关键词: 褐飞虱, 类酵母共生菌, 混合配剂, 种群增长, 生命表

Abstract: The brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera:Delphacidae), is a serious insect pest of rice in many Asian countries. There are many yeast-like symbiotes (YLS) in the fat-body cells of BPH abdomen. YLS has important physiological and trophic functions on the growth, development and fecundity of BPH. Because of the symbiotic relationship between BPH and YLS, it will be a new way to manipulate BPH occurrence through inhibiting YLS. Our previous study demonstrated that fungicide/insecticide mixtures could cause a marked reduction in YLS number in BPH, resulting in a significantly higher mortality of BPH than using the insecticide-imidacloprid alone. In order to identify the key developmental stages of BPH at which the fungicide/insecticide mixtures have the most effectiveness, the life table and Morris-Watt mathematical model were used as a comprehensive evaluation method in analysis of the effects of two fungicide/insecticide mixtures on the BPH population growth. The mixture of 27% toyocamycin & tetramycin P & tetrin B & tetramycin A with imidacloprid and the mixture of 75% trifloxystrobin & tebuconazole WG with imidacloprid significantly inhibited the BPH population growth. The index of population trend of BPH obtained from the treatments with the two mixture pesticides was obviously lower than that of the positive control (imidacloprid only). It can be deduced that the fungicide inhibits the growth of YLS and less YLS transmits from the fat-body to the oocyte. Using the fungicide/insecticide mixtures at the egg-hatching stage and the ovipositional stage of BPH could be an effective strategy for BPH management.

Key words: Nilaparvata lugens, yeast-like symbiotes, fungicide/insecticide mixtures, population growth, life table