Department of Pathobiological Sciences, University of Wisconsin-Madison, 1656 Linden Drive, Madison, WI 53706, USA.
North Shore Mosquito Abatement District, 117 Northfield Road, Northfield, IL 60093, USA.
J Med Entomol. 2023 Mar 6;60(2):384-391. doi: 10.1093/jme/tjac170.
West Nile virus remains the leading cause of arboviral neuroinvasive disease in the United States, despite extensive efforts to control the mosquito vectors involved in transmission. In this study, we evaluated the effectiveness of Altosid SR-20 (active ingredient, S-methoprene 20%) larvicide applications using truck-mounted ultra-low volume (ULV) dispersal equipment to target Culex pipiens Linnaeus (Diptera: Culicidae) and Cx. restuans (Theobald)larvae. A combination of emergence bioassays, open-field measurements of deposited S-methoprene and spray distribution using gas chromatography-mass spectrometry, and assessments of adult Culex spp. populations in response to applications were conducted over the summer of 2020 within the North Shore Mosquito Abatement District (IL, USA). Open-field applications revealed that dispersed Altosid SR-20 using ULV equipment was effective (75% emergence inhibition in susceptible lab strain Cx. pipiens larvae) up to 53 m. In suburban neighborhood applications, we found that S-methoprene deposition and larval emergence inhibition (EI) in front yards did not differ significantly from backyards. An overall EI of 46% and 28% were observed for laboratory strain Cx. pipiens and wild Cx. restuans larvae respectively, and both had an EI significantly higher than the untreated control group. The EI of exposed wild Cx. pipiens larvae did not differ from the untreated controls, suggesting an increased tolerance to S-methoprene. No difference in abundance of gravid or host-seeking adult Culex spp. post-application was detected between treated and untreated sites. These results document the ability of area-wide application to distribute S-methoprene, but this strategy will need further modifications and evaluation for Culex spp. management.
西尼罗河病毒仍然是美国虫媒病毒神经侵袭性疾病的主要原因，尽管已经做出了广泛的努力来控制参与传播的蚊子媒介。在这项研究中，我们评估了使用车载超低容量（ULV）分散设备靶向库蚊属（双翅目：蚊科）和 Cx. restuans（Theobald）幼虫的 Altosid SR-20（有效成分，S-甲氧普林 20%）杀幼虫剂应用的效果。通过使用气相色谱-质谱法进行的出现生物测定、沉积 S-甲氧普林的野外测量以及喷雾分布的组合，以及对应用后成年 Culex spp. 种群的评估，于 2020 年夏季在北海岸蚊虫防治区（美国伊利诺伊州）进行。野外应用表明，使用 ULV 设备分散的 Altosid SR-20 是有效的（易感实验室品系 Cx. pipiens 幼虫的 75%出现抑制），有效距离长达 53 米。在郊区社区应用中，我们发现前院和后院的 S-甲氧普林沉积和幼虫出现抑制（EI）没有显著差异。实验室品系 Cx. pipiens 和野生 Cx. restuans 幼虫的总体 EI 分别为 46%和 28%，均显著高于未处理的对照组。暴露于 S-甲氧普林的野生 Cx. pipiens 幼虫的 EI 与未处理的对照组没有差异，表明对 S-甲氧普林的耐受性增加。处理和未处理地点之间未检测到应用后嗜人血和宿主寻找的成年 Culex spp. 丰度的差异。这些结果证明了区域广泛应用分配 S-甲氧普林的能力，但这种策略需要进一步修改和评估，以用于 Culex spp. 管理。
