Silk Fly Ovipositional and Semiochemical Bioassays

Several species of silk flies (Diptera: Ulidiidae) are extremely destructive sweet corn pests in southern Florida.   They are currently managed with multiple insecticide applications.  Studies were initiated to examine their chemical ecology in hopes that information gleaned could lead to additional management tactics.   Silk flies have been observed to be attracted to noctuid-damaged plants as well as developing from damaged solanaceous crops.  Ovipositional choice assays were conducted consisting of ten pairs of silk flies held over partitioned dishes containing sweet corn silks, frass, pepper and tomato slices to determine which material silk flies preferred to oviposit on.  Still-air olfactory bioassays consisting of snap cap vials attached to bamboo poles were conducted with silk flies to determine if frass was as attractive as or more attractive than corn.  In general, frass was the most attractive material for oviposition and to locomotion.  There were differences in ovipositional preference among the tested species and in degree of oviposition, with frass and silks preferred.  The volatile components of frass, silks, and tassels are being investigated.