[Ethyl 4-methyloctanoate, major component of male pherome in Oryctes rhinoceros (L.) (Coleoptera, Dynastidae)]

Ethyl 4-methyloctanoate, which has already been described in Oryctes monoceros, has been identified, using extracts of effluvia collected from males, as being a major component of the male pheromone of O. rhinoceros. Field trials have been carried out in North Sumatra, Indonesia. Ethyl 4-methyloctanoate synthesized in the laboratory and released at 10 mg/d resulted in the capture of 6.8 insects per week per trap, whereas ethyl chrysanthemate (40 mg/d), an allelochemical compound once used as an attractant, only led to the capture of 0.3 insects, and the control none at all. The insects captured with the pheromone were 81% females, the majority being sexually mature. Discovery of this compound opens up new prospects for O. rhinoceros control.