Pavela Roman, Maggi Filippo, Iannarelli Romilde, Benelli Giovanni
Crop Research Institute, Drnovska 507, 161 06, Prague 6, Ruzyne, Czech Republic.
School of Pharmacy, University of Camerino, via Sant'Agostino, 62032 Camerino, Italy.
Acta Trop. 2019 May;193:236-271. doi: 10.1016/j.actatropica.2019.01.019. Epub 2019 Jan 31.
In the last decades, major research efforts have been done to investigate the insecticidal activity of plant-based products against mosquitoes. This is a modern and timely challenge in parasitology, aimed to reduce the frequent overuse of synthetic pesticides boosting resistance development in mosquitoes and causing serious threats to human health and environment. This review covers the huge amount of literature available on plant extracts tested as mosquito larvicides, particularly aqueous and alcoholic ones, due to their easy formulation in water without using surfactants. We analysed results obtained on more than 400 plant species, outlining that 29 of them have outstanding larvicidal activity (i.e., LC values below 10 ppm) against major vectors belonging to the genera Anopheles, Aedes and Culex, among others. Furthermore, synergistic and antagonistic effects between plant extracts and conventional pesticides, as well as among selected plant extracts are discussed. The efficacy of pure compounds isolated from the most effective plant extracts and - when available - their mechanism of action, as well as the impact on non-target species, is also covered. These belong to the following class of secondary metabolites: alkaloids, alkamides, sesquiterpenes, triterpenes, sterols, flavonoids, coumarins, anthraquinones, xanthones, acetogenonins and aliphatics. Their mode of action on mosquito larvae ranges from neurotoxic effects to inhibition of detoxificant enzymes and larval development and/or midugut damages. In the final section, current drawbacks as well as key challenges for future research, including technologies to synergize efficacy and improve stability - thus field performances - of the selected plant extracts, are outlined. Unfortunately, despite the huge amount of laboratory evidences about their efficacy, only a limited number of studies was aimed to validate their efficacy in the field, nor the epidemiological impact potentially arising from these vector control operations has been assessed. This strongly limits the development of commercial mosquito larvicides of botanical origin, at variance with plant-borne products developed in the latest decades to kill or repel other key arthropod species of medical and veterinary importance (e.g., ticks and lice), as well as mosquito adults. Further research on these issues is urgently needed.
在过去几十年里，人们付出了巨大的研究努力来调查植物源产品对蚊子的杀虫活性。这是寄生虫学领域一个现代且及时的挑战，旨在减少合成杀虫剂的频繁过度使用，因为这种过度使用会加剧蚊子抗药性的发展，并对人类健康和环境造成严重威胁。这篇综述涵盖了大量关于作为蚊幼虫杀虫剂进行测试的植物提取物的文献，特别是水性和醇性提取物，因为它们无需使用表面活性剂就能轻松在水中配制。我们分析了对400多种植物物种获得的结果，指出其中29种对按蚊属、伊蚊属和库蚊属等主要病媒具有出色的杀幼虫活性（即LC值低于10 ppm）。此外，还讨论了植物提取物与传统杀虫剂之间以及选定植物提取物之间的协同和拮抗作用。还涵盖了从最有效的植物提取物中分离出的纯化合物的功效以及（如有）它们的作用机制，以及对非靶标物种的影响。这些纯化合物属于以下几类次生代谢物：生物碱、链状酰胺、倍半萜、三萜、甾醇、黄酮类化合物、香豆素、蒽醌、呫吨酮、番荔枝内酯和脂肪族化合物。它们对蚊幼虫的作用方式从神经毒性作用到抑制解毒酶以及幼虫发育和/或中肠损伤不等。在最后一部分，概述了当前的缺点以及未来研究的关键挑战，包括提高选定植物提取物的功效和稳定性——从而改善其田间性能——的技术。不幸的是，尽管有大量关于其功效的实验室证据，但只有有限数量的研究旨在验证它们在田间的功效，而且也没有评估这些病媒控制操作可能产生的流行病学影响。这严重限制了植物源商业蚊幼虫杀虫剂的开发，这与近几十年来开发的用于杀死或驱赶其他具有医学和兽医学重要性的关键节肢动物物种（如蜱和虱子）以及成年蚊子的植物源产品形成了反差。迫切需要对这些问题进行进一步研究。
