Diversity and trait patterns of moths at the edge of an Amazonian rainforest

From the forest edge to the forest interior, a small-scale gradient in the microclimate exists. Little is known about its influence on the abundance, diversity and morphological traits of insects in Amazonian forests, a major component of global terrestrial diversity. Our study investigates these traits in Arctiinae and Geometridae moths at the interior and the edge of a Peruvian lowland rainforest (Panguana field station, Puerto Inca Province). A total of 1286 Arctiinae and 2012 Geometridae specimens were collected, sorted according to DNA barcodes and identified using relevant type material. Moths' assemblages at the forest edge differed significantly in their composition. At the forest edge, small-sized taxa (Lithosiini, Sterrhinae, Geometrinae) were less abundant whereas larger-sized Arctiini were more abundant. Moths were significantly larger at the forest edge than inside the forest, and these differences hold at subfamily and tribal level, possibly reflecting moth mobility, and abiotic conditions of habitats: larger moths might better tolerate desiccating conditions than smaller moths. A larger proportion of females was found at the forest edge, probably due to differences in the dispersal activity among sexes and/or in the tolerance to desiccation due to size. Our results revealed the edge effect on two rich herbivorous taxa in the Amazon basin. We provide a fully illustrated catalogue of all species as a baseline for further study and conservation purposes.