Population dynamics of brown planthopper, Nilaparvata lugens, and effects of natural enemies in organic rice field
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Key Words：organic rice, brown planthopper (BPH), Nilaparvata lugens, population dynamics, natural enemies
Abstract：To construct the ecological management system of BPH (back planthopper) Nilaparvata lugens (Stal) population, the dynamics of BPH population was investigated systematically in organic rice field, and the effects of natural enemies were studied by the means of life table technique. The results indicated that the BPH population occurred two generations in organic rice fields. The two peak periods were from the end of September to early October and the third ten days of October, respectively, in which the BPH population size was 502.3 individuals per 100 plants,and 164.5 individuals per 100 plants, respectively. The increasing rate of BPH in organic rice field was 31.76% of that in conventional rice field. The natural enemies increased rapidly after rice planted. Spiders, predators and parasites in organic rice field increased 66.10%, 166.67% and 44.24% than those in conventional rice field, respectively. To add up the effects of all kinds of natural enemy factor, predators and parasites had significant influence in controlling BPH, which EIPC value in organic rice fields were higher than that in conventional one.