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Effects Of Larval Treatment With Low Lethal Insecticides On Chemical Communication Systems Of Lepidopteran Moths

Posted on:2005-08-23Degree:DoctorType:Dissertation
Country:ChinaCandidate:H Y WeiFull Text:PDF
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Effectsof LarvalTreatmentwithLow LethalInsecticides onChemicalCommunicationSystemsof LepidopteranMoths Ph.D. Candidate: Wei Hong-yi (Zoology) Directed by: ProfessorDu Jia-wei Asian corn borer (ACB), Ostrinia furnacalis (Guenée), tobacco cutworm (TCW)Spodoptera litura (Fabricius) and cotton bollworm (CBW) Helicoverpa armigera(Hübner) are among the most important insect pests for upland crops in China.Insecticide treatments are currently indispensable for the control of the lepidopteranpests in almost all cropping systems, thus these pest species have been subjected toheavy selection pressure of insecticides. Their larvae were topically applied on dorsalportion of the thoraces with organochloine (endosulfan), organophosphate(malathion), carbamate (carbaryl), pyrethroid (fenvalerate, deltamethrin) insecticidesand a neurotoxicant (eserine)at low lethal doses (LD10-LD30). After maturation of thesurviving larvae, calling behaviors of the female adults were observed, titerand ratiosof sex pheromone components were tested on the bassis of the GC analysis ofovipositor and associated gland extracts from the female moths, responses of malemoths to sex pheromone lures were conducted in wind tunnel assays, and courtshipreactions of the surviving moths with control moths were performed in a cartoncylinder.The results were asfollowing. 1. The insecticides did not affect the calling behaviors of the female survivors.Both control females and female survivors of insecticide treatments, the peak calling IIIAbstractoccurred at 8-9 h after the initiation of scotophase for the Asian corn borer, thetobacco cutworm and the cotton bollworm. At the peak calling period, over 90%ACB individuals, 70-80% CBW and 50-70% TCW females performed the callingbehaviors. 2. Behavioral responding of male survivors to the sex pheromone, especiallyapproaching to and landing on synthetic pheromone lures were affected by someselected insecticides in wind tunnel assays. Percentage of landing on the pheromonesource in ACB male survivors of deltamethrin treating the 1st, 3rd and 5th instarlarvae was 42%, 31% and 30% less than control males, respectively. TCW malesurvivors of deltamethrin and carbaryl treatment were less likely to land on the sexpheromone source than the males of acetone or malathion treatments, but the malesof endosulfan treatment were more likely to land on the source. Probability of takingflight and orientation did not differ from control moths and females survivors ofinsecticide treatments. 3. In the Asian corn borer, 14:Ac, E-/Z-12-14:Ac were identified from the sexpheromone gland. Percentage of 14:Ac was variable in individuals, the insecticidesenlarged its variance. The ratios of E12-tetradecenyl acetate to its Z isomer in thefemales of deltamethrin, malathion ad carbaryl treatments to some instar larvae weredifferent from that of control females. Deltamethrin treatment of ACB 1st and 3rdinstar larvae resulted in 14% and 12% of variation coefficients (C.V.) of ratio of E/Zisomer in those female survivors, whereas the C.V. was less than 10% in the otherfemales. In the tobacco cutworm, Z9E11-14:Ac(major component), Z9E12-14:Ac,E11-14:Ac and Z9-14:Ac were identifiedfrom sex pheromone gland. Percentage of IVAbstractZ9E11-14:Ac in sex pheromone of TCW female survivors of deltamethrin treatmentwas significantly lower than that in the females of other treatments, percentages ofthe other 3 components in the female survivors of deltamethrin treatment weresignificantly higher than that in the females of the other treatments. There were 7components tested in sex pheromone of the cotton bollworm. Deltamethrin enhancedsignificantly the titers of Z11-16:Ald (major component), Z9-16:Ald (activecomponent), Z7-16:Ald and16:Ald. The ratio of Z9-16:Ald to Z11-16:Ald in thefemale sex pheromone of deltamethrin...
Keywords/Search Tags:Ostrinia furnacalis, Spodoptera litura, Helicoverpa armigera, sex pheromone, courtship, wind tunnel, insecticide
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