Microgeographic and vertical distribution of Acromyrmex landolti (Hymenoptera: Formicidae) nests in a neotropical savanna
1998
Lapointe, S.L. | Serrano, M.S. | Jones, P.G.
Nests of the grass-cutting attine ant Acromyrmex landolti (Forel) were excavated in a lowland tropical savanna in eastern Colombia over a period of 27 mo. Of 135 colonies, nests excavated during the dry season were deeper, had more chambers, and were approximately 2.5 times larger than those excavated in the same area of native savanna during the wet season. Chambers containing fungus gardens were found to a depth exceeding 2 m during the dry season. During the rainy season, all chambers containing fungus gardens were located within 30 cm of the soil surface. Individual chamber size did not vary seasonally. During the rainy season, colonies relocated to superficial chambers and were smallest in terms of total colony volume and number of chambers per colony. During the dry season, colonies excavated new chambers to depths where soil moisture asymptotically approached a maximum level. Maps of colony location and microtopography of the savanna revealed an aggregated distribution associated with microrelief. Colonies were aggregated on slightly raised ridges that were most likely caused by surface water runoff. Implications for sampling and control are discussed.
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