Effectiveness of Microbial Control of Heliothis spp. Developing on Early Season Wild Geraniums: Field and Field Cage Tests

Abstract

A field test was conducted to study control of Heliothis spp. larvae on early season wild host plants, primarily wild Geranium spp. Halves of one test plot were either treated with red dye or blue dye alone, while halves of a second test area were treated with blue dye alone or red dye plus a nuclear polyhedrosis virus (NPV). Both blue and red marked moths (11.6 and 5.8% of the captured populations, respectively) were found among adult H. virescens (F.) males caught in pheromone traps near the areas treated with dyes alone. However, only blue marked moths (7.7% of the captured populations) were detected among adults captured near the areas treated with the blue dye alone or red dye plus virus. These results demonstrated a reduction in adult emergence from areas treated with the virus. In a subsequent field cage study, treating wild geranium with NPV formulated either in water, a dust formulation, or in 10% crude cottonseed oil resulted in reductions in adult Heliothis emergence of 91.3, 82.4, and 80.8%, respectively, compared with the untreated control. Although significantly less effective (P = 0.05) than any NPV treatment, a mixture of an insect growth regulator and the bacterium Bacillus thuringiensis Berliner, resulted in a significant (P = 0.05) reduction in emergence compared with the untreated control.