Biological Fly Control on Arkansas Dairies Utilizing Parasitoids

Dairy producers in Arkansas were concerned that fly populations in their herds had developed resistance to chemicals available to control flies. As an alternative approach to conventional fly control with insecticides, the University of Arkansas Cooperative Extension Service and Arkansas Dairy Cooperative Association developed a fly control program utilizing integrated pest management techniques involving the use of parasitoids and limited insecticides to control flies on dairy farms in central Arkansas. With less chemical use for fly control, milk is also less apt to be contaminated with pesticides and resistance to the chemicals should occur less frequently.

A technician delivered fly parasitoids (or parasites) to both control and parasitoid dairies weekly from mid-May to mid-September where also fly populations on cows and around the milking parlor were monitored on the 12 small and mid-sized dairies each year. The project was very successful in controlling flies with parasitoids from the standpoint of number of flies on cows and facilities. Additionally, the costs to control flies with parasitoids and limited insecticide use was comparable in costs to control of flies with the routine use of insecticides. However, more widespread acceptance of fly control with parasitoids among dairy producers would be desirable. Only two producers other than those on the project used parasitoids. Also, some producers utilizing parasitoids in 2001 continued to use more insecticides than needed. In 2002, the use of insecticides by producers using parasitoids was decreased, and fly populations on dairies utilizing parasitoids remained comparable to fly control on dairies utilizing
conventional insecticides.

Fly parasioids were used to adequately control flies on dairy farms for approximately the same costs as conventional insecticides. In both cases, proper manure handling was essential. The data from the demonstrations were displayed at field days in the participating counties and a final summary meeting with producers. Additional data are needed to determine how to best control flies with fly parasites. Also, more demonstrations are needed to get dairy producers to adequately accept control of flies with parasitoids before the use of parasitoids with limited
insecticides can be routinely recommended .