Study On Egg Parasitoids Of Masson Pine Caterpillar (Dendrolimus Punctatus Walker) Under Different Host Population Densities

To study the relationship between Dendrolimus punctatus Walker population dynamics and its egg parasitoids, we set up 30 stand plots in Jinsishan Forest farm, Dongzhi Country, Anhui from 2004 to 2005. Pest density, the species and quantity of parasitoids, data of forest site conditions and chemical control were surveyed in this time. As a result, Trichogramma dendrolimi Matsumura, Telenomus dendrolimusichu Matsumura, Telenomus dasychiri Chen et Wu, Pseudanastatus albitarsis Ashmead are the main egg parasitoids of Dendrolimus punctatus Walker. The data indicated that the parasitism of Pseudanastatus albitarsis Ashmead is the highest among the four species, the second is Telenomus dendrolimusichu Matsumura and Telenomus dasychiri Chen et Wu, the last is Trichogramma dendrolimi Matsumura. The analysis with forest stand factors and chemical control showed that the parasitism rates were at a high level when the pest density was low. The result of correlation analysis showed that the caterpillar densities of previous generation could affect the parasitism rates of following generation. There are no correlations of three parasitism rates in the same generation and different generations. The parasitism rates in forest edge are higher than that in forest center.