College of Natural and Applied Sciences, Department of Zoology and Wildlife Conservation, University of Dar es salaam, P.O. Box 35064, Dar es salaam, Tanzania.
Tropical Pesticides Research Institute, Division of Livestock and Human Diseases Vector Control, Mosquito Section, P.O. Box 3024, Arusha, Tanzania.
Acta Trop. 2015 Feb;142:131-7. doi: 10.1016/j.actatropica.2014.11.012. Epub 2014 Nov 28.
The increased insecticides resistance by vectors and the ecological harm imposed by insecticides to beneficial organisms drawback mosquitoes chemical control efforts. Biological control would reduce insecticides tolerance and yet biodiversity friend. The predatory and non-predatory effects of Gambusia affinis and Carassius auratus on gravid Anopheles gambiae sensu strict and larvae survivorship were assessed. In determining predation rate, a single starved predator was exposed to third instar larvae of An. gambiae s.s. in different densities 20, 60 and 100. Six replicates in each of the densities for both predators, G. affinis and C. auratus, were set up. The larvae densities were monitored in every 12 and 24 h. In assessing indirect effects: An. gambiae s.s. first instar larvae of three densities 20, 60 and 100 were reared in water from a predator habitat and water from non-predator habitat. Larvae were monitored until they emerged to adults where larval survivorship and sex ratio (Female to total emerged mosquitoes) of the emerged adult from both water habitats were determined. Oviposition preference: twenty gravid females of An. gambiae s.s. were provided with three oviposition choices, one containing water from predator habitat without a predator, the second with water from a predator with a predator and the third with water from non-predatory habitat. The number of eggs laid on each container was counted daily. There were 20 replicates for each predator, G. affinis and C. auratus. Survivorship of An. gambiae s.s. larvae reared in water from non-predator habitat was higher than those reared in water from the predator habitats. Many males emerged in water from non-predatory water habitats while more females emerged from predator's habitats water. More eggs laid in tap water than in water from predator habitat and water from predator habitat with live predator. In 24 h, a starved C. auratus and G. affinis were able to consume 100% of the 3rd instar larvae. The findings from this study suggest that G. affinis and C. auratus may be useful in regulating mosquito populations in favour of beneficial insects. However, a small scale trial shall be needed in complex food chain system to ascertain the observed predation and kairomones effects.
载体的杀虫剂抗药性增加和杀虫剂对有益生物造成的生态危害削弱了蚊子的化学控制效果。生物防治可以降低杀虫剂的耐受性，同时对生物多样性友好。评估了食蚊鱼和金鱼对感染疟原虫的按蚊和幼虫存活率的捕食和非捕食作用。在确定捕食率时，将饥饿的单一捕食者暴露于不同密度的三龄疟蚊幼虫中，密度分别为 20、60 和 100。在这两种捕食者（食蚊鱼和金鱼）的每个密度下都设置了 6 个重复。每 12 和 24 小时监测幼虫密度。在评估间接影响时：将三种密度的 20、60 和 100 的疟蚊初孵幼虫在来自捕食者栖息地和非捕食者栖息地的水中饲养。监测幼虫，直到它们孵化成成虫，然后确定来自两种水栖息地的成虫的幼虫存活率和性别比（雌性与总孵化的蚊子）。产卵偏好：提供 20 只感染疟原虫的按蚊雌性，它们有三个产卵选择，一个含有没有捕食者的捕食者栖息地的水，第二个含有有捕食者的捕食者栖息地的水，第三个含有非捕食性栖息地的水。每天统计每个容器上的产卵数量。对于每个捕食者，食蚊鱼和金鱼，都有 20 个重复。在非捕食者栖息地水中饲养的疟蚊幼虫的存活率高于在捕食者栖息地水中饲养的幼虫。许多雄性从非捕食者水栖息地水中孵化，而更多的雌性从捕食者栖息地水中孵化。在自来水中产卵比在捕食者栖息地水中产卵多，而在有活捕食者的捕食者栖息地水中产卵最多。在 24 小时内，饥饿的金鱼和食蚊鱼能够消耗 100%的三龄幼虫。本研究的结果表明，食蚊鱼和金鱼可能有助于控制蚊子数量，有利于有益昆虫。然而，在复杂的食物链系统中，需要进行小规模试验，以确定观察到的捕食和信息素作用。
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