Chemotaxis of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) in response to larvae of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) and host food substrate with tobacco

Abstract

Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is one of the most studied parasitoids for biological control of pest’s moths in postharvest environment. However, little is known about the searching behavior and learning ability of this braconid regarding host localization. Thus, this study aimed to evaluate the chemotaxic behavior of female H. hebetor with and without parasitism experience to olfactory signals associated with types of stored tobacco and white wheat flour, and the presence of the host Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) developed in different diets. The chemotaxic responses of 2-4 day old H. hebetor females with and without previous experience of parasitism were observed in a “Y” type olfactometer. The odors of Virginia and Burley tobacco, wheat flour and E. kuehniella larvae reared with or without tobacco in their diet were evaluated. As a control, only air was used. Females of H. hebetor with no previous experience of parasitism were more responsive to both the host larvae and the different food substrates contrasted with air. In relation to tobacco substrate, both Virginia and Burley, when contrasted with larvae that developed in diet with tobacco, females were more responsive to tobacco volatile. On the other hand, mostly H. hebetor females with parasitism experience were more attracted to host larvae when compared to substrates. The number of non-responsive females with parasitism experience, was significantly lower than in the group of females without experience. Through previous experience, the parasitoid was able to develop associative learning, which may increase the efficiency of host search. This is the first record of tobacco attractiveness for the parasitoid H. hebetor, an important aspect for the success of biological control programs in tobacco storage.