Study on the Sawfly Pristiphora beijingensis

Pristiphora beijingensis, distributing in North China,is an important pest in poplar nursery.It attacks mainly poplar trees belonging to Section Aigeiros. With both amphimixis and parthenogenesis it can develop 8～9 generations a year in Beijing area and over-winters as prepupae in cocoon in the soil.It produces only males if without mating,but both males and females after mating. The females have five instars while males have four instars.According to the study in 1991～1992,the spatial pattern of P. beijingensis is aggregation,the basic unit is clump. Temperature is the key factor for the population dynamics,which influences emergence and hatching. Under the condition of sufficient food and suitable temperature,the population will have an exponential increase with the inner natural increase rate R0=1.4.Using PbNPV,B.t.,and entomopathogenic nematodes to control it,the mortality could reach 92.9%,100% and 85.1% respectively.