Location: Carl Hayden Bee Research Center
2019 Annual Report
Objectives
Honey bees obtain nutrients from pollen and nectar and are thus vulnerable in
landscapes with increased agrochemical exposure and decreased pollen diversity.
Agrochemical use has been increasing, but we do not yet have a comprehensive
understanding of the effects of acute and chronic exposure to these compounds on
colony health and survivorship. The objectives of this project are to evaluate
agrochemical exposure and nutritional stress with respect to bee nutrition, workerqueen interactions, pheromone profiles, queen retention, colony growth and forager activity. Published studies on pesticide exposure and the nutritional value of pollen and bee bread will help determine experimental treatments. The impact of the effects of pesticide exposure on the colony level will be evaluated by continuously monitoring hive weight, temperature and forager activity in row crop agriculture and in nut and fruit pollination. The role of nutrition on Varroa population growth and on colony recovery will also be examined.
Objective 1: Determine the nutritional composition of pollen before and after
conversion to bee bread and determine the effects of pesticide- and nutritionalstress on worker bees and on colony population growth and survival.
1A: Quantify the nutritional composition of pollen and bee bread according to the
time of year when the pollen is collected.
1B: Determine if worker hemolymph protein levels, hypopharyngeal gland development, and virus titers differ depending on pollen source, nutritional composition and time of year.
1C: Determine the effects of pollen contamination with fungicides and mite
treatments alone or in combination on worker hemolymph protein levels,
hypopharyngeal gland development, and virus titers.
1D: Examine the effects of exposure to pesticide-treated row crops on colony growth, nutritional status, phenology and foraging activity.
1E: Evaluate the effects of participation in commercial nut and fruit pollination on colony growth, activity and survivorship.
1F: Examine the effects of insect growth regulators (IGRs) on young adult
development and physiology.
Objective 2: Determine the effects of nutritional stress on Varroa parasitism
success and mite population growth in colonies.
2A: Evaluate the effects of nutrition and pollen source on Varroa reproductive
success and virus transmission.
2B: Assess the nutritional recovery time for colonies after infestation by Varroa.
Objective 3: Identify pesticide stress factors influencing worker-queen
interactions, pheromone production, queen supersedure, and successful queen
replacement.
3A: Evaluate the effects of neonicotinoid exposure on queen pheromone production,
queen supersedure and replacement, and worker-queen interactions.
3B: Evaluate the effects of neonicotinoid exposure on colony overwintering and
almond pollination.
3C: Monitor queen pheromone and ocimene production in colonies exposed to sublethal doses of the insect growth regulator methoxyfenozide.
3D: Monitor queen rearing, attractivenes, and ovary development in queens exposed to sublethal doses of pesticides.
Approach
Subobjective 1A: Determine whether pollens collected by bees in the spring and
summer differ in nutritional composition from pollens collected in the fall prior to overwintering. Pollen and bee bread will be collected from: 1) colonies foraging on undefined pollen sources and 2) colonies foraging on specific plants we provide.
Subobjective 1B: Evaluate the effects of pollen sources on worker and larval
hemolymph protein and lipids, on hypopharyngeal glands, and on virus and Nosema
levels in workers.
Subobjective 1C: Evaluate the effects of pollen with and without the fungicide
Pristine®, and with and without the miticide Amitraz, on colony health and worker
nutritional status during the active season.
Subobjective 1D: 1) Develop methods to link continuous weight and temperature data to hive phenology; and 2) conduct longitudinal and factorial field experiments to examine the effects of pesticide exposure and nutritional effects on changes in colony weight, internal temperature, forager activity and nutritional status.
Subobjective 1E: Examine the effects of participation in commercial pollination,
including agrochemical exposure, on bee colony growth and activity. Honey bee
colonies will be established, evaluated, and their weight and temperature monitored continuously prior to and during deployment to treated and untreated orchards.
Subobjective 1F: Examine the effects of field-relevant dosages of an insect growth regulator on bee hypopharyngeal glands and expression of genes involved in
ecdysteroid-induced gland degradation.
Subobjective 2A: Examine whether virus transmission is affected by the nutritional value of pollen and by bee nutritional stress by exposing bees to pollens of different nutritional value, and to artificial pollen dearth through the use of pollen traps, and monitoring varroa populations and virus incidence.
Subobjective 2B: Evaluate the effects of bee bread, made from pollens collected
during the active season, and of supplemental protein diet, on worker hemolymph
protein concentrations following parasitism by Varroa, in addition to field
experiments to examine colony recovery from Varroa infestation.
Subobjective 3A: Examine the effects of neonicotinoid exposure on pheromone-mediated interactions in bee colonies, with a focus on: Pheromone emissions of (E)-ßocimene, EO, BEP, QMP, and queen (E)-ß-ocimene, colony nutritional status, queen performance, forager effort, pesticide residues, and colony performance.
