Study On The Disaster Forecast Of Masson Pine Caterpillar Dendrolimus Punctatus(Walker)

Pine Caterpillar {Dendrolimus spp.) is the most important forest pest in China. It damages 2 million hm2 of pine stands and causes economic lose about 2 billion RMB per year. The key to control the pine caterpillar disaster is to forecast, which is to collect the pest information from forestland on time and deal with it scientifically. This paper mainly studies on disaster forecast of Dendrolimus punctatus in Guangxi, which is included in damaging period forecast, damaging area forecast, damaging degree forecast, and evaluation to the forecasts. The research results are as follows:1 .Based on the integrated damage index, the pine caterpillar damaging forests can be divided into three groups: severe damage area, moderate damage area and non-damage area. The severe damage stands is in 55 counties, which is 238,117 hm2 and covers 6.3% of the total pine stands in Guangxi. The moderate damage stands is distributed in 25 counties, which is 874,255 hm2 and covers 23.2% of the total pine stands. The non-damage forest is in 26 counties, which is 2,667,289 hm2 and covers 70.5% of the total pine forest. The paper studies the concepts, characters and their relations of severe damage area, moderate damage area and non-damage area.2. Dendrolimus punctatus's active periods can be forecasted by the phenomena of Gossapinus malabaria and Masson pine (Pinus massoniana). The hibernation larvae begin to feed pine needles after hibernation when Gossapinus malabaria begin to germ.3. Markov chain, GM (1,1) and other population forecasting models have been set up.Based on these models. Middle and long term of population dynamic forecasts for Dendrulimus punctatus disasters were made several times respectively in Guangxi Province and the correct rates were 70-95%.4.Forecasting models of pine needle quantity losing, timber growth losing and pine gum quantity losing for Dendrolimus punctatus damaging pine stands have been established.5.Control standards of Dendrolimus punctatus damaging slash pine stands are as follow: 2-4 years old stands shall be protected and control the pest population density when their needles lost 20%.5 -9 years old forests shall be protected when their needles lost 30%;over 10 years old trees shall be protected when their needles lost 40% or more.6. Dendrolimus punctatus larvae can be divided into two groups according to their body color: black larvae and yellow ones. The population density of the pest in stands is related to the ratio of black/yellow larvae. The higher the ratio of black/yellow larvae, the more the population density is. Population forecasting models have been set up according to the ratio of black/yellow larvae. This paper studies the biological and ecological characters of the larvae.7.The program has been lasted for 12 years and its research results have been extended all over Guangxi province. The results have reduced and saved a lot of control cost and produced 833 million RMB benefit since 1991.