Department of Entomology, Instituto Aggeu Magalhaes, Fundação Oswaldo Cruz, Recife-PE, 50740-465, Brazil.
Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA, 95616, USA.
Sci Rep. 2019 Sep 24;9(1):13747. doi: 10.1038/s41598-019-50274-1.
One of the strategies of integrated vector management is to lure gravid mosquitoes for surveillance purposes or to entice them to lay eggs in water containing toxins that kill the offspring (attract-and-kill or trap-and-kill). Typically, the major challenge of this approach is the development of a lure that stimulates oviposition plus a toxin with no deterrent effect. Bacillus thuringiensis var. israelensis (Bti) satisfies the latter criterion, but lures for these autocidal gravid traps are sorely needed. We observed that gravid Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus laid significantly more eggs in cups with extracts from 4th-stage larvae (4 L) of the same or different species. No activity was found when 4 L were extracted with hexane, diethyl ether, methanol, or butanol, but activity was observed with dimethyl sulfoxide extracts. Larval extracts contained both oviposition stimulant(s)/attractant(s) and deterrent(s), which partitioned in the water and hexane phases, respectively. Lyophilized larval extracts were active after a month, but activity was reduced by keeping the sample at 4 °C. In the tested range of 0.1 to 1 larvae-equivalent per milliliter, oviposition activity increased in a dose-dependent manner. In field experiments, Ae. aegpti laid significantly more eggs in traps loaded with larval extracts plus Bti than in control traps with water plus Bti.
综合蚊媒管理策略之一是利用引诱剂吸引怀孕的蚊子进行监测，或者引诱它们在含有杀死幼虫的毒素的水中产卵（引诱-杀死或诱捕-杀死）。通常，这种方法的主要挑战是开发一种既能刺激产卵又能对幼虫无毒的引诱剂。苏云金芽孢杆菌以色列亚种（Bti）符合后一个标准，但这些自相残杀的诱捕器的引诱剂非常需要。我们观察到，怀孕的埃及伊蚊、白纹伊蚊和致倦库蚊在装有同一种或不同种 4 龄幼虫（4L）提取物的杯子中产卵明显更多。当用己烷、乙醚、甲醇或正丁醇提取 4L 时，没有发现活性，但用二甲基亚砜提取物观察到活性。幼虫提取物中既含有产卵刺激物/引诱物，也含有驱避剂，分别分配在水相和正己烷相。冻干的幼虫提取物在一个月后仍具有活性，但将样品保存在 4°C 时活性会降低。在所测试的 0.1 至 1 个幼虫当量/毫升范围内，产卵活性呈剂量依赖性增加。在野外实验中，装有幼虫提取物和 Bti 的诱捕器中，埃及伊蚊产卵明显多于装有水和 Bti 的对照诱捕器。
