The importance of insect biodiversity for vertebrates

Insects are central to ecosystem functioning, including the persistence of many vertebrate species. In this Review, we discuss the range of positive, negative and indirect effects of insects on vertebrates and evaluate the extent to which insect declines could affect vertebrate populations. Insects provide food, structures, sanitation, protection and engineering of ecosystem features that vertebrates depend on. At times, they also cause harm, especially through disease and predation. Almost three-quarters of terrestrial and freshwater vertebrates with available data eat invertebrates — over two-fifths exclusively so — with insects frequently comprising a majority of the diet. Literature on non-trophic interactions is scattered and lacks a common currency for comparison, hampering the capacity to assess the importance of interactions. Taxonomic and geographic biases also hinder comparisons for both trophic and non-trophic interactions. Despite these limitations of the literature and the paucity of strong tests of causal links between insect and vertebrate abundance, the ubiquity of interactions makes clear that widespread insect declines are likely to seriously affect many vertebrate populations. To better understand the implications of changing insect abundance, researchers need improved means for systematically collecting and organizing data about insect–vertebrate interactions as well as better quantification of the importance of these links.