The Valorization of Spent Coffee Grounds Extract as A Prospective Insecticidal Agent Against Some Main Key Pests of Phesolus Vulgaris in Laboratory and Field

Abstract

Exploiting massive amounts of food and agro-waste represents a severe social, economic, and environmental issue. Under the growing demand toward food products free of toxic synthetic insecticides, the methanolic extract of spent coffee grounds (SCGs), which represent the main by-product of coffee production, was applied in the current study as a bioinsecticide against the main pests of the green bean; Spodoptera littoralis, Agrotis ipsilon, Bemisia tabaci, Empoasca fabi and Aphis craccivora. Deterrent assay, contact bioassay, and lethal concentration analysis were performed to reveal the repellent, antifeedant, and oviposition deterrent effects. Parallel to the above-performed bioassays, the phytochemical composition of the SCGs methanolic extract was investigated via High-Performance Liquid Chromatography (HPLC) analysis. Fourteen phenolic acids and five flavonoids in addition to caffeine (alkaloid) have been identified in the extract. Cinnamic, rosmarinic, and gallic acids were the predominant phenolics, while apigenin-7-glucoside was the main flavonoid, followed by naringin, catechin, and epicatechin. The extract of SCGs showed an insecticidal effect, with mortality between 27.5-76% compared to the control (7.4%) and based on the concentration of the extract used. In the same trend, oviposition efficiency revealed different laid egg batches (0.67, 2.33, 7.33, and 8.67 batch/jar) for 100, 50, 25% of the SCGs extract and control. Finally, the major components of SCGs extract were docked into insecticide acetylcholinesterase enzyme to explore their potential of inhibition, where apigenin-7-glucoside showed a higher binding affinity, followed by catechin, compared to the control (lannate). Obtained findings could be a starting point to develop novel bioinsecticides from SCGs.