Studies On Natural Control And Community Diversity On Locusts

The specific research time was from Oct.2005 to Apr.2007, and the research sites were Huaxian, Dali and Heyang. The results are as follows:1. Through investigation in natural enemies and locust kinds on different experimental fields.8 species of locust and 13 species of natural enemy were found. The natural enemy mainly distribute in Coleoptera (4 species), Diptera( 2species), Hymenoptera (1 species) ,Orchopta( 1species),Mantedea( 1 species) and Araneae (4species).2. Through investigation natural enemies and locusts population of the community on different experimental fields and different times. We find: the amount of locust community are at the maximum in July and August, the natural enemy and the happenness of locust have a close relationship, there is a follow effect.3.The dominance of locust and natural enemy population in community is different according to different region, vegetation and time.4.There are close relationship between species richness,dominant,evenness and diversity. Commonly, when the index of species richness is large, the index of dominant is small. the index of evenness is small, the diversity may be good. The community have large power against changeness.5.The predation number of natural enemy to locust per day show: the order of the predation number to Oxya chinensis (Thunberg) is Tenodera aridifolia sinensis (Saussure)ï¹¥Cicindela lactescripta Motschulskyï¹¥Phaneroptera sinensis Uvarovï¹¥Araneae, while that to Locusta migratoria manilensis Meyen is Tenodera aridifolia sinensis (Saussure)ï¹¥Cicindela lactescripta Motschulskyï¹¥Phaneroptera sinensis Uvarov6.The functional response of Cicindela lactescripta Motschulsky adult to the first and second instar nymphs of Oxya chinensis (Thunberg) was investigated in the laboratory. The results showed that the functional responses of C .lactescripta to the first- and second-instar nymphs of O.chinensis fitted Hollingâ…¡type equation. Furthermore, obvious intraspecific interference was also found in the experiment, the average predation number, predation ratio(E) and natural enemy density(P) was described with Hassell model equations.X2 test showed that the theoretical expectation calculated fitted well with the observed value...