Ventilation of the giant nests of Atta leaf-cutting ants: does underground circulating air enter the fungus chambers?
Ventilation of the giant nests of Atta leaf-cutting ants: does underground circulating air enter the fungus chambers?
复制标题
DOI：
10.1007/s00040-012-0243-9
复制
发表时间：
2012-11-01
期刊：
影响因子：
1.3
通讯作者：
Roces, F.
中科院分区：
文献类型：
--
作者：
Bollazzi, M.;Forti, L. C.;Roces, F.
巢穴通风对于切叶蚁（阿塔属）的巨大群体尤其重要。真菌花园和巢室内的蚂蚁消耗大量的 O-2 并产生 CO2，这些巢室位于深层土壤，其特征是高 CO2 和低 O-2 浓度。在这项工作中，在田间的 Atta capiguara 和 Atta laevigata 巢穴中研究了被动巢穴通风，首先，使用丙烷作为示踪气体评估通过巢穴的空气运动以及循环空气中的 CO2 和 O-2 浓度，其次，通过使用水泥铸件和挖掘来暴露内部巢穴形态。结果表明，尽管富含 CO2 的空气流出和富含 O-2 的空气流入分别发生在高位和低位开口处，支持风引起的空气运动穿过巢穴的解释，但在真菌室内从未检测到循环空气。真菌室内的CO2和O-2水平分别随着土壤深度的增加而增加和减少，并且在土壤相中观察到的范围内。从地下巢穴的结构来看，虽然巢穴的外部形状引起了地下空气流通，但流入的空气无法直接到达真菌室。有人认为，蜂群呼吸完全取决于室内空气与邻近巢穴和土壤大气之间的扩散流。循环空气虽然不能直接更新巢室内的空气，但由于地下空气相中 CO2 的减少和 O-2 水平的增加，可以通过增加巢和土壤空气作为 O-2 源和 CO2 汇的能力来促进蜂群呼吸。讨论了蚂蚁和真菌对土壤中常见的高 CO2 和低 O-2 浓度的可能适应。
Nest ventilation should be particularly relevant for the huge colonies of leaf-cutting ants, genus Atta. Considerable amounts of O-2 are consumed and CO2 produced by both the fungus gardens and the ants inside nest chambers, which are located at deep soil layers characterized by high CO2 and low O-2 concentrations. In this work, passive nest ventilation was investigated in field Atta capiguara and Atta laevigata nests, first, by evaluating air movements through the nest using propane as tracer gas as well as the CO2 and O-2 concentrations of the circulating air, and second, by exposing the internal nest morphology with the use of cement casts and excavations. Results showed that even though outflow of CO2-rich air and inflow of O-2-rich air occurred at high-placed and low-placed openings, respectively, supporting a wind-induced interpretation of air movements through the nest, circulating air was never detected inside fungus chambers. The CO2 and O-2 levels inside the fungus chambers increased and decreased with increasing soil depth, respectively, and were in the range observed in the soil phase. Based on the underground nest architecture, it is concluded that although the external shape of the nest induces underground air circulation, the inflowing air is unable to directly reach the fungus chambers. It is argued that colony respiration completely depends on diffusive flows between the chamber air and the adjacent nest and soil atmospheres. Circulating air, although not directly renewing the air inside the nest chambers, may contribute to colony respiration by increasing the capacity of the nest and soil airs to act as an O-2-source and a CO2-sink, because of the decrease in the CO2 and the increase in the O-2 levels in the underground air phase. Possible adaptations of both ants and fungus to the high CO2 and low O-2 concentrations usually found in soils are discussed.