Analysis Of Effects Of Diets,Temperatures And Insecticides On Bradysia Odoriphaga And Bradysia Difformis

Bradysia odoriphaga Yang et Zhang and Bradysia difformis Frey,two main Bradysia insects,are important pests of vegetables and edible mushrooms.They damage together in Gansu,Liaoning,Shandong and other places,and the dominant species in different regions are different.They damage seriously,and excessive reliance on chemical insecticides in the process of control leads to the serious pesticide residues of agricultural products.At present,there are many reports about B.odoriphaga,a few studies on B.difformis.However,any comparative studies of two species has not been reported yet.In this paper,we compared the effects of diets,high temperature stress and representative insecticides on two species systematically,and determined the differences of environmental adaptability between two species.It will provide theoretical basis and technical support for more scientific use of high temperature and insecticides to control B.odoriphaga and B.difformis.The results followed:1.Constructed age-stage two-sex life tables of B.odoriphaga and B.difformis feeding on the six diets,chinese chives,oyster mushroom,fertilizer,artificial diet,onion and lettuce.Two species were found to be different adaptation in diets.For B.odoriphaga,the sequence of preference from high to low is,chinese chives,oyster mushroom,artificial diet,onion,lettuce,fertilizer,and for B.difformis,that is oyster mushroom,chinese chives,artificial diet,onion,lettuce,fertilizer.The mortality of B.odoriphaga larvae feeding on chinese chives and oyster mushroom was 8.66%and 16%,respectively,and the fecundity was 138.64 and 123.12eggs/female respectively,the mortality of B.difformis larvae feeding on chinese chives and oyster mushroom was 19.99%and 4.66%,respectively,and the fecundity was 59.48 and80.25 eggs/female respectively.2.We studied the effects of high temperature stress on the survival of larvae and the subsequent development and reproduction of survival insects and conclude that the heat tolerance of B.difformis is weaker than that of B.odoriphaga.The high temperature above 36?has a significant lethal effect on the two species,adults were the most sensitive and larvae were more tolerant to heat stress.At 38?,The LT₅₀?the median lethal time?of B.odoriphag and B.difformis female adults were 1.427 h and 0.580 h,respectively,and larvae were 2.048h and 0.580 h,respectively.Short-term heat shock adversely affected the development and fecundity of surviving larvae and B.difformis are more serious.Exposure to 38°C for 2 h,the surviving 4^th instar larvae of B.odoriphaga reduced pupation rate?90.75%?by 4.25%compared with control groups?95.00%?,declined fecundity?32.44 eggs/female?by 72.50%compared with the control groups?117.50 eggs/female?,B.difformis reduced pupation rate?69.50%?by 19.50%compared with control groups?89.00%?,declined fecundity?12.44eggs/female?by 79.52%compared with the control groups?60.75 eggs/female?.Exposure to38°C for 1 h,the surviving adults of B.odoriphaga reduced fecundity?56.63 eggs/female?by53.46%compared with the control groups?121.67 eggs/female?,reduced fecundity of B.difformis?22.50 eggs/female?by 63.16%compared with the control groups?61.08eggs/female?.Moreover,it was found that two species feeding on chinese chives were more resistant to high temperature tolerance than feeding on oyster mushroom,The difference was more obvious on B.difformis.3.Determined the effects of high temperature stress on the activity of antioxidant enzymes?POD,CAT,SOD and GSTs?on the two species.The difference between the activities of protective enzymes is the important reason for the adaptability difference of two species.Exposure to 38°C for 1 h,the POD activity of B.odoriphaga female adults were increased by 54.72%compared with control,the POD of B.difformis was decreased by 17.24%compared with control.4.Determined the toxicity difference of insecticides,and analyzed the effects of 4representative insecticides on the growth and reproduction of 2^nd instar larvae.The sensitivity of B.difformis was higher than B.odoriphaga.Botanical insecticides have significant differences in virulence of for the two species,the virulence of garlic oil on the 4^th instar larvae of the B.difformis(LC₅₀0 was 58.023 mg/L)was 2.14 times that of B.odoriphaga(LC₅₀was 124.001 mg/L).The four insecticides had adverse effects on the subsequent development and reproduction of the larvae of two species,and B.difformis was more serious,garlic oil affects on two species was difference,the 4^th instar larvae of B.odoriphaga delayed the development?14.40 d?by 0.87 d compared with control groups?13.53 d?,reduced fecundity?87.82 eggs/female?by 21.53%compared with the control groups?111.92 eggs/female?,B.difformis delayed the development?18.71 d?by 1.67 d compared with control groups?17.04d?,reduced fecundity?45.08 eggs/female?by 30.73%compared with the control groups?30.73 eggs/female?.In addition,it was found that two species feeding on chinese chives were more resistant to drug resistance than feeding on oyster mushroom,the difference was more obvious on B.difformis.5.Determined the effects of representative insecticides on the activity of detoxification metabolic enzymes?CarE and GSTs?on the two species.The difference between the activities of detoxifying metabolites is the important reason for the adaptability difference of two species.Two species larvae treated by diallyl disulfide,the GSTs activity of B.odoriphaga and B.difformis were higher than control,the activation rate were 57.61%and 24.97%,respectively.