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Abstract The microbiota plays an important role in the growth of mosquitoes and the transmission of mosquito‐borne pathogens. The effects of changes in aquatic habitats in which mosquitoes live, as one of the major factors closely associated with the microbial communities of mosquitoes, on the microbiota of different developmental stages remain to be elucidated. Here, we compared the microbiota of larvae and pupae of Aedes albopictus exposed to different ampicillin concentrations and investigated the bacterial composition of adult females. The results demonstrate that the microbial community differed substantially between developmental stages and that samples of the same stages shared similarities, whereas differences were observed between adult females. Based on all observations, we hypothesize that the use of ampicillin caused dysbiosis rather than excluding bacteria from mosquitoes and that the disturbing effect of ampicillin was obvious in adults. Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that most of the bacteria identified in this study were significantly associated with metabolism. Taken together, our results indicate that ampicillin can change the abundance of bacteria, while microbial communities of Ae. albopictus showed obvious stage‐specific characteristics. Further investigations are needed to characterize specific bacterial components that are affected by ampicillin exposure and to quantify their functions, thereby providing a better understanding of the influence of antibiotics on microbial communities at different life stages.

Abstract Background Carboxylesterase overproduction is a frequently observed resistance mechanism of insects to organophosphate insecticides. As a major transmitter of human diseases, mosquitoes in the Culex pipiens complex have evolved 13 carboxylesterase alleles (Ester) that confer organophosphate resistance. Six alleles, EsterB1, Ester2, Ester8, Ester9, EsterB10, and Ester11, have been observed in field populations in China, sometimes co-existing in one population. To differentiate the carboxylesterase alleles found in these field populations, PCR-RFLP was designed for use in resistance monitoring. Results Based on the DNA sequences of resistant and nonresistant carboxylesterase alleles, Ester B alleles were first amplified with PCR-specific primers and then digested with the restriction enzyme DraI. In this step, Ester2 and Ester11 were differentiated from the other Ester alleles. When the other Ester B alleles were digested with the restriction enzyme XbaI, EsterB1 and the susceptible C. p. pallens Ester were screened out. Ester8 and Ester9 were differentiated from EsterB10 and the susceptible C. p. quinquefasciatus esterase allele, respectively, by amplifying and digesting the Ester A alleles with the restriction enzyme ApaLI. The effectiveness of the custom-designed PCR-RFLP was verified in two field mosquito populations. Conclusions A PCR-RFLP based approach was developed to differentiate carboxylesterase alleles in Culex pipiens complex mosquitoes. These processes may be useful in monitoring the evolutionary dynamics of known carboxylesterase alleles as well as in the identification of new alleles in field populations.

A dengue fever outbreak in Guangzhou, Guangdong Province, China, in 2014 resulted in ~37,000 cases and five deaths. Insecticides were sprayed to control the vector of this outbreak, Aedes albopictus (Skuse), a species of mosquito. Aedes albopictus specimens collected from Huadu District (HD), Huangpu District (HP), Luogang District (LG), and Nansha District (NS) in Guangzhou were evaluated using WHO-recommended bioassays for both larvae and adult mosquitoes to determine population resistance to deltamethrin, betacypermethrin, cypermethrin, permethrin, dichlorvos, temephos, propoxur, and DDT. Compared with a susceptible laboratory strain of Ae. albopictus (S-lab), all populations showed decreased sensitivities to the eight insecticides, with resistance ratios (RRs) ranging from 2.2 to 275. The RRs were 6.8-275 for pyrethroids, 2.2-4.4 for organophosphates, 5.7-9.0 for carbamates, and 5.3-94.3 for organochlorines. For adult mosquitoes, all populations were sensitive to dichlorvos with 100% mortalities. Mosquitoes from HP, LG, and NS were also sensitive to propoxur. But for other tested insecticides, different degrees of resistance (mortality rate ranging from 11.7% to 94.7%) were observed. Among the four field populations, the resistance levels are presented as follows in descending order: HP>HD>NS>LG. The levels among insecticides classes were pyrethroids>organochlorines>carbamates>organophosphates. [ABSTRACT FROM AUTHOR]

Selection experiments for resistance to transgenic Bt cotton expressing Cry1Ac toxin in Helicoverpa armigera (Hübner) were conducted using a leaf-feeding method with 42 selection episodes over 45 generations. The cotton bollworm developed resistance to transgenic Bt cotton after 12 generations (F[sub12]) of selection. The survival rate of F[sub12] neonates feeding on leaves of seedling stage for 4 days and bollopening stage for 5 days of R[sub19] line were ca 34 and 72%, respectively, compared with ca 0 and 40% for a non-selected sister strain (NYCS), but lower than or similar to that of F[sub12] feeding on leaves of non-Bt cotton, Sumian 12 (ca 87 or 76%). Resistance to B thuringiensis HD-1 Dipel in neonates (F[sub12]) was ca 6-fold. After 42 generations of selection, the strain developed a very high level of resistance to CrylAc protoxin, 210gkg[sup-1] MVPII wettable powder and 200 glitre[sup-1] MVPII liquid formulation, the resistance ratios being 1680-, 1780- and ca 1200-fold, respectively, compared with a laboratory susceptible strain (HZS). When compared with the non-selected NYCS, the resistance ratios to the above toxins were ca 540-, 580- and 510-fold, respectively, but to Dipel only ca 16-fold. The results indicated that it is very important to develop and implement effective resistance-management strategies and to detect early resistance to Bt cotton in field populations. [ABSTRACT FROM AUTHOR]

We studied coinfection with four genera of bacteria--Borrelia, Bartonella, Anaplasma, and Ehrlichia--in ticks collected between December 2005 and November 2006 from Zhejiang Province and Liaoning Province. Four hundred fifty Haemaphysalis longicornis and 86 Ixodes sinensis ticks were collected and divided into 236 groups. Polymerase chain reaction (PCR) or nested PCR was used to detect the bacteria. The amplicons were sequenced and compared to published sequences. Phylogenic analysis was performed with MEGA3.1 and the data were analyzed using SPSS 11.0. Borrelia, Bartonella, Anaplasma, and Ehrlichia positive rates were 30.1% (71/236), 28.8% (68/236), 1.3% (3/236), and 0.8% (2/236), respectively. One tick was coinfected with all four bacteria (Borrelia, Bartonella, Anaplasma, and Ehrlichia) and another group was coinfected with three bacteria, Borrelia, Bartonella, and Ehrlichia. Statistical analysis showed most coinfections were significant, indicating that once a tick was infected with one bacteria, there was a greater chance to be infected with another bacteria.