Some factors affecting the site and pattern of leaf-cutting activity in the ant Atta cephalotes

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Acromyrmexbob
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Some factors affecting the site and pattern of leaf-cutting activity in the ant Atta cephalotes

Post by Acromyrmexbob » Tue Sep 03, 2019 11:50 pm

Based on a paper by Barrer and Cherrett.

Some interesting observations about leaf selection in Atta cephalotes

1. Relative attractiveness of leaves decreases with age. The suggestion was that this might simply be that newer leaves were easier to cut.
2. Crushed young leaves were smeared on old leaves which made them more attractive which suggests this attraction is in fact chemical. So this attraction is actually chemical.
3. The addition of Quinine sulphate smeared onto the leaf acted as a repellant.
4. The presence of cuts on the leaf raises the possibility that the leaf will be cut more. This is the ants responding to the success of previous foragers.
5. Shaved edge of leaf is more attractive than intact leaf suggesting chemical component is also a factor.

The summary of the paper is as follows

The young leaves of privet are significantly more attractive to the ant, Atta cephalotes
L., than the old, and evidence from other plant species suggests that this relative attractiveness of young leaves is a widespread phenomenon. The relative attractiveness of young
privet leaves is partly due to the presence of attractive chemicals within the leaves. Old
privet leaves probably possess quantities of actively repellent chemicals, which tend to
counteract the influence of more favourable cutting stimuli.
Fresh ant cuts and other types of damage on a leaf increase the probability of further
ant cuts occurring on the same leaf. Leaf-cutting develops with an accelerating bias
towards areas of the plant that are already being successfully exploited by the ants.
Initially, this accelerating bias increasingly favours the more attractive regions of the
plant, usually those with the youngest growth.
Ant-secreted pheromones are not responsible for the high attractive value of ant cuts,
which is due partly to the increased availability of sensory information concerning the
chemical composition of the leaf and partly to the physical geometry of the cut in the
leaf.

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