BACKGROUND Effective mosquito control approaches incorporate both adult and larval stages. For the latter, physical, biological, and chemical control have been used with varying results. Successful control of larvae has been demonstrated using larvicides including insect growth regulators, e.g. the organophosphate temephos, as well as various entomopathogenic microbial species. However, a variety of health and environmental issues are associated with some of these. Laboratory trials of essential oils (EO) have established the larvicidal activity of these substances, but there are currently no commercially available EO-based larvicides. Here we report on the development of a new approach to mosquito larval control using a novel, yeast-based delivery system for EO. METHODS Food-grade orange oil (OO) was encapsulated into yeast cells following an established protocol. To prevent environmental contamination, a proprietary washing strategy was developed to remove excess EO that is adsorbed to the cell exterior during the encapsulation process. The OO-loaded yeast particles were then characterized for OO loading, and tested for efficacy against Aedes aegypti larvae. RESULTS The composition of encapsulated OO extracted from the yeast microparticles was demonstrated not to differ from that of un-encapsulated EO when analyzed by high performance liquid chromatography. After lyophilization, the oil in the larvicide comprised 26-30 percentage weight (wt%), and is consistent with the 60-65% reduction in weight observed after the drying process. Quantitative bioassays carried with Liverpool and Rockefeller Ae. aegypti strains in three different laboratories presented LD50 of 5.1 (95% CI: 4.6-5.6) to 27.6 (95% CI: 26.4-28.8) mg/l, for L1 and L3/L4 mosquito larvae, respectively. LD90 ranged between 18.9 (95% CI: 16.4-21.7) mg/l (L1 larvae) to 76.7 (95% CI: 69.7-84.3) mg/l (L3/L4 larvae). CONCLUSIONS The larvicide based on OO encapsulated in yeast was shown to be highly active (LD50 < 50 mg/l) against all larval stages of Ae. aegypti. These results demonstrate its potential for incorporation in an integrated approach to larval source management of Ae. aegypti. This novel approach can enable development of affordable control strategies that may have significant impact on global health.

中文翻译：

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酵母包裹的精油：作为一种环境友好型杀幼虫剂的新观点。

背景技术有效的蚊子控制方法结合了成年和幼虫阶段。对于后者，已经使用了物理，生物和化学控制，结果各不相同。使用杀幼虫剂（包括昆虫生长调节剂，例如有机磷酸酯萜烯）以及各种昆虫病原微生物物种，已证明成功控制了幼虫。但是，其中一些与健康和环境问题相关。香精油（EO）的实验室试验已经确定了这些物质的杀幼虫活性，但目前尚无可商购的EO型杀幼虫剂。在这里，我们报告使用一种新的，基于酵母的基于EO的传递系统来控制蚊虫幼虫的新方法的发展。方法按照既定规程将食品级橙油（OO）封装到酵母细胞中。为了防止环境污染，开发了专有的洗涤策略以去除在封装过程中吸附到电池外部的过量EO。然后表征负载OO的酵母颗粒的负载OO，并测试其针对埃及伊蚊幼虫的功效。结果当通过高效液相色谱法分析时，从酵母微粒中提取的包封的OO的组成与未包封的EO的组成没有差异。冷冻干燥后，杀幼虫剂中的油占26-30重量％（wt％），并且与干燥过程后观察到的重量减少60-65％一致。利物浦和洛克菲勒Ae进行的定量生物测定。在三个不同实验室中，埃及伊蚊菌株的L1和L3 / L4蚊虫幼虫的LD50分别为5.1（95％CI：4.6-5.6）至27.6（95％CI：26.4-28.8）mg / l。LD90在18.9（95％CI：16.4-21.7）mg / l（L1幼虫）至76.7（95％CI：69.7-84.3）mg / l（L3 / L4幼虫）之间。结论表明，封装在酵母中的基于OO的杀幼虫剂对Ae的所有幼虫阶段均具有高活性（LD50 <50 mg / l）。埃及。这些结果证明了其潜在的整合入Ae幼虫源管理的综合方法中的潜力。埃及。这种新颖的方法可以使人们能够负担得起的控制策略的制定，这可能会对全球健康产生重大影响。LD90在18.9（95％CI：16.4-21.7）mg / l（L1幼虫）至76.7（95％CI：69.7-84.3）mg / l（L3 / L4幼虫）之间。结论封装在酵母中的基于OO的杀幼虫剂对Ae的所有幼虫阶段均具有高活性（LD50 <50 mg / l）。埃及。这些结果证明了其潜在的整合入Ae幼虫源管理的综合方法中的潜力。埃及。这种新颖的方法可以使人们能够负担得起的控制策略的制定，这可能会对全球健康产生重大影响。LD90在18.9（95％CI：16.4-21.7）mg / l（L1幼虫）至76.7（95％CI：69.7-84.3）mg / l（L3 / L4幼虫）之间。结论封装在酵母中的基于OO的杀幼虫剂对Ae的所有幼虫阶段均具有高活性（LD50 <50 mg / l）。埃及。这些结果证明了其潜在的整合入Ae幼虫源管理的综合方法中的潜力。埃及。这种新颖的方法可以使人们能够负担得起的控制策略的制定，这可能会对全球健康产生重大影响。这些结果证明了其潜在的整合入Ae幼虫源管理的综合方法中的潜力。埃及。这种新颖的方法可以使人们能够负担得起的控制策略的制定，这可能会对全球健康产生重大影响。这些结果证明了其潜在的整合入Ae幼虫源管理的综合方法中的潜力。埃及。这种新颖的方法可以使人们能够负担得起的控制策略的制定，这可能会对全球健康产生重大影响。