The Insects’ Community Structure On Eucalyptus Forests And Castanopsis Hystrix Forests With Compared On Biological Characteristics In Their Pest Porthesia Scintillans

The Eucalyptus plantation soil of Guangxi has taken the largest area in China.So the ecological problems of the Eucalyptus plantation soil are rampant at the same time. Eucalyptus pests problem has become an ecological disaster. In order to know the influence of insect community in plants near by the Eucalyptus. The thesis doesresearch in two aspects:firstly, investigating the insect community structure in Eucalyptus. Castanopsis hystrix and the two forest near the boundary line, and analyzing the influence between the Eucalyptus and Castanopsis hystrix by comparing the Species richness, species abundance, index of diversity and evenness, secondly, choosing thePorthesia scintillans who could feed both the leaves of Eucalyptus and Castanopsis hystrix to analyze the influence of the two plants to the behavior habits.Each stage of survival, development duration of the Porthesia scintillans, and explore the causes of the difference above by the analyzing the Leaf blade composition of Eucalyptus and Castanopsis hystrix. The results are as below.1. In the investigate e in Eucalyptus, Castanopsis hystrix and the two forest near the boundary line,15orders,74families,148species and a number of12874individuals insect and meanwhile2orders,8families,28species and a number of459individualsArachnoidea are found in the four types of woodland, among which10orders,38families,57species and a number of3463individuals insect are found in the Eucalyptus,and12orders,43families,71species and a number of3139individuals insect found in the Eucalyptus forest near the boundary line,15orders,61families,98species and a number of3047individuals insect found in the Castanopsis hystrix forests near boundary line,15orders,53families,82species and a number of3225individuals insect found in the pure stands of Castanopsis hystrix.11orders,22families,31species are found both in the Castanopsis hystrix and Eucalyptus.2. The index of diversity and evenness in the Castanopsis hystrix is higher than the ones in the Eucalyptus. The insect diversity index and richness of four types of forest have same sort,that is,Castanopsis hystrix forests near boundary line> pure stands of Castanopsis hystrix> Eucalyptus forest near the boundary line> pure stands of Eucalyptus. The number of orders, families and specie in pure stands of Eucalyptus is the smallest, while it has the largest number of individuals.3. The plants the two forest near the boundary line has a mixed effect like Intercropping.The number of orders, families increasing while the number of individuals declining. The number of injurious insect Lepidoptera nearby the two forest near the boundary line increased, and several kind of injurious insect nearby the two forest near the boundary line are more harmful. Planting the No.9Eucalyptus and Castanopsis hystrix nearby each other would cause potential adverse effects.4. The influence of behavior habits by feeding different diets for Porthesia scintillans is that the larvae would feed the leaf vein of the Eucalyptus, while wouldn’t feed the leaf vein of the feed the leaf vein of the Castanopsis hystrix. Porthesia scintillans fly more frequently if they feed the leaves of the No.9Eucalyptus in the larvaehood. And the spawning behavior of the insect after eclosion differs when they feed differently in the larvaehood.5. The difference of survival rates in larval stage of Porthesia scintillans feeding on different food were not significant, but in the pupal and adult stage, norms like the emergence rate, lowest fecundity, highest fecundity, average fecundity per female, number of eggs per egg mass of Porthesia scintillans feeding on leaves of Castanopsis hystrix were significantly higher than those feeding on leaves of Guanglin No.9Eucalyptus.6. The difference of developmental durations of Porthesia scintillans feeding on different food were not significant, but the duration was shorter of Porthesia scintillans feeding on Eucalyptus leaves of Guanglin No.9. For parasite development, food intake of different food of Porthesia scintillans larvae of the same age was closely related to its parasite development, and with bigger Eucalyptus leaf area intaken, the parasites growth would be better.7. The difference of leaf soluble sugar and tannic contents between Guanglin No.9Eucalyptus and Castanopsis hystrix was not significant. The soluble protein of Guanglin No.9Eucalyptus leaves was significantly higher than Castanopsis hystrix leaves, which could make the parasites feeding on Eucalyptus accumulate more nutrition and develop better. The total phenol content of Guanglin No.9Eucalyptus leaves was significantly higher than Castanopsis hystrix leaves, which could lead to insects resistance decrease if large amounts of Guanglin No.9Eucalyptus leaves were intaken, and more easier to catch diseases and die.8. Comprehensively comparing the effects of feeding on different food on Porthesia scintillans, feeding on Castanopsis hystrix was better for Porthesia scintillans individual survival and increase in population, while Eucalyptus could provide suitable habitat for Porthesia scintillans, which was the potential factor of Porthesia scintillans outbreaking into disaster.