During foraging, ant workers are known to make use of multiple information sources, such as private information (personal memory) and social information (trail pheromones). Environmental effects on foraging, and how these interact with other information sources, have, however, been little studied. One environmental effect is trail bifurcation asymmetry. Ants forage on branching trail networks and must often decide which branch to take at a junction (bifurcation). This is an important decision, as finding food sources relies on making the correct choices at bifurcations. Bifurcation angle may provide important information when making this choice. We used a Y-maze with a pivoting 90° bifurcation to study trail choice of Lasius niger foragers at varying branch asymmetries (0°, [both branches 45° from straight ahead], 30° [branches at 30° and 60° from straight ahead], 45°, 60° and 90° [one branch straight ahead, the other at 90°]). The experiment was carried out either with equal amounts of trail pheromone on both branches of the bifurcation or with pheromone present on only one branch. Our results show that with equal pheromone, trail asymmetry has a significant effect on trail choice. Ants preferentially follow the branch deviating least from straight, and this effect increases as asymmetry increases (47% at 0°, 54% at 30°, 57% at 45°, 66% at 60° and 73% at 90°). However, when pheromone is only present on one branch, the graded effect of asymmetry disappears. Overall, however, there is an effect of asymmetry as the preference of ants for the pheromone-marked branch over the unmarked branch is reduced from 65%, when it is the less deviating branch, to 53%, when it is the more deviating branch. These results demonstrate that trail asymmetry influences ant decision-making at bifurcations and that this information interacts with trail pheromone presence in a non-hierarchical manner.

中文翻译：

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路径分叉不对称和信息素存在或不存在对黑夜蛾路径选择的影响

在觅食过程中，蚂蚁工人们会利用多种信息源，例如私人信息（个人记忆）和社会信息（踪迹信息素）。然而，环境对觅食的影响，以及它们如何与其他信息源相互作用，却鲜有研究。一种环境影响是路径分叉不对称。蚂蚁在分支路径网络上觅食，并且必须经常决定在交叉点（分叉处）采取哪个分支。这是一个重要的决定，因为寻找食物来源依赖于在分叉处做出正确的选择。进行此选择时，分叉角可能会提供重要信息。我们使用了一个带有 90° 分叉的 Y 迷宫来研究 Lasius niger 觅食者在不同分支不对称（0°，[两个分支从正前方 45°]，30° [从直线向前 30° 和 60° 的分支]、45°、60° 和 90° [一个分支直线向前，另一个在 90°]）。该实验是在分叉的两个分支上使用等量的尾迹信息素进行的，或者在仅一个分支上存在信息素的情况下进行的。我们的结果表明，在信息素相等的情况下，路径不对称性对路径选择有显着影响。蚂蚁优先跟随偏离直线最少的分支，这种影响随着不对称性的增加而增加（0°时为 47%，30°时为 54%，45°时为 57%，60°时为 66%，90°时为 73%）。然而，当信息素只存在于一个分支上时，不对称的分级效应就消失了。然而，总体而言，存在不对称效应，因为蚂蚁对信息素标记分支的偏好从未标记分支的 65%（当它是偏差较小的分支时）降低到 53%，当它是更偏离的分支时。这些结果表明踪迹不对称影响蚂蚁在分叉处的决策，并且该信息以非分层方式与踪迹信息素的存在相互作用。