Bloom timing shapes how a bumblebee gut parasite spreads between flowers
Pinilla-Gallego MS, Adler LS
Pollinators
The wild bergamot blooming in your pollinator garden isn't just pretty - when it peaks relative to the rest of your season can quietly influence whether bumblebees visiting it stay healthier or carry heavier parasite burdens.
Researchers wanted to know if having lots of flowers at different times of year changes how a common bumblebee gut parasite spreads from bee to bee. They set up tent experiments with infected and healthy bees, manipulating when wild bergamot peaked in bloom. More flowers early in the season reduced how much parasite infected bees carried, but didn't stop the disease from reaching healthy bees - and higher visitation rates in the second week were linked to more transmission overall.
Key Findings
Donor bees had lower infection intensity when peak bloom occurred early versus late, suggesting more flowers diluted per-flower visit rates and reduced pathogen buildup.
Peak bloom timing did not significantly affect transmission probability to uninfected recipient colonies under 2-week experimental conditions.
Higher inflorescence visitation rates in the second week were positively associated with both donor infection probability and recipient infection intensity.
chevron_right Technical Summary
When bumblebees have more flowers early in the season, infected bees carry lower parasite loads - but that timing shift doesn't reduce how often the disease spreads to healthy bees. The finding suggests that floral abundance patterns through the season shape bee-pathogen dynamics in nuanced ways that matter for pollinator health.
Abstract Preview
Original paper
Effect of peak bloom timing on the transmission of the bumble bee pathogen Crithidia bombi (Trypanosomatida: Trypanosomatidae).
Pathogen spread is a major driver of wild and managed bee decline, with shared floral resources often serving as transmission hubs. However, the abundance of floral resources changes throughout the...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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