Study On Insect Community Structure And The Growth Characteristics Of Defoliator In Eucalyptus Plantation

As one of the main timber species in southern China,eucalyptus has developed rapidly in Guangxi and Guangdong in recent years.In order to pursue high economic benefits,a large area of eucalyptus planting has been carried out,which has also brought huge hidden dangers to the forest structure and ecosystem in southern China.In order to understand the insect community structure of contiguous eucalyptus forest and adjacent contiguous tree species,this paper analyzes the species diversity index,richness and evenness index of eucalyptus insect community,and the main foraging leaf insect pests,The research on the growth habits of the two-line venomous moth and the scorpion moth provides a theoretical scientific basis for the prevention and control of eucalyptus plantation pests.The main findings are as follows:(1)The pupal emergence rate of different leaf eating insects is:eucalyptus forest>eucalyptus forest at the junction of mixed forests>eucalyptus forest at the road junction,The diversity index of Eucalyptus forest was significantly higher than that of the forest at the border,and The evenness of insects in the forest land at the junction was significantly lower than that in Eucalyptus forest;The evenness of insects in the forest land at the junction was significantly lower than that in Eucalyptus forest;At the same time,the pest investigation of Eucalyptus Plantation at the junction of different types showed that:There are many types of insect pests in pure eucalyptus forest,but the number of insect pests at the junction of other types is decreasing,It shows that eucalyptus plantation needs reasonable management and protection to reduce large area of continuous planting,which can effectively reduce the occurrence of large area of pests.(2)The pupal emergence rate of different leaf eating insects was as follows:Pelochrista sp.>Porthesia scintillans>Dappulb tertia Templeton;With the increase of insect age,form 3rd instar,the survival of Dappulb tertia Templeton feed on Eucalyptus leaves was hidher than Pelochrista sp.And Porthesia scintillans;But the worm of Porthesia scintillans larva was groth sharply,so Porthesia scintillans larva feeding on eucalyptus leaf is large in the whole larval stage.Through the comparative study on the survival rate,emergence rate,oviposition rate,growth speed and food intake of three kinds of leaf eating insects,The damage of Pelochrista sp.and Porthesia scintillans to eucalyptus is quite serious,but higher than Dappulb tertia Templeton.(3)The soluble protein content of Pelochrista sp.edible eucalyptus leaves is Significantly higher than edible eucalyptus leaves by Porthesia scintillans and Dappulb tertia Templeton;The tannin of edible eucalyptus leaves by Pelochrista sp.,Porthesia scintillans and Dappulb tertia Templeton.are the same in spring,summer and Autumn.All are highest in summer,lower in spring and Autumn.The total phenol of Pelochrista sp.edible eucalyptus leaves is Significantly higher than edible eucalyptus leaves by Porthesia scintillans and Dappulb tertia Templeton.