Response of Soil Nematodes to Different Pest Control Strategies in the Pear Orchard

To explore the response of soil nematodes to different pest control strategies in the pear orchard, community composition of soil nematodes in the pear orchard was investigated in Beijing. A total of 9 960 soil nematode individuals were captured and classified into 2 classes, 5 orders, 23 families and 43 genera at 0-20 and >20-40 cm soil depth in three plots:conventional plot(frequent chemical control), experimental plot-1(pesticide reduction)and experimental plot-2(pesticide reduction based on botanical pesticides), which were divided according to the different pest control strategies. The number of total soil nematodes collected at 0-20 cm soil depth in the experimental plot-1 was significantly higher(P < 0.05) than that in the conventional plot, but was significantly lower(P < 0.05) than that in the experimental plot-2.The relative abundance of bacterivores at >20-40 cm soil depth in the experimental plot-1 and the experimental plot-2 were significantly lower (P < 0.05) than that in the conventional plot, but the relative abundance of herbivores at >20-40 cm soil depth in the experimental plot-1 and the experimental plot-2 were significantly higher (P < 0.05) than that in the conventional plot. The value of Simpson's dominance index (λ) was higher in conventional plot, while the values of Shannon-Wiener diversity index (H') and Pielou evenness index (J) were higher in experimental plot-1 and experimental plot-2. The results indicate that frequent chemical control affected community structure of soil nematodes in pear orchard and also decreased the diversity of soil nematodes community, but pesticide reduction and application of botanical pesticide reduced the effects on the number and diversity of soil nematodes.