Michaelakis Antonios, Papachristos Dimitrios P, Rumbos Christos I, Benelli Giovanni, Athanassiou Christos G
Department of Entomology and Agricultural Zoology, Benaki Phytopathological Institute, 8 S. Delta Str. 14561 Kifissia, Athens, Greece.
Laboratory of Entomology and Agricultural Zoology, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Phytokou str., 38446, N. Ionia, Magnesia, Greece.
Parasitol Int. 2020 Feb;74:101917. doi: 10.1016/j.parint.2019.04.014. Epub 2019 Apr 18.
In the present study, the larvicidal activity of ageing aqueous suspensions of spinosad against larvae of Culex pipiens biotype molestus, as well as their effect on the oviposition preferences of adult gravid females were evaluated in laboratory bioassays. Spinosad was applied at its label dose and the aqueous stock suspensions were stored for various ageing intervals up to 38 days. Untreated distilled water and diflubenzuron served as negative and positive control, respectively. Stock suspensions were taken after 0, 2, 6, 8, 16, 30 and 38 days of storage for diflubenzuron and after 0, 2, 6, 8, 20 and 27 days for spinosad, and were used for the bioassays. Furthermore, the effect of spinosad on the oviposition response of Cx. p. biotype molestus gravid females was investigated in two-choice oviposition preference bioassays. Spinosad was evaluated at half of its label dose and at its label dose, whereas diflubenzuron and distilled water served as positive and negative control, respectively. Results showed that both insecticides were found highly effective for the control of Cx. p. biotype molestus larvae, for ageing intervals up to 27 and 38 days for spinosad and diflubenzuron, respectively. Spinosad acted immediately after the preparation of the insecticidal solution (LT = 1.5 h), whereas for aged samples, LT values increased with the increase of the ageing interval (LT = 5 days for the 27 days old sample). For diflubenzuron, ageing time increased its insecticidal activity, as for aged diflubenzuron-treated solutions, lower LT values were achieved. In the oviposition preference bioassays, significantly fewer egg rafts were laid in water treated with spinosad at its label dose compared to control. However, this was not the case for water treated with spinosad at half of its label dose. Oviposition Activity Index (OAI) values were always comprised between -0.3 and 0.3, showing no relevant oviposition deterrence or attraction. The results of the present study contribute to our understanding of the effect of ageing on insecticidal solutions widely used in urban areas to control Cx. p. biotype molestus. Although an important vector of high public health importance, Cx. p. biotype molestus has been scarcely studied as target of environmentally and toxicologically reduced risk insecticides, such as spinosad.
在本研究中，通过实验室生物测定评估了多杀菌素老化水悬浮液对骚扰库蚊生物型幼虫的杀幼虫活性及其对成年孕蚊产卵偏好的影响。多杀菌素按其标签剂量施用，水储备悬浮液储存不同的老化时间间隔，最长达38天。未处理的蒸馏水和除虫脲分别作为阴性和阳性对照。储存0、2、6、8、16、30和38天后取除虫脲的储备悬浮液，储存0、2、6、8、20和27天后取多杀菌素的储备悬浮液用于生物测定。此外，在双选产卵偏好生物测定中研究了多杀菌素对骚扰库蚊生物型孕蚊产卵反应的影响。多杀菌素按其标签剂量的一半和标签剂量进行评估，而除虫脲和蒸馏水分别作为阳性和阴性对照。结果表明，两种杀虫剂对骚扰库蚊生物型幼虫的防治均非常有效，多杀菌素和除虫脲分别在长达27天和38天的老化时间间隔内有效。多杀菌素在杀虫溶液配制后立即起作用（LT = 1.5小时），而对于老化样品，LT值随老化时间间隔的增加而增加（27天龄样品的LT = 5天）。对于除虫脲，老化时间增加了其杀虫活性，因为对于老化的除虫脲处理溶液，LT值更低。在产卵偏好生物测定中，与对照相比，用标签剂量的多杀菌素处理的水中产下的卵块明显更少。然而，用标签剂量一半的多杀菌素处理的水并非如此。产卵活性指数（OAI）值始终在-0.3至0.3之间，表明没有相关的产卵抑制或吸引作用。本研究结果有助于我们了解老化对城市地区广泛用于控制骚扰库蚊生物型的杀虫溶液的影响。尽管骚扰库蚊生物型是具有高度公共卫生重要性 的重要病媒，但作为环境和毒理学风险降低的杀虫剂（如多杀菌素）的靶标，对其研究甚少。
