Differences in the searching behavior of two strains of the egg parasitoid Telenomus busseolae (Hymenoptera: Scelionidae)

Abstract

Telenomus busseolae Gahan (Hymenoptera: Scelionidae) is an egg parasitoid, which is under evaluation for possible introduction into Italy as a biological control agent of the Corn Stalk Borer, Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae). Two strains are being considered, one from Africa and the other from Turkey. In a series of laboratory experiments we compared their reproductive capacities, walking behaviour, and host selection behaviour mediated by the sex pheromone and body scales of the host. As reciprocal crosses between the two strains yielded female offspring, they are not reproductively isolated. The two strains were similar in both their reproductive capacity and female longevity. Females of both produced 75-90 eggs and lived on average for 6-7 days. There were differences between the two strains in walking behaviour, searching pattern and in the host location behaviour. The African strain walked faster then the Turkish strain, and showed a slower angular speed and lower turning rate. The African strain showed a significant increase in its speed of movement in response to the host's sex pheromone and a more intense local search after encountering host body scales. These results on intraspecific variability could help choosing an appropriate strain of T. busseolae for corn borer management in Italy.