Study On The Effects Of Temperature On The Development And Control Method To Spodoptera Frugiperda

Spodoptera frugiperda（Smith）（Lepidoptera:Noctuidae）is one of top ten plant pests in the world and invaded our country in 2019.In this paper,the effects of different temperatures on the development and feeding of S.frugiperda were studied.The toxicity of 10 insecticides on S.frugiperda larvae were carried out.The predation effect of adult Eocanthecona furcellate on the first-and second-instar larvae was studied,and the comprehensive control method of S.frugiperda was discussed.The conclusions are as follow:The results of the effect of different temperatures on the development duration of S.frugiperda were showed that all the larval stages could develop normally during22.0～34.0℃.The developmental duration was shortened with the increase of the temperature.The developmental duration of the generation is 30.90d at 25.0℃.It was just took 19.13d to complete generation at 34.0℃.By fitting the linear model,the developmental zero temperature of the egg and the effective cumulative temperature were 9.10℃and 39.84 day-degree.The developmental zero temperature of the larvae and the effective cumulative temperature were 13.70℃and 250.00 day-degree.The developmental zero temperature of the pupa and the effective cumulative temperature were 13.98℃and 116.28 day-degree.The developmental zero temperature of the generation and the effective cumulative temperature were 13.93℃and 370.37 day-degree.From the Logistic model,the upper development thermal threshold of the eggs,larvae,pupa and generations were 36.99℃,33.70℃,34.91℃,and 32.44℃,respectively.In 2019,the effective cumulative temperature of the whole year of the foshan city was 3326.3 day-degree,and it could be calculated that there may occur 8～9generations of S.frugiperda in one year.The average temperature in January was lower than the developmental zero temperature of S.frugiperda,indicating that S.frugiperda usually cannot develop normally in January,and most of them were overwintering.The effective cumulative temperature from June to September was greater than that of S.frugiperda generation,indicating that it could occur at least one generation each month.The results of the feeding of the third-instar larval stage of S.frugiperda on 50kinds of plants were showed that the larvae could feed on the leaves of 37 kinds of plants,including the rice,sugarcane,corn and Eleusine indica.of the grass family;the cabbage（Brassica pekinensis）,Chinese flowering cabbage（Brassica campestris）,Brassica chinensis and mustard（Brassica juncea）of the Brassicaceae;and the longan,litchi,banana,etc.However,Its didn’t feed on the leaves of 13 kinds of plants,such as kale,watercress and balsam pear.The results of the food consumption of the 2nd～6th instar larvae on the leaves of9 kinds of plants,including the corn,sugarcane and tobacco at different temperatures were showed that the food consumption in a day of different larval stages was increased with the increase of the temperature.The 2nd～4th instar larvae exhibited the most food consumption on the corn;the 5th-6th instar larvae got the most food consumption on the tobacco.It was suggested that the most favorite plants of S.frugiperda larvae were the corn and tobacco.Also,there were a large food consumption of S.frugiperda larvae on the sugarcane,pea,banana,sweet potato（Ipomoea batatas）,peanut and Brassica chinensis.In the other hand,they showed a smallest food consumption on the tomato,indicating that S.frugiperda had a low appetite for tomato.The results of the toxicity of the ten insecticides on the third-instar larval stage of S.frugiperda were showed that the LC₅₀ value of emamectin-benzoate was the smallest（0.01 mg/L）,and the toxicity index was the highest.Spinetoram was followed with an LC₅₀ value of 0.03 mg/L.The LC₅₀ values of the cyantraniliprole,chlorfenapyr,tetrachlorantraniliprole and indoxacarb were less,but they also showed a high toxicity on the third-instar larvae.However,the avermectin,bifenthrin,cypermethrin and triflufenacil had the larger LC₅₀ value but the lower contacting insecticidal activity effect.The results of the predation test of adult Eocanthecona furcellate on the first-and second-instar larvae of S.frugiperda were showed that the predation on the larvae was increased with the increase of the larval density during 20.0～35.0℃.According to the Holling-Ⅱmodel,the maximum daily predation of E.furcellate to the first-instar larvae was 476.19,and 370.30 to the second-instar larvae.Moreover,according to the Holling-Ⅲmodel,the maximum daily predation of E.furcellate to the first-instar larvae was 156.13,and 79.04 to the second-instar larvae.In our study,the Holling-III model was considered to be more accurate.