Differential fumigant and contact biotoxicities of biorational essential oil of Indian sweet basil and its active constituent against pulse beetle, Callosobruchus chinensis

Pulses are important source of nutrition. Safe and effective storage of pulses till consumption is a challenging task. Spoilage of pulses by invertebrate pests occurs at both pre and post-harvest conditions. Plant based food protectants is an emerging area of grain protection. This study assessed the differential biotoxicities of Indian sweet basil (Ocimum basilicum essential oil) and its major chemical constituent estragole against the pulse beetle, Callosobruchus chinensis. GC-MS analysis of O. basilicum essential oil (EO) showed estragole (69.77%) and linalool (18.29%) as the main chemical constituent. O. basilicum EO and estragole exhibited a strong fumigant and contact toxicity giving 100% mortality against C. chinensis within an exposure period of 24 h in both without and with food conditions. LC50 of O. basilicum EO and estragole in presence of grain, were 83.33 μL/L air and 185.66 μL/L air and the LD50 values were 0.81 μL/cm2 and 1.67 μL/cm2 respectively. Furthermore, SEM analysis of EO and estragole treated C. chinensis exhibited significant changes in topology of scales on elytron. In-vitro acetylcholinesterase inhibition of C. chinensis, was moderately higher in the treatment with estragole (43.01%) than O. basilicum EO (29.03%). Besides, a significant percent of oviposition deterrence effect was noticed in EO and estragole treated grains. Thus, Indian Ocimum chemotype (O. basilicum) and its active biological compound estragole showed effective potentiality as biorational insecticide for the control of pulse beetle. The main aim of the work was to develop biorational alternative for chemical pesticides by exploring the potential insecticidal activity of O. basilicum essential oil as an ecofriendly approach. •Essential oil of O. basilicum rich in estragole exhibits differential biotoxicities against Callosobruchus chinensis.•O. basilicum EO revealed oviposition deterrence efficacy and inhibition of insect acetylcholine esterase.•SEM analysis of EO and estragole treated C. chinensis exhibited significant changes in topology of scales on elytron.