Insecticide-treated nets (ITNs) undergo a series of tests to obtain listing by World Health Organization (WHO) Prequalification. These tests characterize the bioefficacy, physical and chemical properties of the ITN. ITN procurers assume that product specifications relate to product performance. Here, ITN test methods and their underlying assumptions are discussed from the perspective of the ITN manufacturing process and product characteristics. Data were extracted from WHO Pesticide Evaluation Scheme (WHOPES) meeting reports from 2003 to 2017, supplemented with additional chemical analysis to critically evaluate ITNs bioassays with a focus on sampling, washing and wash resistance, and bioefficacy testing. Production methods for ITNs and their impact on testing outcomes are described. ITNs are not homogenous products. They vary within panels and between the sides and the roof. Running tests of wash resistance using a before/after tests on the same sample or band within a net reduces test variability. As mosquitoes frequently interact with ITN roofs, additional sampling of the roof when evaluating ITNs is advisable because in nets where roof and sides are of the same material, the contribution of roof sample (20–25%) to the average is less than the tolerance for the specification (25%). Mosquito mortality data cannot be reliably used to evaluate net surface concentration to determine regeneration time (RT) and resistance to washing as nets may regenerate beyond the insecticide concentrations needed to kill 100% of susceptible mosquitoes. Chemical assays to quantify surface concentration are needed. The Wash Resistance Index (WRI) averaged over the first four washes is only informative if the product has a log linear loss rate of insecticide. Using a WRI that excludes the first wash off gives more reliable results. Storage conditions used for product specifications are lower than those encountered under product shipping and storage that may exceed 50 °C, and should be reconsidered. Operational monitoring of new ITNs and linking observed product performance, such as bioefficacy after 2 or 3 years of use, with product characteristics, such as WRI, will aid the development of more robust test methods and product specifications for new products coming to market.

中文翻译：

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从工厂到田间：杀虫剂处理网（ITN）生物功效测试的产品特性考虑因素


经杀虫剂处理的蚊帐 (ITN) 经过一系列测试，以获得世界卫生组织 (WHO) 资格预审的资格。这些测试表征了 ITN 的生物功效、物理和化学特性。 ITN 采购商假定产品规格与产品性能相关。这里从ITN制造工艺和产品特性的角度讨论ITN测试方法及其基本假设。数据取自 2003 年至 2017 年世界卫生组织农药评估计划 (WHOPES) 会议报告，并辅以额外的化学分析，以严格评估驱虫蚊帐生物测定，重点是取样、洗涤和耐洗涤性以及生物功效测试。描述了杀虫剂蚊帐的生产方法及其对测试结果的影响。驱虫蚊帐不是同质产品。它们在面板内以及侧面和屋顶之间有所不同。使用前/后测试对网内的同一样品或条带进行耐洗性测试，可减少测试变异性。由于蚊子经常与 ITN 屋顶相互作用，因此在评估 ITN 时建议对屋顶进行额外采样，因为在屋顶和侧面采用相同材料的蚊帐中，屋顶样本 (20–25%) 对平均值的贡献小于容差为规格（25%）。蚊子死亡率数据不能可靠地用于评估净表面浓度，以确定再生时间 (RT) 和耐洗涤性，因为蚊帐再生后的杀虫剂浓度可能会超过杀死 100% 易感蚊子所需的杀虫剂浓度。需要进行化学测定来量化表面浓度。仅当产品具有对数线性杀虫剂损失率时，前四次洗涤的平均耐洗涤指数 (WRI) 才具有参考意义。 使用排除第一次冲洗的 WRI 可提供更可靠的结果。产品规格中使用的存储条件低于产品运输和存储时可能超过 50 °C 的存储条件，应重新考虑。对新的驱虫蚊帐的运行监控以及将观察到的产品性能（例如使用 2 或 3 年后的生物功效）与产品特性（例如 WRI）联系起来，将有助于为即将上市的新产品开发更可靠的测试方法和产品规格。