Occurrence Dynamics Of Primary Pests Of Vegetable In Greenhouse Vegetable In Dongtai Area And Techniques For Controlling Liriomyza Trifolii

The nearly 1.4 million acres of vegetables per year were planted in Dongtai City.They included the green pepper,watermelon,potato,cabbage,leeks,Chinese cabbage,cauliflower,and so on.Pests in vegetable have been a serious threat to the safety of vegetables in Dongtai city for a long time.Therefore,in order to effectively prevent and control the outbreak of pests on vegetables.In this study,we investigated the occurrence of major vegetable pests and detected the biological types of Bemisia tabaci in Dongtai city.A drug screening test was conducted on the important pest on the vegetable,Liriomyza trifolii.The main results are as follows:A systematic survey between 2015 and 2017 found the main insect pest(mite)damage on vegetables in Dongtai area was B.tabaci,Plutella xylostella,Pieris rapae,Spodoptera litura,Spodoptera exigua,L.trifolii and Liriomyza sativae.And the damages of B.tabaci and L.trifolii were the more serious than that of the other.Over the course of three years,the survey found the number of wintering B.tabaci was low.Soon after,the population of B.tabaci was gradually increased.In the past three years,the dynamics of B.tabaci in the peppers of greenhouses were different.Two distinct peaks could be found in 2015.There was only one peak in 2016,and there was only one peak in 2017,it was significantly higher than the peak of the previous two years.The damage of the leaf miner was also increased year by year.In 2015,the infestation rate of the leaf miner was 66.7%,and the average number of larvae channels were 67.7.In 2017,the infestation rate was 90%,and the average number of larvae channels were 44.7.At the same time,a total of 262.5 larvae channels were found in the loofa of the open field.However,the decreased trend of the number of P.xylostella was found in the Dongtai area.For example,In 2015,a total of 52,341 eggs of the second generation were collected from random 100 plants of cabbage in systemic observed site.While,a total of 7241 eggs were collected in 2017.In 2015,the first generation of P.rapae occurred lightly,and the second generation of P.rapae occurred more serious,which was similar to the occurrence of 2016.In 2017,the second generation of P.rapae occurred serious,but the amount of eggs was significantly lower than that of previous years.In 2015,the third generation of S.litura occurred lightly,and the fourth generation occurred even more lightly.The second generation of S.litura occurred lightly in 2016,and the third and fourth generations occurred in large quantities,which were the most serious years in past ten years.In 2017,the second generation of S.litura occurred lightly,the third generation occurred in large quantities,and the fourth generation occurred heavily.The occurrence of S.exigua increased year by year between 2015 and 2017.The main reason is that the area of radish in Dongtai area is being constantly expanded.In 2017,the impaired rate of S.exigua was 46.5%,and the average number per 100 plants in radish field of S.exigua were 3.7.In Dongtai area,Polyphagotarsonemus latus occurred lightly or slight lightly in 2015,2016 and 2017.In order to grasp the cryptic species of B.tabaci in the Dongtai area.The cryptic species detection of samples of B.tabaci collected from different host plants in Dongtai Town,Touzao Town,Anfeng Town,Nanshenzao Town,Xinjie Town,Jianggang Farm and Sancang Town in Dongtai City for two consecutive years in 2015 and 2016 show that the biotype of B.tabaci on vegetables in Dongtai area were all MED,and MEAM1 and other cryptic species were not detected.The pesticide screening test study of trifolii reared on celery showed that in laboratory experiments the 20%vermectins monosultap(91.95%)and cyantraniliprole(86.07%)had the best control effect on larvae,and the effect of spinetoram(94.44%)and cyromazine(94.27%)on pupae were the best.In terms of total control effect,spinetoram(99.05%)and cyromazine(97.53%)had the highest control effect.In conclusion,the control strategy of L.trifolii in Dongtai City is based on agricultural control,physical control and biological control methods.The screened pesticides with high efficiency and environmental friendliness are selected to control L.trifolii.However,in order to postpone the resistance the alternative use of pesticides should be considered.