Indoor Toxicity And Sublethal Effects Of Neonicotinoid Insecticides On Anisolemnia Dilatata

Anisolemnia dilatata is an important natural enemy of many agricultural and forestry pests.It is widely distributed,large in size,active in action,and has high potential for natural population control and biological pest control.Neonicotinoids have absorption,stomach toxicity and contact killing,and have high insecticidal activity against piercing-sucking pests such as aphids.With its high efficiency,low toxicity,broad spectrum and unique toxicological mechanism,and its characteristics of being friendly to the environment and mammals,it has become the fastest developing and most widely used pesticide type in the market in the past 30 years.In this experiment,the sublethal effect of neonicotinoid insecticides on Anisolemnia dilatata was studied,with a view to clarifying its ability of control pests and its own physiological changes under the use of neonicotinoid insecticides,filling the blank of the toxic effect of neonicotinoid insecticides on natural enemy insect Anisolemnia dilatata,and providing theoretical reference for the safe and green use of insecticides in actual production and the synergistic control of aphids by chemical reagents and natural enemy insects.The experimental results are as follows:（1）Acute toxicity test and safety evaluation of seven neonicotinoid insecticides to Anisolemnia dilatata.The acute toxicity of seven neonicotinoid insecticides to Anisolemnia dilatata second instar larvae were determined by membrane method.The LC₅₀of imidacloprid,acetamiprid,dinotefuran,clothianidin,thiacloprid,thiamethoxam and nitenpyram were17.92 mg/L,40.08 mg/L,6.83 mg/L,2.01 mg/L and 10.94 mg,respectively.The order of toxicity from high to low is clothianidin>nitenpyram>dinotefuran>thiacloprid>clothianidin>imidacloprid>acetamiprid.The risk from high to low is clothianidin>dinotefuran>thiacloprid>nitenpyram>clothianidin>imidacloprid>acetamiprid.It was determined that the LC30 of clothianidin,dinotefuran and thiacloprid in the second instar larvae of coccinella decamaculata was 0.56 mg/L,3.44 mg/L and 6.31 mg/L,respectively.（2）The effects of three pesticides LC₃₀on the predation function of Anisolemnia dilatata.After three successive generations of exposure to dinotefuran,thiacloprid and clothianidin,the third generation of Anisolemnia dilatata from F₁to F₃all belonged to Holling-Ⅱpredation functional response model,but the related parameters changed.Compared with the control group,the theoretical maximum predation,predation efficiency and instantaneous attack rate of the third-instar larvae,fourth-instar larvae and adults of the three treatment groups decreased significantly.All parameters decreased with the increase of generations.The processing time of prey was significantly longer than that of control group,and it decreased from generation to generation.The searching effect of Anisolemnia dilatata on aphids showed a downward trend from generation to generation.Among the three insecticides,the predation function of Anisolemnia dilatata in thiacloprid treatment group was the most severely inhibited,followed by dinotefuran treatment group,and clothianidin was the last.（3）The effects of three pesticides LC₃₀on the growth,development and survival rate of Anisolemnia dilatata.After three successive generations of pesticide LC₃₀exposure,the developmental duration of the third instar larvae,fourth instar larvae and pupae of dinotefuran,thiacloprid and clothianidin treatment groups was significantly longer than that of the control group.The survival rate of Anisolemnia dilatata third and fourth instar nymphs were significantly reduced,and the effects of dinotefuran and clothianidin LC₃₀on the emergence rate of each generation of Anisolemnia dilatata were not significantly different from those of the control group.Generally speaking,the negative effects of the three insecticides on the growth and survival rate of the second instar larvae of Anisolemnia dilatata are thiacloprid>dinotefuran>clothianidin.（4）The effects of three pesticides LC₃₀on the reproductive function and longevity of Anisolemnia dilatata.After three generations of continuous treatment with three neonicotinoid insecticides LC₃₀,the pre-spawning period of female Anisolemnia dilatata from F₁to F₃was significantly longer than that of the control group,and the number of eggs laid within 30days and the hatching rate of eggs decreased gradually compared with that of the control group.Compared with the control group,the life span of Anisolemnia dilatata was significantly shortened from generation to generation.Among the three insecticides tested on Anisolemnia dilatata,thiacloprid has the strongest inhibitory effect on its fecundity and longevity,followed by dinotefuran and clothianidin.（5）The effects of three pesticides LC₃₀on detoxification enzymes of Anisolemnia dilatata.By measuring the changes of detoxification enzyme activities in the short term（24 h）after exposure to sublethal doses of three insecticides,it was found that the activities of ACh E,MFO,GST and Car E in the second instar larvae of the Anisolemnia dilatata increased from F₁generation to F₃generation.According to the results of the experiment,it was shown that the four detoxification enzymes played an important role in the detoxification mechanism of thiacloprid,clothianidin,and dinotefuran by the second-instar larva of Anisolemnia dilatata.（6）Experiment on synergistic control of Anisolemnia dilatata and neonicotinoid insecticides against Ceratoglyphina bambusae in forest.The population decline rate and control effect of acetamiprid and Anisolemnia dilatata in the synergistic control of Ceratoglyphina bambusae are higher than those of acetamiprid alone or Anisolemnia dilatata released,which has an excellent control effect.