Host-plant volatiles enhance the attraction of Cnaphalocrocis medinalis (Lepidoptera: Crambidae) to sex pheromone

Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae) is a notorious pest of rice, Oryza sativa L. (Poaceae). Sex pheromones and host-plant volatiles can trap C. medinalis separately. To improve the trap efficiency of synthetic sex pheromone blend, we first tested the synergistic effect of 8 host-plant volatiles, including 2-phenylethanol, 1-hexanol, 1-heptanol, ( Z )-3-hexenal, ( E )-2-hexenal, octanal, valeraldehyde, and methyl salicylate, on the attraction of C. medinalis to the female-produced sex pheromones in electroantennography. The addition of ( E )-2-hexenal, methyl salicylate, valeraldehyde, and ( Z )-3-hexenal increased electroantennogram response of C. medinalis to sex pheromones. Further behavioral testing in wind tunnel experiments indicated that additive ( E )-2-hexenal or methyl salicylate stimulated the landing behaviors of both male and female C. medinalis compared with sex pheromones alone. Field evaluations showed that mixtures of sex pheromones and ( E )-2-hexenal /methyl salicylate resulted in significantly higher catches to male moths than sex pheromones alone. Using 1:1 and 1:10 combinations of the sex pheromones and ( E )-2-hexenal, the attraction of C. medinalis to mixtures showed a synergistic effect of 95% and 110%, respectively. Furthermore, 1:1 and 1:10 mixtures of the sex pheromones and methyl salicylate exhibited a synergistic effect of 69% and 146%, respectively. These results may provide the basis for developing efficient pest management strategies against C. medinalis using host-plant volatiles and insect sex pheromones.