Adaptability Of Spodoptera Litura To Grape And Screening Of Its Control Insecticides

As a worldwide pest,Spodoptera litura(Fabricius)has a wide host range and a wide range of food habits.It can occur for many generations a year and has been endangered throughout China.With the increase of the frequency of S.litura and the expansion of grape planting area in China,the area and number of populations of S.litura on grapes have been increasing,which has threatened the safety of grape production in China.However,whether the grape in China has become the host of S.litura,or the passive transfer due to the expansion of grape planting area and the reduction of conventional host,it is necessary to carry out a detailed and systematic study on the selectivity and adaptability of the host.Therefore,this study evaluated the adaptability of S.litura in different grape varieties.At the same time,the response rules of protective enzymes and detoxifying enzymes after S.litura feeding grape leaves were explored in order to reveal the adaptability between S.litura and grapes.The mechanism provides a new theoretical basis for targeted prevention and control of S.litura.At the same time,in order to effectively control S.litura,the toxicity of different insecticides on larvae and adults of S.litura was evaluated,providing guidance for the effective prevention and control of S.litura larvae and adults.found in study:Different host plants and even different host species of the same species have different effects on the growth,physiology,biochemistry,reproduction,and host selection of S.litura because of different nutrients,secondary biomass,and species.The main results were as follows:1.Different grape varieties have influence on the growth and survival rate of S.litura.The survival rates of young larvae(1~2nd instar)of different grape varieties were different.The peaks of the 2nd instars from high to low were Kyoho(0.8783)> Italia(0.8670)> Red Globe(0.8245)> Vitis amurensis Rupr.(0.7989)> Vitis davidii var.davidii(0.7968)> Summer Black(0.7754);larvae survival rate of S.littoralis feeding on different grape varieties was in the order of Italia(85.11%)> Kyoho(83.07%)> Red Globe(76.07%)> Vitis davidii var.davidii(74.33%)> Vitis amurensis Rupr.(74.07%)> Summer Black(71.66%).The weight and spawning of S.litura feeding on different grape varieties were different,but the difference was not significant.S.litura larvae feeding on different grape varieties have different effects on the growthand development of S.litura,but all can successfully complete the entire life history;S.litura feeding on different grape varieties can normally lay eggs and the eggs can hatch.As a host plant of S.litura,grapes can meet the requirements of S.litura growth and reproduction.Compared with cotton,the survival,dew weight and fecundity of S.litura larvae fed on grapes were lower than those of cotton.The age of 7th instars was higher than that of cotton 6th instars,indicating that S.litura is suitable for grapes.Degree lower than cotton.2.Adults of S.litura can lay eggs on grapes and cotton,but there are differences in preference for spawning of different host plants.The order of spawning of S.litura adults on the seven host plants from high to low was as follows: Vitis davidii var.davidii(826.67±52.07)> Italia(733.33±182.78)> Kyoho(383.33±109.29)> cotton(336.67±59.25)>Summer Black(233.33±46.31)> Vitis amurensis Rupr.(183.33±52.07)> Red Globe(173.33±54.57).Among them,Vitis davidii var.davidii and Italia are significantly higher than Summer black,Red Globe and Vitis amurensis Rupr.3.The detoxification enzymes and protective enzymes of 3rd instar larvae of S.litura feeding on different grape varieties and cotton were determined.The results showed that the specific activities of multi-functional oxidase,glutathione-S-transferase,carboxylesterase and superoxide dismutase in S.litura larvae feeding on Kyoho and Vitis amurensis Rupr.were lower than those of the other four grapes;The specific activity of MFO,GST and SOD in the3 rd instar larvae of S.litura in the leaves of Vitis davidii var.davidii was higher than that of S.litura feeding on other species.The multifunctional oxidase activity of larvae feeding on different grape varieties was higher than that of cotton.4.The toxicity of 15 insecticides against 3rd instar larvae of S.litura was determined using the method of immersion and feed immersion.The results showed that the toxicity of the 3rd instar larvae was: Emamectin benzoa>Cyantraniliprole>Betacypermethrin>Indoxacarb>Chlorantraniliprole>Fenpropathrin>Spinetoram>Cyhalothrin>Methomyl>Chlorfenapyr>Fenvalerate>Spinosad,Carbofuran,Thiocarbohydrazide,Thiodicarb,Abamectin;the toxicity order of feed immersion method to 3rd instar larvae of S.litura is: Emamectin benzoa>Cyantraniliprole>Spinetoram>Indoxacarb>Chlorfenapyr>Beta-cypermethrin>Cyhalothrin>Chlorantraniliprole>Spinosad>Fenpropathrin>Methomyl>Fenvalerate>Abamectin,Carbofuran,Indoxacarb.5.The toxicity of 14 insecticides against adults of S.litura was determined using the adult feeding method.Six insecticides with high lethality and high-speed effect against adult Tawnia were selected,i.e.Emamectin benzoa,Chlorantraniliprole,Flubendiamide,Indoxacarb,Fenpropathrin,Fenvalerate.