Surveillance of cockroach population and evaluation of control effects in households from 2017 to 2019 in Jiading District of Shanghai / 上海预防医学

Objective To learn the population and infestation rates of cockroaches from 2017 to 2019 in Jiading District of Shanghai, to evaluate the effect of cockroach termination in household, and to provide information for cockroach control. Methods Cockroaches were controlled by dinotefuran baits and clean-up in households.Sticky trap and visual method were employed for density monitoring in farmers markets, supermarkets, hotels, restaurants, hospitals, and residential areas.Visual method was used in households before and after using the insecticide. Results Sticky trap result showed the room infestation rate was 3.24%, mean adhesion rate was 3.29%, the density was 0.06 per board, and the density peak appeared in May.Rate of invasion and density decreased year by year.Blattella germanica was the dominant species, counting for 71.88%.The density, and rate of infestation, as determined by sticky trap method, were the highest in the farmers markets, followed by hospitals and residential areas.Determined by visual method, room infestation rate was 1.16%, and the infestation rate was 4.44%.The peak appeared in January.Infestation rate of the farmers markets was the highest, followed by hospitals and residential areas.By visual method, the room infestation rate was 59.01%, and 48.45% for nymphs.The room infestation and ootheca rates were 54.04% and 17.39%.The rate decreased more than 80% in 30 days after use of the insecticide. Conclusion Infestation rate of cockroach remains at low level in Jiading District.The effect of bait combined with environmental cleaning is remarkable.Future work should strengthen monitoring and control in farmers markets, hospitals and residential areas.

Laboratory study on chain-killing efficacy of four gel baits / 上海预防医学

Objective To study the first-time killing efficacy and the chain-killing efficacy of four gel baits against Blattella germanica: 1% chlorpyrifos, 0.05% fipronil, 2.15% imidacloprid, and 0.5% dinotefuran and provide a basis for drug selection in controlling Blattella germanica. Methods Laboratory killing efficacy test was conducted according to the national standard GB/T 13917.7-2009 and the chain-killing efficacy test was conducted for three rounds.The first round of chain efficacy test was conducted by feeding the cockroaches killed in the laboratory efficacy test, and each next round by feeding the cockroaches killed in the last round.Median lethal time (LT50), 95% confidence limit, and toxicological regression equation of each test were calculated by software DPS V9.01. Results The LT50 of the efficacy test with 1% chlorpyrifos gel bait was 0.745 5 (0.603 4-0.890 3) d.The LT50 of the first, second and third chain experiments increased by 3.30, 2.18 and 2.76 times, respectively.The LT50 of the efficacy test with 0.05% fipronil gel bait was 0.846 5(0.464 7-1.228 0)d, and increased by 5.42, 2.09 and 1.48 times, respectively, in the first, second and third chain experiments.The LT50 of the efficacy test with 2.15% imidacloprid gel bait was 3.192 1(2.865 0-3.506 0)d, and increased by 1.13, 1.65 and 1.15 times, respectively in the first, second and third chain experiments.The LT50 of the efficacy test with 0.5% dinotefuran gel bait was 0.997 1(0.805 8-1.191 6) d, and increased by 3.85, 1.37 and 1.78 times, respectively in the first, second and third chain experiments. Conclusion In the laboratory killing efficacy test, 1% chlorpyrifos, 0.05% fipronil, and 0.5% dinotefuran gel baits are better than 2.15% imidacloprid gel bait.In the chain-killing efficacy test, 2.15% imidacloprid and 0.5% dinotefuran gel baits are better than 1% chlorpyrifos and 0.05% fipronil gel baits.Based on our results, we recommend the use of 0.5% dinotefuran gel bait for comprehensive and sustained killing effect.

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.

Selection and risk assessment of resistance to pyriproxyfen in Culex pipiens pallens / 上海预防医学

[ Objective ] To assess the resistance risk of Culex pipiens pallens to pyriproxyfen in Culexpipiens pallens, to predict the rate of resistance development and to provide the reference for scientific and rational application of insecticides. [ Methods ] The resistance strain was developed by group selection, and the realized heritability ( h2 ) of Culex pipiens pallens resistance to deltamethrin was estimated by Tabashnik's method. [ Results] The resistance of Culex pipiens pallens to pyriproxyfen had increased by 5.69-fold after 12 generations of indoor breeding, and the h2 of Culex pipiens pallens to pyriproxyfen was 0.02, indicating that a relatively risk of resistance development. [ Conclusion] The results indicate that Culex pipiens pallens has resistance risk to pyriproxyfen, so the application of the insecticide must be scientific and rational.