Sex pheromone of Callosobruchus subinnotatus

Sex pheromone produced by Callosobruchus subinnotatus females stimulates co nspecific males to walk upwind toward the source. Gas chromatographic and m ass spectrometric analyses of sex pheromone components and their hydrogenat ed derivatives suggested that the sex pheromone consisted of two short-chai n fatty acids, (E)-3-methyl-2-heptenoic acid (E32C7) and (Z)-3-methyl-2-hep tenoic acid (Z32C7). The composition of the sex pheromone was confirmed by electrophysiological and behavioral bioassays with synthetic compounds. A m ixture of 5 ng E32C7 and 5 ng Z32C7 elicited a 2.1-mV male EAG response, wh ereas the solvent control elicited 0.1 mV. Mixtures of the two compounds at various ratios were attractive to males in Y-tube bioassays. A pitfall-typ e trap equipped with a lure impregnated with 1 ng E32C7 and 1 ng Z32C7 was effective in trapping males. Traps baited with the lure caught 80% of males in a glass aquarium during nighttime and 50% during daytime, whereas contr ol traps (solvent treated) in a separate aquarium caught 20% and 10%, respe ctively.