Pomelo seed oil: Natural insecticide against cowpea aphid

Abstract

Cowpea aphid (Aphis craccivora Koch) is a plant pest that causes serious damage to vegetable crops. Extensive use of synthetic chemical pesticides causes deleterious effects on consumers as well as the environment. Hence, the search for environmentally friendly insecticides in the management of cowpea aphids is required. The present work aims to investigate the aphicidal activity of pomelo seed oil (PSO) on cowpea aphids, the possible insecticidal mechanisms, its chemical constituent profile, as well as the toxicity of its primary compounds. The results of the toxicity assay showed that PSO had significant insecticidal activity against aphids with a 72-hour LC50 value of 0.09 μg/aphid and 3.96 mg/mL in the contact and residual toxicity assay, respectively. The enzymatic activity of both glutathione S-transferase (GST) and acetyl cholinesterase (AChE) significantly decreased, as well as the total protein content, after PSO treatment, which suggested that the reduction of AChE, GST, and the total protein content in aphids treated with PSO might be responsible for the mortality of A. craccivora. The GC-MS analysis revealed that PSO contained limonene (22.86%), (9Z,12Z)-9,12-octadecadienoic acid (20.21%), n-hexadecanoic acid (15.79%), (2E,4E)-2,4-decadienal (12.40%), and (2E,4Z)-2,4-decadienal (7.77%) as its five major compounds. Furthermore, (9Z,12Z)-9,12-octadecadienoic acid showed higher toxicity to aphids than both PSO and thiamethoxam (positive control). This study emphasized the potential of PSO as a natural plant-derived insecticide in controlling cowpea aphids and also provided a novel approach for the value-added utilization of pomelo seed.

High Value-Added Application of Natural Products in Crop Protection: Discovery and Exploration of Caffeoyl and Flavonoid Derivatives from Clematis brevicaudata DC. as Novel Insecticide Candidates

“…The AChE could catalyze the hydrolysis of acetylcholine to stop nerve impulses as an essential hydrolase for normal signal transduction of insects. 45 The unchanged AChE activity indicated that compounds 1 and 13 did not act as nerve poisons. Chitinase plays various roles in insects, such as turnover of cuticular chitin, immune defense, increasing potency of venom, and baculo.…”

“…The GST and CarE could activate the detoxification system and alleviate the toxicity symptoms of insects as important detoxification enzymes. , The CarE participated energetically in the resistance of pyrethroid and organophosphorus insecticides in various pest species. − In this study, CarE gained enhanced detoxification ability because of compound 1 , which further suggested that CarE was connected to the detoxification metabolism of 1 . The AChE could catalyze the hydrolysis of acetylcholine to stop nerve impulses as an essential hydrolase for normal signal transduction of insects . The unchanged AChE activity indicated that compounds 1 and 13 did not act as nerve poisons.…”