Effects Of Neem With Trunk Injection On Pear Trees, Insect Pests And Natural Enemies

To supply the theory foundation for developing of neem formula with trunk injection, the effects of neem with injection on pear trees, insect communities of pear orchard, as well as the control effects on major pests were studied by referring to the methods of community ecology and population ecology. The main contents and results are as follows:1. Neem injection of pear trees had no adverse effects on the growth of leaves, fruits, as well as the yield of pear trees.2. Effects of different control measures on insect community of pear orchard are as follows.The insect species of pear orchard treated by neem with trunk injection (calls "injection orchard" as follows) were similar to that of chemical control orchard. However, significant differences in the numbers of species between them were observed. Injection orchard had a minimum number of pests, followed by chemical control orchard; the numbers and dynamics of natural enemies between the two orchards were similar except Stehoconus japonicus. The diversity and stability indexes were very similar to each other between injection orchard and chemical control orchard, while were different to that of CK orchard.3. Effects of neem with trunk injection on major insect pests of pear orchard are as follows.The species number and total number of Coleoptera and Lepidoptera pests in injection orchard were significantly lower than that of the other two orchards, which were mainly due to the molting of larvae caused by injection. In addition, neem with trunk injection could effectively control the population of Stephanitis nashi, Aphis citricola, Psylla chinensis and other small scale insects with piercing and sucking mouth parts. However, neem injection had no satisfactory effects on Grapholitha molesta.4. Effects of neem with trunk injection on natural enemies of pear orchard are as follows.There were significant differences between different types of predators. Generally, neem injection had larger influence to Stethoconus janponicus than Menochilus sexmaculatus, which has a wider extent of feeding sources than the former.5. Control effects of neem with trunk injection on Stephanitis nashi are as follows.The control effects on Stephanitis nashi of neem with trunk injection enhanced as the dose increased. According to it, the corrected control efficiency was more than 70% under the dose of 0.12g active ingredient/cm trunk diameter 28 days after injection, which could be served as an effective dose to control Stephanitis nashi.