Experimental hut to study the indoor behaviour and effects of insecticide-treated bednets on phlebotomine sand flies (Diptera: Psychodidae)

BACKGROUND Behavioural effects of insecticides on endophagic phlebotomine sand fly vectors of Leishmania are poorly understood mainly because of the lack of an experimental hut (EH) in which to study them. OBJECTIVE To build an EH to evaluate the effects of long-lasting insecticide-treated nets (LLINs) on Lutzomyia longiflocosa. METHODS The study had two phases: (1) Laboratory experiments using tunnel tests to select the traps for the EH; and (2) EH construction and evaluation of the effects of deltamethrin and lambda-cyhalothrin LLINs on L. longiflocosa females inside the EH. FINDINGS Phase 1: The horizontal-slit trap was the best trap. This trap collected the highest percentage of sand flies, and prevented them from escaping. Therefore, this trap was used in the EH. Phase 2: The main effects of LLINs on L. longiflocosa in the EH were: landing inhibition, inhibition from entering the bednet, induced exophily, and high mortality (total and inside exit traps). CONCLUSIONS The EH was effective for evaluating the effects of LLINs on endophagic sand flies. Although both types of LLINs showed high efficacy, the lambda-cyhalothrin-treated LLIN performed better. This is the first report of induced exophily in sand flies.

研究背景 目前学界对杀虫剂作用于利什曼原虫（Leishmania）的嗜内栖白蛉（phlebotomine sand fly）媒介的行为效应认知不足，主要原因是缺乏可供相关研究的实验小屋（experimental hut, EH）。研究目的 构建实验小屋（experimental hut, EH），以评估长效杀虫剂处理蚊帐（long-lasting insecticide-treated nets, LLINs）对长绒罗蛉（Lutzomyia longiflocosa）的作用效果。研究方法 本研究分为两个阶段：（1）实验室筛选阶段：采用隧道试验筛选适配实验小屋的诱捕器；（2）实验小屋构建与评估阶段：在实验小屋内评估溴氰菊酯（deltamethrin）与氯氟氰菊酯（lambda-cyhalothrin）处理的长效杀虫剂蚊帐对长绒罗蛉雌虫的作用效果。研究结果 第一阶段：水平缝隙诱捕器为最优诱捕器，其捕获白蛉的比例最高，且可有效阻止白蛉逃逸，因此该诱捕器被应用于实验小屋中。第二阶段：实验小屋内长效杀虫剂处理蚊帐对长绒罗蛉的主要作用效应包括：着陆抑制、蚊帐进入抑制、诱导外栖以及高死亡率（含总死亡率与出口诱捕器内死亡率）。研究结论 本研究所构建的实验小屋可有效评估长效杀虫剂处理蚊帐对嗜内栖白蛉的作用效果。尽管两种长效杀虫剂处理蚊帐均表现出较高的防控效能，但氯氟氰菊酯处理的长效蚊帐效果更优。本研究首次报道了白蛉的诱导外栖现象。