The sweet tooth of adult parasitoid Cotesia rubecula: Ignoring hosts for nectar

Investing time and energy into survival and reproduction often presents a trade-off to many species of animals. In parasitic wasps, both hosts and sugar sources contribute to the forager’s fitness but are often found in different locations. The decision to search for hosts or for food can have a strong impact on fitness when the forager’s lifetime is short and resources are not abundant. We investigated the tendency of flowers and hosts to attract 1-day-old female Cotesia rubecula Marshall (Hymenoptera: Braconidae) with different feeding histories in a wind tunnel. Only well-fed wasps exhibited a preference for hosts. In comparison, unfed wasps visited hosts and flowers in equal proportions. Feeding experience had a strong impact on the searching behavior and the number of landings on both resources. Host and food stimuli seem to be equally attractive to hungry parasitic wasps such as C. rubecula. We expect that under field conditions the time available for active food searching in female C. rubecula is short and influenced by the presence of hosts. KEY WORDS: foraging behavior; food experience; flowers; energy state; conservation of natural enemies