In the 5-time field experiments and broad demonstrations, effects of volume and application formulae of several pesticides on the population densities of major inset pests and natural enemies in the soybean field were determined. Results from the Ducan’s multiple range test indicated that 300 g/ha of Omethoate (fine granule) and 45 g/ha of Fenvalerate in the seedling stage and 300 g/ha of Chloromethiuron suspensoid in the flowering stage may control pests and protect major natural enemies. Application of these pesticides in the corresponding soybean stages is an effective way that mediates the conflict between chemical and biological controls in the field. There are over 170 species of natural enemies whose hosts are known in the soybean field in China. These natural enemies play important roles in controlling the soybean pests. However, farmers still strongly rely on chemicals to control these pests because natural enemies are not able to timely curb the pest infestations when there is a pest outbreak. Frequent chemical application in a higher volume will ruin the ecological balance. The conflict between biological and chemical controls has become a hot issue in the soybean production worldwide. Our objectives in this study are to decide the effective low concentrations of commonly used pesticides, determine the effect of the third and fourth generations of pesticides on the major insect pests and natural enemies in the soybean field and propose feasible control methods by coordinating control and chemical controls.
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