In Argentina, the mosquito Aedes aegypti (L.) (Diptera: Culicidae) is distributed from subtropical to temperate climates. Here, we hypothesized that the expansion of Ae. aegypti into colder regions is favoured by high-phenotypic plasticity and an adaptive inhibition of egg hatching at low temperatures. Thus, we investigated the hatching response of eggs of three populations: one from a subtropical region (Resistencia) and two from temperate regions (Buenos Aires City and San Bernardo) of Argentina. Eggs collected in the field were raised in three experimental colonies. F1 eggs were acclimated for 7 days prior to immersion at 7.6 or 22°C (control eggs). Five immersion temperatures were tested: 7.6, 10.3, 11.8, 14.1 and 16°C (range of mean winter temperatures of the three localities). A second immersion at 22°C was performed 2 weeks later to assess the inhibition to hatch under favourable conditions. After the first immersion, we compared the proportions of hatched eggs and dead larvae among treatment levels, whereas after the second immersion we compared the hatching response among the three populations. The factors that most influenced the egg hatching response were the geographical origin of the populations and the immersion temperature, but not the acclimation temperature. The proportions of hatching and larval mortality at low temperatures were higher for Resistencia than for Buenos Aires and San Bernardo, whereas the hatching response at ambient temperature was lower for San Bernardo than for Buenos Aires and Resistencia. The results support the hypothesis that populations from colder regions show an adaptive inhibition of egg hatching.

中文翻译：

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不同冬季条件下对埃及伊蚊种群卵孵化的差异抑制作用

在阿根廷，蚊子埃及伊蚊(L.) (双翅目：Culicidae) 分布于亚热带至温带气候。在这里，我们假设扩展埃。埃及人高表型可塑性和低温下对卵孵化的适应性抑制有利于进入较冷的地区。因此，我们调查了三个种群的卵的孵化反应：一个来自亚热带地区（Resistencia），两个来自阿根廷的温带地区（布宜诺斯艾利斯市和圣贝尔纳多）。在田间收集的鸡蛋在三个实验菌落中饲养。F1 鸡蛋在浸入 7.6 或 22°C（对照鸡蛋）之前适应 7 天。测试了五个浸泡温度：7.6、10.3、11.8、14.1 和 16°C（三个地区的冬季平均温度范围）。2 周后在 22°C 下进行第二次浸泡，以评估在有利条件下孵化的抑制作用。第一次浸泡后，我们比较了不同处理水平的孵化卵和死亡幼虫的比例，而在第二次浸泡后，我们比较了三个种群的孵化反应。影响卵孵化反应的最重要因素是种群的地理起源和浸泡温度，而不是驯化温度。Resistencia 在低温下的孵化率和幼虫死亡率高于 Buenos Aires 和 San Bernardo，而 San Bernardo 在环境温度下的孵化反应低于 Buenos Aires 和 Resistencia。结果支持来自较冷地区的种群显示出对卵孵化的适应性抑制的假设。影响卵孵化反应的最重要因素是种群的地理起源和浸泡温度，而不是驯化温度。Resistencia 在低温下的孵化率和幼虫死亡率高于 Buenos Aires 和 San Bernardo，而 San Bernardo 在环境温度下的孵化反应低于 Buenos Aires 和 Resistencia。结果支持来自较冷地区的种群显示出对卵孵化的适应性抑制的假设。影响卵孵化反应的最重要因素是种群的地理起源和浸泡温度，而不是驯化温度。Resistencia 在低温下的孵化率和幼虫死亡率高于 Buenos Aires 和 San Bernardo，而 San Bernardo 在环境温度下的孵化反应低于 Buenos Aires 和 Resistencia。结果支持来自较冷地区的种群显示出对卵孵化的适应性抑制的假设。