Studies On Structure And Dynamics Of Main Vegetables Insect Community Of Changsha

Insect community in vegetable fields was researched in this paper, including CommunityStructure, Dynamic Sequential Character, Diversity and so on. Moreover, the relationship amongeach sub-community was discussed in different vegetable fields. So the research has importantpractice meaning to ecological control on insect pests of vegetable.In this paper, the diversity, evenness and dominance of insect community in vegetable fields(the cowpeas, the sea cabbage, the eggplant and the cucumber) were analyzed by systematicinvestigation during Oct. 2005 to Jan. 2007 in Changsha. Results showed that the insectcommunity on vegetables in Changsha includes 12 orders and 51 families and 114 species. Thepests that have been defined include 73 species, which hold the 64.1% of whole community. Theenemy that have been defined include 41 species, account for 35.9%. And there is significantdifference in vegetables insect kind and quantity. The most difference of the insect communityon different vegetables shows that there are species quantitatively variation in each insectassembly.According to our investigations in the vegetable fields of suburbs in Changsha, thedominant species (or taxa) were Maruca testulalis Geyer, Plutellaxy lostella Linnaeus, Aphissp., Phullotreta striolata Fabricius, Henosepilachna vigintioctopunctata Motschulsky,Tetranychus cinnabarinus Boisduval and Diaphania indica Saunders in the group of insect pests;were Propylaea japonica Thunberg and Leisaxy ridis Pallus in the group of predator; wereTrichogramma evanescens Webstwood and Aphidius gifuensis Ashmead in the group ofparasitoid. However, the different pests appear in the different times. And in the differentvegetables, the time and damage extent of the same special pest is also different. And they hadpursuing effect to the pests.According to the dynamic analysis of insect community in three kinds of cowpea ecologicalenvironments the result indicate that, in different test area, the characteristic value of insectcommunity is significant different. The difference of the kind and quantity of insect population inthe pest's sub-community, the natural enemy's sub-community and the whole insect communityis significant. In the fragmentary planter area, the species of sub-community and their quantityare higher than the others. And their dominants were prominent. But the varying trends of thediversity index, evenness index in the large expanse of planter area was accord with that in the mix planter area, while the result in the fragmentary planter area is mach more significantdifference.According to the dynamic analysis of insect group in the sea cabbage and the eggplant eachseason indicated that, the community structure changed regular in different season, adapting theclimatic condition, temperature variation and their growth situation in Changsha. Through themethod of system clustering, the insect group in the sea cabbage field all the year can be dividedinto four classes, and the eggplant into three.