Insect herbivory on seedlings of rainforest trees: effects of density and distance of conspecific and heterospecific neighbours

1. Natural enemies of plants such as insect herbivores can contribute to structuring and maintaining plant diversity in tropical forests. Most research in this area has focused on the role of specialised enemies and the extent to which herbivory on individual plant species is density-dependent.
2. Relatively few insect herbivores specialise on a single host plant species. Insect herbivores that feed on more than one plant species may link the regeneration dynamics of their host species through ‘apparent competition’ or ‘apparent mutualism’.
3. We investigated herbivory and survival of seedlings of two tropical tree species (Cordia alliodora and Cordia bicolor) in the forests of Barro Colorado Island (Panama). We used experiments and observations to assess seedling fate in relation to the presence of conspecifics and heterospecifics across a range of spatial scales.
4. Herbivory significantly increased seedling mortality and was highest at high local densities of C. alliodora seedling...