关键词: 异色瓢虫, 呋虫胺, 亚致死效应, 捕食功能, 生长发育

Abstract: 【Aim】 To explore the effects of aphids treated with sublethal concentrations of dinotefuran on the predation function and growth and development of Harmonia axyridis, so as to provide the theoretical basis for protection against natural enemies and utilization of natural enemies of pests and effective management of wheat aphids. 【Methods】 H. axyridis larvae of various instars were fed with the 3rd instar nymphs of Sitobion miscanthi treated with sublethal concentrations (LC₂₀ and LC₃₀) of dinotefuran by leaf-dipping method. After being fed with aphids treated with dinotefuran, the predation amounts N_a, instantaneous attack rates a, handling time T_h, daily maximum predation amounts N_a-max, predation efficiency a/T_h and duration of various developmental stages of H. axyridis were detected and calculated. 【Results】 The predation of H. axyridis larvae on the 3rd instar nymphs of S. miscanthi fitted with the Holling’s disc equation. Fed with the 3rd instar nymphs of S. miscanthi treated with LC₂₀ and LC₃₀ of dinotefuran, the handling time T_h of H. axyridis larvae on S. miscanthi extended, the instantaneous attack rates a, daily maximum predation amounts N_a-max, and predation efficiency a/T_h reduced as compared to those in the control group (H. axyridis larvae fed with the 3rd instar S. miscanthi nymphs non-subjected to dinotefuran treatment). The predation efficiency a/T_h of the 1st instar larvae was most significantly affected by LC₂₀ and LC₃₀ of dinotefuran among all instars, being reduced by 24.03% and 50.48%, respectively, as compared with those in the control group. The searching efficiency of H. axyridis larvae on S. miscanthi nymphs showed different degrees of decline, and the duration of H. axyridis larvae of various instars was prolonged at varying degrees. The inhibitory effect of aphids containing pesticides on the predation function and growth and development of H. axyridis increased with the increase of dinotefuran concentration. 【Conclusion】 The predation function, growth and development of H. axyridis could be inhibited by feeding on the 3rd instar S. miscanthi nymphs treated with sublethal concentrations of dinotefuran. Pesticide spraying should be done during the peak period of the 4th instar larvae of H. axyridis with the highest predation efficiency and minimized impact by pesticides, which may help reduce the negative effects of pesticides during aphid control and enhance the protection and utilization of natural enemies.

Key words: Harmonia axyridis; dinotefuran, sublethal effect, predation function, growth and development