QTL Determining Diel Flight Activity in Male Culex pipiens Mosquitoes.

Members of the Culex pipiens complex differ in physiological traits that facilitate their survival in diverse environments. Assortative mating within the complex occurs in some regions where autogenous (the ability to lay a batch of eggs without a blood meal) and anautogenous populations are sympatric, and differences in mating behaviors may be involved. For example, anautogenous populations mate in flight/swarms, while autogenous populations often mate at rest. Here, we characterized flight activity of males and found that anautogenous strain males were crepuscular, while autogenous strain males were crepuscular and nocturnal, with earlier activity onset times. We conducted quantitative trait locus (QTL) mapping to explore the genetic basis of circadian chronotype (crepuscular vs. crepuscular and nocturnal) and time of activity onset. One major-effect QTL was identified for chronotype, while 3 QTLs were identified for activity onset. The highest logarithm of the odds (LOD) score for the chronotype QTL coincides with a chromosome 3 marker that contains a 15-nucleotide indel within the coding region of the canonical clock gene, cryptochrome 2. Sequencing of this locus in 7 different strains showed that the C-terminus of CRY2 in the autogenous forms contain deletions not found in the anautogenous forms. Consequently, we monitored activity in constant darkness and found males from the anautogenous strain exhibited free running periods of ~24 h while those from the autogenous strain were ~22 h. This study provides novel insights into the genetic basis of flight behaviors that likely reflect adaptation to their distinct ecological niches.

Environmental management and mosquito control / 上海预防医学

With global warming, mosquitoes and mosquito-borne diseases are spreading rapidly in many regions across the world and producing substantial morbidity and mortality.According to recent studies, mosquito population structure, density and distribution in urban environment are under dynamical changes with continuous urbanization and the consequent environment changes.Surface sewers and under-ground catch basins are becoming major mosquito breeding habitats. Population structure in surface sewers varies with the environment, Aedes albopictus is the dominant species in residential areas.Charac-terized with high population density and mobility, residential areas are easier for mosquito-borne disease spreading, so more attention should be paid to Aedes albopictus control in urban residential areas.Increased underground garages and subway traffic generated new breeding habitats and over wintering sites for mosquitoes in urban environment, control measures should be taken for such environments, since urban underground spaces are always the transit hub of vehicles, which may facilitate the spread of mosquito and its vectored virus, particularly, Culex molestus, Aedes albopictus and Culex tritaeniorhynchus can all be found breeding in underground catch basins.Frequent reports of Culex tritaeniorhynchus breeding in urban surface and underground environment suggest that Culex tritaeniorhynchus is gradually adapted to the new urbanized habitats, which may produce great effect for mosquito population structures in urban environment.Breeding habitats management is the most effective measures for mosquito control, qualified mosquito surveillance can help understand the fluctuation of mosquito species and provide timely warning, at the same time, regular risk assessment for mosquito-borne disease is essential for disease control and prevention.