Bezerra-Santos Marcos Antonio, Zeni Valeria, Pistillo Onofrio Marco, Bedini Stefano, D'Isita Ilaria, Benelli Giovanni, Germinara Giacinto Salvatore, Volf Petr, Otranto Domenico
Department of Veterinary Medicine, University of Bari, Bari, Italy.
Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy.
PLoS Negl Trop Dis. 2024 Dec 30;18(12):e0012787. doi: 10.1371/journal.pntd.0012787. eCollection 2024 Dec.
The olfactory response of insect vectors such as phlebotomine sand flies is a key facet for investigating their interactions with vertebrate hosts and associated vector-borne pathogens. Such studies are mainly performed by assessing the electrophysiological response and the olfactory behaviour of these arthropods towards volatile organic compounds (VOCs) produced by hosts. Nonetheless, few studies are available for species of the subgenera Lutzomyia and Nyssomyia in South America, leaving a void for Old World sand fly species of the genus Phlebotomus. In this study, we evaluated the olfactory responses of Phlebotomus perniciosus, one of the most important vectors of Leishmania infantum in the Old World. To test the P. perniciosus behavioural response to VOCs, 28 compounds isolated from humans and dogs were assessed using electrophysiological (i.e., electroantennogram, EAG) and behavioural assays (i.e., Y-tube olfactometer). In the EAG trials, 14 compounds (i.e., acetic acid, nonanoic acid, 2-propanol, 2-butanol, pentanal, hexanal, nonanal, trans-2-nonenal, decanal, myrcene, p-cymene, verbenone, 2-ethyl-1-hexanol, and acetonitrile) elicited high antennal responses (i.e., ≥ 0.30 mV) in female sand flies, being those VOCs selected for the behavioural assays. From the 14 compounds tested in the Y-tube olfactometer, nonanal was significantly attractive for P. perniciosus females, whereas myrcene and p-cymene were significantly repellents (p < 0.05). The attraction indexes varied from 0.53 for nonanal (i.e., most attractive) to -0.47 to p-cymene (i.e., most repellent). Overall, our results shed light on the role of olfactory cues routing host seeking behaviour in P. perniciosus, with implications to develop sustainable sand fly monitoring as well as control in leishmaniasis endemic areas.
白蛉等昆虫媒介的嗅觉反应是研究它们与脊椎动物宿主及相关媒介传播病原体相互作用的关键方面。此类研究主要通过评估这些节肢动物对宿主产生的挥发性有机化合物（VOCs）的电生理反应和嗅觉行为来进行。然而，南美洲的卢氏白蛉亚属和奈氏白蛉亚属物种的相关研究很少，这使得旧大陆白蛉属的沙蝇物种存在研究空白。在本研究中，我们评估了旧大陆利什曼原虫最重要的媒介之一——嗜人按蚊的嗅觉反应。为了测试嗜人按蚊对VOCs的行为反应，使用电生理（即触角电图，EAG）和行为测定法（即Y型管嗅觉仪）评估了从人和狗身上分离出的28种化合物。在EAG试验中，14种化合物（即乙酸、壬酸、2-丙醇、2-丁醇、戊醛、己醛、壬醛、反式-2-壬烯醛、癸醛、月桂烯、对伞花烃、马鞭草烯酮、2-乙基-1-己醇和乙腈）在雌性沙蝇中引起了高触角反应（即≥0.30 mV），这些VOCs被选用于行为测定。在Y型管嗅觉仪中测试的14种化合物中，壬醛对嗜人按蚊雌性具有显著吸引力，而月桂烯和对伞花烃则具有显著驱避作用（p < 0.05）。吸引指数从壬醛的0.53（即最具吸引力）到对伞花烃的-0.47（即最具驱避性）不等。总体而言，我们的结果揭示了嗅觉线索在引导嗜人按蚊寻找宿主行为中的作用，这对在利什曼病流行地区开展可持续的沙蝇监测及控制具有重要意义。
