BT RISK ASSESSMENT FOR LEPIDOPTEROUS PESTS OF COTTON
Southern Insect Management Research Unit
2009 Annual Report
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.
Field studies comparing the number of heliothine larvae per unit area on paulowina plant 38 inches apart and cotton planted at normal densities with 38 inches between rows were conducted at the Brown Loam Branch Experiment Station. Studies were conducted at the Brown Loam Experiment Station to develop management practices for paulowina plantings. After establishment of the plants, the plants seem very hardy to methods of pruning. Plots pruned close to the soil level with saw blades and plots cut with a 6-foot clipper recovered from the pruning and new stem foliage were soon present. Large Cage (6x6m) studies were conducted at the Mississippi State University Department of Entomology in which velvet leaf, paulowina, and cotton were randomly place inside the cages prior to the release of mated female moths (both tobacco budworm and cotton bollworm). After a 48-hour period of oviposition, the moths were removed from the cages and the number of eggs was recorded for each plant. Data indicate that both tobacco budworm and cotton bollworm moths preferred to lay eggs on velvetleaf, followed by paulowina, and least on cotton. Paulowina plants had 1.9 times more tobacco budworms eggs as compared to cotton and 1.6 times more bollworm eggs as compared to cotton. Additional experiments have been initiated in Starkville, MS. This project was monitored by face to face meetings at Stoneville.