Evaluation of insecticidal activities of oroxylum indicum plant extracts against pulse beetle callosobruchus chinensis (Coleoptera Bruchidae)

Studies on insecticidal properties of Oroxylum indicum (L.) Kurz against Callosobruchus chinensis (L.) were carried out in the Department of Entomology at G.B. Pant University of Agriculture and Technology, Pantnagar, during the rabi season, 2022-23. Under laboratory conditions, different plant extracts of O. indicum leaf, bark, capsule, seed, and neem leaf are phytochemically analysed and tested against C. chinensis in methanol and hexane solvent at different concentrations. In the evaluation of different extracts for contact and fumigant toxicity against C. chinensis, in terms of contact toxicity, the methanol neem leaf extract consistently showed the highest corrected mortality %. At 72 hrs, it achieved a corrected mortality of 85.78 % from 57.82 % after 24 hrs. The methanolic O. indicum seed extract also showed significant corrected mortality %, ranging from 61.24 % to 79.53 % from 24 hrs to 72 hrs, respectively, at a 12 % concentration. Similarly, in fumigation, methanolic neem leaf extract showed the highest mortality of 50 % after 24 hrs and 93.33 % after 72 hrs at 12 % concentration, and among the O. indicum plant extracts, methanol extract of O. indicum seed shows the highest mortality, ranging from 33.33 % to 66.67 % over 72 hrs at 12 % concentration. Different extracts were also evaluated for oviposition deterrence and adult emergence deterrence against C. chinensis; the results revealed that. At a 5 % concentration, the methanol extract of neem leaf showed the highest oviposition deterrence with a value of 84.10 %, while the methanol extract of O. indicum seed showed the second-highest deterrence at 75.47 %. For adult emergence deterrence, the methanol extract of neem leaf showed the highest efficacy with a deterrence of 87.32 % followed by the methanol extract of O. indicum seed with a deterrence of 57.97 %.