Butterfly and moth communities differ in their response to habitat structure in rainforests of Mount Cameroon
Abstract
Mechanisms structuring tropical communities are still under-studied, especially in Afrotropical rainforests. Although insect herbivores are considered to depend on plant diversity, we hypothesized that vegetation structure, together with other microhabitat characteristics, can be more important for some insects.
Here, we compared habitat associations of fruit-feeding butterflies and moths, two ecologically different groups of Lepidoptera, in three rainforest localities in foothills of Mount Cameroon, West/Central Africa. Based on a comprehensive dataset of 16,040 specimens of 398 species systematically collected by 240 traps at 48 plots (altogether 9.68 ha), we analyzed how plant community composition, habitat openness, and forest structure affect communities of butterflies and moths.
We expected different habitat descriptors to predict communities of the two insect groups. Habitats of tropical fruit-feeding moth communities have never been studied before.
In both analyses of species richness and community structure, butterfly communities depended mostly on forest openness. Moth species richness depended on plant diversity and forest openness, whilst the latter substantially influenced their community composition.
Additionally, we revealed differences in habitat associations between understory and canopy communities of both groups. Whilst species richness of understory communities was not influenced by any habitat characteristics, it generally followed the general patterns in canopies.
By contrast, composition of understory communities followed the general patterns, whilst effects of habitat characteristics on canopy communities were minor for butterflies and none for moths. The differences between such closely related groups of herbivorous insects warn against generalization based on single-taxon studies and highlight the need of community-wide research of tropical rainforests.