Influence of Environmental Covariates on Pollinator Community Occupancy, Detection, and Richness Across Urban Gardens...

Pollination is a vital ecosystem service essential for the reproduction of most flowering plants. However, pollinators, especially insects, are in dramatic worldwide decline, threatening food security and global biodiversity. Urban areas, when managed well, can act as critical corridors and reserves for pollinators, benefiting ecosystems beyond the urban environment. This study assessed plant-pollinator interactions in urban gardens across the Mid-Atlantic (USA) region, focusing on two native plants: dense blazing star (Liatris spicata ) and clustered mountain mint (Pycnanthemum muticum ). Over 350 visual surveys in 52 gardens recorded 361 pollinator detection events involving 14 taxa, with five taxa dominating the detections. Using multispecies occupancy models (MSOMs) in a Bayesian framework, we evaluated how site and survey factors influenced species occupancy, detection, and richness. Species occupancy ranged from 0.04 (Halyomorpha halys ) to 0.86 (Halictidae), with little influence from external variables. Detection was influenced by plant species, survey start time, Julian date, and urban distance. For instance, honey bees (Apis mellifera ) and wasps (Vespoidea) were more likely to visit P. muticum , while Atalopedes campestris favored L. spicata . Detections of Halictidae increased in urban areas, while Bombus spp. were more common in rural settings. Our study demonstrates that MSOMs can be an effective tool for monitoring and investigating the urban pollinator community. We were able to estimate occupancy for the 14 observed insect taxa, nine of which were detected fewer than eight times. We also estimated effects of detection covariates that impacted multiple taxa and provided insight into ways to improve future pollinator monitoring efforts. These findings further our understanding of how plant species and the urban setting may variably influence pollinator activity and highlight the importance of urban gardens in supporting diverse insect communities.