THE INFLUENCE OF THE HOST-PLANT OF DIAMOND-BACK MOTH (PLUTELLA-XYLOSTELLA) ON THE PLANT PREFERENCES OF ITS PARASITOID COTESIA-PLUTELLAE IN SRI-LANKA

In Y-tube olfactometer tests, female Cotesia plutellae Kurdjmov (Hymen optera: Braconidae), a major parasitoid of Plutella xylostella (L.) in southeast Asia, preferred the odour of the brassica type (Blue Lake c abbage) on which they had developed. Such plants were even preferred t o the odour of caterpillar-infested and damaged leaves of another bras sica (Early Phenomenal cauliflower). However, within one brassica type , the odour of caterpillar-infested leaves was preferred to that of un infested and undamaged leaves. Odours of both Blue Lake and Early Phen omenal were preferred to the control odour (water). However, following the transfer of the parasitoid from Blue Lake to another cabbage (Bru nswick) for one generation, females no longer distinguished between Bl ue Lake and Early Phenomenal.