THE EFFECT OF SHORT-RANGE HOST ODOR STIMULI ON HOST FRUIT FINDING ANDFEEDING-BEHAVIOR OF PLUM CURCULIO ADULTS (COLEOPTERA, CURCULIONIDAE)

In laboratory assays, we investigated responses of female plum curculi os (PCs), Conotrachelus nenuphar (Herbst), to host and nonhost fruit o r leaf odor when PCs were crawling on experimental tree branchlets or twigs. In choice tests where test specimens were hung from the ends of a wooden crosspiece, PCs made significantly more visits to host plum fruit than to plum leaves, nonhost tomato fruit, wax models of plum fr uit, or blanks (wire). In similar tests, PCs made significantly more v isits to plum leaves compared to nonhost maple leaves or to blanks. PC s in test chambers that contained host or nonhost odor were significan tly more prone to feed on wax plum models in the presence of odor from host fruit or host leaves compared to odor from nonhost fruit or leav es or a water blank. In choice tests offering alternating cluster type s on an apple branchlet, PCs visited leaf clusters bearing a host appl e fruit more than leaf clusters without a fruit. In tests to assay the distance at which PCs can detect an individual host fruit, PCs crawle d from the central stem of an apple branchlet onto a side stem signifi cantly more often when an apple fruit on a side stem was hung 2 cm fro m the central stem compared to 4 or 8 cm away. Our combined results su ggest that PCs use host fruit odor to locate host fruit at close range .