Liverpool School of Tropical Medicine, Liverpool, UK.
Pennsylvania State University, State College, PA, USA.
Parasit Vectors. 2022 Mar 28;15(1):111. doi: 10.1186/s13071-022-05220-y.
There is a pressing need to improve understanding of how insecticide resistance affects the functional performance of insecticide-treated nets (ITNs). Standard WHO insecticide resistance monitoring assays are designed for resistance surveillance and do not necessarily provide insight into how different frequencies, mechanisms or intensities of resistance affect the ability of ITNs to reduce malaria transmission.
The current study presents some novel laboratory-based assays that attempt to better simulate realistic exposure of mosquitoes to ITNs and to quantify impact of exposure not only on instantaneous mortality, but also on blood-feeding and longevity, two traits that are central to transmission. The assays evaluated the performance of a standard ITN (Permanet® 2.0; Vestergaard Frandsen), a 'next generation' combination ITN with a resistance-breaking synergist (Permanet® 3.0) and an untreated net (UTN), against field-derived Anopheles gambiae sensu lato mosquitoes from Côte d'Ivoire exhibiting a 1500-fold increase in pyrethroid resistance relative to a standard susceptible strain.
The study revealed that the standard ITN induced negligible instantaneous mortality against the resistant mosquitoes, whereas the resistance-breaking net caused high mortality and a reduction in blood-feeding. However, both ITNs still impacted long-term survival relative to the UTN. The impact on longevity depended on feeding status, with blood-fed mosquitoes living longer than unfed mosquitoes following ITN exposure. Exposure to both ITNs also reduced the blood-feeding success, the time spent on the net and blood-feeding duration, relative to the untreated net.
Although a standard ITN did not have as substantial instantaneous impact as the resistance-breaking net, it still had significant impacts on traits important for transmission. These results highlight the benefit of improved bioefficacy assays that allow for realistic exposure and consider sub- or pre-lethal effects to help assess the functional significance of insecticide resistance.
迫切需要提高对杀虫剂抗性如何影响经杀虫剂处理的蚊帐（ITN）功能性能的理解。世界卫生组织标准杀虫剂抗性监测检测方法旨在进行抗性监测，不一定能深入了解不同频率、机制或强度的抗性如何影响 ITN 降低疟疾传播的能力。
本研究提出了一些新的实验室检测方法，试图更好地模拟蚊子对 ITN 的实际暴露情况，并不仅量化暴露对即时死亡率的影响，还量化暴露对吸血和寿命的影响，这两个特征是传播的核心。这些检测方法评估了标准 ITN（Permanet® 2.0；Vestergaard Frandsen）、具有抗性破坏增效剂的“下一代”组合 ITN（Permanet® 3.0）和未处理的网（UTN）的性能，针对来自科特迪瓦的具有 1500 倍拟除虫菊酯抗性的田间衍生的按蚊按蚊。
研究表明，标准 ITN 对抗性蚊子几乎没有引起瞬时死亡率，而抗药性网则导致高死亡率和吸血减少。然而，与 UTN 相比，两种 ITN 仍然对长期生存产生影响。对寿命的影响取决于摄食状态，与 ITN 暴露后未摄食的蚊子相比，吸血的蚊子寿命更长。与未处理的网相比，暴露于两种 ITN 还降低了吸血成功率、在网上花费的时间和吸血持续时间。
尽管标准 ITN 没有抗药性网那样立竿见影的即时影响，但它仍然对传播的重要特征产生了重大影响。这些结果强调了改进的生物功效检测方法的好处，这些方法允许进行现实暴露并考虑亚致死或亚致死效应，以帮助评估杀虫剂抗性的功能意义。
