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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.

Meikle W G; Kistler, H Corby; Hoffman G D; Carroll, Jeffery
USDA - Agricultural Research Service
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