PARENT SESSION
Oral Session #41: Agroecology and Urban Ecology. Presiding: M. Liebman.
Wednesday, August 8, 2001. 8:00 AM to 12:15 PM. Hall of Ideas L&M.
Variation among host plants in preference and parasitism of the insect herbivore, Lygus hesperus.
BENSEN, TIFFANY1, INOUYE, B1, TEMPLE, STEVEN1, 1
ABSTRACT- It is well known that host plants influence the interactions between insect herbivores and their natural enemies. In agricultural systems, this idea can be applied to diversify the crop plant environment and create or enhance biological control of an insect pest. Parasitism of the agricultural insect pest, Lygus hesperus (Hemipteran:Miridae), by the specialist egg parasitoid, Anaphes iole (Hymenoptera:Mymaridae) is known to vary with host plant. We hypothesized that interplanting a crop with a host plant that lygus bugs prefer but one on which they also experience high rates of parasitism will create natural biological control in the crop system. We measured preferences of lygus bugs for nine different host plants and quantified the rates of parasitism of lygus bugs by A. iole on these host plants; the results show differences among host plants in preference and in rates of parasitism. Using the number of eggs laid as a measure of preference, lygus bugs preferred Chenopodium album first and Amaranthus retroflexus second. Parasitism was highest on A. retroflexus and next highest on Solanum nigrum. We also collected weekly insect population samples from each host plant plot; these data allow hypotheses regarding the mechanisms responsible for the observed differences among host plants. Given these results, A. retroflexus shows most promise for biological control given that lygus bugs lay high numbers of eggs on this plant and suffer high levels of parasitism.
KEY WORDS: Lygus hesperus, Anaphes iole, parasitism, tritrophic interactions