Hoverflies in high tunnel systems: Species richness, seasonal patterns, and landscape influence

Hoverflies (Syrphidae) are valuable contributors to agricultural systems, providing ecosystem services as pollinators and natural enemies of pests such as aphids. Despite their importance, little is known about their diversity and seasonal activity in protected culture systems. High tunnels offer extended growing seasons and partial climate control, creating unique microenvironments that can influence insect communities and are common in temperate regions. This study aims to understand syrphid fly species richness, seasonal patterns, and the influence of surrounding landscape complexity on hoverfly populations in high tunnel vegetable production across Indiana. Syrphids were sampled monthly from October 2022 to October 2024 at 18 farms along an urban-rural landscape. Yellow sticky cards, standardized crop and weed surveys, and weather stations were used to collect data on insect presence, crop composition, and environmental conditions. We hypothesize that high tunnels with greater surrounding vegetation diversity and warmer seasonal temperatures will support higher syrphid abundance and richness, particularly aphidophagous species. Understanding the phenology and landscape-level drivers of syrphid fly populations will inform integrated pest management strategies and promote conservation of beneficial insects in high tunnel systems.