Zuharah Wan Fatma, Lester Philip J
School of Biological Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
J Vector Ecol. 2010 Jun;35(1):100-5. doi: 10.1111/j.1948-7134.2010.00035.x.
The influence of predators on mosquito populations may be direct through predation or indirect through sub-lethal responses of adult mosquitoes in life history traits such as oviposition behavior. In New Zealand, the backswimmer, Anisops wakefieldi, is a common predator of mosquito larvae found in temporary and permanent water bodies. We predicted that the New Zealand native mosquito, Culex pervigilans, whose larvae are vulnerable to predation of Anisops, would likely avoid the containers with the presence of Anisops or its kairomone. We established temporary water containers without predators, free-roaming predators, caged predators (which were unable to eat mosquitoes), or containers from which predators were removed immediately prior to the experiment (these containers would have remnant kairomones from the predators). Each treatment with Anisops had predator densities of one, three, or nine Anisops. Contrary to our predictions, when choosing oviposition habitats, Cx. pervigilans appeared to ignore the presence of free-roaming Anisops, caged Anisops, and water with Anisops kairomone. We thus observed no significant differences between the numbers of egg rafts laid by Cx. pervigilans in the different predator treatments nor were the number of egg rafts significantly affected by the density of predators. Rather than the presence of predators, environmental factors including temperature, humidity, and pressure were significantly correlated with mosquito oviposition. These mosquitoes appeared to either ignore the presence of the predator, had no ability to detect the presence of predators, or perhaps the cues from Anisops predators were not sufficiently strong enough to alarm these mosquitoes. We argue that the mosquito has not evolved the ability to detect the presence of these predators while ovipositing.
捕食者对蚊子种群的影响可能是直接的（通过捕食），也可能是间接的（通过成年蚊子在产卵行为等生活史特征中的亚致死反应）。在新西兰，仰泳蝽（Anisops wakefieldi）是在临时和永久性水体中发现的蚊子幼虫的常见捕食者。我们预测，新西兰本土蚊子致倦库蚊（Culex pervigilans）的幼虫易受仰泳蝽捕食，它可能会避开有仰泳蝽或其信息素存在的容器。我们设置了没有捕食者的临时水容器、自由活动的捕食者、笼养捕食者（无法捕食蚊子），或在实验前立即移除捕食者的容器（这些容器会有捕食者残留的信息素）。每种有仰泳蝽的处理中，捕食者密度分别为1只、3只或9只仰泳蝽。与我们的预测相反，在选择产卵栖息地时，致倦库蚊似乎忽略了自由活动的仰泳蝽、笼养的仰泳蝽以及含有仰泳蝽信息素的水的存在。因此，我们观察到在不同捕食者处理下，致倦库蚊产下的卵筏数量没有显著差异，捕食者密度也未对卵筏数量产生显著影响。与捕食者的存在相比，包括温度、湿度和气压在内的环境因素与蚊子产卵显著相关。这些蚊子似乎要么忽略了捕食者的存在，没有能力察觉捕食者的存在，要么也许来自仰泳蝽捕食者的线索不够强烈，不足以警示这些蚊子。我们认为，蚊子在产卵时尚未进化出察觉这些捕食者存在的能力。
