Centre for Ecology and Conservation, University of Exeter, Cornwall Campus, Penryn, UK.
Department of Migration, Max Planck Institute of Animal Behaviour, Radolfzell, Germany.
Proc Biol Sci. 2021 Sep 29;288(1959):20211805. doi: 10.1098/rspb.2021.1805. Epub 2021 Sep 22.
The sun is the most reliable celestial cue for orientation available to daytime migrants. It is widely assumed that diurnal migratory insects use a 'time-compensated sun compass' to adjust for the changing position of the sun throughout the day, as demonstrated in some butterfly species. The mechanisms used by other groups of diurnal insect migrants remain to be elucidated. Migratory species of hoverflies (Diptera: Syrphidae) are one of the most abundant and beneficial groups of diurnal migrants, providing multiple ecosystem services and undergoing directed seasonal movements throughout much of the temperate zone. To identify the hoverfly navigational strategy, a flight simulator was used to measure orientation responses of the hoverflies and to celestial cues during their autumn migration. Hoverflies oriented southwards when they could see the sun and shifted this orientation westward following a 6 h advance of their circadian clocks. Our results demonstrate the use of a time-compensated sun compass as the primary navigational mechanism, consistent with field observations that hoverfly migration occurs predominately under clear and sunny conditions.
太阳是候鸟在白天最可靠的定位天体线索。人们普遍认为，昼行性昆虫利用“时间补偿的太阳罗盘”来调整太阳在一天中不断变化的位置，这在一些蝴蝶物种中得到了证实。其他昼行性昆虫迁徙群体所使用的机制仍有待阐明。食蚜蝇（双翅目：蝇科）是最丰富和有益的昼行性迁徙昆虫之一，它们在温带地区提供多种生态系统服务，并进行定向季节性迁徙。为了确定食蚜蝇的导航策略，使用飞行模拟器测量了食蚜蝇在秋季迁徙期间对天体线索的定向反应。当食蚜蝇能够看到太阳时，它们会朝向南方，并且在它们的生物钟提前 6 小时后，这种方向会向西偏移。我们的研究结果表明，时间补偿的太阳罗盘是主要的导航机制，这与食蚜蝇迁徙主要发生在晴朗和阳光充足的条件下的实地观察结果一致。
