Effects Of Reducing Pesticide Control Measures On Main Natural Enemy Communities In Paddy Fields Of Zhejiang Province

Rice is one of the most important food crops in China.The occurrence of rice pests and diseases seriously affects its production and development.Under the background of advocating green prevention and control of chemical fertilizer and pesticides in recent years,it is of great significance to integrate the whole solution of rice diseases and insect pests to ensure rice production.In this study,the effects of sex pheromones and pesticides(species,dosage and combination)on the diversity of natural enemy communities in paddy fields in Zhejiang Province were evaluated by field sweeping and pot sampling identification.Toxicity of indoor populations was determined by combination of pesticide film method and egg card impregnation method in order to provide theoretical basis for integrated control of rice diseases and insect pests.The main findings are as follows.1.The species and quantity of natural enemies community in different regions were significantly different.The species of natural enemies in Jinhua paddy field were 504 from 38 species in 22 families.The species of natural enemies in Wenling paddy field were 205 from 14 specie in 10 families.The analysis of community characteristics of natural enemies under pheromone treatment showed that the effects of different quantitative attractants on natural enemy community were different,the diversity of natural enemy community decreased significantly when one sex attractant was set,and the diversity of natural enemy community occupied different niches was different when two or three attractants were set,but the diversity index of natural enemy community in paddy field was not remarkablely different from that in control.2.The results of rice stem borers control experiment showed that the richness and diversity of natural enemy communities in paddy fields were significantly decreased by chlorfenamide,Cyantraniliprole,methamidoavermectin,Bacillus thuringiensis and methoxylazide,and the differences between treatments were significant.The results of controlling delphacidae,thanatephorus cucumeris and ustilaginoidea oryzae at late stage showed that the mixture of 21% pentazole alcohol oil suspension with 10% Nitenpyram water and 1% leucine water suspension with 21% thiamethoxam water suspension significantly reduced the diversity of natural enemy communities in paddy fields.3.The indoor toxicity test of Trichogramma chilonis showed that the mortality rate of adults reached 100% after exposure to methamidoavermectin,thiamethoxam and bromocyanamide for 6 hours at the recommended concentration in the field.The mortality rates of other medicines from high to low were: pentazole alcohol > Nitenpyram > leucine > thuringiensis Bacillus > chlorfenamide.The development and emergence rate of eggs larvae of Trichogramma furnacalis treated with pesticides from low to high were as follows: avermectin < thiamethoxam < bromocyanamide < pentazole alcohol < Nitenpyram < Bacillus thuringiensis < chlorfenamide.Good compatibility of chlorfenamide and Bacillus thuringiensis with Trichogramma borer.