Meeting Abstract
92.5 Monday, Jan. 6 14:30 Host-searching tactics in two groups of parasitoids that attack the hawkmoth Manduca sexta. WILSON, J.K.*; WOODS, H.A.; University of Montana keatonwilson@me.com
Insect parasitoids face the immense problem of finding an appropriate host in the complex natural world. Signals that parasitoids might use to find hosts are noisy, with insects being bombarded on all fronts in the olfactory, visual and auditory media. In particular, insects have incredible olfactory capabilities, and many parasitoids use olfaction to find hosts. Though some parasitoids cue in on scents given off directly by hosts, those signals are far weaker than those produced by plants. For this reason, parasitoids often use the volatiles emitted by plants as host-finding cues. Additionally, if herbivores cause significant fitness reductions in plants, it is in the plants’ best interest to attract parasitoids as defenders, and there has been a great body of work in recent years uncovering plant volatiles that are emitted in response to herbivory. Here, we explore the host-searching tactics of two parasitoids of the sphingid caterpillars Manduca sexta and M. quinquemaculata in southeastern Arizona – a larval parasitoid, the tachinid fly Drino rhoeo, and a set of species that parasitize Manduca eggs. We tested both groups for olfactory and visual responses to host-plants as well as host eggs and larvae. Small hymenopteran egg parasitoids in particular appear to use airborne plant volatiles to find hosts, while larger larval-parasitoid flies rely on both visual and olfactory stimuli. Understanding how insect parasitoids find hosts is important for two reasons. First, parasitoids can clearly have strong evolutionary and population-level forces on herbivorous insects in natural systems, so host-finding and its connected physiological systems represent the method by which these forces act. Second, because insect parasitoids are often used in bio-control, basic research on host-finding can lead to better and more cost-effective techniques for rearing and releasing them.
