Propolis chemical composition across landscapes

The United States has seen contractions in habitat and floral resources due to agricultural and urban land use expansions, leading to changes in landscape configuration, including increased landscape simplification and habitat fragmentation. Limited non-crop vegetation leads to landscape-level deficits in food availability for honey bees, Apis mellifera, and numerous studies have documented the ramifications of these deficits on bee health. Beyond food, certain plants provide resin, which honey bees process into propolis, a sticky substance composed of plant resins and balsams, bee-derived wax, and salivary gland secretions. Collection of resins by foragers varies with geographic region, collection time, and vegetation availability. However, little is known about how anthropogenic change affects resin collection, propolis production, and, ultimately, honey bee health, via propolis’s antimicrobial or immunoregulatory properties from its phytochemicals.
Honey bee colonies will be placed across landscapes that vary in proportion of forested areas, as trees are the primary source of resin for propolis production. Non-volatile and volatile components of propolis will be identified through GC-MS and SPME/GC-MS analysis, respectively. Additionally, pathogen challenges will be completed with Nosema ceranae and Israeli Acute Paralysis Virus (IAPV), and mortality observed following the supplementation of sucrose with or without propolis. We hypothesize that the chemical composition of propolis will change across landscapes, with propolis collected from colonies in areas with higher proportions of forested areas containing a greater diversity of phytochemicals. Further, as a supplement, propolis produced by colonies in higher forested areas will enhance honey bee health and survival when pathogen challenged.