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Bioactivity Of Benzoylphenylurea Insecticides Against Two Plant-bugs

Posted on:2012-05-02Degree:MasterType:Thesis
Country:ChinaCandidate:Z G GuoFull Text:PDF
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This paper systematically compared the biological activity and field control effect of four typical benzoylurea insecticides to two kinds of Miridae. It included the toxicity to Apolygus lucorum and Adelphocoris lineolatus, the biological activity to different instars of Apolygus lucorum, the later influence of growth and reproduction, the toxigenicity process, poisoning symptoms, mode of action, the temperature coefficient, and evaluated the field control effect. The main results are as follows:1,It also possess higher toxicity of benzoylurea insecticides to two Miridae. In four tested benzoylurea insecticides, chlorfluazuron has the highest toxicity to 2nd instar nymphs of Apolygus lucorum, which LC50 was 51.63mg/L; hexaflumuron has the highest toxicity to 3rd instar nymphs, the LC50 was 66.87mg/L; triflumuron has the highest toxicity to 4th instar nymphs, the LC50 was 93.04mg/L, and the toxicity of three insecticides were higher than that of malathion. The toxicity of hexaflumuron to 3rd instar nymphs of Adelphocoris lineolatus has no difference with endosulfan.2,Sub-lethal doses of benzoylurea insecticides can significantly affect the growth and development of Apolygus lucorum. When the nymphs were treated with LC30~40 dosage of benzoylurea insecticide, it can obviously affect the growth and development of their survival. Hexaflumuron has the greatest impact on the tested nymph. Treated with this insecticide, 2nd instar nymphs has slower development, less oviposition amount and shorter lifetime of adult, and 4th instar nymphs also have reduced emergence rate.3,It has significant impact on adult fecundity and the survival of nymphs after the adults were treated by benzoylurea insecticide. Although it has lower direct touch effect of the cowpea, which were dipped in the 1000 times dilution of the four benzoyl-urea insecticides respectively, feeding to the adults, but it can severely affect its'reproduction. It can spawn eggs about 88.3 per female of the hexaflumuron treated adult, while the control was 125.6. Although some egg of the treatments can hatch, but the mortality rate of nymphs was 95.6%.4,Benzoylurea insecticides has a strong contact activity to Apolygus lucorum. The toxicity of four benzoylurea to this insects were determined by dipping method, mixed drug method and drop method. The results showed that the toxicity by dipping method was higher than mixed drug method, which indicated that the action mode of benzoylurea included not stomach poisoning. And the results of drop method showed that benzoylurea insecticides had a strong contact activity.5,In a certain temperature range, benzoylurea insecticides showed positive temperature coefficient to Apolygus lucorum.6,Benzoylurea insecticides had a good field control effect on Adelphocoris lineolatus. 5% hexaflumuron EC and 5% chlorfluazuron EC showed good effect on the nymphs by spraying with 1125 mL/hm2, 1500 mL/hm2 and 2250 mL/hm2 respectively. The control efficacy 1500 mL/hm2 and 2250 mL/hm2 dosage were all more than 95% after 7 days treated.
Keywords/Search Tags:Apolygus lucorum, Adelphocoris lineolatus, benzoylurea insecticides, biological activity
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