Objective To determine the population composition, density and distribution of vectors in Yulin urban area, providing evidence for control of these insects. Methods Human baited net trap method and lamp baited trap method were employed for mosquito collection, cage-trapping for fly collection and sticky-paste for cockroach collection. Results Mosquitoes caught belonged to 5 species 4 genera, with Culex pipiens pallens being the dominant species. The average density based on the human baited net trap method was 19.11 per net per hour, or 1.61 per lamp per hour based on lamp baited trap method. The density in the urban area was higher than that in the villages. Flies belonged 23 species 19 genera 5 family, and the common species were Chrysomya megacephala, Lucilia sericata, Musca domestica, Muscina stabulans, Boettcherisca peregrine and L. cuprina, accounting for 36.49%, 20.41%, 14.78%, 10.61%, 8.65% and 2.61%, respectively. The average density was 4.42/ cage, the highest density observed in the farm produce markets. Cockroach density was 16.28/piece·night, highest observed in the restaurants, with Blattella germanica being the predominant species. The peak of flies and cockroaches was in August, and that of mosquitoes in July. Conclusion The population composition, density and distribution of vectors were basically grasped. Integrated measures should be taken with focus on such major areas as restaurants, farm produce markets and residential areas.

Objective To evaluate the resistance in Culex pipiens pallens to commonly used insecticides in different areas of Shaanxi province. Methods Larval mortality for 4 insecticides and LC₅₀ of 8 insecticides determined via the dosing method and median lethal dose method, respectively. Results The resistance level of Cx. pipiens pallens in all five areas was high except the population in Yulin city, which had elementary resistance to permethrin. The LC₅₀ values for larvae to β - cypermethrin, permethrin, deltamethrin, cypermethrin, DDT, DDVP, parathion and propoxur were 0.001 82-0.012 24, 0.008 16-0.094 19, 0.000 58-0.005 59, 0.002 76-0.020 17, 0.100 96-1.296 86, 0.144 11-0.512 40, 0.001 47-0.007 06, and 0.234 60-1.182 37 mg/L, respectively. The highest resistance level to all pesticides was found in Baoji city, except for deltamethrin, cypermethrin and parathion, while the lowest level was found in Yulin city, except for parathion and propoxur. Conclusion The development of mosquito resistance was closely related with the use of insecticides. Therefore, it is important to ensure appropriate administration and regular resistance surveillance to defer and prevent the occurrence of resistance in mosquitoes.

Objective To investigate the community structure of gamasid mites in a plague area of Dingbian county for further revelation of the role of these species in transmitting and preserving the plague bacillus. Methods The mites were collected from rodent bodies and nests, fixed in Hoyer’s medium and identified under the microscope. Results A total of 463 gamasid mites under 6 species, 5 genera and 3 families were collected. The dominant species included Haemogamasus kitanoi, Haemolaelaps glasgowi and Eulaelaps cricetuli, accounting for 40.6%, 33.0% and 24.8%, respectively, followed by a small amount of Macrocheles matrius, Macrocheles decoloratus and Laelaps algericus. Eight hundred fifty-nine rodents were captured and 135 nests were investigated. The dominant host mammal was Meriones unguiculatus, accounting for 90.9% of the total captives. The mite-carrying rate was 7.3% in M. unguiculatus and 23.7% of all nests. Most of the collected mites were female. Conclusion The community structure of gamasid mites is simple in this area with only a few species parasitic on the dominant host rodents. The dominant gamasid mites found on M. unguiculatus included H. kitanoi, H. glasgowi and E. cricetuli.

【Abstract】 Objective To study dividing line and influence factor of Aedes albopictus in Shaanxi province.  Methods Adult mosquitoes were captured by mosquito?net trap, light trap and mosq?ovitrap method.  Results Ae.albopictus distributed widely in Baoji and Hancheng city, and mainly at the special places such as worn type deposit places and junk recycle bin in Longxian and Tongchuan city. There was no Ae.albopictus in Yijun, Huangling and Yichuan. The peak of Ae.albopictus was in August in Baoji city and in September in Hancheng city. Temperature was possible the decisive factor that affected dividing line of Ae.albopictus. Conclusion The western boundary of Ae.albopictus was in Baoji city, the northern ones in Longxian, Tongchuan and Hancheng. Compared to light trap, mosquito?net trap and mosq?ovitrap method were best for the surveillance of Ae.albopictus, which would provide the ecological evidence for the control of mosquitoes.

