ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Wolbachia spp. are maternally transmitted Gram-negative endosymbiotic bacteria. With infection occurring in a wide range of invertebrates, Wolbachia is estimated to infect 65% of insect species and 28% of mosquito species in nature. An early embryo death, a phenotype referred to as cytoplasmic incompatibility (CI), will occur when infected males mate with uninfected females, or females that carry different type of Wolbachia. CI provides reproductive advantage to infected females, resulting in spread of Wolbachia into mosquito population. Furthermore, Wolbachia can confer mosquito resistant to a variety of human pathogens, including dengue virus, yellow fever virus and malaria parasites. This has led to large efforts to develop Wolbachia-based vector control strategies. One is referred to as population replacement, in which a disease susceptible wild type vector population is modified into a disease resistant population, resulting in blocking of disease transmission. Another is population suppression, in which CI mating is induced in the target population, resulting in suppression, or even eradication of a vector population.
Objective To establish the susceptibility baselines of Anopheles sinensis to commonly used insecticides. Methods The An. sinensis was provided by the National Institute of Parasitic Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, which was reared in the laboratory for more than 50 years without exposure to any pesticides. Impregnation method and filter paper contact method were used to determine the susceptibility to commonly used insecticides for the larvae and adults of An. sinensis. Results The susceptibility baselines of An. sinensis larvae to deltamethrin, beta-cypermethrin, permethrin, dichlorvos, BPMC, fenitrothion, and temephos were established by impregnation method; the results were described as y＝13.0586＋3.8987x, y＝9.2950＋2.1510x, y＝10.3449＋4.4594x, y＝4.3319＋8.7669x, y＝11.3541＋11.2014x, y＝11.5447＋6.9681x, and y＝10.8033＋4.6466x, respectively. The susceptibility baselines of adult An. sinensis to deltamethrin, beta?cypermethrin, permethrin, and BPMC were established by filter paper contact method; the results were described as y＝12.5204＋3.6871x, y＝10.2596＋3.0291x, y＝8.4266＋2.6610x, and y＝13.8210＋5.0963x, respectively. Conclusion The susceptibility baselines of An. sinensis larvae to seven insecticides and those of adult An. sinensis to four insecticides have been established. The results can be used as the reference for the discriminating doses for the larvae and adults of An. sinensis in China.
Objective To investigate the main factors affecting the microhabitat selection of plateau pika (Ochotona curzoniae) during summer in the alpine meadow and alpine desert of Altun Mountain National Nature Reserve, Xinjiang Uygur Autonomous Region, China and to provide a basis for the prevention and control of plateau pika. Methods A total of 69 test sample sites (5 m×5 m) in the caves with pika activity and 62 control sites in nearby similar habitats without pika activity were set and investigated from July to August 2012. The ecological factors of areas where the samples were located were recorded, including elevation, number of plant species, vegetation coverage, vegetation height, soil hardness, and distance from the roads. Results There were significant differences in vegetation height, vegetation density, slope, elevation, vegetation types, and soil hardness between the test sites and control sites (P＜0.05). According to the results of principal component analysis, the main factors affecting the habitat selection of plateau pika were slope (0.886), number of plant species (-0.865), and soil hardness (0.834). Conclusion The plateau pika prefers the habitats with higher elevation, steeper slope, lower vegetation height, higher vegetation density, and lower soil hardness in alpine meadow or alpine desert, which provides an important basis for regulating the population density of plateau pika by improving the vegetation.
Objective To analyze the epidemiological features of hemorrhagic fever with renal syndrome (HFRS) and associated environmental risk factors for HFRS and associated environmental risk factors for HFRS in Liaoning province, China during 2005-2007, and to provide a scientific basis for HFRS control measures. Methods The epidemic data of HFRS in Liaoning province were collected. Analysis was performed to determine the correlation between the epidemic features of HFRS and environmental factors such as mean temperature, relative humidity, rainfall, sunshine, urban rodent density, rural rodent density, and virus?carrying rate. Results There were 7298 cases of HFRS in Liaoning province from 2005 to 2007, and 78 of them died. The mean annual incidence of HFRS was 5.78/100 000, and the mortality was 0.06/100 000; the incidence and mortality were higher in males than in females; 59.55% of the cases and 69.23% of fatal cases were aged 35-60 years; 61.98% of the cases and 56.41% of fatal cases were farmers. The peak of incidence appeared mainly in November to January and March to May, while the trough period was in July to October, showing the seasonal characteristics in mixed epidemic area; the mean annual incidence of HFRS was relatively high in the cities of Benxi (13.70/100 000), Huludao (12.92/100 000), Jinzhou (11.30/100 000), Dandong (10.21/100 000), and Fushun (9.84/100 000). The incidence of HFRS was negatively correlated with temperature but positively correlated with rainfall, rural rodent density, and virus-carrying rate; the Spearman rank correlation coefficients were -0.351, 0.400, 0.449, and 0.377, respectively, and the P values were 0.023, 0.009, 0.003, and 0.016, respectively. Conclusion In Liaoning province, HFRS is prevalent mainly in winter and spring and among young male farmers. The prevalence of HFRS is closely related to temperature, rainfall, rural rodent density, and virus-carrying rate in the same year.
Objective To study the food intakes of Blattella germanica, Periplaneta americana, and Periplaneta fuliginosa and the effects of temperature and food types on their food intakes. Methods High carbohydrate food, high protein food, and high fat food were provided for the three species of cockroaches; the food intakes of cockroaches were observed at different temperatures, and the effect of temperature on food intakes was statistically analyzed. Results For common starch food (water content 5.70%), the average daily food intakes of each cockroach (mg/d ) at 8 ℃, 16 ℃, and 32 ℃ were as follows: 2.10±0.28, 8.47±0.57, and 8.69±0.58 for female B. germanica, and 1.76±0.67, 7.04±1.25, and 4.51±0.20 for male B. germanica; 25.78±1.31, 65.56±13.73, and 142.94±13.00 for female P. americana, and 17.67±5.31, 32.94±4.82, and 76.81±7.55 for male P. americana; 32.07±10.02, 46.90±8.42, and 92.46±7.77 for female P. fuliginosa, and 15.38±2.15, 17.21±2.26, and 50.61±3.05 for male P. fuliginosa. For B. germanica, the average daily food intakes (mg/d) of each late instar nymph, female adult, and male adult were as follows: 1.78±1.03, 1.06±0.61, and 0.50±0.29 for peanuts, 2.04±1.18, 1.54±0.89, and 0.58±0.34 for dried meat floss, and 2.53±1.46, 1.73±1.00, and 0.71±0.41 for red dates. Conclusion As temperature increases, the food intake of B. germanica first increases and then decreases, showing a parabolic pattern, while the food intakes of P. americana and P. fuliginosa increase linearly. B. germanica has the highest intake for high starch food, followed by high-protein food, and had the lowest intake for high-fat food; for each food, the food intake was the highest in late?instar nymphs, followed by female adults and male adults.
