Analysis On Arthropod Community Characteristics Of Colocasia Esculenta L. And Ipomoea Aquatica Forsk Fields In Changsha

The community structure and temporal dynamics of arthropod communities were studied and the relationship between arthropod community and habitat in Colocasia esculenta L.Schott and Ipomoea aquatica Forsk fields were discussed by used the knowledge and techniques of ecology,taxonomy,statistics,and computer science in field system and laboratory breeding observation.The results will has certain practical significance for the reasonable control of the main pests in C.esculenta and I.aquatica fields.The results were as follows:(1)The composition of arthropod community in C.esculenta and I.aquatica fields: A systematic survey of arthropod communities in C.esculenta and I.aquatica fields were investigated in Hunan Agricultural University's YunYuan teaching base.A total of 74 species of arthropods were collected and recorded,belonging to 2 class,12 orders and 43 families.According to the relationship nutrition and feeding of arthropod in vegetable fields,the community were divided into five sub-communities: defoliators group,sucking group,predators group,parasitoids group and neutralities group.The defoliators group and sucking group were called as herbivorous group.The predation and parasitism groups were also called natural enemy groups.There were 42 species of herbivorous groups,26 species of natural enemies,and 6 species of neutral arthropods.The main species of herbivorous group were Prodenia litura Fabricius,Phyllotreta striolata Fabricius,Chrysolina aurichalcea and Taiwania circumdata Herbst,etc.The main species of puncture groups were aphids,Leptocorisa chinensis Dallas,and Stollia guttiger Thunberg.The main species of predatory group were the Erigonidium graminicolum Sundvall,Harmonia axyridis Papas,Tenodera sinensis Saussure,and Metasyrphus corollae Fabricius.The main species of the parasitic group were Trichogramma evanescens Westwood and Charops bicolor(Szepligeti),etc.(2)The characteristics of arthropod community in C.esculenta and I.aquatica fields.The community characteristics of two different vegetable arthropod communities were analyzed using community characteristics parameters.The results showed that the diversity index,richness index,and evenness index of I.aquatica were higher than C.esculenta,but the dominance index was lower.The changes of arthropod community of different vegetable at different time points were analyzed by the time series change and community characteristic index change of the ecological function groups of arthropod communities.The results showed that the change trends of different ecological functional groups of different vegetable arthropods were different,especially the dynamic differences between leafy and sucking groups were larger.(3)The arthropod community structure of C.esculenta and I.aquatica: The comprehensive indicators of community structure in vegetable fields were constructed and evaluated by used the principal component analysis to analyze the index of arthropod community characteristics.The results showed that Simpson diversity index was the most important measure for arthropod community structure.The relationship between the diversity index of arthropod community and other characteristic indexes were analysised by used the grey system analysis method.The results showed that the uniformity index> richness index> number of individuals> dominance index> dominance concentration degree in C.esculenta field.The richness > uniformity> number of individuals> dominance concentration degree> dominance index in I.aquatica field.(4)Effects of meteorological factors on the arthropod community characteristics of C.esculenta and I.aquatica.The relationship between meteorological factors and community characteristic index were studied.The results showed that the community characteristic index of vegetable fields was significantly impacted by the continuous heavy precipitation process and the continuous high temperature process.The migration of migratory insects were closely related to precipitation.The relationship between the the corresponding index of arthropod community characteristics and the seven meteorological factors were analyzed by the grey system analysis: maximum temperature,minimum temperature,average temperature,maximum humidity,minimum humidity,average humidity and rainfall during each survey.The correlation coefficient between the seven meteorological factors and arthropod community characteristics did not exceed 0.7.It indicated that single factor had limited impact on the artisan community characteristics index of vegetable fields.