Subobjective 3B: Examine the effects of pesticide exposure on colony overwintering and almond pollination 1) during fall production of winter bees and 2) when colonies produce replacement bees for winter bees during the first annual forage by monitoring compounds listed in Subobj. 3A.
Subobjective 3C: Examine the effects of an insect growth regulator (IGR) on QMP and ocimene production in bee colonies offered different pesticide dosages in pollen and/ or syrup in controlled field studies.
Subobjective 3D: Examine the effects of an IGR on queen ovary development and
attractiveness by exposing larval queens to either contaminated wax or contaminated food and subsequently monitoring queen productivity.
Progress Report
This report documents progress for bridging project 2022-21000-020, which is currently undergoing NP305 office of scientific quality review.
Under Sub-objective 1D, the hive weight and temperature data collected from commercial apiaries from August 2016 to March 2018 has been analyzed and compared to hive assessment data, Varroa mite density data and pesticide residue data. Samples of bee bread were submitted for analysis of essential fatty acids.
Under Sub-objective 1E, a field experiment involving the exposure of honey bee colonies to field relevant concentrations of neonictinoid pesticides was carried to its completion in March 2019. Colony-level behavior, thermoregulation and internal hive carbon dioxide levels were monitored in Arizona, and a parallel experiment was conducted simultaneously by ARS researchers in Poplarville, Mississippi. Results are being prepared for publication.
Under Sub-objective 2B, the effects of nutrition on Varroa population sizes and virus levels in honey bee colonies were investigated in field experiments. We found that bees do not have a chance to recover from Varroa infestations because mites migrate into colonies in the fall and re-infest them. In our study, mite migration increased Varroa populations and virus levels and there is no difference between colonies with and without optimized nutrition.
Under Sub-objective 3A, a field experiment was conducted to assess chronic effects of the neonicotinoid imidacloprid on queen-worker interactions, queen pheromone signaling, and on individual and colony performance. Colonies were given sublethal doses of imidacloprid (0, 20, and 100 parts per billion, or ppb) in sugar syrup in a simulated six week long early fall nectar flow and were evaluated before, immediately after, and sometime after exposure to contaminated syrup. Bees were not affected during the initial collection of contaminated sugars in early fall; rather, bees experienced delayed effects from persistent neonicotinoid residues in sugar stores during winter dearth when consumption of honey stores is high. Mid-winter colonies previously given the high dose reared less brood, had smaller adult populations, stored less pollen, and had lower queen signaling than other colonies. This study demonstrates that neonicotinoid pesticides may affect honey bees not only during initial food collection and storage, but also during later consumption of contaminated stores.
Under Sub-objective 3B, a field experiment was repeated last fall to evaluate sublethal effects of the neonicotinoid imidacloprid on queen-worker interactions, queen pheromone signaling, and individual and colony performance in 60 overwintering colonies. The experiment was prematurely terminated by the Federal government shutdown (loss of a critical evaluation time point, end of winter dearth) in January 2019. The experiment will be attempted for a third time in FY20.
Under Sub-objective 3C, we are currently repeating experiments and monitoring colony health and pheromone communications after exposure to sublethal concentrations of methoxyfenozide, an insect growth regulator used as a pesticide, for a third time with more colonies during this summer and early fall. Samples will be processed, and behavioral monitoring assessed after collection.
Under Sub-objective 3D, a field experiment testing whether methoxyfenozide influenced the likelihood that a queenless colony will rear a queen, queen ovary development, and queen mating ability is being replicated a third time.
Accomplishments
Review Publications
Li, J., Heerman, M.C., Evans, J.D., Li, W., Rodriguez-Garcia, C., Hoffman, G.D., Zhao, Y., Huang, S., Li, Z., Hamilton, M.C., Chen, Y. 2019. Pollen reverses decreased lifespan, altered nutritional metabolism, and suppressed immunity in honey bees (Apis mellifera) treated with antibiotics. Journal of Experimental Biology. 222:jeb202077. https://doi.org/10.1242/jeb.202077.
Meikle, W.G., Corby-Harris, V.L., Carroll, M.J., Weiss, M., Snyder, L.A., Meador, C.A., Beren, E.D., Brown, N.J. 2019. Effects of sublethal exposure of methoxyfenozide in feeding supplement on honey bee colony activity and thermoregulation. PLoS One. 14(3):e0204635. https://doi.org/10.1371/journal.pone.0204635.
Colin, T., Meikle, W.G., Paten, A., Barron, A. 2019. Long-term dynamics of honey bee colonies following exposure to chemical stress. Science of the Total Environment. 677:660-670. https://doi.org/10.1016/j.scitotenv.2019.04.402.
Ricigliano, V.A., Mott, B.M., Maes, P., Floyd, A.S., Fitz, W., Copeland, D.C., Meikle, W.G., Anderson, K.E. 2019. Honey bee colony performance and health are enhanced by apiary proximity to US Conservation Reserve Program (CRP) lands. Scientific Reports. 9:4894. https://doi.org/10.1038/s41598-019-41281-3.
