Abstract: Understanding drivers of insect population declines is essential for the development of successful conservation plans, but data limitations restrict assessment across spatial and temporal scales. Museum records represent a source of historical data that can be leveraged to investigate temporal trends in insect communities. Several formerly common native lady beetle (Coccinellidae) species are no longer present, or exceedingly rare, across the state of Ohio, USA. The decline of these native coccinellids has been attributed to competition with established alien species and landscape change. Our goalwas to assess the relative importance of these drivers in reshaping the composition of the lady beetle community. Our approach to addressing our goal was to examine distribution patterns for native lady beetles over 12 decades using museum records and evaluate the relative importance of alien species and landscape change as drivers contributing to changes in communities. We compiled occurrence records for lady beetle species collected in Ohio by county from 1900-2018. To assess the influence of landscape change, we analyzed historical land use and land cover data at the county and decade resolution to align with the spatial and temporal resolution available for the museum specimen data. To evaluate the relative influence of alien species and landscape change as drivers on the captures of native species, we constructed negative binomial generalized additive models. Here we show evidence of declines in captures of Adalia bipunctata, Coccinella novemnotata, Hippodamia convergens, Coleomegilla maculata, and Chilocorus stigma. Importantly, the timing, severity, and drivers of these documented declines were species-specific. We found strong associations between increased collection of alien lady beetles and decreased collections of H. convergens, C. maculata, and C. stigma. However, we found that both A. bipunctata and C. novemnotata exhibited signs of decline as early as the 1950s and were rarely captured prior to the detection of alien species. Instead, these declines were strongly associated with agricultural land cover, which has decreased in area and shifted from diversified cropping systems to intensely managed corn and soybean. In conclusion, our study documented shifts in Ohio lady beetle communities beginning in the 1950s and continuing through the 2000s as alien species supplanted natives. Drivers of declines in captures were species-specific, emphasizing that mechanisms driving population losses cannot be generalized even among closely related species. These findings also indicate the importance of museum holdings and the analysis of species-level data when studying temporal trends in insect populations of conservation concern.
