Mating Competitiveness of Irradiated Lobesia botrana (Lepidoptera: Tortricidae) in Male-Only and Both Sex Release Strategies under Laboratory Cage Conditions

SIMPLE SUMMARY: The sterile insect technique/inherited sterility (SIT/IS) has been successfully implemented to suppress or eradicate pestiferous species of Lepidoptera. The SIT/IS involves the release of mass-reared and gamma-irradiated moths (partially sterile males and fully sterile females) to achieve matings with wild moths. The success of any SIT/IS project depends, inter alia, on the overflooding ratio of released sterile moths to wild moths and the efficiency of male-only versus bi-sex releases of irradiated moths. The current laboratory study aims to understand the efficacy of overflooding ratios and the use of male-only releases compared with bi-sex releases for SIT/IS against the European grapevine moth, Lobesia botrana (Denis and Schiffermüller). ABSTRACT: This laboratory study explored the concept of whether irradiated male-only releases are more or equally efficient as releases of both irradiated males and females in the context of using the sterile insect technique/inherited sterility (SIT/IS) for the management of the European grapevine moth Lobesia botrana. The current study examined the mating competitiveness of 150-Gy-treated L. botrana male and female moths or 150-Gy-treated male moths only, with untreated moths in laboratory cages. Our results showed that the release of both sexes significantly increased the competitiveness value (C) and the biological efficiency index (BE) as compared with male-only release, and this was independent of the male to untreated male ratio. Moreover, a single release of 150-Gy-treated and untreated males and females at a 1:1:10:10 ratio (untreated male:untreated female: treated male:treated female) significantly reduced egg hatch, and the number of first-generation offspring (F(1)) was small. The emergence of F(2)-moths per untreated F(1) male and female moth was low, but these undesired fertile moths should be eliminated in order to achieve effective control. The results presented herein provide useful information on the impact of 150-Gy-treated male-only, versus releases of both treated males and females on untreated moths, which is essential to managing L. botrana populations with SIT/IS.