【Abstract】 Objective To investigate the resistance of Culex tritaeniorhynchus to insecticides used frequently in high incidence areas of Japanese encephalitis in Shaanxi province. Methods The density of mosquitoes was calculated by labor hour method. Larva death rate of five insecticides and LC50 of eight insecticides were determined by distinguishing dosage method and median lethal dose method respectively. Results The average density of Cx.tritaeniorhynchus in breeding farm was 194.91/man· hour. The mortality of mosquitoes in Nanzheng, Hanyin, Hanbin and Pingli county was 1.84％-13.65％ and 10.86％-31.25％ after treatment by DDVP and deltamethrin for 24 h. Maximum LC50 of the same insecticide in different areas was1.27-8.00 times of the minimum. Conclusion Cx.tritaeniorhynchus developed different resistance to tested insecticides in four investigation sites, except that it was susceptible to cypermethrin in Hanbin, Nanzheng county and to DDT in Pingli, Nanzheng county. Cx.tritaeniorhynchus populations had developed high resistance to DDVP and deltamethrin, moderate resistance to permethrin. Rotational or mixed use of insecticides with different action mechanisms should be adopted to postpone the development of insecticide resistance.

Objective To provide scientific data for deratization by comparing the control effect of coumatetraly,brodifacoum and sodium diphacinone in the laboratory and the field.Methods Selective feeding method in single cage was used to determine the palatability of the poison baits and the control effect in the laboratory.A hennery in dingbian county and two sanitariums in the suburbs of xi'an were selected as test fields and the powder trace method was used to determine the rodent density.Results The feeding indexes to coumatetraly,brodifacoum and sodium diphacinone were 0.61,0.24 and 0.51 respectively,which reached A,B and A grade respectively.The corrected mortality in the laboratory was 100%,reaching A grade.And that in the field were 91.34%,80.94% and 88.39% respectively,which also reached A,B and B grade respectively.Conclusion Three anticoagulants had good palatability and good control effect in the laboratory.Especially,the control effect of coumatetraly was the best among three anticoagulants.

Objective To know species composition and habitats of mosquitoes in the border area of Aedes albopictus distribution area in Shaanxi province,and to evaluate effect of mosq-ovitrap and photocatalytic mosquito and fly trap.Methods Choosing 6 different habitats in three survey sites from July to September in 2006.Putting the mosq-ovitrap to observe attracted adults and larvae of Ae.albopictus,and photocatalytic mosquito and fly trap to observe attracted adults.Results Ae.albopictus was found in Baoji and Hancheng city.Average mosquito and oviposition positive index(MOI) by mosq-ovitrap was 17.92.Reproduce fastigium of Ae.albopictus was in Augest.The highest MOI of Ae.albopictus was in hilly area and woodland,was 33.20.Total 925 mosquitoes were collected in three survey sites by photocatalytic mosquito and fly trap.8 species of 5 genera were recongnized. Culex pipiens pallens was the dominant species.It was 76.11% of the total. Cx.pipiens pallens, Armigeres subalbatus and Cx.tritaeniorhynchus distribute in all habitats investigated. Cx.tritaeniorhynchus is more in the area of breeding and cultivation.Conclusion The distribution of Ae.albopictus is same as history data. Cx.pipiens pallens, Cx.tritaeniorhynchus and Ar.subalbatus are dominant populations in this area.The mosq-ovitrap and photocatalytic mosquito and fly trap have a high attractive effect.

