Study On The Toxicity,Developmen And Reproduction Of Cyclosporin A To Mythimna Separata,Helicoverpa Armigera And Ostrinia Furnacalis

Henan Province is located in Huang huai hai alluvial plain,in which corn production plays an very important role in grain production.It is of great significance to control insect pests in corn field for the stable improvement of corn yield in our province.At present,there are some problems in pest controlling in maize filed,such as excessive use of pesticides,increasing pest resistance,imbalance of farmand ecosystem and serious environmental pollution.In order to solve the above problems,exploiting new pesticides with high efficiency,low toxicity and low residue,or finding the synergists of current pesticide are effective methods.Cyclosporine A is a kind of immunosuppressive drug,which can inhibit the insect immune system,and has a certain insecticidal activity.As a secondary metabolic product of biological source,Cyclosporine A shows differenttoxicological mechanism with that of most of pesticides,we explored its insecticidal activities against main lepidoptera pests(Mythimna separata,Helicoverpa armigera and Ostrinia furnacalis)in the maize filed and tested the mixed effects with current commonly used insecticides.1 Toxicity.and mixed effects of cyclosporin A with current commonly used insecticides on M.separata.The toxicity of cyclosporine A to the 3rd instar M.separata was determined by diet mixing bioassay,the regression equation was y=1.33x+2.53,and the LC50 was 69 μM(80 mg/L).At the same time,it had a significant inhibitory effect on bodyweight of armyworm.Meanwhile,treatments with sublethal doses of cyclosporin A lead to significant decrease of pupation rate,eclosion rate,oviposition number,ovarian tube length,adult life span of the female,amount of eggs and hatching rate of the M.separate.The insecticidal activity of Cyclosporine A against M.separatawere enhanced when it was mixed with spinosad,avermectin or Cry1Ac.The mixture of cyclosporine Ad azadirachtin showed additive effect in insecticidal activity.2 Toxicity and mixed effects with current commonly used insecticides of cyclosporin A to H.armigeraThe toxicity of cyclosporine A to the newly hatched H.armigera was determined by diet mixing bioassay,the regression equation was y=1.32x+2.16,and the LC50 was 50 μM(60 mg/L).At the same time,it had a significant inhibitory effect on the body weight of H.armigera.Meanwhile,treatment with sublethal dose of cyclosporine A caused to significant decrease of pupation rate,eclosion rate,oviposition number,ovarian tube length,adult life span of the female,amount of eggs and hatching rate of the H.armigera.The mixtures of Cyclosporine A and Cry1Ac enhanced insecticidal activity to H.armigera.3 Toxicity and mixed effects with current commonly used insecticides of cyclosporin A to O.furnacalis:The toxicity of cyclosporine A to the second instar O.furnacalis was determined by diet mixing bioassay,the regression equation was y=1.54x+1.89,and the LC50 was 100.76μM(120 mg/g).When the corn borer was fed with sublethal dose of cyclosporine A,the development duration of corn borer was significantly prolonged,the pupation rate and emergence rate were significantly decreased,the number of eggs laid and the length of ovarian tube of female corn borer were significantly decreased,and the efficacy of cyclosporine A was enhanced when it was combined with methyclovir salt or azadirachtin.The toxicity and joint toxicological evaluation of cyclosporine A to the three main lepidopteran pests showed that cyclosporine A had good insecticidal activity against the three main lepidopteran pests,and its sublethal effect could significantly inhibit the occurrence of the population.Meanwhile,it showed synergy after being combined use with pesticides.Given the excellent insecticidal activity to these three insect pests,cyclosporin A has athe potential to be developed to a new type of pesticide or the synergist.Meanwhile,the effects of cyclosporin A on insect growth and development may be helpful for the design the new pesticides,or genetically modified crops.However,the specific insecticidal mechanism and the role in the development of insect remains to be further in-depth study.