Facultative mutualism between imported fire ants (solenopsis invicta) and a legume (senna occidentalis)

摘要

Extrafloral nectaries of Senna occidentalis attract imported fire ants which protect the plant against two species of herbivores, the cloudless sulphur butterfly (Phoebis senna) and the sleepy orange butterfly (Eurema nicippe). Ant-defended plants had increased growth as measured by plant height and number of leaves, and increased reproductive effort as measured by numbers of pods, numbers of seeds, and weight of pods, compared to ant-excluded plants (using Tanglefoot barriers). Survival of herbivore eggs and larvae was reduced in the presence of ants suggesting that ants provide plants with protection from larval herbivory thus increasing the amount of primary production which in turn allows greater reproductive output.