| Systematic investigation and analysis of insect communities in wheat fields were carried out. The results indicated that there were 10 orders, 62 families, 113 species of insects, including 8 orders, 18 families, 51 species of phytophagous insects. 5 orders, 11 families, 23 species of predators; 2 orders, 12 families, 24 species of parasitoids; and 1 order, 12 families, 15 species of detritivores and bloodsuckers. Using the best sequent division method, the seasonal dynamics of insect communities was analysed in two years and the control strategies in different periods were given. Moreover, the seasonal dynamics and structure of insect community in wheat fields were reseached from nutrient class and guild view.Two highly specific monoclonal antibodies, namly EGA-4A9 and EGA-2C4, were developed against M.avenae using hybridoma technique.The two McAbs were produced with the gut homogenate of Adonia variegate which had eaten M.avenae as immunogen and had high absorption values even they were diluted over 4.096×106 times.They did not cross-react with any other insects and predators tested. Moreover, they did not react with the A.variegate which had predated other aphids.These McAbs were tested with the methods of double antibody sandwich ELISA using SBA clonotrying system/HRP.The result showed that these two McAbs belonged to IgG2a subclass. SDS-PAGE and Western blot analysis indicated that McAb EGA-4A9 reacted with the polypeptides with molecular weight of 21 KDa and 23 KDa and MCAb EGA-2C4 reacted with the polypeptides with molecular weight of 20 KDa,22 KDa and 23KDa.The result indicated that these two McAb's combining proteins were the middle products which M.avenae had digested in the gut of ladybird beetle,and they did not have the corresponding protein zone to the M.avenae antigen.The comparasions of three types of ELISAs showed that an indirect ELISA was higher than a direct ELISA in sensitity and a double antibody sandwich ELISA was the lowest in sensitity. The sensitities of an indirect ELISA and a direct ELISA was 0.083 and 0.33μg/ml protein antigens, respectively, while a double antibody sandwich ELISA was too lowly sentitive to be able to be used. At the different temperature and meal size, the decayed curve of prey in the gut of predator became a single-peak mode which rose firstly and declined subsequently because the prey's combining protein was the middle product with M.avenae had digested. Temperature had a great effect on prey detection periods. With the temperature increasing, prey detection periods decreased. Especially when the temperature was up to 30℃,the decay rate of prey increased sharply and the dectection period was very short, only 1.17 day. At the temperature rang of 15℃to 20℃,the decay rate of prey was slower than at 25℃and the detection periods prolonged from 3.10 to 3.52 days. The meal size also affected the detection period remarkably. While the number of prey which consumed by predators increased from one adult to three adults, the prey detection periods lengthened from 2.80 to 4.25 days at 25℃.The monoclonal antibody EGA-4A9 was used to test the arthropod predators from the Inner Mongolla Agricultural University's wheat field. The results indicated that there were great many kinds of ladybirds and they had a great control effect on the M.avenae.Among these natural enemies, the quantities of A.variegate and Propylea japonica were the largest and their positive rates were higher than others, so they had the better control effect on M.avenae.The total positive rate of predatory natural enemies inceased with the increase of the M.avenae density. Correlation analysis indicated that the total positive rate of predatory natural enemies had a significant relation to the density of M.avenae(p<0.03).We evaluated the control effect of the major predatory natural enemies in the field using McAbs of M.avenae and investgation,and all these results provided the basis for the effective use of predatory natural enemies.
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