Howard Annabel F V, Zhou Guofa, Omlin Francois X
Human Health Department, International Centre of Insect Physiology and Ecology (icipe), PO Box 30772-00100, Nairobi, Kenya.
BMC Public Health. 2007 Aug 9;7:199. doi: 10.1186/1471-2458-7-199.
Biological control methods are once again being given much research focus for malaria vector control. This is largely due to the emerging threat of strong resistance to pesticides. Larvivorous fish have been used for over 100 years in mosquito control and many species have proved effective. In the western Kenyan highlands the larvivorous fish Oreochromis niloticus L. (Perciformes: Cichlidae) (formerly Tilapia nilotica) is commonly farmed and eaten but has not been previously tested in the field for malaria mosquito control.
This fish was introduced into abandoned fishponds at an altitude of 1,880 m and the effect measured over six months on the numbers of mosquito immatures. For comparison an untreated control pond was used. During this time, all ponds were regularly cleared of emergent vegetation and fish re-stocking was not needed. Significant autocorrelation was removed from the time series data, and t-tests were used to investigate within a pond and within a mosquito type any differences before and after the introduction of O. niloticus. Mulla's formula was also used on the raw data to calculate the percentage reduction of the mosquito larvae.
After O. niloticus introduction, mosquito densities immediately dropped in the treated ponds but increased in the control pond. This increase was apparently due to climatic factors. Mulla's formula was applied which corrects for that natural tendency to increase. The results showed that after 15 weeks the fish caused a more than 94% reduction in both Anopheles gambiae s.l. and Anopheles funestus (Diptera: Culicidae) in the treated ponds, and more than 75% reduction in culicine mosquitoes. There was a highly significantly reduction in A. gambiae s.l. numbers when compared to pre-treatment levels.
This study reports the first field trial data on O. niloticus for malaria mosquito control and shows that this species, already a popular food fish in western Kenya, is an apparently sustainable mosquito control tool which also offers a source of protein and income to people in rural areas. There should be no problem with acceptance of this malaria control method since the local communities already farm this fish species.
生物防治方法再次成为疟疾媒介控制研究的重点。这主要是由于对杀虫剂产生强烈抗药性这一新兴威胁。食蚊鱼用于蚊虫控制已有100多年历史，许多物种已被证明有效。在肯尼亚西部高地，食蚊鱼尼罗罗非鱼（鲈形目：丽鱼科）（原尼罗罗非鱼）普遍养殖并食用，但此前尚未在实地进行疟疾蚊虫控制测试。
将这种鱼引入海拔1880米的废弃鱼塘，并在六个月内测量其对蚊虫幼虫数量的影响。作为对照，使用了一个未处理的池塘。在此期间，定期清理所有池塘中的挺水植物，无需重新投放鱼类。从时间序列数据中去除了显著的自相关性，并使用t检验来研究在引入尼罗罗非鱼前后，同一池塘内以及同一蚊虫类型中的任何差异。还对原始数据使用穆拉公式来计算蚊虫幼虫的减少百分比。
引入尼罗罗非鱼后，处理过的池塘中蚊虫密度立即下降，而对照池塘中则增加。这种增加显然是由于气候因素。应用了穆拉公式来校正这种自然增长趋势。结果表明，15周后，这种鱼使处理过的池塘中冈比亚按蚊复合组和有害按蚊（双翅目：蚊科）的数量减少了94%以上，库蚊数量减少了75%以上。与处理前水平相比，冈比亚按蚊复合组的数量有极显著减少。
本研究报告了尼罗罗非鱼用于疟疾蚊虫控制的首个实地试验数据，并表明这种在肯尼亚西部已经是受欢迎的食用鱼的物种，是一种明显可持续的蚊虫控制工具，同时也为农村地区的人们提供了蛋白质和收入来源。由于当地社区已经养殖这种鱼类，因此接受这种疟疾控制方法应该没有问题。
