Performance of Cotesia flavipes (Hymenoptera: Braconidae) in parasitizing Chilo partellus (Lepidoptera: Crambidae) as affected by temperature and host stage

The braconid larval parasitoid, Cotesia flavipes, is used as a biological control agent against the crambid Chilo partellus, a serious pest of cereal crops in eastern and southern Africa. We examined the survival, development parameters, and body growth patterns of the host and its parasitoid at different temperatures (22, 26, and 30 °C) using third and fourth instars of Ch. partellus. For non-parasitized hosts, larval mortality tended to be highest at lowest temperature and for parasitized at third host instars only at highest temperature. Development time of Co. flavipes immatures significantly decreased with host instar and with temperature. Sex ratio of Co. flavipes varied from male- to female-biased with increase in temperature. The increase in body weight of parasitized fourth instar Ch. partellus was higher than in non-parasitized larvae at all temperatures. Parasitism by Co. flavipes had no effect on the food uptake by Ch. partellus, but significantly less food was consumed by both parasitized and non-parasitized larvae at 26 °C. The results of this study were discussed in light of the performance of Co. flavipes under different climatic conditions.