Fumigant toxicity of monoterpenes against fruitfly, Drosophila melanogaster

• Forty monoterpenes were evaluated for insecticidal activity towards D. melanogaster.
• The (±)-citronellal and (+)-pulegone were the most toxic monoterpenes to D. melanogaster.
• The oxygenated monoterpenes exhibited high toxicity than monoterpene hydrocarbons.

Monoterpenes are the major components of essential oils from many aromatic plants, partly contributed to the insecticidal properties of essential oils. In this study, the fumigation activity of 40 pure monoterpenes against fruitfly, Drosophila melanogaster, were evaluated. Results from fumigation tests revealed that terpinolene, 3-carene, eugenol, thymol, carvacrol, isoeugenol, citral, (±)-citronellal, cuminaldehyde, (−)-verbenone, and (+)-pulegone exhibited strong fumigation activity against D. melanogaster. In addition, the (±)-citronellal and (+)-pulegone (aldehydes and ketones) were the most toxic monoterpenes to D. melanogaster with LC50 values of 0.015 and 0.02 μl/L, respectively. Oxygenated monoterpenes were found to be with higher toxicity as compared with monoterpene hydrocarbons. The present results indicated that (±)-citronellal and (+)-pulegone exhibit a potential for the development of new botanical insecticides against the D. melanogaster, suggesting that further studies of a number of medically important dipterans might be warranted.