Objective To evaluate the potential of Aedes aegypti to transmit West Nile virus(WNV) in China. Methods Ae. aegypti was infected orally with WNV and after 12 to 14 days’ incubation allowed to transmit the virus through bite wounds. RT-PCR, virus isolation with C6/36 and indirect immunofluorescence assay were implimented to detect WNV in experimentally infected mosquitoes and Leghorn chicken. Results It was found that the WNV loaded in the susceptible host leghorn was the highest in the 2nd day after infection, indicating that it was the best time for the evaluation of the transmission. Ae. aegypti could be infected by WNV with a susceptibility rate of 63.3%, and transmitted the virus to healthy Leghorn chicken by bite wounds with a transmission rate is 30.0%. Conclusion Ae. aegypti is a potential vector of WNV in some areas such as Hainan province, likely to cause outbreaks of West Nile fever in China in future. Actions are to be taken for the control and prevention of the vecor.

【Abstract】 Objective To know the knockdown efficacy of mosquito?net treated by pesticides on mosquito in Beiwan. Methods The net treated by BASF® pesticide, the net treated by BASF® pesticide after washing twenty times and the net treated by FendonaTM recommended by WHO were used in treated area, and common military nets were selected in the control areas. Aedes vexans, the dominant species in Beiwan, was collected by mosquito aspirators and released into nets. The first knockdown time, medium knockdown time and total knockdown time were recorded, and then compare the knockdown time of 4 kinds of mosquito?net. Results For the knockdown efficacy to mosquito, the order was net treated by BASF® pesticide＞net treated by BASF® pesticide after washing twenty times＞net treated by FendonaTM recommended by WHO. The first knockdown time for three kinds of mosquito net  was  all  within 7 min, and there was no significant difference among them (F＝2.375, P＝0.174).  Medium knockdown time was 17 min, and there was significant difference between net treated by BASF® pesticide and  net treated by BASF® pesticide after washing twenty times (P＝0.036). All the mosquito would be knocked down within 27 min for net treated by BASF® pesticide and net treated by BASF® pesticide after washing twenty times and 54 min for net treated by FendonaTM. There was significant difference among them (P＜0.001). Conclusion The knockdown efficacy of net treated by pesticides could be better than non?treated net in Beiwan.

【Abstract】 Objective To study the control effect of source reduction to Aedes albopictus population. Methods Various measures were taken to reduce Ae.albopictus breeding sites in the Forest Park, and the Internal Combustion Engine Research Institute was as control without any measures. Mosquito and oviposition trap and CO₂ trap were used to evaluate the experiment. Results After source reduction, Ae.albopictus adult and larvae density gradually decreased, and the relative population indexes（RPI） were under 35 and the decline rates of density were more than 50% after treatment for 2 to 3 weeks. Conclusion It was effective to control Ae.albopictus population by source reduction.

Objective To compare the efficacy of two traps catching mosquitoes.Methods The methods of CO ₂ trapping lamp and mosquito-curtain trap were used in this study.Results There were the same mosquitoes species captured by two kinds of traps.There were 1548 mosquitoes,and Culex pipiens pallens, Aedes albopictus and Armigeres subalbatus accounted for 87.86%,11.95% and 0.19% respectively.The mosquito density index of CO ₂ trapping lamp catching mosquitoes was 21.8/lamp·hour,which was lower than that of mosquito-curtain trap(84.0/curtain·hour).Conclusion The CO ₂ trapping lamp could be used to monitor the mosquito population,especially it was the preferred method in the epidemic area of mosquito-borne disease.

Objective To amplify the 3'end gene sequence of voltage-dependent sodium channel from Aedes aegypti.Methods Total RNA was extracted from the female adult of Ae.aegypti,and a single stranded cDNA was reverse transcripted with Trsa,then to design the positive and negative control,a 3'end cDNA was amplified by nested PCR and 3'RACE technique,and cloning and sequence analysis were performed.Results A total of 809 bp PCR product was obtained,including the coding sequence with 208 amino acids and non-coding sequence with poly(A) tail.Similarity analysis by DNAstar 5.0 showed high similarity(about 65%) comparing to the same region of amino acid sequence from Musca domestica.Conclusion The 3'end cDNA sequence of voltage-dependent sodium channel from Ae.aegypti was successfully obtained.

