From communities to continents: Beta diversity of herbivorous insects

Recent progress in molecular systematics that assists species identifications, and in on-line databases of ecological and museum collections that enable the integration of insect distribution data represent important developments facilitating beta diversity studies. The increase in alpha and gamma diversities of insect herbivores from temperate to tropical communities is driven largely by a parallel increase in plant diversity while the diversity of insect herbivores per plant species remains constant. Likewise, the high beta diversity of insect herbivores along altitudinal gradients is only partially explained by changes in plant diversity, while abiotic factors and the abundance of natural enemies may also be important. The high alpha diversity of insect herbivores in lowland tropical forests is not matched by beta diversity as locally co-existing species represent a large proportion of regional species pools. The role of dispersal limitation in the distribution of herbivorous insects in tropical forests could be minor, as short-lived insects are efficient colonisers of their mostly long-lived woody hosts.