Study On The Insecticidal Action Of Insecticides On Gypsy Moth(Lymantria Dispar L.)(Lepidoptera:Lymantriidae)

Toxicities of 14 pesticides to the 2nd?4th-instar larvae and spawn of Lymantria dispar(Linnaeus)were measured using in the laboratory.And in the same time the effection of fufenozide a molting hormone analogue and 20-hydroxyecdysone a plant source molting hormone was researched using transmission electron microscopy(sem)technologyThe result of toxicity text using 14 pesticides to the 2nd-instar larvae Lymantria dispar(Linnaeus)in 72h shows that the virulence of sophocarpidine is the best and its LC50 is 0.000520mg/L whose virulence factor up to 18344.23 times to chlorbenzuron.And the virulence of chlorbenzuron is the lowest.The result of six insect growth regulator to the 2nd-instar Lymantria dispar(Linnaeus)in 72,96,144,168 h shows that the virulence increased inordinately followed time extension,and reduced the gap with other drug gradually.The virulence of 14 pesticides to 4th-instar larvae shows that the virulence keeps higher level with natural organic insecticide,pyrethroids in 72h.The virulence of sophocarpidine is the best and its LC50 is 0.00173mg/L whose virulence factor up to 154331.21 times to chlorbenzuron.The virulence of chlorbenzuron is the lowest to 4th-instar and its LC50 is266.993 mg/L.The virulence of insect growth regulator pesticides to 4th-instar in 72,96,144,168 h shows that the virulence increased inordinately followed time extension which is similar to the result of 2nd-instar.Even it shows the same virulence to organophosphorus insecticides.The result that make a comparison with the virulence of 14 pesticides to 2nd,4th-instar larvae shows that the virulence reduced inordinately followed larva instar growth.The result of 14 pesticides to the death of spawn shows that cyhalothrin shows up higher poison effect,the kill rate of different dilution ratio is greater than 99%,imidacloprid takes second place.the kill rate of 500 times dilut of beta-cyfluthrin,sophocarpidine,dursban is greater than 90%,however,the kill rate drop rapidly with the dilut of agent concentration,even it is lower than 50%.Acephate shows up lower poison effect,the kill rate of 500 times dilution ratio is 5.18%.Six virulence of insect growth regulator pesticides shows up a little poison effect.The kill rate of lufenuron is the highest in the 500 times dilution ratioes which is only 68.73%.And diflubenzuron,triflumuron,methoxyfenozide,fufenozide have not obvious inbibitional effectText that the influence of fufenozide and 20E on the integument ultrastructure of newly moulted 5th instar larvae of Lymantria disper(Linnaeus)shows that two drugs can cause unnormal fatal ecdysis.It shows that the larvaes stop feeding,break away from head and,the body of treated insects became nigrescence and shrinking,and was to death.Ultrastructure of newly moulted shows that two drugs can cause the phenomenon of ecdysis,the ecdysial space started to form,and new cuticulin layer was much less than the old.In the same time,the integument ultrastructure shows that if observed the change of organelle in body wall epidermis cell.The body wall epidermis cell shows that organelle reduced obviously,a small percentage of blank space occurred around nucleolus,and the contents in cytoplasm were reduced,a large number of electron area low density appeared in the epidermal cells dealt with 20-E till to larwal death.