Contrasting Inter- and Intraseasonal Patterns of Beetle Trophic Guilds (Insecta: Coleoptera) in a Tropical Montane Semiarid Region

Seasonal variation strongly influences insect communities, particularly in seasonally dry ecosystems where climatic conditions and resource availability fluctuate markedly throughout the year. We investigated inter- and intraseasonal variation in the species richness and composition of beetle (Coleoptera) trophic guilds in a tropical montane semiarid region of Brazil. Beetles were sampled with pitfall traps during 2 periods of the dry season and 2 periods of the rainy season. Species richness and composition of the overall assemblage and of detritivorous, herbivorous, and predatory guilds were evaluated using generalized linear mixed effects models and multivariate analyses. Seventy-one species belonging to 14 families and 43 genera were recorded. Most species occurred during the rainy season, particularly during its onset. Species composition differed markedly between the beginning and the end of the rainy season, indicating pronounced intraseasonal turnover, whereas little variation was observed within the dry season. Seasonal responses differed among trophic guilds. Detritivorous beetles were concentrated mainly at the beginning of the rainy season, herbivorous beetles exhibited a broader temporal distribution extending into the dry season, and predatory beetles showed high species turnover during the rainy season despite relatively stable richness. These results demonstrate that beetle trophic guilds respond differently to temporal variation in environmental conditions and resource availability. Intraseasonal climatic fluctuations contribute substantially to temporal turnover, emphasizing the importance of considering both inter- and intraseasonal variation to understand beetle community dynamics in seasonally dry ecosystems.