Effect of inherited sterility and Bacillus thuringiensis on mortality and reproduction of Phthorimaea opercullela Zeller (Lepidoptera: Gelechiidae)

Abstract

The effect of a commercial formulation of Bacillus thuringiensis (Dipel^® 2X) upon F₁ progeny of irradiated and nonirradiated Phthorimaea operculella male parents was investigated. F₁ progeny of irradiated parents was more susceptible to B. thuringiensis than that of nonirradiated parents. A combination of irradiation and B. thuringiensis led to higher mortality in F₁ progeny of P. operculella. The LC₅₀ was 0.406 g/100 ml for F₁ progeny of nonirradiated parents, but 0.199 g/100 ml for those of irradiated parents. There was a great reduction in the pupal weight, fecundity and egg hatchability of F₁ progeny of irradiated parents compared to nonirradiated parents. Such reduction was increased by applying a higher concentration of B. thuringiensis. A combination of the inherited sterility technique and B. thuringiensis application gave a good control result against P. operculella.