Location: Honey Bee Research
Project Number: 2022-21000-020-00-D
Project Type: In-House Appropriated
Start Date: Feb 7, 2019
End Date: Dec 31, 2020
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.
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.