Pollen defenses negatively impact foraging and fitness in a generalist bee (Bombus impatiens: Apidae)

Plants may benefit from limiting the community of generalist floral visitors if the species that remain are more effective pollinators and less effective pollenivores. Plants can reduce access to pollen through altered floral cues or morphological structures, but can also reduce consumption through...

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Bibliographic Details
Published in:Scientific reports 2020-02, Vol.10 (1), p.3112-3112, Article 3112
Main Authors: Brochu, Kristen K, van Dyke, Maria T, Milano, Nelson J, Petersen, Jessica D, McArt, Scott H, Nault, Brian A, Kessler, André, Danforth, Bryan N
Format: Article
Language:English
Subjects:
Adaptation
Animals
Appetitive Behavior
Bees
Bees - classification
Bees - physiology
Behavior, Animal
Bombus impatiens
Chemical defense
Cucurbita
Female
Flowers
Flowers - anatomy & histology
Hindgut
Melanization
Morphology
New York
Physiology
Plant Defense Against Herbivory
Pollen
Pollination
Pollinators
Stress response
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Summary:Plants may benefit from limiting the community of generalist floral visitors if the species that remain are more effective pollinators and less effective pollenivores. Plants can reduce access to pollen through altered floral cues or morphological structures, but can also reduce consumption through direct pollen defenses. We observed that Eucera (Peponapis) pruinosa, a specialist bee on Cucurbita plants, collected pure loads of pollen while generalist honey bees and bumble bees collected negligible amounts of cucurbit pollen, even though all groups of bees visited these flowers. Cucurbit flowers have no morphological adaptations to limit pollen collection by bees, thus we assessed their potential for physical, nutritional, and chemical pollen traits that might act as defenses to limit pollen loss to generalist pollinators. Bumble bee (Bombus impatiens) microcolonies experienced reduced pollen consumption, mortality, and reproduction as well as increased stress responses when exposed to nutritional and mechanical pollen defenses. These bees also experienced physiological effects of these defenses in the form of hindgut expansion and gut melanization. Chemical defenses alone increased the area of gut melanization in larger bees and induced possible compensatory feeding. Together, these results suggest that generalist bumble bees avoid collecting cucurbit pollen due to the physiological costs of physical and chemical pollen defenses.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-020-58274-2