Objective To investigate the community structure of mesquitoes and their ecological distribution at Hancheng city in 2006,and to evaluate efficacy of the mosq-ovitrap for monitoring Aedes albopictics in the field.Methods Using human baited net trap,light trap and mosq-ovitrap method for adults,and container method for larvae investigation.Results Mosquitoes collected from Hancheng city belonged to 5 genera 7 species,Human were attacked mainly by Ae.albopictus, Culex pipiens pallens, Armigeres subalbatus, Culex tritaeniorhynchus.The positive container index of larvae investigation was 34.38.The density of adults by human baited net trap method was 7.16 individuals per hour,1.13 individuals per hour by light trap method.The positive mosquito index of mosq-ovitrap was 15.32% in the field,the average amount of adults were 1.37 per trap,and the oviposition index by mosq-ovitrap was 14.41%.The positive mosquito index in September was higher than that in others and was 18.25%.The oviposition index was also the highest in September and was 21.25%.The oviposition index by mosq-ovitrap was higher than that by white paper cups( χ ²=45.14, P<0.001).The density of adults was the highest at the special places(worn type deposit places,junk recycle bin,and so on),and in the village was higher than in the urban,in the area for rest and recreation was higher than in cultivition area.The positive container index of larvae at the village was higher than at the urban,in the area for rest and recreation was higher than in cultivition area.Conclusion Ae.albopictus, Cx.pipiens pallens, Ar.subalbatus and Cx.tritaeniorhynchus were dominant population attacking human in this area.The mosq-ovitrap had a high attractive effect to Ae.albopictus adults and eggs.It can be applied for monitoring Ae.albopictus.The investigation provided some basic information for controling mosquitoes.

Objective To study the relationship between ecological factors and the number of species of rodents in Shanxi province.Methods The multiple linear regression analysis.Results According to geographical features,Shanxi province was divided into six geographical regions of rodents:desert area along the Great Wall,Loess Plateau,Guanzhong plain,Qinling mountain district,Hanjiang basin and Dabashan mountain district.Four ecological factors which possibly affect the number of species of rodents in different zoogeographical regions were studied.The results showed that there were positive correlation between the number of species and temperature,precipitation,percentage of forest areas and areas of each zoogeographical region.Higher temperature and adequate precipitation were good for plant growth which was indispensable to rodents.Forests offer rodents hidden places and foods.But area casted less influence on the number of species than other factors did.The vertical distribution of rodents was also studied,which indicated that the number of species of rodents went down as heigt got higher.The natural landscape also cast influence on the species diversity,in another word,the more complicated the natural landscape was,the more species of rodents there were.Conclusion The ecological factors cast influence on the species diversity of rodents.

The results of the epidemiological investigation showed that Leptotrombidium ( L.) subpalpale was distributed mainly in the focis of wild rat type HFRS, which was a dominant species in this area, the constituent rate was 60.34%.The density of larva was higher in November and December.It's geographic distribution was correlated with the HFRS cases distribution in the focis, and the Apodemus agrarius, main infections resources of HFRS, bore high 314.83 (November) and 239.75 (December) of chigger mite index.From the L.(L.)subpalpale larva collected from HFRSV antigen positive rats and from the L.(L.)subpalpale larva captured with small blackboards, and then bited the mice infected with HFRSV, we isolated one HFRSV strain for each, which confirmed that L.(L.)subpalpale be subject to HFRSV and that forms the determined factor for L.(L.)subpalpale as the vector of HFRS.

The present survey was carried out from December,1992 to December.1993 in Huian Chemical Plant natural focus of HFRS in Shanxi Province.1.Altogether 403 small mammals were collected in the endemic area, they were identified as eight species.belonging to seven genera,two orders,the predominant species of host animals was Apodemus agrarius, the constituent rate was 73.7%,and the constituent rate of Cricetulus triton was l6.13%.The density of rodents was higher from October to December,the highest in November.2.Altogether 39239 specimens of cligger mites from small mammals in the area was determined, and the six species of chigger mites belonged to five genera, three subfamilies. The chigger mites L.subpalpale was a dominant species for the area, the constituent rate was 60.34%, the density of the larva was higher in November and December.The constituent rate of L.scutellare was 39.39%,the density of the larva was higher in october.3. Cricetulus triton was parasited by six species of chigger mites. The infected rate was 61.11%. Apodemus agrarius by four species, the infected rate was 74.65%. Hosts of L.subpalpale and L.scutellare were extensive and indistinctive.4.Chigger mites L.scutellare spreading HFRSV has been verified. L.subpalpale may play the part of medium in spreading HFRSV,that is an interesting problem and should be investigated further.