts of transgenic corn (e.g., Bt corn) on non-target organisms; and 3) Develop genetic and molecular methods to investigate corn insect biology and plant-insect interactions.

Approach:
Laboratory trials will examine how resistance alleles from European corn borer (ECB) colonies impact dispersal and survival of neonates after exposure to various Bt toxins. Movement and avoidance behaviors will be evaluated using video-tracking and bioassays with lyophilized leaf tissue incorporated into artificial diet. Results of the laboratory trials will guide selection of appropriate treatments for subsequent semi-field experiments. The marker development and screening strategies used for identifying Bt resistance linkage groups in ECB will be adapted for developing molecular markers associated with behavioral adaptations in ECB. We will characterize gene flow and genetic structuring among ECB populations in Pennsylvania (PA). We will use a panel of 74 SNP markers, previously identified and verified from EST sequences, in population genetics analyses to determine the effects of potential geographic barriers on ECB gene flow separately for the pheromone races, and determine if genetic structuring is associated with host plant association in the E race. The development of laboratory tests to evaluate possible effects of stressors from GE crops involves two phases. The first phase is development of a standardized protocol for testing an orally administered test substance on a specific insect and life stage. The second phase is using these protocols to parallel test (a.k.a. ring test) the selected insect at three or more laboratories. We will take a mass-screening approach to validate EST-derived SNPs for WCR using the Illumina Golden Gate SNP assay platform. We anticipate that about 75% of the 4,111 candidate SNPs we have identified will produce a designable assay, which would translate into nearly 3,100 assays. These candidate SNPs, for which an assay can be designed, will be tested for polymorphism against samples of rotation-resistant WCR populations from Illinois and wild-type populations from Iowa. Information from the Illumina GenCall and GTS Reports software will be used to remove bad SNPs and bad samples. Complementing the genomics and bioinformatics groundwork, we will investigate Bt resistance traits by integrating structural and functional genome information. SNP markers will be used for mapping QTL studies of ECB, and population studies of ECB and WBC. Our experiments will investigate separate native resistance (NR) sources leading to differential feeding or survival of WCR larvae on roots, of WCR adults on silks, and of corn earworm (CEW) larvae on silks. For both lepidopteran and coleopteran pests, we will narrowly define chromosomal segments of the corn genome that harbor NR alleles. We will also create large sets of inbred and hybrid isolines to enable future mechanistic analysis of the effects of the NR alleles on both target and non-target insects.

Last Modified: 11/24/2014
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