Journal of Chemical Ecology, Vol. 23, No. 5, 1997 ATTRACTION OF FEMALE ORIENTAL FRUIT FLY, Bactrocera dorsalis, TO VOLATILE SEMIOCHEMICALS FROM LEAVES AND EXTRACTS OF A NONHOST PLANT, PANAX (Polyscias guilfoylei) IN LABORATORY AND OLFACTOMETER ASSAYS ERIC B. JANG, 1 '* LORI A. CARVALHO, 1 and JOHN D. STARK2 * Tropical Fruit & Vegetable Research Laboratory Agricultural Research Service, US Department of Agriculture P.O. Box 4459, Hilo, Hawaii 96720 2Puyallup Research and Extension Center Washington State University Puyallup, Washington 98371 (Received July 16, 1996; accepted January 7, 1997) Abstract—Fresh whole leaves and solvent-water leaf extracts of the hedgerow plant panax, Polyscias guilfoylei (Bull), were tested for their attractiveness to male and female Oriental fruit flies, Bactrocera dorsalis, in laboratory flight tunnel and cage olfactometer bioassays. Fresh mature whole panax leaves were found to be attractive to mated female oriental fruit flies in the flight tunnel. Response of males and virgin females was low and in most instances not significantly different from controls. Attraction of mated female flies to the layers resulting from a methylene chloride-water partition or a hexane- water partition of freshly ground leaves using small McPhail traps was greatest in the methylene chloride fraction. When methylene chloride and water layers were tested competitively in a multiple-choice rotating olfactometer, the meth- ylene chloride fraction was more attractive. Tests involving the methylene chloride-water interface (an emulsion of the two partitioned layers) with and without a standard attractant NuLure, showed the emulsion layer to be sig- nificantly more attractive than the other fractions or NuLure. In outdoor cage olfactometer assays of methylene chloride and water fractions, activity was greatest in the methylene chloride fraction. The results suggests that volatile semiochemicals from this nonhost plant are attractive to mated female Oriental fruit flies. The results are discussed in relation to the chemical ecology of B. dorsalis and the potential use of this nonhost plant for detection and control of female Oriental fruit flies in the field. *To whom correspondence should be addressed. 1389 0098-033I/97/0500-1389S12.50/0 © 1997 Plenum Publishing Corporation