Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Bailrigg, Lancashire, United Kingdom.
Laboratório Doenças Parasitárias, Instituto Oswaldo Cruz-Fiocruz, Pavilhão Arthur Neiva, Av. Brasil, Rio de Janeiro, RJ, Brazil.
PLoS Negl Trop Dis. 2020 Oct 20;14(10):e0008798. doi: 10.1371/journal.pntd.0008798. eCollection 2020 Oct.
In South America the sand fly Lutzomyia longipalpis is the predominant vector of Leishmania infantum, the parasite that causes canine and human visceral leishmaniasis. Co-location of synthetic male sex-aggregation pheromone with an insecticide provided protection against canine seroconversion, parasite infection, reduced tissue parasite loads, and female sand fly densities at households. Optimising the sex-aggregation pheromone + insecticide intervention requires information on the distance over which female and male Lu. longipalpis would be attracted to the synthetic pheromone in the field.
METHODOLOGY/PRINCIPAL FINDINGS: Wild Lu. longipalpis were collected at two peridomestic study sites in Governador Valadares (Minas Gerais, Brazil). Sand flies were marked with coloured fluorescent powder using an improved protocol and then released into an existing domestic chicken shed at two independent sites, followed by recapture at synthetic-pheromone host-odour baited traps placed up to 30 metres distant from the release point. In total 1704 wild-caught Lu. longipalpis were released into the two chicken sheds. Overall 4.3% of the marked flies were recaptured in the pheromone baited experimental chicken sheds compared to no marked flies recaptured in the control sheds. At the first site, 14 specimens (10.4% of the marked and released specimens) were recaptured at 10m, 36 (14.8%) at 20m, and 15 (3.4%) at 30m. At the second site, lower recapture rates were recorded; 8 marked specimens (1.3%) were recaptured at 5 and 10m and no marked specimens were recaptured at 15m. Approximately 7x more marked males than females were recaptured although males were only 2x as common as females in the released population. 52% of the marked Lu. longipalpis were collected during the first night of sampling, 32% on the second night, and 16% on the third night.
CONCLUSIONS/SIGNIFICANCE: The study established that both male and female sand flies can be attracted to the synthetic sex-aggregation pheromone in the presence of host odour over distances up to at least 30m in the field depending on local environmental and meterological conditions.
在南美洲，沙蝇卢氏长尾蚊是利什曼原虫的主要传播媒介，这种寄生虫会导致犬类和人类内脏利什曼病。将合成雄性聚集信息素与杀虫剂共同投放，可防止犬类血清转化、寄生虫感染、组织寄生虫载量减少以及家庭中雌性沙蝇密度增加。优化雄性聚集信息素+杀虫剂干预措施需要了解野外条件下雌性和雄性卢氏长尾蚊会被合成信息素吸引多远的距离。
方法/主要发现：在巴西米纳斯吉拉斯州瓦拉达里斯的两个半户内研究点采集野生卢氏长尾蚊。用改良的方案用彩色荧光粉标记沙蝇，然后将其释放到两个独立的现有家庭鸡舍中，然后在距离释放点 30 米远的合成信息素宿主气味诱捕器中重新捕获。总共将 1704 只野生捕获的卢氏长尾蚊释放到两个鸡舍中。在有信息素诱饵的实验鸡舍中总共捕获了 4.3%的标记苍蝇，而在对照鸡舍中没有捕获到标记苍蝇。在第一个地点，在 10m 处捕获了 14 只标本（标记和释放标本的 10.4%），在 20m 处捕获了 36 只（14.8%），在 30m 处捕获了 15 只（3.4%）。在第二个地点，记录到的回收率较低；在 5m 和 10m 处捕获了 8 只标记标本，在 15m 处没有捕获到标记标本。尽管雄性在释放种群中的数量是雌性的两倍，但被捕获的标记雄性苍蝇是标记雌性苍蝇的 7 倍左右。标记的卢氏长尾蚊中有 52%是在采样的第一晚收集的，32%是在第二晚收集的，16%是在第三晚收集的。
结论/意义：该研究确定，在野外条件下，只要当地的环境和气象条件允许，雄性和雌性沙蝇都可以被合成性聚集信息素在宿主气味的存在下吸引，吸引距离可达至少 30 米。
