Experimental Evidence for Defense of Inga (Mimosoideae) Saplings by Ants

Inga densiflora and I. punctata have foliar nectaries that are visited by a variety of ants. Extrafloral nectar secretion on new leaves is continuous throughout the day and night; ant activity on both old and new leaves is also continuous. Experiments compared the effectiveness of five species of ants in removing caterpillars and three other types of insect herbivores from leaves. All ant species tested could remove insect herbivores to some extent; of these ants, Pheidole biconstricta was the most effective. Leaves from which ants were excluded suffered substantially greater damage than control leaves. Ant—defense is a generalized and effective defense operating in the protection of Inga saplings against herbivores, but the extent of protection may vary according to what species of ants visit the nectaries–a consequence of facultative mutualism.