Dietary consumption of the plant phytochemical, gelsemine, by worker honey bees (Apis mellifera L.) affects queen bee egg laying.

Authors: Goblirsch, Michael; HAMILTON, ADAM - University Of Illinois; Carlson, Molly; ROBINSON, GENE - University Of Illinois; Adamczyk Jr, John

Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2025
Publication Date: 2/21/2025
Citation: Goblirsch, M.J., Hamilton, A.R., Carlson, M., Robinson, G.E., Adamczyk Jr, J.J. 2025. Dietary consumption of the plant phytochemical, gelsemine, by worker honey bees (Apis mellifera L.) affects queen bee egg laying.. Apidologie. (2025)56/29. https://doi.org/10.1007/s13592-025-01151-6.
DOI: https://doi.org/10.1007/s13592-025-01151-6

Interpretive Summary: Yellow or Carolina jasmine/jessamine is a flowering plant that is native to the Southeastern U.S. and Central America. Its abundant, fragrant flowers can be attractive to honey bees especially when other floral resources may not be available. In recent years, beekeepers in the Southeastern U.S. have become concerned that this plant is hurting their bees when they feed on it. Some beekeepers have even been forced to relocate their hives away from this plant when it is blooming. One potential cause for the negative effects yellow jessamine has on hive health may stem from a compound called gelsemine, which is an alkaloid present in the plant’s nectar and pollen. However, we still do not know how gelsemine hurts bees including the queen. In this study, we used Queen Monitoring Cages (QMCs), which are small cages that are maintained under laboratory conditions and are composed of a single queen, some worker bees, a plastic honey comb for the queen to lay eggs, and food. We exposed the worker bees in the QMCs to a range of gelsemine doses in sugar for up to 15 days. We then quantified the daily responses of number of eggs laid, number of worker bees present near the queen, worker bees that died, and consumption of food and water. Our findings show that number or queen eggs was significantly reduced when exposed to the higher doses of gelsemine.

Technical Abstract: Commonly referred to as yellow or Carolina jasmine/jessamine, Gelsemium sempervirens is a flowering plant that serves as a model for the study of plant-pollinator interactions. The plant produces abundant, fragrant flowers during the early spring that may be visited by honey bees (Apis mellifera), particularly when other floral resources are scarce. Beekeepers in the Southeastern U.S. have anecdotally observed signs of hive intoxication and weakening when yellow jessamine is in bloom, with implications for colony management. The phytochemical gelsemine, which is a toxic indole alkaloid present in the plant’s pollen and nectar may be linked to these observations. Few, if any studies, have looked at the effects of ecologically relevant concentrations of gelsemine on honey bee health at the colony level, and more specifically, on queen bee fecundity. We used Queen Monitoring Cages (QMCs), microcolonies composed of a queen and a small number of worker bees to investigate the impact of gelsemine exposure on queen fecundity, worker mortality, and resource consumption under laboratory conditions. We exposed the workers in the QMCs to gelsemine by adding it to sugar solution using field-relevant concentrations that ranged from 20 to 200 ppm for up to 15 days. We found that queen fecundity was significantly reduced in two of four experiments: one experiment where QMCs were exposed for seven days to 200 ppm gelsemine and one experiment where QMCs were exposed for 15 days to 100 ppm gelsemine. No effects were seen in one experiment where QMCs were exposed to gelsemine for seven days at 100 and 200 ppm and one experiment where QMCs were exposed for 14 days at 20 and 100 ppm, although there was a trend for decreased egg-laying by queens in QMCs exposed to either dose of gelsemine in the later of these two experiments. Overall, worker mortality was low; however, in three of the four experiments, workers from the control condition consumed significantly more sugar solution than those in QMCs provisioned with the higher of two concentrations of gelsemine tested, suggesting a deterrence effect. Use of the QMC system therefore permitted exploration into one facet of gelsemine’s potential impact on honey bee colony health, queen bee fecundity, and promotes additional research looking at the behavioral and physiological mechanisms that may be contributing to this response.