Objective Study the relationship of geographical landscapes and mosquito distribution in rice growing districts.Methods The survey sites were established according to variance of geographical landscapes.The species and densities of adult mosquito were investigated with mosquito net,and the constitution of different geographical landscapes was extracted with romote sensing(RS) and geography information system(GIS),and then the relationship between geographical landscapes and mosquito distribution was analysised by SAS software.Results There were four species of Culex in 13 survey sites,accounting for 82.53% of all the captured mosquito species.The quantity of Culex pipiens pallens was the most among the captured mosquitoes,about 3950 mosquito.The results showed that the distribution of mosquitoes had the close relationship with geographical landscapes.There were significant positive correlations between the amount of Cx.modestus and the percent of residential area,the quantity of Anopheles sinensis and the percent of rice field area,the number of Cx.tritaeniorhynchus and the percent of rice field and forest areas,the amount of Cx.pipiens pallens and the percent of sewage,woodland and glebe areas.Conclusion The combination of RS and GIS can effectively monitor the variance of geographical landscapes factors in the paddy growing districts,which can be used to the control of mosquito-borne diseases.

Objective Discrimination dosages of 5 insecticides to adult mosquito of Culex pipiens pallens were calculated from full long-dosage probit line which was established by known "susceptible" strains.Methods Mosquitoes were tested by WHO test kits with mortality assessed after 24 hours.Results Discrimination dosages of dichlorvos,deltamethrin,lambda-cypethrin,permethrin and allethrin to adult mosquito of Cx.pipiens pallens were 3300,7700,7900,250 and 200 mg/L,respectively.Conclusion Discrimination dosages of 5 insecticides to adult mosquito could be used for the resistance detection of Cx.pipiens pallens in China.

Objective Study on relationship of the environment factors with the populations of Anopheles sinensis and An.jeyporiensis, and explore the possible influence of the new villages building which was part of the Chinese west development plan in southern part of Yunnan province on these two vector populations. Methods The relationship of populations of An.sinensis and An.jeyporiensis with the environment factors in southern part of Yunnan province were studied using geographic information system(GIS) system. Results The dominance of An.sinensis could be mimiced by linearity model with DTF and KFA [d=0.3621-3.26×10 ^-4×DTF ^-8.0854×10 ^-7×KFA ( R ²=0.642, F test P=0.000)]; The dominance of An.sinensis had the negative relationship with the DTF (Person=-0.683, P=0.002) and the KFA (Person=-0.735, P=0.001). The population density of An.jeyporiensis could be mimiced by linearity model with KRL [Ni=263-0.0541×KRL ( R₂=0.633, F test P=0.000)], and it had the negative relationship with the KRL (Person=-0.825, P=0.000). The dominance of An.jeyporiensis could be mimiced by linearity model with DTF [d=7.9204×10^-4×DTF-0.0232 (R²=0.267, F test P=0.023)], and it had the positive relationship with DTF (Person=0.562, P=0.012). Conclusion In the process of new villages building, the changing of some environment factors origining from building action could lead to population fluctuation of these two malaria vectors.

