Moth communities are more diverse in the understory than in the canopy of a tropical lowland rainforest in NW Ecuador

Tropical rainforests are the most species-rich terrestrial habitats and
provide distinct niches for specialization and speciation, in part due to
their vertical stratification. Stratification is observed in many insect
orders as a result of abiotic factors, resource availability, competition
and behavior. Here, we investigate the stratification of five clades of
Lepidoptera: Erebidae-Arctiinae, Geometridae, Hedylidae, Saturniidae and
Sphingidae, which differ in many aspects of their ecology and traits. The
study was carried out in a tropical rain forest of the Chocó region in NW
Ecuador. We used funnel traps equipped with weak UV-lamps to sample moths
simultaneously in the canopy and understory in four forest habitats. We
identified species using reference collections and DNA barcoding and
present a qualitatively unique database for Neotropical rainforests, with
12,472 individuals of 676 species collected in 48 nightly catches. Average
species richness was higher in the understory (73.54 ± 22.58) than in the
canopy (59.09 ± 17.24), and median sample sizes were similar (understory:
217.5 (160.5 - 336), canopy: 187.5 (138 - 328.5)). We found taxon-specific
patterns: Arctiinae and Sphingidae – the stronger flyers – were more
species-rich and abundant in the canopy, and weaker flyers Geometridae and
Saturniidae were more species-rich and abundant in the understory. We
assume that predation pressure, availability of nectar and host plants
shape the vertical distribution of moth assemblages. Communities largely
overlapped, were highly nested in each stratum and between habitat types,
and differences in composition among habitats were mainly driven by
elevation. We found more species in regenerating forests compared to old
growth forests, while sample size was independent of the abiotic factors
elevation, temperature, humidity. Our results allow a comprehensive
insight into differences in stratification of five moth clades in a
tropical rainforest at high taxonomic resolution with respect to habitat
types and influences of environmental factors.