Arthropod diversity and abundance in Beltsville, Maryland

The steady decline of insect populations worldwide is well-known, but it is still critical to study these trends in more geographic and taxonomic detail. We are interested in studying the arthropod diversity in Beltsville, Maryland, as the soil in the region primarily consists of very fine, sandy loam, which provides a unique habitat. As part of a broader research project on anthropogenic impacts on local insect populations, we undertook extensive insect sampling in four plots of common milkweed (Asclepias syriaca) in Beltsville. We sampled 280 pitfall traps, 280 sticky traps, and 840 pan traps from June to mid-August of 2024. Except for the sticky traps, specimens were collected in propylene glycol. All specimens were identified to the family, superfamily, or order level, and categorized as predators, parasitoids, decomposers, herbivores, or fungivores. Insect diversity and abundance were plotted over time and compared with weather patterns (temperature, precipitation events, and evaporation) and soil moisture. We identified specimens from 10 insect orders, 2 arachnid orders, and a total of 115 families, including 22 hymenopteran parasitoid families. Notable finds included specimens from the families Mythicomyiidae and Xylophagidae (Diptera), and Histeridae, Zopheridae, and Hydrophilidae (Coleoptera). Findings from our study will be compared with published insect sampling data from this region, which can help inform how the local insect population has changed over time and if certain families have experienced declines in recent years. Our study will contribute to ongoing conversations on insect assessments and conservation needs.