Analysis Of Dendrolimus Punctatus Walker Population Outbreak Dynamics With Catastrophe Models

To determine the community stability of arthropods and the dynamics of Mason pine caterpillars (Dendrolimus punctatus Walker), the cusp catastrophe models were developed based on diversity index, richness index, evenness index of defoliators, predators, parasitoids, sap sucking insects and the ratio of pests and natural enemies in Daqing Mountain in Guangxi Province during a complete outbreak of Mason pine caterpillars. The models were tested with data of Guiyang in Hunan Province and the result was in accordance with reality.Utilization of Mason pine caterpillars adults captured data in Hunan Guiyang during 2007 to 2008, the relationship between the larvae density and adults captured were made certain. The evaluationfunction is T = 3.024×(p^0.439). And the dynamics indexes were calculated. To forecast thepopulation dynamics of mason pine caterpillars, an unfold catastrophe model based on logistic equation deformation and analysis table were constructed.The results showed that during the outbreak process of the pine caterpillars, the arthropod communities in the outbreak areas were apparently unstable; in the non-outbreak years, the arthropod communities in the outbreak areas were in a sub-stable state; in the non-outbreak areas, the insect communities were in a sub-stable state in outbreak years, and the arthropod communities were apparently in a stable state in non-outbreak years. During the increasing phrase of the pine caterpillars, the non-stable state of communities would most likely lead to their outbreak. During the declining phrase, if the system was still in a non-stable state, it would also lead to consecutive outbreak, depending on the effects of various factors. The outbreak takes on nonlinear and catastrophic characteristics. Defoliators are the most important regulating factors.A system with various groups evenly related is relatively stable. Pest outbreaks are the expression of the arthropod communities that tend to be stable. This study demonstrates that the cusp catastrophe models can be applied to forecast the stability of arthropod communities and the dynamics of Mason pine caterpillars.Logistic equation deformation can be utilized to forecast the catastrophe trend of mason pine caterpillars. The equation showed that, a special U value existed. When the formulas met(?), the population of mason pine caterpillars was in stable, while if the formulas met (?), the population of mason pine caterpillarsmay breakout in a great possibility.Analysis table was developed to forecast the outbreak of mason. pine caterpillars. In the paper, types of outbreak frequency, diversity of surface vegetation H' , trend index I, needle conservation P, pest density N and stability of insects community ware adopted. The table owned the characters of easily controlled and practicability.