Geographical variation in female sex pheromones of the rice leaffolder moth, Cnaphalocrocis medinalis: identification of pheromone components in Japan

Sex pheromone components of the Japanese rice leaffolder moth, Cnaphalocroc is medinalis Guenee (Lepidoptera: Pyralidae) were identified from oviposito r extracts of virgin females as (Z)-11-octadecenal, (Z)-13-octadecenal, (Z) -11-octadecen-1-ol and (Z)-13-octadecen-1-ol at a ratio of 11:100:24:36 by GC-EAD, GC, GC-MS. The total amount was estimated to be ca.0.9 ng/female. F ield bioassays in Kagoshima, Japan, showed that the two aldehydes are essen tial for male attraction and the alcohols may have a synergistic effect on the aldehydes. A rubber septum containing 0.9 mg of the four components at the natural ratio was shown to be an effective lure for monitoring this pes t in Japan. The above four components are quite different from the sex pher omone components reported previously for the same species of either Philipp ine or Indian origin; components were shown to be (Z)-11-hexadecenyl acetat e and (Z)-13-octadecenyl acetate at a ratio of 98:2 in the Philippine blend and 1:10 in the Indian blend. Furthermore, in the field tests in Japan, ne ither the Philippine blend nor the Indian blend showed any attractive activ ity, while the Japanese blend attracted significant numbers of male moths. These results suggest that there are remarkable geographical variations in the sex pheromone composition of this species or there are several distinct species using different sex pheromone blends.