Selectivity and sublethal effects of some frequently-used biopesticides on the predator Cyrtorhinus lividipennis Reuter (Hemiptera: Miridae)

The green miridbug, Cyrtorhinus lividipennis, is an important predator of the rice brown planthopper, Nilaparvata lugens. In this study, the selective toxicity of seven commercial biopesticides for C. lividipennis was examined under laboratory conditions; abamectin was the most selective to C. lividipennis, followed by matrine and azadirachtin. Veratridine, rotenone, Bacillus thuringiensis and Beauveria bassiana showed less selectivity for C. lividipennis. Subsequently, matrine, abamectin and azadirachtin were selected for sublethal assessments with respect to C. lividipennis due to their high toxicities to N. lugens. C. lividipennis treated with sublethal concentrations (LC₁₀ and LC₂₀) of the three biopesticides could distinguish volatiles released from healthy and N. lugens-infested plants indicating that the biopesticides tested did not affect the foraging ability of surviving miridbugs. Azadirachtin decreased the consumption capability of C. lividipennis when the densities of N. lugens were 20, 30, 40 and 50 insects per vial. Sublethal concentration treatment did not impact the pre-oviposition period or egg hatchability of C. lividipennis. However, the fecundity of C. lividipennis exposed to azadirachtin and abamectin increased by 27–41% compared to the untreated individuals. In summary, abamectin or matrine together with C. lividipennis could be considered an effective, sustainable pest management strategy for rice.