Onen Hudson, Kaindoa Emmanuel W, Nkya Joel, Limwagu Alex, Kaddumukasa Martha A, Okumu Fredros O, Kayondo Jonathan K, Akol Anne M, Tripet Frédéric
Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, School of Biosciences, Makerere University, P.O. Box 7062, Kampala, Uganda.
Department of Entomology, Uganda Virus Research Institute, Plot 51/59 Nakiwogo Road, P.O. Box 49, Entebbe, Uganda.
Malar J. 2025 Jan 9;24(1):4. doi: 10.1186/s12936-025-05242-8.
Members of the Anopheles gambiae complex are major malaria vectors in sub-Saharan Africa. Their larval stages inhabit a variety of aquatic habitats in which, under natural circumstances, they are preyed upon by different taxa of aquatic macroinvertebrate predators. Understanding the potential impact of predators on malaria vector larval population dynamics is important for enabling integrated local mosquito control programmes with a stronger emphasis on biocontrol approaches. This study experimentally evaluated the predation efficacy and foraging strategy of three common aquatic macroinvertebrate predators of An. gambiae, diving beetles (Coleoptera), backswimmers (Hemiptera), and dragonfly nymphs (Odonata) in a semi-field system in South-Eastern Tanzania.
An array of alternating small and large basins used as aquatic habitats was created in two compartments of a semi-field system and filled with well water. Field-collected adult diving beetles, backswimmers or dragonfly nymphs were randomly assigned to these habitats and Anopheles arabiensis larvae were added as prey in half of the habitats. The number of mosquito larvae consumed, predator mobility across habitats and mortality were recorded at 24, 48 and 72 h.
The presence of An. gambiae larvae in habitats significantly increased the survival of backswimmer and dragonfly nymphs, which are not mobile. In contrast, diving beetles survived well under any initial condition by preferentially flying away from habitats without prey to nearby larger habitats with prey. The larval predation rates of predacious diving beetle, backswimmer and dragonfly nymphs were stable over time at a mean of 3.2, 7.0 and 9.6 larvae consumed each day.
This study demonstrates that aquatic macroinvertebrate predators display adaptive foraging behaviour in response to prey presence and aquatic habitat size. It also confirms the ability of these predators to significantly reduce An. gambiae larval densities in aquatic habitats, thus their potential for consideration as additional biocontrol tools for mosquito population reduction.
冈比亚按蚊复合体的成员是撒哈拉以南非洲地区主要的疟疾传播媒介。它们的幼虫阶段栖息在各种水生栖息地中，在自然环境下，会受到不同类群的水生大型无脊椎动物捕食者的捕食。了解捕食者对疟疾传播媒介幼虫种群动态的潜在影响，对于实施更加强调生物防治方法的地方蚊虫综合控制计划至关重要。本研究在坦桑尼亚东南部的一个半野外系统中，通过实验评估了三种常见的冈比亚按蚊水生大型无脊椎动物捕食者，即潜水甲虫（鞘翅目）、仰泳蝽（半翅目）和蜻蜓若虫（蜻蜓目）的捕食效率和觅食策略。
在半野外系统的两个隔间中创建了一系列交替排列的小水池和大水池作为水生栖息地，并用井水填充。将野外采集的成年潜水甲虫、仰泳蝽或蜻蜓若虫随机分配到这些栖息地，并在一半的栖息地中添加阿拉伯按蚊幼虫作为猎物。在24、48和72小时记录被消耗的蚊虫幼虫数量、捕食者在栖息地之间的移动情况以及死亡率。
栖息地中存在冈比亚按蚊幼虫显著提高了不具移动能力的仰泳蝽和蜻蜓若虫的存活率。相比之下，潜水甲虫在任何初始条件下都能很好地存活，它们会优先从没有猎物的栖息地飞到附近有猎物的更大栖息地。捕食性潜水甲虫、仰泳蝽和蜻蜓若虫的幼虫捕食率随时间保持稳定，平均每天分别消耗3.2、7.0和9.6只幼虫。
本研究表明，水生大型无脊椎动物捕食者会根据猎物的存在和水生栖息地的大小表现出适应性觅食行为。它还证实了这些捕食者能够显著降低水生栖息地中冈比亚按蚊幼虫的密度，因此它们有潜力被视为减少蚊虫数量的额外生物防治工具。
