MRC Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
Parasit Vectors. 2011 Jul 28;4:153. doi: 10.1186/1756-3305-4-153.
Intensive anti-malaria campaigns targeting the Anopheles population have demonstrated substantial reductions in adult mosquito density. Understanding the population dynamics of Anopheles mosquitoes throughout their whole lifecycle is important to assess the likely impact of vector control interventions alone and in combination as well as to aid the design of novel interventions.
An ecological model of Anopheles gambiae sensu lato populations incorporating a rainfall-dependent carrying capacity and density-dependent regulation of mosquito larvae in breeding sites is developed. The model is fitted to adult mosquito catch and rainfall data from 8 villages in the Garki District of Nigeria (the 'Garki Project') using Bayesian Markov Chain Monte Carlo methods and prior estimates of parameters derived from the literature. The model is used to compare the impact of vector control interventions directed against adult mosquito stages--long-lasting insecticide treated nets (LLIN), indoor residual spraying (IRS)-- and directed against aquatic mosquito stages, alone and in combination on adult mosquito density.
A model in which density-dependent regulation occurs in the larval stages via a linear association between larval density and larval death rates provided a good fit to seasonal adult mosquito catches. The effective mosquito reproduction number in the presence of density-dependent regulation is dependent on seasonal rainfall patterns and peaks at the start of the rainy season. In addition to killing adult mosquitoes during the extrinsic incubation period, LLINs and IRS also result in less eggs being oviposited in breeding sites leading to further reductions in adult mosquito density. Combining interventions such as the application of larvicidal or pupacidal agents that target the aquatic stages of the mosquito lifecycle with LLINs or IRS can lead to substantial reductions in adult mosquito density.
Density-dependent regulation of anopheline larvae in breeding sites ensures robust, stable mosquito populations that can persist in the face of intensive vector control interventions. Selecting combinations of interventions that target different stages in the vector's lifecycle will result in maximum reductions in mosquito density.
针对疟蚊种群的强化抗疟运动已证明可大幅降低成蚊密度。了解疟蚊整个生命周期的种群动态对于评估单独和联合使用媒介控制干预措施以及辅助新型干预措施的设计都很重要。
我们开发了一种包含降雨依赖性承载能力和蚊虫幼虫在滋生地中密度依赖性调节的冈比亚按蚊复合体种群生态模型。该模型使用贝叶斯马尔可夫链蒙特卡罗方法，根据文献中的参数先验估计，对来自尼日利亚加基区 8 个村庄的成蚊捕获量和降雨量数据进行拟合。该模型用于比较针对成蚊阶段（长效驱虫蚊帐、室内滞留喷洒）和针对水生蚊阶段的媒介控制干预措施的影响，包括单独使用和联合使用对成蚊密度的影响。
在幼虫阶段通过线性关联幼虫密度与幼虫死亡率来实现密度依赖性调节的模型，对季节性成蚊捕获量具有良好的拟合度。在存在密度依赖性调节的情况下，有效蚊繁殖数取决于季节性降雨模式，并在雨季开始时达到峰值。除了在体外发育期间杀死成蚊外，长效驱虫蚊帐和室内滞留喷洒还会导致滋生地中产卵减少，从而进一步降低成蚊密度。将针对蚊生命周期水生阶段的幼虫杀灭或蛹杀灭剂等干预措施与长效驱虫蚊帐或室内滞留喷洒相结合，可以显著降低成蚊密度。
在滋生地中对按蚊幼虫进行密度依赖性调节可确保蚊群具有稳健、稳定的特征，能够在强化媒介控制干预措施的情况下持续存在。选择针对媒介生命周期不同阶段的干预措施组合，将导致蚊密度的最大降低。
