Document: PED-3-56-27

Host selection among parasitoids of macrolepidoptera: A matter of host taxa, susceptibility or availability?

BARBOSA, P.* and A.CALDAS

University of Maryland, College Park, MD 20742 USA ¹

Abstract:
Available studies suggest that differences in vulnerability of herbivores to parasitoids is often associated with differences in herbivore behavior or morphology. The latter are often species-specific traits important in host-finding for parasitoids specializing on particular taxa (i.e., "taxon-specific" parasitoids). However, there are also many parasitoids that are habitat or niche specialists and select related and/or unrelated hosts, occurring in similar or identical habitats. Host selection may be a function of cues associated with the host's food or shelter, as well as those associated with host phenology, voltinism, or abundance. Leaf-feeding macrolepidopteran larvae were collected from black willow (Salix nigra (Marsh)) and box elder (Acer negundo L.) in riparian habitats. Larvae were reared individually to determine sources and levels of parasitism. Observed pattern of parasitism of macrolepidoptera over five years provides insights into variation in host species use by an array of different parasitoids. Although over the 5 years 23.45% of collected larvae were parasitized, because host species were so scarce, for only 18 (of 58) species were more than 10 individuals reared (over the 5 years). Among the 58 parasitoids species, 42 were associated with hosts on box elder, 41 with hosts on black willow, and 25 attacked hosts on both tree species. Thirty three parasitoid species had at least two hosts and some were reared from as many as 5 to 6 host species. In this habitat sharing of hosts by parasitoids is commonly observed, although the realized degree of sharing may be less than the potential degree of sharing.

Keywords: Parasitoid, host-selection, parasitoid-host interactions

This abstract is being presented at: 1:15 PM in session:
Oral Session #15: Parasitoids and Diseases.