Micro-Environmental Factors Affecting Diel Patterns of Foraging in the Leaf-Cutting Ant Atta cephalotes (L.) (Formicidae: Attini)

(1) A range of micro-weather factors including trail and nest entrance temperatures, relative light intensity, relative humidity of the air and atmospheric pressure were measured each day when Atta cephalotes started foraging. None of these factors determined when activity started. (2) Neither + or...

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Bibliographic Details
Published in:The Journal of animal ecology 1974-02, Vol.43 (1), p.143-153
Main Authors: Lewis, T., Pollard, G. V., Dibley, G. C.
Format: Article
Language:English
Subjects:
Animal nesting
Ants
Foraging
Forest soils
Fungi
Insect larvae
Insect nests
Leaf cutting ants
Luminous intensity
Rain
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Summary:(1) A range of micro-weather factors including trail and nest entrance temperatures, relative light intensity, relative humidity of the air and atmospheric pressure were measured each day when Atta cephalotes started foraging. None of these factors determined when activity started. (2) Neither + or - temperature differentials between the interior and exterior of nests, nor rapidly or slowly changing trail temperatures, stimulated foraging. (3) Rain delayed the start of foraging and caused ants already at a cutting site or on the trail to return to the nest or shelter. (4) The total number of leaf fragments cut per foraging period was appreciably correlated with light intensity and trail temperature, but neither these nor any of the three other micro-weather factors measured (see 1), either singly or combined, adequately accounted for the changes in the total number of fragments collected daily by ants on a single trail. (5) A biological explanation is suggested as to why ants that usually forage by night sometimes change to foraging by daylight. There is much circumstantial evidence which suggests that foragers on a particular trail are stimulated to collect substrate containing a different nutrient balance or traces of plant metabolites, depending on the amount of brood in the fungus gardens they service. By collecting fragments in daylight when the sugar, amino acid and aromatic content of leaves is greater than in darkness, ants may be able to supply larvae directly with trace nutrients essential for their development, or provide the fungus with extra readily assimilable nitrogen to encourage its rapid growth.
ISSN:0021-8790
1365-2656
DOI:10.2307/3163