Objective To investigate the breeding habit of Aedes albopictus in the outdoor discarded tires,and studied the measures for irradication.The result provides guidance for control Dengue fever.
Methods Adopt sludge spoon method to check Aedes larva breeding habits,growth trend and wintering situation;measure the quantity and chemical index of the larvae breeding water in outdoor tyres monthly;and soaking liquid method to determine the resistance and pesticidal kill effect to Aedes mosquito.
Results (1) Aedes albopictus larva emerged during April-November in the circumstancial discarded tires outdoor,the larva density increased in June-September with peak in July.The time distribution has no difference from other containers in which Aedes albopictus breed.But the breeding rate in discarded tires was 2.2 times higher (χ2=53.97,P<0.01).The breeding rate of Aedes albopictus in outdoor tire is 100%,while in other containers is 51.6%.The eggs of Aedes albopictus hibernate in stagnant water or mud in outdoor discarded tires from December to March of the following year.The water in which breed Aedes albopictus possess the same chemical character as the water breed other species of mosquito or the water no mosquito breeds.The chemical character consists the pH,dissolved oxygen,Chloride,nitrite nitrogen and ammonia nitrogen.(2) The resistance of Aedes albopictus to four common insecticides was much more increased.The resistance to DDVP and Permethrin has twiced as comparing with the situation 2003 year before.Moreover,the resistance to Deltamethrin and Cypermethrin has increased 10-20 times.Diazinon 1.0-5.0mg/L,pirimiphos-methyl 0.5-5.0 mg/L,Abate granules 0.4-1.4 mg/L is able to irradicate the larva,the effect lasts 2-4 weeks.(3) To bore hole for drain out the stagnant water in waste tires,or to adopt certain water proof measures to keep dry inside the discarded tires are effective:the density of adult Aedes albopictus would decrease about 81%-95%,RPI would decline 50.
Conclusion Boring hole to drain out the stagnant water in discarded tires,or to adopt certain water proof measure could greatly decrease the density of Aedes albopictus;discarded tires in piles should be kept under shelter avoid from accumulate rainfall.In according to that Aedes albopictus eggs could survive still while the stagnant water in tire become dry,we have advised do not import discarder tires from abroad and the domestic epidemic areas of Dengue,and destroy discarded tires from the epidemic areas of Dengue.The discarded tires should be recognized as "black pollution" in environmental sanitation and required to be regulated by the law as soon as possible.
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