Summary of tracer performance for bollworm (Helicoverpa zea) and tobacco budworm (Heliothis virescens) control in Arkansas cotton, 1998-1999.

In 1998, the bollworm and tobacco budworm caused an estimated 4.66% yield loss to cotton in Arkansas or an approximate loss of 29.0 million dollars (Williams, 1999a). Each pest alone is capable of causing considerable damage and in Arkansas, the population mix can vary from year to year and location to location. The statewide population mix in 1998 was approximately 44% bollworm / 56% tobacco budworm (Williams, 1999b). Continued reliance on pyrethroid insecticides as the major control measure for the Heliothine complex has resulted in increased levels of resistance for both species (Bagwell,1999; Brown et al., 1998; Sparks et al., 1993). Tracer is currently the only commercial example from a new class of insecticides called spinosyns and is a fermentation metabolite of the soil inhabiting microorganism Saccharopolyspora spinosa, an actinomycete. It has both stomach and contact activity against many caterpillar pests and was first registered for use on cotton in 1997. Tracer has a novel mode of action and acts by disrupting acetylcholine binding in nicotinic acetylcholine receptors at the postsynaptic nerve cell ending (Salgado, 1997). In these studies, Tracer was compared to traditional insecticides to determine its potential for use as a control tactic for the bollworm and tobacco budworm.