Sublethal Effects Of Imidacloprid And Fenpropathrin On Cydia Pomonella

Codling moth(Cydia pomonella L.), which can make the fruits falling from trees after entering into fruits, and make the fruits losing commercial value even no yields, often cause serious losses to the farmers and can be controlled by chemical measurment. After using pesticides, the target enzyme and metabolic enzymes of insect can be influenced by the sublethal effects of pesticide, and the others including eco-behavior, fertility changes, growth and development and resistance development to a certain extent and so on can be influenced as well. To Clarify the effect of sublethal dose of insecticides on Cydia pomonella, the two common insecticides imidacloprid and fenpropathrin were choosed to test LC10 and LC20 concentrations on Cydia pomonella, then the developmental duration and developmental situation were observed, as well as the time-effect of MFOs, GSTs and Car Es, and its Km and Vmax values were analyzed after treated with the dose of LC10 and LC20. Which aimed to clarify the resistence generation mechanism and provide the theoretical basis on proper using of pesticide. The results are as bellow:1. By using stomach toxicity method, toxicity of imidacloprid and fenpropathrin to codling moth 2 and 3 instar larval were measured using stomach poison method. The results show, imidacloprid LC10 and LC20 concentration to codling moth 2 and 3 instar larval was 5.842 mg/L and 9.003 mg/L, 10.772 mg/L and 22.764 mg/L; fenpropathrin LC10 and LC20 concentration to codling moth 2 and 3 instar larval was 1.851 mg/L and 2.808 mg/L, 3.035 mg/L and 4.650 mg/L.2. By using biochemical analysis, the activity and enzyme dynamic parameters of Car Es, MFOs, GSTs were tested, of which codling moth 3 instar larval was treated by imidacloprid and fenpropathrin LC10 and LC20 concentrations. The results show, after treated by imidacloprid LC10 concentration, the activity of Car Es, GSTs, MFOs were maximum at 12 h, 48 h and 36 h, respectively; after treated by imidacloprid LC20 concentration, the activity of Car Es, GSTs, MFOs were maximum at 36 h, 12 h and 36 h, respectively. The Km of Car Es and MFOs magnified at all time point, but Vmax decreased; The Km of GSTs decreased at all time point, but Vmax magnified.After treated by fenpropathrin LC10 concentration, the activity of Car Es, GSTs, MFOs were maximum at 24 h, 12 h and 36 h, respectively; after treated by fenpropathrin LC20 concentration, the activity of Car Es, GSTs, MFOs were maximum at 12 h, 24 h and 24 h, respectively. The Km of Car Es magnified at all time point, but Vmax decreased; The Km of GSTs and MFOs decreased at all time point, but Vmax magnified.3. By using life table technology, the developmental duration, pupation rate, eclosion rate, the average egg numbers oviposited by one female, hatching rate and population life parameter of codling moth were tested, which was treated by imidacloprid and fenpropathrin LC10 and LC20 concentration. The results show, after treated F0 generation of codling moth by imidacloprid LC10 and LC20 concentrations, the developmental duration of 3th, 4th and 5th instar larvaes of F0 generation were shorter, but the pupae developmental duration, longer. The developmental duration of the F1 generation was not affected, but pre-oviposition period was longer, number of eggs per female and adult longevity was lower. The mean generation time and instrinsic growth rate were lower, the net reproduction rate and finite increase rate were little changed, and the population doubling time was little lower.After treated F0 generation of codling moth by fenpropathrin LC10 and LC20 concentrations, The developmental duration of 3th, 4th, 5th instar larvae and pupae of the F0 generation were longer. And pupation rate, emergence rate, number of eggs per female, hatchability of F0 generation were lower, respectively, however adult longevity was non-significantly changed. The developmental duration and pre-oviposition period of the F1 generation were longer, respectively, total oviposition period and adult longevity were shorter, and number of eggs per female was lower. The finite increase rate, net reproduction rate and intrinsic rate of increase were lower, but the mean generation time and the population doubling time were longer.