Santamaría E, Cabrera O L, Avendaño J, Pardo R H
Entomology Group, National Institute of Health, Bogotá, Colombia.
Entomology Group, National Institute of Health, Bogotá; Entomology and Vector Borne Diseases Group, De La Salle University, Bogotá, Colombia.
J Vector Borne Dis. 2016 Oct-Dec;53(4):317-326.
BACKGROUND & OBJECTIVES: Phlebotomine sandflies lose their legs after exposure to pyrethroids. In some insects leg loss helps to defend them from intoxication and predation, a phenomenon known as autotomy. A field observation has shown that sandflies that have lost some legs are still able to blood-feed. The aims of the study were to determine whether leg loss in sandflies, after exposure to deltamethrin, is due to autotomy and to establish the effect of the leg loss on blood-feeding.
Two experiments were carried out with Lutzomyia longipalpis: (i) Females were individually exposed to a sublethal time of deltamethrin and mortality and the number of leg loss were recorded; and (ii) Groups of females with complete legs or with 1-3 legs lost due to pyrethroid exposure were offered a blood meal and percentages of blood-fed and fully-fed females were recorded.
Most females lost a median of 1 leg within 1-48 h post-exposure to deltamethrin. Mortality (after 24 h) was significantly higher for exposed females with lost legs (31.1%), compared to exposed females with complete legs (7.3%), and there were no differences in mortality between females with complete legs and the control (unexposed females). There were no differences between the three treatments in the percentages of blood-fed and fully-fed females.
INTERPRETATION & CONCLUSION: Leg loss in sandflies is a toxic effect of pyrethroids and there was no evidence of autotomy. The loss of up to three legs after exposure to pyrethroids does not affect blood-feeding behaviour in laboratory and probably also in wild conditions.
白蛉在接触拟除虫菊酯后会失去腿部。在一些昆虫中，腿部脱落有助于保护它们免受中毒和捕食，这种现象称为自残。一项野外观察表明，失去部分腿部的白蛉仍能吸血。本研究的目的是确定白蛉在接触溴氰菊酯后腿部脱落是否是由于自残，并确定腿部脱落对吸血的影响。
用长须罗蛉进行了两项实验：（i）将雌性个体分别暴露于亚致死时间的溴氰菊酯中，记录死亡率和腿部脱落数量；（ii）为因拟除虫菊酯暴露而腿部完整或失去1-3条腿的雌性群体提供血餐，记录吸血和饱血雌性的百分比。
大多数雌性在接触溴氰菊酯后1-48小时内平均失去1条腿。与腿部完整的暴露雌性（7.3%）相比，腿部脱落的暴露雌性（24小时后）死亡率显著更高（31.1%），腿部完整的雌性与对照组（未暴露雌性）之间的死亡率没有差异。在吸血和饱血雌性的百分比方面，三种处理之间没有差异。
白蛉腿部脱落是拟除虫菊酯的毒性作用，没有自残的证据。接触拟除虫菊酯后失去多达三条腿不会影响实验室条件下的吸血行为，在野外条件下可能也是如此。
