Roads are partial barriers to foraging solitary bees Agapostemon virescens in an urban environment
Markovits, Chloe Marine
2023
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Roads are prominent features in human-altered landscapes, yet little is known about how they influence the movement of foraging insects. In summer 2022, I studied whether roads posed barriers to movement of the solitary bee Agapostemon virescens in Medford, Massachusetts using a mark-recapture experiment. I established three study sites: 25x25m squares bisected by an active road with a pot of ... read moreflowering Echinacea purpurea at each corner. Over the course of two weeks, I uniquely marked foraging bees and recorded the pot where initial capture and subsequent recaptures occurred. A bee recaptured at a different pot than the previous capture was recorded as either an along-road or an across-road movement. I marked 90 bees, 68 of them were recaptured at least once, and 54 were recaptured at least twice. I found that A. virescens was twice as likely to move along the same side of the road than across it. Still, 35% of orthogonal movements involved road crosses indicating that roads only partially impede movement. In addition, distance between pots reduced bee movement while the number of flowers increased movement to a pot. The number of foragers visiting each square differed significantly from one another; forager abundance was negatively associated with impervious surface but not the number of flowers or traffic intensity. My results provide compelling evidence that roads impede but do not completely block foraging bees. This study also demonstrates that small patches of habitat serve as foraging resources for bees in cities and underscores the strength of population level experiments.
Thesis (B.S.)--Tufts University, 2023.
Submitted to the Dept. of Biology.read less - ID:
- ff365k83m
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