Structure Dynamics Of Arthropod Communities,Niche Of The Main Pests And Their Enemies In Cucumber Field

In this paper,there are two main research items:first,diversity and structure of the arthropod community.The dynamics of the arthropod community structure were studied using community diversity analysis,optimization cut-apart analysis.Second research item is temporal niche breadths and overlaps of the dominant pests and natural enemies.By the analysis of temporal niche breadths and overlaps,this paper discusses the interaction between domiant pests and their enemies.All the research can provide cucumber pests control with scientic data for HeXian County in AnHui province.The results are as follows:(1)Primary investigation on arthropod community in cucumber field50 species of arthropod on 100 plants cucumbers were collected and identified in cucumber field in 2006,belonging to 41 families,10 orders.Of which 27 species belonging to 20 families are the phytophagous sub-community.Of which 16 species belonging to 13 families are the predator sub-commnity.52 species of arthropod on 100 plants cucumbers were collected and identified in cucumber field in 2007,belonging to 44 families,11 orders.Of which 26 species belonging to 21 families are the phytophages sub-community.Of which 17 species belonging to 15 families are the predator sub-commnity.The dominant pests are Bemisia tabacis,Aphids,Phaedon brassicae Balys and Diaphania indicas in cucumber field;The dominant enemies are Theridonn octomacutatum Boes.et strs,Erigonidium gramincolum,Orius minutuses,Propylaea japonica,Misumenops tricuspidatuses.(2)The dynamics and structure analysis of arthropod communityRelative aboundance of phytophagous sub-community in cucumber field is 0.9609～0.9937 in 2006,Of which the promiant population is Homoptera insects;Relative aboundance of predacious sub-community is 0.0068～0.0233,Of which the the promiant population is spider enemies.Relative aboundance of phytophagous sub-community and predacious sub-community in cucumber field are 0.5008～0.9112 and 0.0769～0.4571 in 2007.The dominant concentration of the arthropod communities in 2006 and in 2007: phytophagous sub-community＞arthropod community＞predacious sub-community. Diversity indexes show the orders in two years:predacious sub-community＞arthropod community＞phytophagous sub-community.(3)The seasonal dynamic of arthropod community and different sub-communitiesThe phytophagous sub-community and the arthropod community have the same trend in terms of their individual numbers in two years.The result indicates:the individual numbers of arthropod community are affected by phytophagous sub-community.The species numbers of arthropod community and different sub-communities have the same trend in two years in growing period of cucumber,the species numbers reached the peak in the 35^th cucumber life cycle in 2006;The species numbers reached the peak in the 63th cucumber life cycle in 2007.The 2 years results indicates that species numbers of arthropod community are affected by phytophagous sub-community and predacious sub-community.The analysis of the population trend in structure of arthropod show that diversity index and evenness have the same trend,and the phytophagous sub-community is the domiant community in the arthropod community.(4)The Cluster Analysis is used to evaluate development of community structure and the important position of pest in the arthropod communityThe Cluster Analysis show the arthropod community and phytophagous sub-community can be grouped into 4 clusters respectively,and the predacious sub-community can be grouped into 5 cluster in growing period of cucumber in 2006.The Cluster Analysis show the arthropod community and the predacious sub-community can be grouped into 5 clusters respectively,and the phytophagous sub-community can be grouped into 6 cluster in growing period of cucumber in 2007.The results also reflect a dissociation trend among different classes,complex in the community structure and a transition state sometimes in the community dynamics.(5)Analysis of arthropod community dynamics in cucumber field by optimization cut-apartBased on the result of optimization cut-apart to time of arthropod community,the phytophagous sub-community and the predacious sub-community,in 2006 the periods are divided into 4 stages.In 2007 the periods are divided into 5 stages or 6 stages.(6)The Principal Components Analysis is used to evaluate the arthropod community in two years in cucumber field by the structure indices of the arthropod communityThe result indicates accumulation contribution rate of the three principal components was 98.2086%in 2006.Accumulation contribution rate of the three principal components was 99.3421%in 2007.(7)Analysis of temporal niche breadths and overlaps of the dominant pests and their natural enemies in cucumber fieldThe result in 2006 show that the breadths index of Bemisia tabacis is maximum (0.6845) and Diaphania indicas is minimum(0.1532)among the pests,breadths index of Theridonn octomacutatum Boes.et strs is maximum(0.8238)and Misumenops tricuspidatus is minimum(0.4128)among the natural enemies.Bemisia tabacis and Theridonn octomacutatum Boes.et strs have wide distribution resource and have powerful ability of resource-utilizing.While Diaphania indicas and Misumenops tricuspidatus have small distribution on resource.The overlaps index of Lycosidae vs Diaphania indicas and Misumenops tricuspidatus vs Aphids are higher,the index is 0.2343 and 0.1614 respectively.The result in 2007 show that the breadths index of Phyllotreta striolata is maximum(0.8610) and Phaedon brassicae Baly is minimum(0.2607)among the pests, breadths index of Theridonn octomacutatum Boes.et is maximum(0.9467) and Misumenops tricuspidatuses is minimum(0.4116) among the natural enemies.The overlaps index of Diaeretiella rapae vs Aphids and Clubiona japonicola vs Phaedon brassicae Baly are higher,the index is 0.1228 and 0.1174 respectively.