The toxicity of Sapindus saponaria and Piper hancei extracts against Bactrocera dorsalis

Botanical extract as alternative insecticides to chemical pesticides are widely studied globally. This study aims to evaluate the toxicity of ethanol extracts of S. saponaria and petroleum ether extracts of P. hancei against B. dorsalis. The two extracts were diluted into four different concentrations and applied to test tubes to form a pesticide film. Ten pairs of adult flies were introduced into the test tubes and kept for 2 hours before being transferred to the plastic box for further rearing. Mortality was observed and recorded at 3, 6, 12, 24, and 36 hours, and the corresponding LC50 values were analyzed. The results showed that the 80 mg/ml and 40 mg/ml S. saponaria extract achieved mortality rates (MR) of 96.67% and 76.67% within 36 hours, respectively, while concentrations below 20 mg/ml resulted in MR no higher than 30%. For P. hancei, the extracts of 20 mg/ml, 10 mg/ml, and 5 mg/ml caused MR of 100%, 98.33%, and 68.33% within 36 hours, respectively, while the 2.5 mg/ml extract resulted in a 30%. Notably, the 20 mg/ml P. hancei extract achieved a 91.67% MR within just 6 hours. The LC50 values of S. saponaria ranged from 151.89 mg/ml to 24.49 mg/ml from 3 to 36 hours, while those of P. hancei ranged from 12.90 mg/ml to 3.63 mg/ml. In conclusion, both botanical extracts demonstrated certain toxicity and exhibited a cumulative effect, while the P. hancei extract also showed strong knockdown effect. These results indicate that both plants have potential insecticidal activity, and further research on their detailed chemical constituents and mechanisms of action is required in the future.