Which One Tastes Better? Testing Distinct Baits to Evaluate Fruit‐Feeding Butterfly Assemblages (Lepidoptera: Nymphalidae) in a Subtropical Region

Standardised sampling protocols are essential for improving biodiversity assessments, particularly for indicator groups such as fruit‐feeding butterflies. Although fermented banana is the most widely used bait in tropical regions, rotten fish is the best bait for catching fruit‐feeding butterflies in high‐altitude sites. Few studies have evaluated the effectiveness of alternative attractants in the subtropical region worldwide, where environmental conditions and resource availability differ markedly. We tested the effectiveness of two bait types, fermented banana with sugarcane juice and rotten fish, in capturing fruit‐feeding butterflies across contrasting habitats (native grasslands and Restinga Forests) in the Pampa biome, southern Brazil. Using Van Someren–Rydon bait traps, we compared richness, abundance, diversity and species composition to evaluate how bait type and habitat influence assemblage structure. Contrary to expectations that rotten fish would attract more butterflies, fermented banana consistently had higher richness, abundance and diversity in both habitats. Rotten fish attracted fewer individuals and species, showing a narrower representation of butterflies. Species composition also differed between baits, with banana capturing a broader subset of the regional pool. Habitat influenced diversity patterns regardless of bait, in which Restinga Forests supported more diverse fruit‐feeding butterfly assemblages with forest‐dwelling species, whereas grasslands were dominated mainly by the Satyrini tribe. Our results demonstrate that fermented banana with sugarcane juice is the most effective bait for sampling fruit‐feeding butterflies in subtropical regions. We recommend its use as a standardised protocol to ensure adequate coverage and comparability across habitats, thereby improving short‐ and long‐term monitoring and biodiversity assessments in the subtropics.