Herbivore Diets, Herbivore Colonization, and the Escape Hypothesis

The escape hypothesis predicts that isolated individuals of a given plant species will escape their specialized herbivores and so survive better than individuals growing in clumps. This phenomenon could promote plant coexistence. I examined assumptions underlying the hypothesis by considering insect herbivores associated with neotropical Passiflora vines. I found that the hypothesis was probably of only limited value because plants were attacked by a range of herbivore species, most of which were not really specialized. Furthermore, some oligophagous herbivore species colonized isolated P. pittieri more readily than they colonized plants that were near to other P. pittieri plants: isolated plants did not escape herbivory. Because of the activities of herbivores that feed on >1 plant species, @>2 plant species that share herbivores may not show independent patterns of herbivory or independent local distributions.