Study On Relationship Of Kdr (Knockdown Resistance, Kdr) Of Blattella Germanica To Permethrin With Kdr Gene Frequency

Blattella germanica is normal home pest which can transmits many of disease by taking itself as vector of pathogen such as virus, bacterial, and parasite ovum; Blattella germanica also could be the allergen to human body, thus Blattella germnica bring great harassment to the peoples' living. Presently, the chemical pesticide is taken as the major material to protect people from harassment of Blattella germanica, but with high frequency and single kind utilization of pesticide in the control of Blattella germanica, the resistance of Blattella germanica to pesticide became urgent and arose widely attention. Pyrethroid is one kind of bionic pesticides with characters of quick knocking down the pest, high pesticide efficiency, low retaining in the environment, and little danger to non-target biology. But with time past, the resistance of pest to the pyrethroid is found to develop quickly as well as its extension application scale. So it is urgent to do research of monitoring the resistance situation of Blattella germanica and controlling of the resistance Blattella germanica in early time. It is discovery in the research of resistance mechanism of Blattella germanica to pyrethroid that the knock down resistance (kdr), which is the first confirmed resistance mechanism of target non-sensitive, is also one major resistance mechanism besides the metabolism ones. In molecule biology study on the kdr mechanism, kdr is found to relate with substitute of Leucine with phenylalanine in the IIS6 region of insect sodium channel protein gene. In China, no study on kdr mechanism of Blattella and relationship of kdr of Blattella germanica to permethrin with kdr gene frequency has been reported, study in thispaper will not only do good to preview the kdr resistance situation of Blattella germanica in Beijing, but also could make substantial theory basement for postponing the kdr resistance of Blattella germanica development, extension of the efficiency of presently pesticides on Blattella germanica, and monitoring on the kdr resistance occurrence in the early time. Conclusions of this paper could be drawn as followed:First, some stains Blattella germanica, which have been collected from different sites in Beijing, are done kdr resistance examination to pyrethroid in the way of glass test. The kdr resistance coefficients of JFX, AHQ, XCL, LFB, DTL and DTL stains are 2.13, 3.86, 6.31, 8.70, 5.07 and 3.36 respectively; the LFB and DTL stains display higher kdr resistance than the rest stains, which lead to conclusion that resistance of Blattella germanica to permethrin have been obtained by some Blattella germanica populations in Beijing.Second, the LFB stain, which displays higher resistance to permethrin, is taken as sample to RT-PCR, clone and sequence on the IIS4-IIS6 region of sodium channel protein gene. Comparing the cloned sequence of ES4-IIS6 region with the same region sequence of Blattella germanica in the GeneBank, L993F typical point mutation accounting for the kdr of pest to permethrin is found. Base on these experiments, kdr of Beijing LFB Blattella germanica stain to permethrin is ensured.Third, the PASA (PCR Amplification of Specific Allele) system examination on the kdr gene point mutation is also set up in this paper. In the case of LFB Blattella germanica stain, the RR percent is 12.5%, the RS percent is 32.5%, and the SS percent is 55.0%, kdr gene frequency is 2.88%.In the case of JFX Blattella germanica stain, the RR percent is 0.00%, the RS percent is 87.2%, and the SS percent is 12.8%, kdr gene frequency is 0.07%.