1a.Objectives (from AD-416)
The objective of this cooperative research project is to conduct risk assessment research for Lepidopterous pests of Bt-crops. This research should enhance Bt-resistance management strategies which are designed to delay the onset of resistance development in target insects.
1b.Approach (from AD-416)
This agreement will determine the effect of Bt crop production on the population genetics of bollworm, tobacco budworm, and fall armyworm. Specific issues will be:. 1)a better overall understanding of gene flow and population structure for the pests;. 2)Bt-resistance allelic frequency estimates over time;. 3)the impact of changing refuge strategies and dynamic agroecosystems on managing resistance to Bt; and. 4)the impact of Bt-suppressed population densities on insecticide resistance, e.g. the recent pyrethroid resistance in bollworm. The cooperator will be actively involved in all phases of this research including the collection of test insects from across the U. S. Cotton Belt. Pyrethroid resistance assays will be conducted in the cooperator's laboratory. Insect tissue will then be sent to the USDA-ARS for use in genetic marker analysis and carbon isotope analysis. Other technologies (e.g. secondary plant chemical detection in insect tissue and oxygen and nitrogen isotope analysis) will be used as they become available to further understand the population ecology of the pests in relation to Bt resistance management.
Bollworm resistance monitoring continued in 2009 for the third year. Pyrethroid resistance levels in bollworm in 2009 remained similar to previous years except in Virginia where resistance levels rose dramatically. A post-doc began to work on revising a Bt resistance model, but he was subsequently hired by USDA-ARS, so this work was not completed during 2009. A new post-doc has now been hired and should complete some modeling work during 2010. A graduate student evaluated the degree of long-distance movement of bollworm compared to local movement. Local movement was the dominant factor within a season, but long-distance movement was important between seasons. The project was monitored through emails, telephone calls, and site visits.