Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.
International Center of Excellence for Malaria Research, Tom Mboya University, College of Maseno University, Homa Bay, Kenya.
Malar J. 2023 Oct 5;22(1):298. doi: 10.1186/s12936-023-04741-w.
The rise of insecticide resistance against malaria vectors in sub-Saharan Africa has resulted in the need to consider other methods of vector control. The potential use of biological methods, including larvivorous fish, Bacillus thuringiensis israelensis (Bti) and plant shading, is sustainable and environmentally friendly options. This study examined the survivorship of Anopheles arabiensis and Anopheles funestus larvae and habitat productivity in four permanent habitat types in Homa Bay county, western Kenya.
Predator densities were studied in a laboratory setup while habitat productivity and larval survivorship was studied in field setup.
Fish were observed as the most efficient predator (75.8% larval reduction rate) followed by water boatman (69%), and dragonfly nymph (69.5%) in predation rates. Lower predation rates were observed in backswimmers (31%), water beetles (14.9%), water spiders (12.2%), mayflies (7.3%), and tadpoles (6.9%). Increase in predator density in the field setup resulted in decreased Culex larval density. Larval and pupa age-specific distribution was determined and their survivorship curves constructed. Combined larvae (Stage I-IV) to pupa mortality was over 97% for An. arabiensis and 100% for An. funestus. The highest larval stage survival rate was from larval stages I to II and the lowest from larval stage IV to pupa. Stage-specific life tables indicated high mortality rates at every developmental stage, especially at the larval stage II and III.
Determination of the efficiency of various larval predators and habitat productivity will help with the correct identification of productive habitats and selection of complementary vector control methods through environmental management and/or predator introduction (for instance fish) in the habitats.
撒哈拉以南非洲地区抗杀虫剂的疟疾病媒昆虫数量不断增加，这导致需要考虑其他控制病媒的方法。包括食蚊鱼、苏云金芽孢杆菌以色列亚种（Bti）和植物遮荫在内的生物防治方法具有可持续性和环境友好性。本研究调查了肯尼亚西部霍马湾县四种永久性生境中阿拉伯按蚊和冈比亚按蚊幼虫的存活率和生境生产力。
在实验室设置中研究了捕食者密度，而在野外设置中研究了生境生产力和幼虫存活率。
观察到鱼类是最有效的捕食者（75.8%的幼虫减少率），其次是水黾（69%）和蜻蜓若虫（69.5%）。在捕食率方面，负子蟾（31%）、龙虱（14.9%）、水蜘蛛（12.2%）、蜉蝣（7.3%）和蝌蚪（6.9%）的捕食率较低。在野外设置中增加捕食者密度会导致库蚊幼虫密度降低。确定了幼虫和蛹龄的特定分布，并构建了它们的存活曲线。阿拉伯按蚊和冈比亚按蚊的综合幼虫（第 I-IV 期）到蛹的死亡率超过 97%和 100%。幼虫阶段 I 到 II 的存活率最高，而从幼虫阶段 IV 到蛹的存活率最低。阶段特异性生命表表明，每个发育阶段的死亡率都很高，特别是在幼虫阶段 II 和 III。
确定各种幼虫捕食者的效率和生境生产力将有助于正确识别有生产力的生境，并通过环境管理和/或在生境中引入（例如鱼类）捕食者来选择补充性的病媒控制方法。
