The use of pesticides in rice can not only manage the pest but also influence non-target organisms. The rove beetle (Paederus fuscipes), which is an important predator of the brown plant hopper (Nilaparvata lugens) in rice ecosystems, was tested to investigate acute and chronic effects of emamectin benzoate. The results from this study show that the LC50 of emamectin benzoate to adults of P. fuscipes at 72 h was 3.07 (1.84-4.54) mg a.i. L-1, whereas the LC50 of emamectin benzoate to the second instar larvae of P. fuscipes at 72 h was 2.58 (1.95-3.19) mg a.i. L-1. Tested sublethal doses (LC10 and LC30) had significant effects on the second instar developmental time of P. fuscipes compared with that of the control. The LC30 dose had a negative influence on the pre-imaginal developmental duration and the feeding potential of treated P. fuscipes larvae. Additionally, the LC30 reduced the pre-oviposition period, the fecundity and the body weight of adults emerged from treated larvae of P. fuscipes. In the sublethal experiment with adults, the fecundity and the feeding potential were significantly reduced at the LC30 dose. These results revealed that sublethal doses of emamectin benzoate negatively affected the development and biological activities of P. fuscipes, and we conclude that more attention should be paid to the use of this chemical as part of integrated pest management strategies.
Keywords: Emamectin benzoate; Lethal and sublethal concentrations; Nilaparvata lugens; Paederus fuscipes; Rice.
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