5 research outputs found
The Importance of Time and Place: Nutrient Composition and Utilization of Seasonal Pollens by European Honey Bees (Apis mellifera L.)
Honey bee colonies have a yearly cycle that is supported nutritionally by the seasonal progression of flowering plants. In the spring, colonies grow by rearing brood, but in the fall, brood rearing declines in preparation for overwintering. Depending on where colonies are located, the yearly cycle can differ especially in overwintering activities. In temperate climates of Europe and North America, colonies reduce or end brood rearing in the fall while in warmer climates bees can rear brood and forage throughout the year. To test the hypothesis that nutrients available in seasonal pollens and honey bee responses to them can differ we analyzed pollen in the spring and fall collected by colonies in environments where brood rearing either stops in the fall (Iowa) or continues through the winter (Arizona). We fed both types of pollen to worker offspring of queens that emerged and open mated in each type of environment. We measured physiological responses to test if they differed depending on the location and season when the pollen was collected and the queen line of the workers that consumed it. Specifically, we measured pollen and protein consumption, gene expression levels (hex 70, hex 110, and vg) and hypopharyngeal gland (HPG) development. We found differences in macronutrient content and amino and fatty acids between spring and fall pollens from the same location and differences in nutrient content between locations during the same season. We also detected queen type and seasonal effects in HPG size and differences in gene expression between bees consuming spring vs. fall pollen with larger HPG and higher gene expression levels in those consuming spring pollen. The effects might have emerged from the seasonal differences in nutritional content of the pollens and genetic factors associated with the queen lines we used
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The Neuropeptide Corazonin Promotes Higher Rates of Foraging in Apis mellifera Workers
Honey bee workers take on specific roles within the colony. Young adult workers (~1 week old) perform in-hive tasks such as cleaning or brood care (“nursing”), while older workers forage for pollen, nectar, and water. This behavioral shift is regulated by hormones such as juvenile hormone (JH) and vitellogenin (vg), however the role of other hormones in this process is less-well understood. Additionally, stressors like poor nutrition and infection can accelerate this behavioral transition leading to precocious foraging and may result in reduced forager performance and accelerated colony decline. The neurohormone corazonin (crz), an 11 amino acid peptide with structural similarity to vertebrate gonadotropin-releasing hormone (GnRH) and invertebrate adipokinetic hormone (AKH), plays a part in determining caste identity in ants and other Hymenopterans. Harpegnathos ants performing nest-associated tasks have higher levels of vg and low levels of crz, while ants performing tasks outside of the nest have low vg and higher crz expression. Crz is a proposed stress hormone demonstrating a variety of functions across several groups of insects, however, the exact purpose of this hormone has yet to be identified in honey bees. In this study, I explore the molecular mechanism underlying the nutritional stress response that leads to precocious foraging, and whether crz is involved in this response. Additionally, I examine whether crz plays a role in the behavioral transition of honey bee nurses to foragers by injecting honey bee workers in the head with crz peptide. I found that although age did not have a significant effect on crz expression, starvation altered crz expression. Finally, I found that bees injected with crz take greater amounts of foraging trips than bees injected with a control and bees that were left un-injected
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Octopamine mobilizes lipids from honey bee (Apis mellifera) hypopharyngeal glands
Recent widespread honey bee (Apis mellifera) colony loss is attributed to a variety of stressors, including parasites, pathogens, pesticides and poor nutrition. In principle, we can reduce stress-induced declines in colony health by either removing the stressor or increasing the bees' tolerance to the stressor. This latter option requires a better understanding than we currently have of how honey bees respond to stress. Here, we investigated how octopamine, a stress-induced hormone that mediates invertebrate physiology and behavior, influences the health of young nurse-aged bees. Specifically, we asked whether octopamine induces abdominal lipid and hypopharyngeal gland (HG) degradation, two physiological traits of stressed nurse bees. Nurse-aged workers were treated topically with octopamine and their abdominal lipid content, HG size and HG autophagic gene expression were measured. Hemolymph lipid titer was measured to determine whether tissue degradation was associated with the release of nutrients from these tissues into the hemolymph. The HGs of octopamine-treated bees were smaller than control bees and had higher levels of HG autophagy gene expression. Octopamine-treated bees also had higher levels of hemolymph lipid compared with control bees. Abdominal lipids did not change in response to octopamine. Our findings support the hypothesis that the HGs are a rich source of stored energy that can be mobilized during periods of stress.12 month embargo; published 16 April 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
The Importance of Time and Place: Nutrient Composition and Utilization of Seasonal Pollens by European Honey Bees (Apis mellifera L.)
