Objective:
The horn fly is a serious pest of cattle, and the control of this fly has become problematic for cattle producers. Control is generally accomplished through the use of chemical insecticides, particularly the pyrethroids and organophosphates (OPs). Many populations of the fly have become resistant to the pyrethroid class of insecticides. Resistance to OP insecticides has been documented, and as this type of resistance spreads, more expensive control measures will be required and producer costs will rise accordingly. Presenting producers with novel fly control strategies will be important to ensure control can be accomplished with economic feasibility in mind. It is also possible that the utility of pyrethroids and OPs can be extended by designing application regimes that maximize the efficiency of the applied insecticide and yet help maintain susceptibility of the population. The objective of this project is to evaluate different insecticide treatment regimes for their ability to maintain insecticide susceptibility in wild populations. Additionally, the life cycle of the fly will be evaluated to identify vulnerabilities that might be exploited by the development of transgenic horn flies developed in conjunction with a current ongoing project.

Approach:
1. Use bioassays and molecular assays to track insecticide resistance gene flow in response to different insecticide treatment protocols. Focus on target site resistance to pyrethroid and OPs and associated fitness costs that might be manipulated to maintain susceptibility in populations. 2. Development of transgenic horn fly strains that attack vulnerabilities in the life cycle of the fly may provide alternative control strategies. Identify genes that regulate these vulnerabilities and investigate their suitability for development of control methodology based on transgenic fly.