THE EFFECTS OF DOMESTICATION OF BRASSICA AND PHASEOLUS ON THE INTERACTION BETWEEN PHYTOPHAGOUS INSECTS AND PARASITOIDS

Domesticated plants which have been the subject of artificial selectio n have altered allelochemistry and nutrient content. Insects that feed on these plants, as well as the parasitoids that attack these insects , have been forced to adapt to these changes, Here we present results from two studies, one involving the herbivore Pieris rapae (Lep.: Pier idae) and its parasitoid Cotesia glomerata (Hym.: Braconidae), and the other involving the seed eating beetle Zabrotes subfasciatus (Col.: B ruchidae) which is parasitized by Stenocorse bruchivora (Hym.: Braconi dae). In these studies we examined the effects of plant domestication on herbivore and parasitoid performance and on the host location behav ior of parasitoids. We tested the hypothesis that as a result of plant domestication, cultivars provide a higher quality resource for herbiv ores and their parasitoids than their wild relatives. Results from the se two studies show that, overall, herbivore and parasitoid performanc e was higher on cultivated plant species than on wild species. Further more, choice experiments revealed that parasitoids were more attracted to cultivars than to related wild plants, The higher attractiveness o f cultivated plants suggests that the volatile phytochemicals used by these parasitoids during the process of host location have not been lo st or reduced as a result of plant domestication, me discuss hen: natu ral selection may have operated on parasitoids to locate hosts on plan ts on which their performance is high. (C) 1998 Academic Press.