目的 比较不同剂量多杀菌素Natular G30在生活污水与小型净水中对致倦库蚊海口种群的控制效果, 为其在蚊虫控制中的应用提供依据。方法 用海南省海口市生活污水与小型净水中的致倦库蚊幼虫和水, 在外环境以减退率为指标, 分别测定Natular G30 10、20、40和80 mg/m2对蚊虫的控制效果。试验中, 两次测量试验水体的水质pH值、温度、总固体含量、盐度、溶解氧含量。结果 生活污水的pH值、溶解氧含量分别为(9.62±0.43)、(12.79±3.01)mg/L, 小型净水分别为(8.91±0.39)、(7.77±3.46)mg/L, 二者差异有统计学意义(P＜0.05)。在生活污水中, 多杀菌素有效浓度为10和20 mg/m2时, 蚊虫控制持效时间为12 d, 40和80 mg/m2处理的则＞30 d;而在小型净水中, 所有4个浓度均有超过30 d的持效期。两种水体所有剂量在第1天对1、2龄期幼虫的减退率即接近100%, 3、4龄期幼虫在第3～7天出现100%减退, 而蛹在第1天的减退率基本为负值。结论 多杀菌素Natular G30对致倦库蚊幼虫的控制效果具有高效、持久的特点;且对1、2龄幼虫的毒性高于对3、4龄幼虫的毒性, 对蛹无明显的毒杀作用。因其在小型净水中的效果优于生活污水, 使用时应根据水质调整剂量。

Objective The efficacy of spinosad Natular G30 against Culex pipiens quinquefasciatus was evaluated at different doses with comparing sewage habitat and small body of water with waste plants habitat, so as to provide evidence for mosquito control. Methods Using wild Cx. pipiens quinquefasciatus larvae and water in sewage and small body of water in Haikou, Hainan province, the efficacy of Natular G30 at 10, 20, 40, 80 mg/L was tested, percentage reduction was taken as efficacy index. The pH, temperature, total solids, salinity, dissolved oxygen of habitat water were determined at any two points of time during the trial period. Results There were significant differences (P＜0.05) between pH and dissolved oxygen in the two habitats, while no differences between temperature, total solids, salinity. The pH and dissolved oxygen of sewage water were (9.62±0.43) and (12.79±3.01) mg/L, and those in small body of water with wasted plants were (8.91±0.39) and (7.77±3.46) mg/L. The residual efficacy of Natular G30 at 10 mg/m2 and 20 mg/m2 against Cx. pipiens quinquefasciatus in sewage breeding site lasted for 12 days, while 40 mg/m2 and 80 mg/m2 in both habitats was more than 30 days. In two tested habitats, after one day of Natular G30 using, the first and second instar mosquito reduction was nearly 100%, but for the third and forth instar larvae, 100% reduction date was at three to seven days. To our surprise, the reduction of pupae was negative after one day insecticide applied. Conclusion Spinosad has high and long-lasting efficiency against Cx. pipiens quinquefasciatus larvae. Its effectiveness is better when applied in the habitats of small body of water with wasted plants than that of sewage. Spinosad has a very higher efficacy to control the first and second instar young larvae than the third and forth instars larvae, but no noticeable effect on pupae. To control Cx. pipiens quinquefasciatus, the spinosad rate should be adjusted based on the characteristics of habitat water.