| Phalanta phalantha(Drury)belongs to Lepidoptera,Nymphalidae,the larvae is one of which mainly damages recious tree of Homalium harnanense Gagnep.To understand the occurrence regularity of Phalanta phalantha accurately,and develop scientific prevention and microbial control strategy,this article mainly studied the biological characteristics and microbial control.The main results are stated briefly as follows:1.Biological characteristics of Phalanta phalantha(Drury)Combing laboratory with field observation,we studied the biological characteristics and happening regularity of Phalanta phalantha(Drury),it included morphologic characteristic,larval age,behavior,life history and the influence for the growth and development for Phalanta phalantha(Drury)of the temperature.The result showed there has nine overlapping generations a year in hainan.The period of damage period is from April to October.The peak of harm period are May and July.The larvae underwent 5 instars,and the head width is the most important indicators of larval instars.The cubic curve have the best fitting results,followed by the quadratic curve.Phalanta phalantha(Drury)could complete ageneration from 19? to 34?.The development threshold temperature of one complete generation were 10.605 ?,and their effective accumulated temperatures were 566.786 degree days.Accorded to the meteorological data in hainan,the average annual generation number of Phalanta phalantha(Drury)were 8.5 generation.2.Toxicities of microbial pesticides to larvae were determined in doorIt was antithesis of chemical pesticide that lambda-cyhalothrin(2.5%)anddeltam ethrin(2.5%),and water was blank control group.Toxicities of microbial pesticides to larvae were determined by leaf dipping method.The results showed that Bacillu s thuringiensis(8000 IU/?l)and avermectins(3.0%)have good control effect in the 1 arvae of Phalanta phalantha(Drury).3,5,7 days after applying insecticides,the m edian lethal concentration(LC50)of Bacillus thuringiensis(8000 IU/?l)respectively w as 441.20,316.189,221.86mg/L,and the median lethal concentration(LC50)of aver mectins(3.0%)respectively was 2.21,2.08,2.11mg/L.In the field efficacy trials,the microbial pesticides were diluted into three concentration,and it included thuringiensis(8000 IU/?l)?avermectins(3.0%)and the mixture of Bacillus thuringiensis(8000 IU/?l)and avermectins(3.0%).The chemical pesticides and water respectively as control group.It seted up three repeats.Before applying insecticides,each district was used 5 sampling method to survey,the initial population number were surveyed in five tree of Homalium harnanense Gagnep of each pot,remaining live worm number showed be srveyed after 1,3,5,7 days.The results showed the achieved prevention of avermectins(3.0%)was good in the early,but validily period was short.The achieved prevention of Bacillus thuringiensis(8000 IU/?l)was poor in the early,but achieved prevention continued to increase in the later.It had a good effect.7 days after applying insecticides,the control effect of Bacillus thuringiensis were above 80%.3.The joint toxicity of mixture of Bacillus thuringiensis to larvaeBacillus thuringiensis(800IU/?l)compounded with deltamethrin(2.5%)?lambda-cyhalothrin(2.5%)and avermectins(3.0%),and the larva's control effect of Phalanta phalantha(Drury)was determined.The best toxicities of mixture was that Bacillus thuringiensis(8000 IU/?l)compounded with avermectins(3.0%),and the cotoxicity co efficient was 149.06.It showed synergistic effect and the optimal concentration ratio was 44:1.The cotoxicity coefficient df other two mixturere spectively was 97.56 a nd 85.98,and it showed additive effect.Through the forest control trial,the larva's control effect of the mixture of Bac illus thuringiensis(8000 IU/?l)and avermectins(3.0%)was determined.The mixtur e of Bacillus thuringiensis(8000 IU/?l)and avermectins(3.0%)had certain insectic idal effect in the early,and the mixture had more control effect than Bacillus thuri ngiensis(8000 IU/?l).The mixture had a good effect. |
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