Department of Biological Sciences, Missouri University of Science and Technology, Rolla, Missouri, USA.
Department of Computer Sciences, Missouri University of Science and Technology, Rolla, Missouri, USA.
Insect Sci. 2018 Jun;25(3):487-498. doi: 10.1111/1744-7917.12433. Epub 2017 Feb 16.
Increasing evidence has shown that the energy use of ant colonies increases sublinearly with colony size so that large colonies consume less per capita energy than small colonies. It has been postulated that social environment (e.g., in the presence of queen and brood) is critical for the sublinear group energetics, and a few studies of ant workers isolated from queens and brood observed linear relationships between group energetics and size. In this paper, we hypothesize that the sublinear energetics arise from the heterogeneity of activity in ant groups, that is, large groups have relatively more inactive members than small groups. We further hypothesize that the energy use of ant worker groups that are allowed to move freely increases more slowly than the group size even if they are isolated from queen and brood. Previous studies only provided indirect evidence for these hypotheses due to technical difficulties. In this study, we applied the automated behavioral monitoring and respirometry simultaneously on isolated worker groups for long time periods, and analyzed the image with the state-of-the-art algorithms. Our results show that when activity was not confined, large groups had lower per capita energy use, a lower percentage of active members, and lower average walking speed than small groups; while locomotion was confined, however, the per capita energy use was a constant regardless of the group size. The quantitative analysis shows a direct link between variation in group energy use and the activity level of ant workers when isolated from queen and brood.
越来越多的证据表明，蚁群的能量消耗与蚁群的大小呈次线性增长，因此较大的蚁群的人均能量消耗低于较小的蚁群。有人假设社会环境（例如有蚁后和幼体存在）对次线性群体能量学至关重要，并且对与蚁后和幼体分离的工蚁进行的一些研究观察到群体能量学与大小之间存在线性关系。在本文中，我们假设次线性能量学是由蚁群活动的异质性引起的，也就是说，较大的群体相对具有更多不活跃的成员，而较小的群体则具有较少的不活跃成员。我们进一步假设，如果工蚁群体被允许自由移动，则其能量消耗的增长速度将比群体大小慢，即使它们与蚁后和幼体隔离。由于技术困难，以前的研究仅为这些假设提供了间接证据。在这项研究中，我们在长时间内同时对分离的工蚁群体应用了自动化行为监测和呼吸测量法，并使用最先进的算法对图像进行了分析。我们的结果表明，当活动不受限制时，大群体的人均能量消耗较低，活跃成员的比例较低，平均行走速度也较低；而当运动受到限制时，人均能量消耗则与群体大小无关，而是一个常数。定量分析表明，当蚁后和幼体分离时，工蚁群体能量消耗的变化与工蚁的活动水平之间存在直接联系。
