Fumigant toxic activity and reproductive inhibition induced by monoterpenes on Acanthoscelides obtectus (Say) (coleoptera), a bruchid of kidney bean (Phaseolus vulgaris L.)
Résumé
The toxic activity of some characteristic monoterpenoids: p-cymene, α-pinene, camphor, linalool, terpineol, cuminaldehyde, cinnamaldehyde, anethole, carvacrol, thymol, estragole and eugenol, was tested against Acanthoscelides obtectus (Say), a bruchid pest of kidney bean (Phaseolus vulgaris L.). A fumigant toxic effect was observed and LC50 concentrations for 24h and 48h were calculated for adults. Besides this effect, a reproductive inhibition was observed. This inhibition involved female fecundity, oviposition, and the development of neonate and intracotyledonal larvae. The effects of monoterpenes on oviposition, larval penetration inside the seeds and emergence were determined. All monoterpenes revealed a more or less pronounced vapour toxicity and significantly inhibited beetle reproduction. Oxygenated monoterpenoids: carvacrol, thymol, eugenol, linalool and terpineol were identified as the most efficient compounds in both respects and the structure-activity relationship is discussed. © 1995.