Soybean seeds suffer attacks of various pests that result in a decreased yield in northeastern China. Until recently, people use pesticides such as insecticides to achieve the goal of controlling pests. Chitosan extracted from deacetylation of chitin is promising candidates as a seed-coating agent to control agrotis ypsilon, soybean pod borer, and soybean aphid effectively. An experimental study on influences of chitosan with different concentrations on pest controlling and soybean growth was made in the paper. Coating based on chitosan was used as a feeding deterrent and for enhancing the germination and quality of soybean seeds. Results indicated that all chitosan coating had a significant effect on antifeeding against pests; with the increasing concentration, antifeedant rate (AR) were increased obviously, especially when in the concentration of 5%, santifeedant rate of agrotis ypsilon, soybean pod borer, and soybean aphid reached 82.89%, 87.24%, and 80.21%, respectively. Also chitosan coating increased seed germination, plant growth, and soybean yield efficiently, especially when, in the concentration of 5%, the yield was increased by about 20% compared with CK. The application of chitosan in soybean seed coated is an appropriate option to control pests replacing high-toxicity pesticides and enhance soybean yield. 1. Introduction Soybean is one of the major economic crops and famous for its rich plant proteins in China. However, during the soybean growth process, soybean suffers attacks of various pests such as agrotis ypsilon, soybean pod borer, and soybean aphid that result in considerable crop losses in northeastern China. Agrotis ypsilon is a cosmopolitan important underground pest with a wide distribution in China, which can attack many kinds of seedlings of crops and trees. Soybean pod borer is a devastating insect pest of many legume crops in tropical and semitropical regions, such as Africa and southeastern Asia. Larvae are pale-colored and feed on the floral parts and pods of legume plants, rendering them unmarketable. Plants are not killed, but a large proportion of the pods may be damaged and unmarketable. Flowers are also eaten and destroyed. Soybean aphid has a tube-like mouthpart that sucks juices and nutrients from the plant. Plants may yellow and become stunted, reducing pod and seed production if aphid populations become extremely high. The honeydew acts as a substrate for sooty mould to develop which turns the leaves black and rubbery. To prevent considerable economic losses, many studies [1–3] have developed for crop protection,
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