Occurrence And Control Of Acantholyda Posticalis And Cephalcia Infumata In Luoshan,Ningxia

Acantholyda posticalis and Cephalcia infumata were two important forest pests in Ningxia Luoshan Nature Reserve.The larvae of Acantholyda posticalis and Cephalcia infumata eat the needles of Pinus oleifera and Pinus sylvestris,causing damage to forest growth and even death,and seriously endangering forest ecological health,so the control of the two species of sawfly should not be neglected.In this study,we conducted biological and ecological studies on the two species of sawfly,and also tested four biological agents to provide theoretical support and scientific basis for the green control of the two sawfly.The main research results are as follows:1.Through indoor rearing and field observation,it was found that the Acantholyda posticalis in Ningxia Luoshan 1 year 1 generation,in late April began to pupate,the first half of June reached the high adult period,adult mating soon began to lay eggs.The eggs were arranged in a single row on the needles of Pinus tabuliformis to late July after the larvae matured began to spit down the tree,in the soil under the canopy to do soil chamber overwintering.The Cephalcia infumata start to pupate in early May and fledge in early June.reached the high adult period,The eggs are arranged in a single row on the needles of Picea crassifolia and all larvae come down in late August and overwinter in the soil directly below the nest.2.Overcooling point of overwintering larvae of two species of sawfly was measured by an overcooling point tester.The overcooling point of the 4th instar larvae of was-22.4℃,that of the 5th instar larvae was-21.1℃,and that of the 6th instar larvae was-20.7℃.The subcooling points of the 4th instar larvae of Cephalcia infumata were-23.6℃,-22.4℃ for the 5th instar larvae,and-21.3℃for the 6th instar larvae.3.Field surveys of overwintering larvae,eggs and juveniles of the two species of sawfly revealed that the overwintering larvae of Acantholyda posticalis were mainly distributed in 10-20 cm of soil,while the overwintering larvae of Cephalcia infumata were mainly distributed in 0-10 cm of soil.The overwintering larvae,eggs and first generation larvae of both species were aggregated and the reasons for aggregation were determined by both their own factors and environmental factors.The occurrence of first instar larvae of both two species of sawfly were most correlated with stand density.4.The results showed that doxorubicin was the most toxic to the two species of sawfly,and the indoor lethality rate of all four agents was higher than 80%,and the field efficacy of doxorubicin and avermectin was the best.