Seed Treatment By Cyantraniliprole To Control The Black Cutworm Agrotis Ipsilon In The Corn Field

Corn is one of the three major grain crops in our country and the grain-economy-feed ternary structure crop.Since the 20 th century,"precision seeding" technique of corn has been introduced into China,monoseeding has many advantages,such as reducing the labour cost,decreasing the quality of seed,promoting high yield,et al.The cropping pattern has been adept by more and more farmers.The key of monoseeding is to ensure “one seed,one seedling”,therefore,it is important to guarantee the emergence rate,and prevent the infection of pathogenic bacteria and pests in the seedling stage.The black cutworm,Agrotis ipsilon,is one of the major pests during the seedling stage of corn,the pest could cause a loss to corn yield via destroying the tender tissues or cut the corn stalk.At present,chemical control is still the major method of controlling the black cutworm,Agrotis ipsilon,the registered pesticides are mainly organic pHospHorus,carbamate and pyrethroid insecticides.Howerer,with the high dose and high application frequency of the same kind of insecticide,A.ipsilon have generated different degrees of resistance to these three kinds of traditional pesticides.Therefore,it is essential to develop new insecticides with new mechanism,efficiency and safety to non-target biology.Cyantraniliprole is an anthranilic diamide insecticide developed by DuPont Co.,Ltd.,which has high contact,stomach poisoning and internal absorption activity,and has a good control effect on Lepidoptera pests.In this paper,we determined the virulence and sub-lethal effects of cyantraniliprole on the A.ipsilon larvae,and determined the safe dosage of the seed coating,explicited the control efficiency and the period of preserving effect on A.ipsilon.At last,we make a comprehensive evaluation of the application prospect of cyantraniliprole on the the control strategy of A.ipsilon.Major results are as follows:1.Cyantraniliprole has high toxicity to A.ipsilon,LC50 of fourth instar is 0.354 ug/g.After treated by LC5,LC20,LC50 dosage of cyantraniliprole,the duration of larvae and pupae were prolonged significantly,the survival rate of larvae,the pupation rate of larvae,eclosion rate of pupae,the female and male adult longevity,the fecundity of per female,as well as the hatchability of eggs laid by parent adults were reduced greatly.The intrinsic rate of increase(r),the finite rate of increase(λ)and the net reproduction rate(R0)were significantly lower than that in control group.Therefore,cyantraniliprole at lethal and sublethal dosage could slow the speed of the population development of A.ipsilon.2.At 15°C,20°C and 25°C,cyantraniliprole at 2,4 and 8 g AI kg-1seed was safe on the germination and emergence of three kinds of corn(Xianyu 335,Zhengdan 958,Zhenjie 5),and cyantraniliprole could promote the growth of plant height and other physiological indicators of corn.In greenhourse,corn were treated by cyantranliprole at dosages of 2 g AI kg-1 seed and sowed,at 14 d after seedling emergence inoculated the fourth insatr,after 5 d the percentage of tillers with A.ipsilon damage was less than 10%,the morality of larvae were higher than 80%,however the damage rate was 60% ~ 90% in the control group.Therefore,2 g AI kg-1 has high effects against A.ipsilon,regared as the recommended dose of field experiment.3.2015~2016 year,in spring corn field,when artificial inoculatin of fourth instar larvae at 5d of seedling emergence,after insect inoculation 14 d the efficiency was 87.20% and 80.90%,significantly higher than that of chlorantraniliprole at same dosages of 76.02% and 67.07%;In summer corn field,the fourth instar larvae were inoculated at 5d after seedling emergence,the efficiency was 85.04% and 83.67% after insect inoculation for 10 d,also higher obviously than that of chlorantraniliprole 78.25% and 73.60%.4.Corn were treated by cyantraniliprole at 2 g AI kg-1 seed and sowed,at different time after seedling emergence,the corn stalk with cyantraniliprole were collected and feed on the 3-6 instar larvae.After spring corn seedling emergence for 14 d,the mortality of 3-4 instar larvae were 80.00%~87.88%,the mortality of 5-6 instar larvae were 60.00-73.33%.After the summer corn seedling emergence for 7d,the mortality of 3-6 instar larvae was76.67%-86.67%.The growth rate and lignification degree of summer maize were significantly higher than that of spring maize,which made up the disadvantage of shortening period of preserving effect and meeting the requirement of prevention and control of A.ipsilon.