Effect of a Substerilizing Dose of Radiation on the Mating Competitiveness of Male and on the Mating Propensity of Female Helicoverpa armigera (Lepidoptera: Noctuidae)

Abstract

In this article we report the results of experiments conducted with Helicoverpa armigera (Hubner) to determine the effects of a substerilizing dose of gamma radiation (100 Gy) on the mating competitiveness of treated males and the effect on the mating propensity of females with which they mate. Mating competitiveness of treated and untreated male moths was measured at two different release ratios inside field-cages in a cabbage field. A 1?:1/ and a 4?:1/ ratio were used while keeping a constant density of moths per cage. The mean number of matings recorded was not significantly different at either ratio, suggesting that treated males of this species are equally as competitive as their untreated counterparts. In the mating propensity studies, virgin female H. armigera were first mated to treated or untreated males and then re-exposed to untreated males 24 hours later. No statistical differences were found in the number of females that re-mated from either group. Thirty point eight percent of the females first mated with treated males and 29.17% of the females first mated to untreated males re-mated in this study. When both types of females were re-exposed to untreated males in the same field-cage, a higher percentage (38.3%) of females that had initially mated with a treated male re-mated than those initially mated with a untreated male (31.7%), although the differences were not significant.