Urbanization Causing Negative Impact on Ground-Nesting Bumblebees: Study

Landscapes with increasing paved roads and constructions are causing a negative impact on ground-nesting bumblebees, finds a new study.

Researchers Shalene Jha from the University of Texas at Austin and Claire Kremen from the University of California - Berkeley, have found that bumblebees prefer landscapes with natural habitat and floral diversity to nest and pollinate.

Bumblebees are important pollinators, providing pollination services to plants. Unlike honeybees, bumblebees do not make harvestable honey. They nest on the ground and each colony has a queen and a group of workers. The workers are sisters who forage for flowers to collect food for the larvae.

Researchers studied the native California bumblebee, dubbed Bombus vosnesenskii, found in farms and natural reserves. By genetically identifying the bees, they were able to spot bees belonging to the same colony. Using this information as well as the bees' locations, experts were able to determine the number of bees in a colony and how far they forage from their nesting grounds in search of food supplies.

They found that bumblebees forage longer distances from their home nest in search of flowers rich in species, if the landscape near their nest does not offer floral diversity. They prefer species-rich floral patches than dense floral patches.

Bumblebees are found less in numbers in landscapes with impervious constructions. Rapid urbanization is affecting the bees, forcing them to forage longer distances locating diverse floral patches. This affects the pollination services provided to plants, said the researchers.

Researchers suggest that increasing natural and species-rich floral habitats could improve nesting opportunities for bumblebees. Understanding how the bees move around landscapes could also help in preserving biodiversity, they said.

"We are potentially in a pollinator crisis," Jha, lead author of the study, said in a statement.

"Honey bees are declining precipitously, and wild bees have also been exhibiting population declines across the globe. Native bees provide critical pollination services for fruit, nut, fiber and forage crops. Understanding how bees move around the landscape can help us both preserve biodiversity and improve crop yields."

The findings of the study are published in the journal Proceedings of the National Academy of Sciences.