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Abstract

Eggs of the potato tubermoth(PTM)Phthorimaea operculella (Zeller) obtained from 150 or 300 Gy-irradiated moths, either inbred or out-crossed to untreated counterparts, were offered as host material to three generalist Trichogramma species; Trichogramma cacoeciae, Trichogramma evanescens, and Trichogramma principium, to determine the ability of these egg parasitoids to develop in F1 sterile eggs. All eggs laid by the different parental crosses at 150 or 300 Gy, were acceptable and suitable for Trichogramma development. However, innochoiceand paired comparison tests, eggsfrom 300 Gy-irradiated parents were significantly less preferredcomparedwith eggs laidbynon-irradiated moths.No intra-specific differences forPTMsterile eggs were recorded amongthe tested Trichogramma species. Themean number of wasps emerging from each egg types was not affected by an interaction between parental crosses and applied doses. Overall, this study demonstrates that release of irradiated and non-irradiated moths at a 5 : 1 over-flooding ratio and Trichogramma over potatoes in small plexiglass boxes, is complementary and more effective in reducingPTMF1-emerged progeny than either technique used alone. The results provide baseline data for developing an integrated control approach by using inherited sterility technique in conjunction with Trichogramma for PTM population suppression. Key words: Phthorimaea operculella, Trichogramma, biological control, egg parasitoid, gamma irradiation, inherited sterility