ARC Centre of Excellence in Vision Science, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia.
PLoS One. 2013;8(3):e58801. doi: 10.1371/journal.pone.0058801. Epub 2013 Mar 6.
Insects face the challenge of navigating to specific goals in both bright sun-lit and dim-lit environments. Both diurnal and nocturnal insects use quite similar navigation strategies. This is despite the signal-to-noise ratio of the navigational cues being poor at low light conditions. To better understand the evolution of nocturnal life, we investigated the navigational efficiency of a nocturnal ant, Myrmecia pyriformis, at different light levels. Workers of M. pyriformis leave the nest individually in a narrow light-window in the evening twilight to forage on nest-specific Eucalyptus trees. The majority of foragers return to the nest in the morning twilight, while few attempt to return to the nest throughout the night. We found that as light levels dropped, ants paused for longer, walked more slowly, the success in finding the nest reduced and their paths became less straight. We found that in both bright and dark conditions ants relied predominantly on visual landmark information for navigation and that landmark guidance became less reliable at low light conditions. It is perhaps due to the poor navigational efficiency at low light levels that the majority of foragers restrict navigational tasks to the twilight periods, where sufficient navigational information is still available.
昆虫在明亮的阳光照射和昏暗的光照环境中都面临着到达特定目标的挑战。无论是昼行性昆虫还是夜行性昆虫，它们使用的导航策略都非常相似。尽管在低光照条件下，导航线索的信噪比很差，但它们确实如此。为了更好地了解夜间生活的进化，我们研究了夜行性蚂蚁 Myrmecia pyriformis 在不同光照水平下的导航效率。M. pyriformis 的工蚁会在傍晚的黄昏时分独自离开巢穴，进入一个狭窄的光线窗口，在特定的桉树树上觅食。大多数觅食者会在清晨的黄昏时分返回巢穴，而少数几只则会在整个晚上试图返回巢穴。我们发现，随着光照水平的下降，蚂蚁会停顿更长时间，走得更慢，找到巢穴的成功率降低，它们的路径也变得不那么直了。我们发现，在明亮和黑暗的条件下，蚂蚁主要依赖视觉地标信息进行导航，并且地标引导在低光照条件下变得不太可靠。也许是因为在低光照水平下导航效率较差，大多数觅食者将导航任务限制在黄昏时段，在这个时段仍然可以获得足够的导航信息。
