Effective pheromone lures for monitoring the rice leaffolder moth, Cnaphalocrocis medinalis (Lepidoptera: Crambidae)

Abstract

Several factors affecting the attractiveness of traps baited with synthetic sex pheromone components of Cnaphalocrocis medinalis were examined in the laboratory and field. In the laboratory, among the four pheromone components Z11-18:Ald, Z13-18:Ald, Z11-18:OH and Z13-18:OH, the major component, Z13-18:Ald, was shown to be essential for attraction and Z11-18:Ald was a potent synergist for the major component. The alcohols also showed an apparent synergistic effect in the laboratory bioassay when their mixture was combined with an aldehyde mixture. The addition of the geometric isomers of the four components at levels greater than 5% of the purified 4-component blend showed significant inhibitory effects on the pheromonal activity in the laboratory. In contrast, no synergistic effect of the alcohols on the aldehydes was shown in the field. A range of loadings of the pheromone rubber septa (0.01–3.42 mg) was tested and all remained attractive for at least 1 month with optimum attractiveness of 0.86 mg/septum. No significant effects were obtained when the ratio of Z11-18:Ald to Z13-18:Ald was changed. Rubber septa containing 0.86 mg of the four components ( E-isomers <5%) at the natural ratio are being effectively used for monitoring C. medinalis.