| Dengue fever is an imported mosquito borne disease mainly transmitted by Aedes albopictus and Aedes aegypti in China. In recent years, due to the importation of the traveler who was carrying dengue virus from abroad, and the higher density in some A. albopictus distributed areas, almost every year since 2000, there were local cases of dengue fever outbreak in Southeast and Southwest China such as Guangdong province, Fujian province, Zhejiang province and Yunnan province. Although A. Aegypti can transmit dengue virus stronger than A. Albopictus, our government had pay more and more attention to this mosquito control lot of effective strategy. Based on vector surveillance by National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, the A. aegypti distribution areas has been decreasing in Leizhou Peninsula in Guangdong province and Hainan island. After more then ten years silent, two local dengue fever outbreak events in Leizhou peninsula from Sep. to Oct.,2007 had give us an alarm to pay attain to this areas. By now, the most quickly and effective mosquito control during this disease out break is chemical control, so the mosquitoes insecticide resistance should be monitored regularly.Larvae and pupae of A. albopictus were collected using WHO metheds at their peak period from Haikou Hainan province, Guangzhou Guangdong province, Nanchang Jiangxi province, Quzhou Zhejiang province, Cixi Zhejiang province, Shanghai, Qingdao Shandong and Beijing in 2009-2010. And four wild populations of A. aegypti larvae from Zhanjiang Guangdong Province, Danzhou, Changjiang autonomous County, Sanya Hainan Province. The resistant levels of mosquito to seven insecticides (deltamethrin, beta-cypermethrin, permethrin, fenirothion, Temephos, DDVP. BPMC) were compared with the sensitive strain. Meanwhile, to understand the risk of the A. albopictus resistance to pyrethroid insecticides, we screened A. albopictus'resistant strains to deltamethrin, and assessed its resistance risk, provided theoretical basis for the treatment of mosquito. In order to get a preliminary understanding of A. albopictus to deltamethrin resistance mechanism. This paper preliminarily studied the effect of deltamethrin mixed with three synergist synergistic. The conclusions are as follows:1. The sensitivity of different populations of A. albopictus larvae to pyrethroid insecticides showed significant regional differences, compared with the susceptible strain data. Cixi Zhejiang province, larvae of A. albopictus obtained higher resistance ratio, to deltamethrin, beta-cypermethrin, permethrin the ratios are:15.16,7.32 and 7.76 folds; while the rest wild populations are more sensitive. As organophosphate and carbamate insecticides, with a long history of used in the field of agriculture, A. albopictus has no resistance, but the sensitivity is not high, it must be used with caution.2. Compared with the susceptible strain data, A. aegypti larvae in Zhanjiang Guangdong province has the higer resistance to commonly used insecticides, followed by the wild population in Danhou city. The resistance ratios in Zhanjiang city of deltamethrin, beta-cypermethrin, permethrin are:13.07,6.74 and 7.94 folds. The results of the A aegypti population to organophosphorus and carbamate insecticides, are more sensitive. There are several populations are more sensitive than the of the susceptible strain.3. Wild populations of A. albopictus collected in Shanghai as the starting population, after 8th generation continuous screening through the use of deltamethrin indoor, the resistance ratio is 26.71 folds, increased resistance is 2.74 times, the realized heritability 0.2876, compared with the susceptible strain. From the above results, we can find that the development of resistance to deltamethrin of A. albopictus is more rapid, which has a high resistance risk.4. Through piperonyl butoxide (PBO), triphenyl phosphate (TPP), maleic acid diethyl ester (DEM) synergists with deltamethrin at the three different ratios, the synergism of PBO to deltamethrin shows a significant function among test results of wild populations in Cixi city and resistance selection population of Shanghai. We may conclude that Multi-Oxidase are involved in the degradation of deltamethrin of A. albopictus.Culex tritaeniorhynchus is one of the major media of Japanese B encephalitis. In order to get the resistance level of Cx. tritaeniorhynchus to commonly used insecticides and the relationship between the resistances of larvae and adult, provide theoretical basis for the chemical control of mosquito, we measured the larvae and adult mosquitoes in Donggang City, Liaoning Province. The conclusions are listed as below:In Donggang City, Liaoning Province, wild populations of Cx. tritaeniorhynchus larvae have a high resistance to organophosphate insecticides. The resistance ratio of DDVP, parathion and fenitrothion were 186.7,40313.6 and 34,0fold respectively compared with those of the published susceptible; while pyrethroid resistance is in the low-level, but adults to deltamethrin, permethrin, fenitrothion has a high resistance level. Adult and larval assay disclosed discrepancy of resistant level in this mosquito population. |
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