| The experiment site about 35hm2 was set up in jinjinang village of wancheng county in Changsha city during March to November 2002. The objective of experiment was that paddy pests were ecological regulation and management mainly by spiders and other natural enemies. Comparison chemical controlled fields (for short C. C. F) with integrated pests management fields (for short IPMF), results showed that the entironment and paddy based-ecosystem of IPMF was improved and optimized and abilities against the insect pests of the natural enemies were stronger in the IPMF than that in the C. C. F. The quantity of pesticide was reduced above 50% in the IPMF.l.The result of sampling natural predator on the ridge of paddyfield during spring ploughing stage showed that quantities of spiders and predatory increased markedly from the end of April to the beginning of May, which prepared for the rebuilding community of natural predator in paddyfield. So weed on ridge of paddyfield should be reserved properly on behalf of spiders during this time.2. Inverstigation of spiders community showed that dominant species of paddyfield spiders were Pirata subpirticus, Nimeliata insecticeps, Tetrgnatha maxillosa Thorell, Theridion octomaculalum Bodes in paddyfields of jinging village in 2002.3. Dominances of the major species of spiders community in the paddyfield were analysed as follows:dominance of Ummeliata insecticepsvtere larger than that of Pirata subpirticus during full growth stage of early-season paddy. However the situation was versed in middle-season paddy on August 10th . The dominance of the former fluctuated with that of the latter in later-season paddy fields. Theridio octomaculum Bdoes immigrated inpaddyfield at the end of May, whose dominance was larger than that of Tetragnatha maxillosa thorell from the booting stage to maturing stage in the fields. Theridio octomaculum Bdoes immigrated in paddyfield at tilloring prophase in early-season paddy and late-season paddy. Dominance of Theridio octomaculum Bdoes fluctuated with Tetragnatha maxillosa thorell in middle-season paddy whose dominance was larger than that of Theridio octomaculum Bdoes in late-season paddy, but smaller than that of Tetragnatha maxillosa thorell in tilloring stage of middle-season paddy and late-season paddy. Fluctuation of dominance of the major species of spiders in C. C. F was smaller than that in IPMF.4.Analysis on dynamics of spiders community indicated that richness and dynamics of spiders community in IPMF were larger than that in C. C. F. Richness and dynamics of spiders community were reduced obviously after pesticide was sprayed in C. C. F. The negative effected when pesticide was sprayed repeatedly. Richness and dynamic of spiders community reached a peak during tasseling stage and grouting stage, then declined during maturing stage.5. Investigating on 500 hills during different growth stages of early-season paddy, middle-season paddy and late-season paddy respectively, During the early-season paddy, the result of sampling predatory insects showed sum of Paederus fuscipes curtis, Verania discolor (Fabrivius), Caclosoma, Cyrtorrhinas livispennasReuter, Mictoveia horrathi of early-season paddy were 595 in C. C. F, 885 in IPMF. However, during the late-season paddy 664 in C. C. F, 924 in IPMF and during the middle-season paddy were 1128 in Nol,1172 in No2 respectively. Pesticide did harm to larva of Verania discolor (Fabricius), Microvelia horrathi. Effect of pesticide on larvae of Verania discolor (Fabricius), Microvelia horrathi was obvious.6. Survey on parasitoid showed that the peak of rate of planthopper parasiticided by Agamermis sp were at the end of June and the beginning of July in early-season paddy and in August and September in both middle-season paddy fields and late-season paddy fields. During the early season paddy the rate of planthopper parasitized by Agamermis sp were 2.4108% in C. C. F, 4.5752% in IPMF respectively, but during the late-season paddy were 2. 6234% in C. C. F, 5.4054% and were... |
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