University of Vermont, Department of Civil and Environmental Engineering, Burlington, VT 05405, USA.
Parasit Vectors. 2011 May 10;4:72. doi: 10.1186/1756-3305-4-72.
Synthetic insecticides are employed in the widely-used currently favored malaria control techniques involving indoor residual spraying and treated bednets. These methods have repeatedly proven to be highly effective at reducing malaria incidence and prevalence. However, rapidly emerging mosquito resistance to the chemicals and logistical problems in transporting supplies to remote locations threaten the long-term sustainability of these techniques. Chinaberry (Melia azederach) extracts have been shown to be effective growth-inhibiting larvicides against several insects. Because several active chemicals in the trees' seeds have insecticidal properties, the emergence of resistance is unlikely. Here, we investigate the feasibility of Chinaberry as a locally available, low-cost sustainable insecticide that can aid in controlling malaria. Chinaberry fruits were collected from Asendabo, Ethiopia. The seeds were removed from the fruits, dried and crushed into a powder. From developmental habitats in the same village, Anopheles arabiensis larvae were collected and placed into laboratory containers. Chinaberry seed powder was added to the larval containers at three treatment levels: 5 g m(-2), 10 g m(-2) and 20 g m(-2), with 100 individual larvae in each treatment level and a control. The containers were monitored daily and larvae, pupae and adult mosquitoes were counted. This experimental procedure was replicated three times.
Chinaberry seed powder caused an inhibition of emergence of 93% at the 5 g m(-2) treatment level, and 100% inhibition of emergence at the two higher treatment levels. The Chinaberry had a highly statistically significant larvicidal effect at all treatment levels (χ2 = 184, 184, and 155 for 5 g m(-2), 10 g m(-2) and 20 g m(-2), respectively; p < 0.0001 in all cases). In addition, estimates suggest that sufficient Chinaberry seed exists in Asendabo to treat developmental habitat for the duration of the rainy season and support a field trial.
Chinaberry seed is a very potent growth-inhibiting larvicide against the major African malaria vector An. arabiensis. The seed could provide a sustainable additional malaria vector control tool that can be used where the tree is abundant and where An. arabiensis is a dominant vector. Based on these results, a future village-scale field trial using the technique is warranted.
合成杀虫剂被广泛应用于目前广泛使用的疟疾控制技术，包括室内滞留喷洒和处理过的蚊帐。这些方法已被证明在降低疟疾发病率和患病率方面非常有效。然而，蚊子对这些化学品的抗药性迅速出现以及向偏远地区运输物资的后勤问题，威胁到这些技术的长期可持续性。楝树（Melia azederach）提取物已被证明对几种昆虫具有有效的生长抑制作用。由于树木种子中的几种活性化学物质具有杀虫特性，因此不太可能出现抗药性。在这里，我们研究了楝树作为一种当地可得、低成本的可持续杀虫剂的可行性，该杀虫剂可用于控制疟疾。从埃塞俄比亚的 Asendabo 收集了楝树果实。将种子从果实中取出，干燥并粉碎成粉末。从同一村庄的发育栖息地收集了 Anopheles arabiensis 幼虫，并将其放入实验室容器中。将楝树种子粉末添加到幼虫容器中，处理水平分别为 5 g/m2、10 g/m2 和 20 g/m2，每个处理水平有 100 个幼虫和一个对照。容器每天进行监测，并计数幼虫、蛹和成年蚊子。该实验程序重复了三次。
楝树种子粉末在 5 g/m2 的处理水平下导致 93%的成虫出现受到抑制，在两个更高的处理水平下完全抑制了成虫的出现。楝树在所有处理水平下都具有高度统计学显著的杀幼虫效果（χ2 = 184、184 和 155 分别为 5 g/m2、10 g/m2 和 20 g/m2；在所有情况下，p < 0.0001）。此外，估计表明，Asendabo 存在足够的楝树种子，可以在雨季期间处理发育栖息地，并支持田间试验。
楝树种子是一种非常有效的生长抑制剂，可抑制主要的非洲疟疾传播媒介 An. arabiensis。该种子可以提供一种可持续的额外疟疾媒介控制工具，可在楝树丰富且 An. arabiensis 是主要传播媒介的地方使用。基于这些结果，将来有必要在村庄范围内进行使用该技术的田间试验。
