Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
Trans R Soc Trop Med Hyg. 2011 May;105(5):247-53. doi: 10.1016/j.trstmh.2011.01.009. Epub 2011 Feb 26.
Insecticides play a crucial role in controlling the transmission of mosquito-borne diseases and the development and spread of insecticide resistance is a major threat to sustainable control. Guidelines developed by the WHO to monitor for insecticide resistance recommend using 1-3 day old, non blood fed female mosquitoes. This standardisation facilitates comparison between different tests, which is important when monitoring for spatial or longitudinal variations in resistance in the field. However, mosquitoes of this age cannot transmit human pathogens. In order to transmit disease, the mosquito must live long enough to pick up the pathogen via a blood meal, survive the extrinsic incubation period and then pass on the pathogen during a subsequent blood meal. Previous studies have reported declines in insecticide resistance with mosquito age. If widely applicable this would have important implications for predictions of the impact of resistance that are based on results from WHO bioassays. This study investigated the impact of senescence and blood feeding on insecticide induced mortality in six different mosquito populations and found higher mortality after insecticide exposure in older mosquitoes in three populations of Aedes aegypti and two Anopheles gambiae populations. Age dependent changes in the expression of a known insecticide detoxification gene, GSTe2, and in the frequency of a target site mutation (kdr 1014F) were investigated in an attempt to explain the results.
杀虫剂在控制蚊媒疾病的传播方面发挥着至关重要的作用，而杀虫剂抗性的发展和传播是可持续控制的主要威胁。世界卫生组织制定的监测杀虫剂抗性的指南建议使用 1-3 日龄、未吸血的雌性蚊子。这种标准化有助于不同测试之间的比较，当监测现场抗性的空间或纵向变化时，这一点非常重要。然而，这个年龄段的蚊子无法传播人类病原体。为了传播疾病，蚊子必须活得足够长，以便在吸血时感染病原体，在体外孵育期存活下来，然后在随后的吸血时传播病原体。以前的研究报告称，随着蚊子年龄的增长，杀虫剂抗性会下降。如果这一现象普遍存在，那么基于世界卫生组织生物测定结果预测抗性影响的预测将产生重要影响。本研究调查了衰老和吸血对六种不同蚊子种群中杀虫剂诱导死亡率的影响，结果发现，在埃及伊蚊和两种冈比亚按蚊的三个种群中，年老蚊子在接触杀虫剂后死亡率更高。研究还调查了已知杀虫剂解毒基因 GSTe2 的表达随年龄的变化，以及靶标位点突变（kdr 1014F）的频率，试图解释这些结果。
