Experimental Zoology Group, Wageningen University, Wageningen, The Netherlands.
Laboratory of Entomology, Wageningen University, Wageningen, The Netherlands.
Malar J. 2020 Oct 7;19(1):357. doi: 10.1186/s12936-020-03403-5.
When seeking a human for a blood meal, mosquitoes use several cues to detect and find their hosts. From this knowledge, counter-flow odour-baited traps have been developed that use a combination of CO, human-mimicking odour, visual cues and circulating airflow to attract and capture mosquitoes. Initially developed for monitoring, these traps are now also being considered as promising vector control tools. The traps are attractive to host-seeking mosquitoes, but their capture efficiency is low. It has been hypothesized that the lack of short-range host cues, such as heat and increased local humidity, often prevent mosquitoes from getting close enough to get caught; this lack might even trigger avoidance manoeuvres near the capture region.
This study investigated how close-range host cues affect the flight behaviour of Anopheles female malaria mosquitoes around odour-baited traps, and how this affects trap capture performance. For this, a novel counter-flow odour-baited trap was developed, the M-Tego. In addition to the usual CO and odour-blend, this trap can provide the short-range host cues, heat and humidity. Systematically adding or removing these two cues tested how this affected the trap capture percentages and flight behaviour. First, capture percentages of the M-Tego with and without short-range host cues to the BG-Suna trap were compared, in both laboratory and semi-field testing. Then, machine-vision techniques were used to track the three-dimensional flight movements of mosquitoes around the M-Tego.
With heat and humidity present, the M-Tego captured significantly more mosquitoes as capture percentages almost doubled. Comparing the flight behaviour around the M-Tego with variable close-range host cues showed that when these cues were present, flying mosquitoes were more attracted to the trap and spent more time there. In addition, the M-Tego was found to have a better capture mechanism than the BG-Suna, most likely because it does not elicit previously observed upward avoiding manoeuvres.
Results suggest that adding heat and humidity to an odour-baited trap lures more mosquitoes close to the trap and retains them there longer, resulting in higher capture performance. These findings support the development of control tools for fighting mosquito-borne diseases such as malaria.
当蚊子寻找人类进行吸血时，会利用多种线索来发现和定位宿主。基于这一知识，开发了逆流气味诱捕器，该诱捕器利用 CO、模拟人体气味、视觉线索和循环气流的组合来吸引和捕获蚊子。最初这些诱捕器是为监测而设计的，但现在也被认为是很有前景的病媒控制工具。这些诱捕器对寻找宿主的蚊子具有吸引力，但捕获效率较低。有人假设，缺乏近距离宿主线索（如热量和局部湿度增加）通常会阻止蚊子靠近并被捕获；这种缺乏甚至可能在捕获区域附近触发回避动作。
本研究调查了近距离宿主线索如何影响气味诱捕器周围雌性疟疾病媒按蚊的飞行行为，以及这如何影响诱捕器的捕获性能。为此，开发了一种新型的逆流气味诱捕器，即 M-Tego。除了通常的 CO 和气味混合物外，这种诱捕器还可以提供近距离宿主线索，即热量和湿度。系统地添加或去除这两个线索，测试了这如何影响诱捕器的捕获百分比和飞行行为。首先，在实验室和半野外测试中，比较了有和没有近距离宿主线索的 M-Tego 和 BG-Suna 诱捕器的捕获百分比。然后，使用机器视觉技术跟踪蚊子在 M-Tego 周围的三维飞行运动。
当存在热量和湿度时，M-Tego 的捕获量显著增加，捕获百分比几乎翻了一番。比较 M-Tego 周围有或没有可变近距离宿主线索的飞行行为表明，当这些线索存在时，飞行中的蚊子会被诱捕器吸引，并在那里停留更长时间。此外，与 BG-Suna 相比，M-Tego 具有更好的捕获机制，这很可能是因为它不会引发之前观察到的向上回避动作。
结果表明，在气味诱捕器中添加热量和湿度可以吸引更多的蚊子靠近诱捕器，并使它们在那里停留更长时间，从而提高捕获性能。这些发现支持开发控制工具来对抗疟疾等蚊媒疾病。