Objective To evaluate the effect of mosquito nets treated by deltamethrin effervescent tablets or emulsifiable concentrate(EC) on Culex pipiens pallens and Cx.pipiens quinquefasciatus. Methods Mosquitoes were forced to contact treated nets. Results The efficacy of two formulation of deltamethrin to Cx.p.pallens reached 100% at the concentration of 2 mg·ai/m ², but that to Cx.p.quinquefasciatus was under 100% at the concentration of 10 mg·ai/m ². The LC ₅₀ of mosquito nets treated with deltamethrin effervescent tablets and EC to Cx.p.pallens were 0.23 mg·ai/ml and 0.31 mg·ai/ml, respectively. There were statistical differences between them ( t=3.04, P=0.023). However, the LC ₅₀ of net treated with deltamethrin effervescent tablets and EC to Cx.p.quinquefasciatus were 1.16 mg·ai/ml and 1.33 mg·ai/ml, respectively. There were no statistical differences between them( t=1.65, P=0.470). The control efficacy of deltamethrin effervescent tablets and EC to Cx.p.pallens and Cx. p.quinquefasciatus increases with the concentration of chemicals, and nevertheless the values of LT ₅₀ distinctly shorten. Mortality and median knockdown time of net treated by deltamethrin effervescent tablets to Cx.p.pallens and Cx.p.quinquefasciatus were more infective than that of deltamethrin EC. Conclusion Effervescent tablets, as a new formulation to treat mosquito nets, had a good effect against mosquitoes.

Objective To control mosquitoes during outbreak of mosquito-borne disease and disaster, 02Ⅰ type of motor-mounted ultra low volume(ULV) system was designed and developed. Methods 02Ⅰ type of motor-mounted ULV system contains three parts: motorcycle, ULV sprayer and control system. The evaluation experiment were conducted at the peak of mosquito population at the dusk and mosquitoes were collected by man-bait bednet trap. The results were showed by the decrease rates of mosquito population. Results It showed that the 02Ⅰ type of motor-mounted ULV system has characteristics of mechanistic stability, high efficiency and easy operation. After 1% rich-d-cyphenothrin spray(5.25 L/hm ²), density of mosquitoes were decreased by 84%-96%, while the dose was added to 6.75 L/hm ², the density was decreased by 100%. Conclusion 02Ⅰ type of motor-mounted ULV system is suitable to vector control at outbreak of mosquito-borne disease and disaster.

Objective To learn about the olfactory behavior of Periplaneta americana to ricin. Methods The infrared sensor was employed to keep investigating for 24 h. Results There was significant difference between the average frequency of P.americana attracted to ricin ( F=9.67) and that to distilled water ( F=5.57) or the control ( F=5.40) ( χ2=16.70, P<0.01), but the retention time in the box was not significantly different ( χ=5.047, P>0.05). Conclusion P.americana was positively attracted to ricin.

Objective To study the effect of integrated control aimed at mosquito larvae in the urban environment. Methods The health education to the urban residents and treatment of mosquito breeding sites were conducted in the test zone of Nanjing city. The densities of Culex and Aedes mosquitoes were monitored by light traps and ovitraps. Results The population related index(PRI) of Culex and Aedes mosquitoes were 0.123 and 0.132 respectively, and decreased by 87.7% and 86.8% respectively. The mean of mosquito population was 1.2 for one lamp and the decreased rate of positive breeding sites was 95.5%. Conclusion There is good effect in the urban integrated control aimed at mosquito larvae. It is valuable and practicable to adopt the strategy of the integrated mosquito control in the city. For example, health education is conducted to all people by government, their own mosquito breeding sites are cleared away by the urban residents themselves, the mosquito breeding sites in the public places are cleaned up and the larvicide is used in permanent breeding sites by pest control operators(PCO).

Objective To know the species composition of mosquito and their density in a battalion of a military base in Zhejiang province for mosquito control effectively. Methods CO _{2 trapping method. Results 888 mosquito individuals three species of three genera, including of 696 Culex tritaeniorhynchus(78.38%), 186 Anopheles sinensis(20.94%), and 6 Armigeres subalbatus(0.68%), were collected. Cx.tritaeniorhynchus was the dominant species. Blood-feeding mosquitoes accounted for 1.39%. The difference of blood-feeding rates between Cx.tritaeniorhynchus and An.sinensis, have no statistical significance (χ²=1.106,Ρ>0.05). The difference of blood-feeding rates of Cx.tritaeniorhynchus collected from ricefield and from hogpen, have statistical significance (χ²=11.881,Ρ=0.001). Conclusion The species composition of mosquito and their density in Zhejiang province were attained. This study provided scientific evidence for mosquito control.}

