MULTIPLE BLOOD FEEDING BY MOSQUITOES

蚊子在病原体传播中的作用最敏感的两个组成部分是每天存活的概率和人类吸血的频率。 大多数病媒传播疾病的模型都假设蚊子的生存和进食行为不会随着年龄的增长而改变。 到目前为止，这种假设还没有受到强烈的挑战，因为没有准确的方法来估计蚊子一生中流行病学不同部分的年龄或识别蚊子叮咬的人;测量蚊子的实际年龄和宿主喂养模式是困难或不可能的。 我们已经开发出了新的，更准确的方法，可以确定第一次如果生存和宿主接触的频率增加，随着蚊子媒介变老，成为传染性。 在这个更新的建议中，我们将使用这些方法来测试的假设，即埃及伊蚊的日常生存概率和频率的人类吸血增加蚊子的年龄。 年长的女性Ae.埃及人在流行病学上最重要，因为他们比年轻的蚊子更容易感染和传播登革热病毒。 为了确定野生蚊子的实足年龄长达约21天的年龄，我们分析表皮碳氢化合物（CH）。 我们可以通过DNA指纹识别程序来重建蚊子的吸血行为，该程序可以识别蚊子进食的人。标记重捕研究中的高重捕率（约30%）使我们能够研究自然环境中自由放养的蚊子的生存、扩散和吸血。我们的研究有2个具体的目标，我们将在泰国西北部进行，在那里AE。埃及传播的登革热病毒是地方病。 在目标1中，我们将比较观察到的年龄结构（CH年龄分级）和喂养模式（DNA指纹）的野生蚊子的模式下，假设这些组件的传播保持不变，蚊子变老。 在直接测试我们的研究假设之前，我们将定义我们目前的标记-再捕获方法的局限性，并选择最佳程序进行后续实验，研究存活、扩散和吸血的年龄依赖性差异。 在我们的最后一组实验中，我们将通过释放2个不同的年龄组并比较它们的重新捕获率、存活率和吸血行为来直接测试存活和吸血频率的动态随蚊子年龄增加的想法。在每次实验结束时，杀虫剂处理将杀死任何幸存的释放蚊子，以免它们感染和传播病毒。

Daily probability of survival and frequency of human blood- feeding are the 2 most sensitive components of a mosquito's role in pathogen transmission. Most models of vector-borne diseases assume that survival and feeding behavior do not change as mosquitoes grow older. Until now this assumption has not been strongly challenged because accurate methods for estimating age across epidemiologically different portions of a mosquito's lifetime or identifying the people a mosquito had bitten were not available; measurement of mosquito chronological age and host- feeding patterns were difficult or impossible. We have developed novel, more accurate methods that can determine for the 1st time if survival and frequency of host contact increase as mosquito vectors grow older and become infective. In this renewal proposal we will use these methods to test the hypothesis that Aedes aegypti's daily probability of survival and frequency of human blood-feeding increase as mosquitoes age. Older female Ae. aegypti are epidemiologically most important, because they are more likely to be infected with and transmit dengue virus than younger mosquitoes. To determine the chronological age of wild mosquitoes up to approximately 21 days of age we analyze cuticular hydrocarbons (CH). We can reconstruct mosquito blood- feeding behavior with a DNA fingerprinting procedure that identifies the person(s) from which a mosquito took its meal(s). High recapture rates in mark-recapture studies (approximately 30 percent) allow us to investigate survival, dispersal, and blood- feeding for free-ranging mosquitoes in the natural environment. Our study has 2 specific aims that we will carry out in northwestern Thailand, where Ae. aegypti-borne dengue virus is endemic. In Aim 1 we will compare the observed age structure (CH age-grading) and feeding patterns (DNA fingerprinting) of wild mosquitoes to the patterns expected under the assumption that these components of transmission remain constant as mosquitoes grow older. Before directly testing our research hypothesis in Aim 2 we will define the limitations of our current mark- recapture methods and select the best procedure for subsequent experiments on age-dependent differences in survival, dispersal, and blood-feeding. In our last set of experiments we will directly test the idea that dynamics in survival and blood- feeding frequency increase with mosquito age by releasing 2 distinct age cohorts and comparing their recapture rates, survival, and blood-feeding behavior. Insecticide treatments at the end of each experiment will kill any surviving released mosquitoes before they could become infective and transmit virus.