Temperature niche and body size condition phenological responses of moths to urbanization in a subtropical city

Abstract

Urbanization in temperate climates often advances the beginning and peak of biological events due to multiple factors, especially urban heat islands. However, the effect of urbanization on insect phenology remains understudied in more tropical areas, where temperature may be a weaker phenological cue. We surveyed moths across an urban gradient in a subtropical city weekly for a year to test how impervious surface and canopy cover impact phenology at the caterpillar and adult life stages. For macro-moths, we also examine how these effects vary with life history traits. When pooling all individuals, we found no effect of urbanization proxy variables on timing of caterpillar or adult phenology. At the species-specific level, we found timing of peak adult macro-moths is influenced by canopy cover, which also interacts with two traits: temperature niche and body size. Cold-adapted species delay timing of peak abundance in more shaded sites, while warm-adapted species were not affected. Smaller species, associated with lower dispersal ability, were more phenologically sensitive to canopy cover than larger bodied species. These results highlight the importance of canopy cover within cities and its interaction with species' traits in mediating impact of urbanization on moth phenology in subtropical systems.