(Z)–11–hexadecenyl acetate and (Z)–13–octadecenyl acetate improve the attractiveness of the standard sex pheromone of the yellow rice stem borer Scirpophaga incertulas (Lepidoptera: Pyralidae) in northern Vietnam

The attractiveness of a combined lure containing the pheromone components of the yellow rice stem borer Scirpophaga incertulas (Walker) and the rice leaf folder Cnaphalocrosis medinalis (Guenée) to mixed populations of the two species was tested in northern Vietnam. Rubber septa lures containing a 1:3 ratio of (Z)–9–hexadecenal and (Z)–11–hexadecenal were tested alone and in combination with a 1:1 blend of (Z)–11–hexadecenyl acetate and (Z)–13 octadecenyl acetate in field experiments in summer rice crops at two locations. Lures containing (Z)–9–hexadecenal and (Z)–11–hexadecenal were attractive to S. incertulas males. The addition of (Z)–11–hexadecenyl acetate and (Z)–13–octadecenyl acetate significantly improved catches by 120% on average in five out of six replicated field experiments. No C. medinalis were captured, confirming previous research that the blend of (Z)–11–hexadecenyl acetate and (Z)–13–octadecenyl acetate is not attractive to this species in northern Vietnam. Ovipositor washings from virgin female S. incertulas collected from rice crops in Vietnam were analysed by gas chromatography coupled to mass spectrometry. Hexadecanal, (Z)–9–hexadecenal, (Z)–11–hexadecenal, (Z)–9–octadecenal, and (Z)–11– hexadecen–1–ol were detected in relative amounts of 18:34:100:20:54 with (Z)–11–hexadecenal estimated to be present at up to 5 ng/female. Traces of (Z)–11–hexadecenyl acetate were also present, but (Z)–13–octadecenyl acetate was not detected. Add one or two sentence(s) to give short conclusion and/or interpretation of the results