Efficacy of Ocimum tenuiflorum essential oil as grain protectant against coleopteran beetle, infesting stored pulses

Abstract

In the present investigation, essential oil (EO) of Ocimum tenuiflorum and its principal constituent (eugenol) was evaluated for its toxicity and mode of action against Callosobruchus maculatus. Furthermore, fumigant toxicity and germination studies on the application of O. tenuiflorum EO and eugenol against C. maculatus on different pulses was also studied. Fumigant activity studies revealed that EO toxicity was significantly (p < 0.05) influenced by concentration and exposure time. In fumigant toxicity assay without food, O. tenuiflorum EO and eugenol showed LC50 value of 278.6 and 256.5 µL/L air, respectively, at one hour exposure. Further, O. tenuiflorum EO displayed fumigant toxicity via inhibiting acetylcholinesterase activity. Pulses treated with O. tenuiflorum EO showed 70% of C. maculatus mortality at 250 µL/L air concentration after 24 h. Furthermore, these treatments didn’t affect the seed viability of the pulses tested. Hence, the application of O. tenuiflorum EO has potential scope as a botanical insecticide.