HONEY-BEE (HYMENOPTERA, APIDAE) BEHAVIORAL-RESPONSE TO PRIMARY ALFALFA (ROSALES, FABACEAE) FLORAL VOLATILES

One potential method to increase honey bee, Apis mellifera L., pollination in alfalfa, Medicago sativa L., seed fields is to develop populations that emanate greater quantities of honey bee attractive floral volatiles. Our study was designed to determine the concentrations for five antennally perceived alfalfa floral volatiles-cis-3-hexenyl acetate, linalool, methyl salicylate, ocimene, and 3-octanone-that optimize honey bee behavioral response, and relative attraction of the alfalfa floral volatiles to honey bees. Studies were conducted in a screened flight chamber and used a single colony of italian honey bees. Linalool was the only compound attractive to honey bees at the optimized concentration. Two other compounds, 3-octanone and methyl salicylate, were repellent. The remaining two compounds, cis-3-hexenyl acetate and ocimene, were neither attractive nor repellent when compared with the blank sample. Honey bee defensive behavior was observed when bees were exposed to cis-3-hexenyl acetate. Behavioral response to combinations of these floral volatiles was not determined. Present data suggest that plant breeders should simultaneously select for increased relative concentration of linalool and decreased relative concentration of both 3-octanone and methyl salicylate in the floral aroma to enhance honey bee visitation of alfalfa.