Objective Find out the mosquito species and density in a military camp on Beijing suburb and search the new method of mosquito monitoring. Methods CO ₂ trapping lamp method, comparing with mosquito net trapping method at the same time. Results By CO2 trapping lamp method, total 676 mosquitoes were trapped, divided into 2 genus and 2 species. 95.71% of the total were Culex pipiens pallens, 4.29% were Aedes albopictus. Most of Culex pipiens pallens were trapped in work area and grove in the camp before midnight, and most of Aedes albopictus were trapped in life area and grove before dawn. By mosquito net trapping method, tatal 178 mosquitoes(within 2 h) were trapped, 83.70% of the total were Culex pipiens pallens,and 16.30% were Aedes albopictus. Conclusion Preliminary research on the mosquito species and density in a military camp on Beijing suburb showed that the CO₂ trapping lamp method is a reliable method of mosquito monitoring.

Objective To study the attractive efficacy of animals traps and animals blood to mosquitoes.Methods Animals blood were used to attract mosquitoes in laboratory and animals traps were used to attract mosquitoes in the field.Results In laboratory,the bred Culex pipiens pallens prefers to feed pig's blood,the bred Aedes albopictus and Ae.aegypti prefer to feed cattle's blood;and the most favorable blood feeding ratios of above three species are 51%,47% and 44% respectively.In the field,chicken attracted more wild Cx.pipiens pallens(1420) than rat,pigeon and sparrow,but rarely attracted Ae.albopictus(11).Conclusion The bred Cx.pipiens pallens prefers to feed pig's blood,the bred Ae.albopictus and Ae.aegypti prefer to feed cattle's blood;Chicken are more attractive to wild Cx.pipiens pallens.

Objective To study the activity of relationship between esterase,acetylcholinesterase and the resistance to propoxur in the larva of Culex pipiens pallens. Methods WHO bioassay and spectrophotometric method were used. Results A strain from field selected using propoxur in lab for generations with 12.07-fold resistance ratio was abtained,which the parent was 4.77-fold. The difference of esterase activity between sensitive and resistant strain was not significant. Otherwise,the acetylcholinesterase activity between two strains existed significant difference at high concentration (100×10 ^-6,10×10 ^-6 and 1×10 ^-6) propoxur. The inhibiting rate was (93.92±0.65)%,(91.69±0.54)% and (87.03±1.14)% respectively in sensitive strain,and (89.81±0.92)%,(87.41±1.66)% and (83.84±0.36)% respectively in resistant strain. Conclusion Metabolic detoxification induced by esterase play a minor role in propoxur-resistant strain. The insensitive AChE may be the main factor in related to the propoxur resistance.

Objective To establish plaque assay for the quantitative detection of West Nile virus(WNV). Methods Vero cell was selected to be infected with WNV. Approximately 24 h before beginning the titration protocol,Vero cells were plated in 6-well plates to form an even monolayer. Virus in specimens was serially diluted and added to each well to infect the cells. The plates were covered with agarose overlay medium and incubated in an incubator. The plates were stained by a solution of Neutral red,and the number of plaques was counted. Results The plaques appeared as clear circles( 1-3 mm) against a red or pink background. The quantity of virus in infected mouse brain tissues was 107 pfu. Conclusion The plaque assay is confirmed as an efficient and rapid protocol of quantitatively detecting WNV in experimentally infected mosquitoes and Leghorn chicken.

Objective To find disadvantage of resistant strain by comparing the major biological characteristics of susceptible strain with resistant strain and calculating the fitness of resistant strain,for the better theories about reasonable utilization of pesticides.Methods The biological characteristics about bloodsucking,reproduction and development of resistant and susceptible strains were observed and recorded,and the life table of the experimental populations was constituted.Results The bloodsucking rate of resistant strain was lower than that of susceptible strain and the difference was significant.The mortality of eggs of resistant strain was higher than that of susceptible strain and the difference was significant.The developmental duration of eggs,larvae and pupae were longer than that of susceptible strain and the difference was significant.The resistant strain was calculated to have fitness value of 0.66 relative to the susceptible strain.Conclusion The resistant strain was related to disadvantage of reproduction and development.

