A species of bumblebee imported to Hokkaido as a pollinator for greenhouse vegetables is rapidly expanding its presence in the wild and threatens to disturb the prefecture’s native ecosystem.

Buff-tailed bumblebees, which are 1 to 2 cm and characterized by their white-tipped abdomens, have settled only in Hokkaido so far as the climate is similar to that of the species’ native Europe.

Experts say the infestation could threaten not only to eliminate native bees but also hamper pollination as it sometimes opens a hole in petals and collects nectar without touching the pistils or stamens and thus doesn’t transport the pollen.

A feral bumblebee was first seen in what used to be the town of Mombetsu in southern Hokkaido in 1996 and has since been observed in 128 of the prefecture’s 179 municipalities.

In recent years, the bees have been seen in Daisetsuzan National Park, Shiretoko Peninsula and Kushiro Marsh, which are all home to rare species of animals and plants.

“The bee could destroy the habitat of rare plants in Hokkaido,” an Environment Ministry official said.

To protect the ecosystem, the ministry in 2006 classified the buff-tailed bumblebee as a specific alien species that presents a risk to ecosystems, human lives, and farming, forestry and fishing businesses, and has restricted the import, breeding and storing of the species.

The ministry also obliges farmers to set up nets to stop the bumblebees from leaving greenhouses once they enter.

The prefectural government in 2007 formed a citizens’ volunteer group dubbed the “Busters.” With the support of 300 volunteers, 43,000 buff-tailed bumblebees were captured in fiscal 2012.

The University of Tokyo’s Laboratory of Conservation Ecology has helped collect data on the number of bumblebees observed and captured, and has analyzed the species’ favorite flowers and their behavioral patterns.

As many as 100 queens can be born in one hive. They tend to be more active at the beginning of spring when they start to build a hive and the fall when they start preparing for hibernation.

“The species has stronger vitality than domestic species and expanded its habitat thus far,” said Hironobu Shimada of the prefectural government’s Biodiversity Division. “We are seeking more public support.”

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