Roulston, T. | bioRxiv Science

bioRxiv2023

Montane Central Appalachian Forests Provide Refuge for the Critically Endangered Rusty Patched Bumble Bee (Bombus affinis)

The mountains of Central Appalachia are rich with environmental variance and host a wide variety of community types and diverse flora and fauna. The once common Rusty-Patched Bumble Bee (RPBB, Bombus affinis) has experienced widespread declines and was believed to have been extirpated throughout the Lower Midwest, Northeast and Appalachian regions of the United States (U.S.). We document the occurrence and environmental associations of a contemporary population within Central Appalachia using a dataset of 274 observations spanning nine years and over 2,000 surveys. We show that Appalachian RPBB are strongly associated with high elevation, heavily forested landscapes, especially those with West to Northwest facing aspects. Measures of forest species composition are also associated with RPBB observations. While only 38 percent of surveys occurred on U.S. National Forest lands, 84 percent of observations occurred in these areas, suggesting distinct forest habitat conditions associated with U.S. Forest Service lands play a role in the persistence of this species. The Appalachian region is rugged and difficult to systematically survey, and our analysis represents the first assessment of the species presence and habitat associations within the region. Appalachian RPBB populations are likely geographically and genetically isolated from Upper Midwest populations and additional research is needed to prioritize future conservation efforts across the current and potential range of the species.

ecology↗

bioRxiv2019

Learning may help pollinators find their host plants in polluted landscapes

Pollination strongly contributes to food production, and often relies on pollinating insects. However, atmospheric pollution may interfere with pollination by disrupting floral plumes that pollinators use to navigate to flowers.\n\nIn this study, we examine the impacts of pollution-induced elevated ozone levels on the composition of a floral blend of Nicotiana alata and examine the response of innate and trained Manduca sexta to the ozone-altered blend.\n\nOzone exposure altered the floral blend of N. alata, and disrupted the innate attraction of naive M. sexta to the altered blend. However, associative learning can offset this disruption in attraction. Moths that were enticed with visual cues to an artificial flower emitting an ozonated blend learned to associate this blend with a nectar reward after just one rewarded experience. More importantly, moths that were rewarded while experiencing the unozonated floral blend of their host subsequently found the ozonated floral blend of the same host attractive, most likely due to experience-based reinforcement of ozone-insensitive cues in the blend.\n\nThe attraction of moths to both unaltered and ozonated plumes is critical for tolerating polluted landscapes. At the host plant, where moths feed, floral emissions are relatively pure. As floral odors travel away from the host, however, they become degraded by pollution. Therefore, targeting the flower requires recognizing both conditions of the odor. The ability to generalize between the pure and ozone-altered scents may enable pollinators like M. sexta to maintain communication with their flowers and reduce the impact anthropogenic oxidants may have on plant-pollinator systems.

animal behavior and cognition↗