Objective To study the susceptibility of Aedes aegypti to DEN-2 virus among 4 geographic strains from China and Baro of Indonesia.Methods Aedes aegypti of different geographic population were infected with dengue 2 virus through oral and indirect fluoroimmunoassay was used to detect antigen the virus in brain of Aedes aegypti.Results(1) Using mice- blood-sugar virus suspension,the infection rate of Baro strain to dengue 2 virus shows significant variation with Hainan strain's( P=0.007 9< 0.01) and Taiwan strain's( P=0.0116<0.05).But no significant variation with Guangdong strain's( P>0.05).(2) With the reduction of virus titre(TCID _{50<.sub>),the infection rate of every geographic strain to dengue 2 virus shows extraordinarily marked downtrend.(3) No significant difference has shown in susceptibility of every strain of full-blood by mice and pig- blood-sugar virus suspension.Conclusion The infecting effects of different geographic strains of Aedes aegypti to dengue 2 virus show significant difference.}

Objective This paper intends to study the genetic variation of Aedes aegypti from Hainan,Guangdong and Taiwan of China and Baro of Indonesia respectively.Methods Random-amplified polymorphic DNA polymerase chain reaction(RAPD-PCR) was used to analyze the DNA polymorphism and unweighted pair group method with arithmetic mean(UPGMA) was used as cluster analysis for DNA of Aedes aegypti aegypti.Results(1)Out of total 113 RAPD bands received,109( 96.46) presented the polymorphism.(2)The cluster of analysis by UPGMA showed elected samples can be divided into different groups:Hainan,Guangdong,Taiwan strain of China and Baro strain of Indonesia.The inheritic distance of Guangdong strain and Baro strain was the closest.The Taiwan strain was relatively independent group.Conclusion RAPD is an useful method to detected and classify Aedes aegyptii.The analysis of polymorphic DNA reveals that there have inheritic differentiation in different population of Aedes aegypti.

Objective To study the living capacity of pyrethroid-resistant strains of Culex pipiens pallens for the scientific basis about chemical control of mosquitoes.Methods Culex pipiens pallens was selected successively with lambda-cyhalothrin、deltamethrin?tetramethrin in laboratory.Some biological parameters were compared between sensitive strain and resistant strain.Results It was found that the rates of bloodfeeding and surviving in larvae and pupae of resistant strain declined.Relative fitness of lambda-cyhalothrin-resistant by net reproductive rates(R ₀) was 0.41.Relative fitness of deltamethrin-resistant by net reproductive rates(R ₀) was 0.47.Relative fitness of tetramethrin-resistant by net reproductive rates(R ₀) was 0.29.Conclusion There existed low relative fitness among resistant strains of Culex pipiens pallens.

Objective To determine whether DEN-2 can survive in diapause eggs and be transmitted vertically to progeny of infected Aedes albopictus.Methods Reverse transcription-polymerase chain reaction(RT-PCR) combined with virus isolation in C6/36 cell were used for assay of the DEN-2 in diapause eggs and progeny of infected Aedes albopictus in labortary.Results DEN-2 was detected in diapause eggs and progeny after termintaed diapause.The total positive rate of pools was 9.6%,the minimum infection rate of the progeny was 1:294.3;DEN-2 was not isolated from the progeny of the first oviposition cycle.The minimum infection rates were not significantly different for the second and third oviposition cycle(χ ²=0.01, P>0.05).Conclusion DEN-2 can survive in diapause eggs and be transmitted vertically to progeny of Aedes albopictus.

Objective:To understand the mechanisms of Den-2 virus infection on Balb/C laboratory mice.Methods:The laboratory mice were injected intravenously in its abdoman with a defined titers of Den-2 virus.Results:It showed Balb/C laboratory mice could be infected with Den-2 virus,although it was not the susceptible host of dengue virus.It can develop a 1-2 days detectable viremia,Den-2 antibody can be detected in the 4 ^thday after injected.In the first two days,the infection rates of macrophages in abdomical cavity were high,but dropped rapidly.4 days later,the rates were very low.Conclusion:Balb/C laboratory mice can be used for study on the animal model infected with Den-2 virus.

