Studies On Bioecology And Management Of The Red Turpentine Beetles

The red turpentine beetles (Dendroctonus valens LeConte) is forest pest expand speedily which was firstly detected in Shanxi province in 1998. In recent years, it had spread to Hebei and Henan provinces and threatened pines to damage them in north and northwest in China. To control the pest and carry out the management project, the biology and ecology of the red turpentine beetles in China need be researched. Based on the investigation for three years , its biology , ecology and control measure were studied with observations in field and feeding in laboratory. The beetle occurs with one generation in one year or three generations in two years; the period of adult is 60 to 90 days; the egg period is 10 to 11 days; the larva period is 70 to 90 days and the pupae period is 12 days. The adults fly in daytime and rest in tunnel or soil surrounding ground of host tree at night. The overwintered adult begin to fly in the middle ten days of April, the flourishing period appears in the middle ten days of May and its flying is over at the end of June. The pest begin to lay eggs in the first ten days of May, the flourishing period appears in the late ten days of June, the peak period of hatching emerges in the last ten days of June to the first ten days of July. The new generation began to fly in the first ten days of September. In this period, the new adult partly fly to attack the pine when the exterior condition is adaptive, but 90 percent of new adults live through the winter in tunnel. The overwintered elder larvas started to pupate in the middle ten days of May, the peak period of pupaion in the middle or late ten days of June, and then the adults began to emerge. There is a maturation stage of 10 to 20 days before the new adult fly off from hole. Then in the first ten days of July the new adult begin to lay eggs, the peak period appears in the middle ten days of August, the eggs could be seen in the last ten days of September. The eggs begin to hatch in the last ten days of July, the flourishing period of hatch in the middle ten days of August, 90 percent of the them overwinter with elder and second or third instar larva, the others overwinter with adults when the condition is adaptive. The pupa exuviate twice with an interval 4 to 5 days; the adult mate once or more times duringlaying eggs, it laid 8 to 10 eggs everyday; there are two flying summit period in May and July to September; the beetles damage trees at the edge of stand than that inner of stand, and the trees on the north side of the hill were damaged more several than that on the sourth side of the hill, the trees of valley were damaged more than trees of hillside, trees of the low canopy density were invaded more than that of the high canopy density; the red turpentine beetles don' t like activity under the high temperature or strong ray, the adult died in a shout time when it was placed in the condition of 32 ; It is necessity that stratified sampling is used to investigate to the trees and the new stumps, and the spatial distributing pattern of the red turpentine beetles was Negative Binomial Distribution. And the control measure especially the application of eelwomu fungus and pheromone were approached; Two kinds of eelworm were selected to control the red turpentine beetles in laboratory; the mortality of the beetle could reach 75 percent when the insecticid to be used with pouring in trunk, spraying and inserting the noxious stick in the tunnal were used.