Urban landscapes may be able to support native bee conservation, study finds

Vacant properties in Detroit may help sustain bee colonies

(Photo by Oli Scarff/Getty Images)
(Photo by Oli Scarff/Getty Images)

DETROIT – Bumblebee populations were larger in Detroit than in less urbanized areas, a study by researchers at the University of Michigan found.

More than 500 bees from 10 species were identified at 30 sites in southeast Michigan. Bumblebees were sampled from nature reserves and urban gardens and farms in Dexter, Ann Arbor, Ypsilanti, Dearborn and Detroit.

The bees were captured with handheld nets and insect traps.

The most abundant bumblebee species sampled during the study was the common eastern bumblebee, followed by the brown-belted bumblebee and the two-spotted bumblebee.

In sites outside of Detroit, the study found that more urbanization tended to lead to decreased abundance and diversity of bumblebee populations. However in Detroit, that wasn’t the case.

In Detroit, the sites with the most impervious surfaces coverage had nearly the same amount of bumblebees captured as U-M's E.S. George Reserve, a nature preserve near Pinckney with the lowest impervious surface cover proportion in the study.

Impervious surfaces include buildings, concrete parking structures and asphalt roads.

According to researchers, vacant residential properties in Detroit may help sustain bee colonies, as the lots are often mowed less frequently and are less likely to be treated with pesticides and herbicides.

The study also found that urbanization seems to affect male and female bees differently.

Bee colonies consist of one reproductive female, female workers and males whose role is to mate.

The researchers found that observed declines in overall bumblebee abundance and diversity with increasing urbanization were driven by declines in female workers, while male abundance and diversity were unrelated to urbanization.

The study highlighted the importance of heterogeneity in urban areas, the researchers said, and suggested that urban landscapes can be managed to support native bee conservation.

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