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.

A low-cost and highly efficient biosorbent for the removal of fluoride from drinking water from spent mushroom compost (SMC) that was carbonized (spent mushroom compost biochar, SMCB) coated by aluminum hydroxide. Adsorption studies were performed to investigate the influence of adsorbent dosage, initial fluoride concentration, contact time, pH, and coexisting ions on fluoride adsorption. The fluoride adsorption capacity of the coated SMCB was greater than that of uncoated SMCB. Fluoride adsorption by coated SMCB followed the Langmuir isotherm model, and the maximum adsorption capacity was 36.5 mg/g. The fluoride concentration could be reduced to below 1 mg/L from an initial fluoride concentration of 10 mg/L. While the pH of the solution did play an important role in the fluoride removal capacity, with the SMCB performed well under a wide pH range, from 6.0 to 8.0. These findings indicate that fluoride can effectively be removed from drinking water using modified mushroom cultivation waste biomass.