Studies On The Effects Of Plant Secondary Substances On Spodoptera Litura And Control Technique To Spodoptera Litura

Spodoptera litura(Lepidoptera:Noctuidae),is one kind of cosmopolitan insect pests and damages many crops.In this paper,a systematic study was made on Spodoptera litura in the respect of plant secondary substances,pesticide susceptibility, detoxication enzyme and control by combining new type pesticide with AucaNPV etc. in order to provide scientific basis for effective control ofSpodoptera litura.1.Effects of different plant secondary substances on growth and development of Spodoptera litura.Effects of nicotine,nicotine salt,rutin on the growth and development of Spodoptera litura were investigated.All of three kind of plant secondary substances had marked influence on Spodoptera litura larvae and the effects were positively related to the concentration of seconday substances.Nicotine led to the highest mortality of Spodoptera litura,nicotine salt and rutin took the second and the last places,respectively.The effect of delaying the growth of Spodoptera litura of rutinwas greater than rose of two types of nicotine and CK.There was no marked difference between nicotine and nicotine salt.At the same time,Rutin also delayed the growth of pupae time and lightened the pupa mass of Spodoptera litura.2.Effects of plant secondary substances on the insecticide susceptibility and the activity of detoxifying enzymes of Spodoptera lituraThe susceptibilities of the 3th instar larvae of Spodoptera litura fed on diets treated with nicotine,nicotine salt and rutin to AutoNPV,Fipronil and Spinosad were studied.The activities of CarE,GST and AchE in different treated larvae were also tested.The results showed that nicotine and nicotine acid improved significantly the susceptibility of Spodoptera litura to insecticides,but the effect of rutin was the contrary.Nicotine and rutin had different degrees of influences on the activities of CarE,GST and AchE.The three plant semi-chemicals restrained the activities of CarE to different degrees,however,they induced the activities of GST and AchE.3.Effects of different crops on the livability and the activity of detoxifying enzymes of Spodoptera lituraMarked differences of the livability and the activity of detoxifying enzymes of Spodoptera litura existed between the theatments of larvae feeding on common cotton, resistant cotton,Chinese cabbage and tobacco.Larvae feeding on tobacco showed the highest mortality,resistant cotton took the second place,and commom cotton and Chinese cabbageled to the lowest mortality.Among the four host plants,Chinese cabbage was obviously the best host crop to Spodoptera litura larva and led to the greatese activity of three kind of detoxifying enzymes of Spodoptera litura.Tobacco restrained markedly the activities of CarE,while resistant cotton restrained markedly the activities of GST and AchE.4.Control effects of combining new type pesticide with AucaNPV.The toxicities of AucaNPV and Spinosad separately,to Spodoptera litura were determinded in laboratery the results showed that the LC₅₀of AucaNPV and Spinosad to Spodoptera litura were 3907.27PIB/ml,and 14.86mg/L resepectively Changing the thinner from water to 5×10⁶PIB/mLAucaNPV,the LC₅₀of Spinosad to Spodoptera litura decrease to 12.03 mg/L.Though AucaNPV increased the mortality of Spodoptera litura larva treated with Spinosad,the extent of increasing showed that improve that AucaNPV had no significant enhancing effect on Spinosed in 48h...