Toxicity and biochemical effects of essential oils of Anethum graveolens L. and Melaleuca cajuputi Powell against Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

Laboratory experiments were carried out to find out the toxicity and biochemical effects of the essential oils (EO) of Anethum graveolens and Melaleuca cajuputi on lesser grain borer Rhyzopertha dominica. Fumigation toxicity experiment was carried out against R. dominica adults by using the essential oils of A. graveolens and M. cajuputi showed 100% and 72% mortality respectively in 40 μl/L at 24 h. Biochemical studies such as total protein, acetylcholinesterase, alpha and beta carboxylesterase, glutathione-s-transferase were carried out to evaluate the impact of essential oils on R. dominica adult. The experimental results showed that the protein content in lethal concentration (LC50) of A. graveolens (17.32 μg/μl) and M. cajuputi (15.72 μg/μl) oils decreased about 4.75%, 13.58% respectively, when compared to control (18.19 μg/μl). Both the essential oils were disturbed the normal acetylcholinesterase, carboxylesterase and glutathione-s-transferase activity when compared to control. These results proved that A. graveolens essential oils showed the potential to control experimented insect pest; hence this essential oil may be used as an alternate for synthetic insecticide to control the R. dominica.