Objective:To study the infection of Wolbachia in mosquitoes in China.Method:Specific primers derived from the wsp gene sequence were used to amplify DNA of Wolbachia from mosquitoes in China by polymerase chain reaction(PCR).Results:The characteristic 600bp products were observed after amplification of extracts from 4 subspecies of Culex pipiens complex and 4 geographical strains of Aedes albopictus.However,the products haven't been found in the strains of Aedes aegypti,Aedes vexans, and Anopheles stephensi.The strains of Wolbachia which infect Culex pipiens complex and Ae.albopictus in China belong to pip group by means of the use of group-specific wsp PCR primers.It was found that there were double infections of A and B group Wolbachia in Ae.albopictus in China.Conclusion:The strains of Wolbachiainfected in the mosquitoes in china have been successfully detected and classified by this method.

Objective:To study the factor Xagene-directed anti-coagulant(AFXA) from Aedes aegypti in China in molecular biologic levels.Methods:Degenerate oligo-nucleotide primers PCR was used to amplify from its genome DNA,then the amplified fragment was cloned into T vector to sequence.Results:A 300bp AFXA gene fragments was obtained and sequenced.There was a 63bp intron in it comparing with cDNA sequence.Conclusion:This gene fragment from Haikou strain may be a new gene type of factor Xagene-directed anti-coagulant.

The resistant strains of Culex pipiens pallens to Deltamethrin were selected for 5 generations with different dose (LC ₅₀ dose,LC ₉₅ dose).Two resistant strians were obtained,namely R50 strain and R95 strain.In the former,LC ₅₀ rose steadily from 0.24ppb to 12.16ppb(51 fold).In the latter,LC ₅₀ reached 7.18ppb from 0.24ppb (27 fold).It is found that resistance to Deltamethrin of the susceptible strain increase quickly when it was selected with Deltamethrin,and it was also found that it's development of resistance was delayed when the susceptible strain was selected with high dose.

Ovarian follicle development was retarded and content of RNA decreased after diapause of Culex tritaeniorhynchus Giles occured.The present paper is the results of effect of Juvenile hormone Ⅲ on ovarian follicle development and the content of RNA of Culex tritaeniorhynchus Giles in diapause under experimental condition.It was showed that the smaller follicles in ovaries enlarged and the content of RNA increased after topical treatment with synthetic Juvenile hormone Ⅲ,and it was not found the influence of Juvenile hormone Ⅲ on content of protein in ovarian.

Culex pipiens pallens was selected successively for 8 generations with tetramethrin in laboratory.The LC ₅₀ of selected strain increased from 0.140 ppm to 1.829ppm after 3 generations of selection (13.07 folds).Then the LC ₅₀ went down every generation.The LC ₅₀ is only 0.643ppm (4.57 folds) at the 6th generation.After that increase of LC ₅₀ is not steady.Some biological parameters were compared between S strain and R strain,It was found that the rates of bloodfeeding and surviving in larvae and pupae of the 8th generation of R strain declined.Relative fitness by net reproductive rates (R ₀) was 0.29.

It was reported in the paper that the results of comparison of residual effect ofpyrethroids-impregnated bednets against Culex pipiens quinquefasciatus,including permethrin (EC,500 mg a.i./m ²）, deltamethrin (WP, EC, SC, 25mg a.i./m ²） and alphacypermethrin (EC, SC,40mg a.i./m ²）.It was found that pyrethroids - impregnated bednets were effective afterimpregnated for 256 days.There were no differerance between different formula of the samepyrethroid.

To study the mechanism of mosquito pyrethroid resistance, in laboratory with immersion, a permethrin-resistant strain of Cular pipiens pallens was seleced.After 2O generations,it attained a stable level of 70-foId permethrin resistance.In the meanwhile it was found that itS exiStant abiIity decreased.