Abstract
Chemical pesticides are commonly used during the cultivation of agricultural products to control pests and diseases. Excessive use of traditional pesticides can cause environmental and human health risks. There are ongoing searches for new plant-derived pesticides to reduce the use of chemical pesticides. In this study, tea saponin extracts of different purities were extracted from Camellia oleifera seeds using AB-8 macroporous resin and gradient elution with ethanol. The insecticidal effects of the tea saponin extracts were evaluated by contact toxicity tests and stomach toxicity tests using the lepidopteran pest of tea plantation, Ectropis obliqua. The total saponins extracted using 70% ethanol showed strong contact toxicity (LC50 = 8.459 mg/L) and stomach toxicity (LC50 = 22.395 mg/L). In-depth mechanistic studies demonstrated that tea saponins can disrupt the waxy layer of the epidermis, causing serious loss of water, and can penetrate the inside of the intestine of E. obliqua. After consumption of the tea saponins, the intestinal villi were shortened and the cavities of the intestinal wall were disrupted, which resulted in larval death. This study highlights the potential of tea saponins as a natural, plant-derived pesticide for the management of plant pests.
Highlights
Tea is one of the most popular non-alcoholic beverages in the world today, favored for its unique aroma and taste [1]
Tea saponins were extracted from Camellia oleifera seeds using ethanol and purified using
The extracted tea saponins were analyzed by High-performance liquid chromatography (HPLC) (Figure S2)
Summary
Tea is one of the most popular non-alcoholic beverages in the world today, favored for its unique aroma and taste [1]. Ectropis obliqua Prout (Lepidoptera:Geometridae) is a chewing defoliator in tea plantations, causing devastating effects on the quality, yield, and growth of tea plants [2,3]. E. obliqua is the primary target pest in tea cultivation [5]. E. obliqua is mainly controlled by chemical pesticide spraying [6]. Tea is a direct receptor of aerial pesticides, and pesticide residues may cause food safety and other issues. Studies have shown that only a small amount (about 0.3%) of pesticides can enter the target organism and that most pesticides (99.7%) will eventually enter the environment, posing environmental safety hazards [7]. Plant-derived products can be more environmentally friendly and can represent cost-effective alternatives to control phytophagous insects and plant-pathogenic microorganisms. Biological control of this pest has become the method of choice [5]
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