In many tropical lowland rainforests, topographic variation increases environmental heterogeneity thus contributing to the extraordinary biodiversity of tropical lowland forests. While a growing number of studies have addressed effects of topographic differences on tropical insect communities at regional scales (e.g., along extensive elevational gradients), surprisingly little is known about topographic effects at smaller spatial scales. The present study investigates moth assemblages in a topographically heterogeneous lowland rainforest landscape, at distances of less than a few hundred meters, in the Golfo Dulce region (SW Costa Rica). Three moth lineages – Erebidae-Arctiinae (tiger and lichen moths), the bombycoid-complex, and Geometridae (inchworm moths) – were examined by means of automatic light traps in three different forest types: creek forest, slope forest, and ridge forest. Altogether, 6543 individuals of 419 species were observed. Moth assemblages differed significantly between the three forest types regarding to species richness, total abundance and species composition. Moth richness and abundance increased more than four-fold and eight-fold from creek over slope to ridge forest sites. All three taxonomic units showed identical biodiversity patterns, notwithstanding their strong differences in multiple eco-morphological traits. An indicator species analysis revealed that most species identified as characteristic were associated with either the ridge forest alone, or with ridge plus slope forests, but very few with the creek forest. Despite their mobility, local moth assemblages are highly differentially filtered from the same regional species pool. Hence, variation in environmental factors significantly affects assemblages of tropical moth species at small spatial scales.

Full species list_moth survey_Costa Rica_La Gamba_Rabl et al.

Full species list and abundances from the publication Rabl, D., et al. 2019. Moth assemblages in Costa Rican Forest mirror small-scale topographic heterogeneity

Habitat descriptors_moth survey_Costa Rica_La Gamba_Rabl et al.

Habitat descriptors from the publication Rabl, D., et al. 2019. Moth assemblages in Costa Rican Forest mirror small-scale topographic heterogeneity