A study on mode of antifeedant effects of epilimonol against Leptinotarsa decemlineata

Colorado potato beetle, Leptinotarsa decemlineata (Say), neonate larvae and adults were bioassayed with the antifeedant epilimonol. Three-day exposure of neonate larvae resulted in increasing delays in development (appearance of 4th instars) corresponding to increasing dosages. At a dosage of 20 g/cm², development was delayed by about 40% without other detrimental effects. Mouthpart coating of adult beetles with epilimonol emulsion resulted in significant feeding reductions, while injection of epilimonol into the haemolymph of female adults did not elicit significant feeding reduction or oviposition suppression. The results indicated that epilimonol did not elicit significant internal toxicity, and feeding reductions were most likely exerted by action on chemoreceptors on mouthparts or in the preoral cavity.