Honey bee colonies have a yearly cycle that is supported nutritionally by the seasonal progression of flowering plants. In the spring, colonies grow by rearing brood, but in the fall, brood rearing declines in preparation for overwintering. Depending on where colonies are located, the yearly cycle can differ especially in overwintering activities. In temperate climates of Europe and North America, colonies reduce or end brood rearing in the fall while in warmer climates bees can rear brood and forage throughout the year. To test the hypothesis that nutrients available in seasonal pollens and honey bee responses to them can differ we analyzed pollen in the spring and fall collected by colonies in environments where brood rearing either stops in the fall (Iowa) or continues through the winter (Arizona). We fed both types of pollen to worker offspring of queens that emerged and open mated in each type of environment. We measured physiological responses to test if they differed depending on the location and season when the pollen was collected and the queen line of the workers that consumed it. Specifically, we measured pollen and protein consumption, gene expression levels (hex 70, hex 110, and vg) and hypopharyngeal gland (HPG) development. We found differences in macronutrient content and amino and fatty acids between spring and fall pollens from the same location and differences in nutrient content between locations during the same season. We also detected queen type and seasonal effects in HPG size and differences in gene expression between bees consuming spring vs. fall pollen with larger HPG and higher gene expression levels in those consuming spring pollen. The effects might have emerged from the seasonal differences in nutritional content of the pollens and genetic factors associated with the queen lines we used
The Importance of Time and Place: Nutrient Composition and Utilization of Seasonal Pollens by European Honey Bees (Apis mellifera L.)
Honey bee colonies have a yearly cycle that is supported nutritionally by the seasonal progression of flowering plants. In the spring, colonies grow by rearing brood, but in the fall, brood rearing declines in preparation for overwintering. Depending on where colonies are located, the yearly cycle can differ especially in overwintering activities. In temperate climates of Europe and North America, colonies reduce or end brood rearing in the fall while in warmer climates bees can rear brood and forage throughout the year. To test the hypothesis that nutrients available in seasonal pollens and honey bee responses to them can differ we analyzed pollen in the spring and fall collected by colonies in environments where brood rearing either stops in the fall (Iowa) or continues through the winter (Arizona). We fed both types of pollen to worker offspring of queens that emerged and open mated in each type of environment. We measured physiological responses to test if they differed depending on the location and season when the pollen was collected and the queen line of the workers that consumed it. Specifically, we measured pollen and protein consumption, gene expression levels (hex 70, hex 110, and vg) and hypopharyngeal gland (HPG) development. We found differences in macronutrient content and amino and fatty acids between spring and fall pollens from the same location and differences in nutrient content between locations during the same season. We also detected queen type and seasonal effects in HPG size and differences in gene expression between bees consuming spring vs. fall pollen with larger HPG and higher gene expression levels in those consuming spring pollen. The effects might have emerged from the seasonal differences in nutritional content of the pollens and genetic factors associated with the queen lines we used.This article is published as DeGrandi-Hoffman, Gloria, Vanessa Corby-Harris, Mark Carroll, Amy L. Toth, Stephanie Gage, Emily Watkins deJong, Henry Graham, Mona Chambers, Charlotte Meador, and Bethany Obernesser. "The Importance of Time and Place: Nutrient Composition and Utilization of Seasonal Pollens by European Honey Bees (Apis mellifera L.)." Insects 12, no. 3 (2021): 235. doi:10.3390/insects12030235.</p