CHEMICAL COMPOSITION AND INSECTICIDAL EFFECTS OF AZADIRACHTA INDICA AND HELIANTHUS ANNUUS LEAVES EXTRACTS ON ANTIOXIDANT AND CHOLINERGIC ENZYMES IN WEEVILS

Abstract

Azadirachta indica and Helianthus annuus are reported to possess insecticidal potentials due to presence of a myriad of chemical compounds in them. Synthetic insecticides are not eco-friendly and could induce resistance in target insects. Certain botanical agents are capable of insecticidal actions, with no harm to the ecosystem. Fresh leaves of Azardiracta indica and Helianthus annuus were collected air-dried, pulverized and subjected to Soxhlet extraction using methanol and rotary evaporation to obtain A. indica leaf methanol extract (AILME) and Helianthus annuus leaf methanol extract (HALME). The extracts were chemically characterized using High-Performance Liquid Chromatography (HPLC). Enzyme assays were carried with the extracts against the superoxide dismutase (SOD), catalase and acetylcholinesterase of maize and bean weevils. The HPLC Chromatogram of AILME alone was found to contain β – caryophylene, trans- β – farnes, α – ionone, phytol, ascaridol, phyllene, quercetin, azadirachtol, azadirachnol, Azadirachta A, myricetin and α – funebren. However, the chromatogram of a mixture of AILME and HALME showed presence of β – caryophylene, trans- β – farnes, furostan, α – ionone, phytol, ascaridol, caffeic acid, α – amyrin, β – amyrin, α – tochopherol, quercetin, azadirachtol, Azadirachta A, avanasterol, myricetin, α – funebren,
phytic acid, lecithin and cephalin. The mixture of AILME and HALME reduced the activities of SOD, catalase and acetylcholinesterase enzymes in the maize weevil and bean weevil comparable to Dichlorvos and Phostoxin. Azadirachta indica and Helianthus annuus leaves contain compounds which could induce insecticidal actions in maize weevils and bean weevils, via oxidative and anti cholinergic mechanisms.