農業情報研究所＞環境＞環境・自然保護・生物多様性＞2019年5月5日

セイヨウオオマルハナバチ導入で世界中の自生マルハナバチが絶滅危機

　“Each year more than 2 million bumblebee colonies are exported from factories in Europe to greenhouses in more than 60 countries. These industrial bumblebees are bred and sold for their fantastic pollination skills: their plump, hairy bodies are perfect to shake the pollen of the male part of the plant to the female. This buzz pollination – so-called because of the sound it makes – can lead to a 30% increase in the yield of tomatoes, compared with pollination by hand, with a wand.

　The battle to save the world's biggest bumblebee from European invaders,The Guardian,19.5.4

The first time José Montalava saw the world’s largest bumblebee he was six years old and visiting his grandfather’s house in rural Chile. “It was in the tomato patch, a huge, loud, fluffy orange thing buzzing around. I remember trying to grab it, but it kept getting away, although it looked too heavy to fly,” he recalls.

During Montalava’s childhood, these giant golden bumblebees (Bombus dahlbomii) – which can measure up to 40mm and have been dubbed “flying mice” – were a common sight in the town where he grew up in central Chile. “It’s such a striking, charismatic, colourful bumblebee that used to herald spring,” says the 36-year-old entomologist. “Now it’s totally disappeared from my hometown and many other areas.”

Montalava says he first became aware the bee was in trouble after he was asked to take part in a study on the potential impact on the native species of importing a European bumblebee.

“In 2003, we would see thousands of the native bumblebees in the gardens of the university just outside the capital, Santiago, where I worked. The flowers were covered with these big, fluffy orange bees.”

A few years later, however, they were nowhere to be seen. And soon they had also disappeared from the coastal cliffs covered in wild flowers that Montalava visited every year for the annual survey. “You hear how species like lions and rhinos could go extinct on the other side of the word, but I grew up with this one and I’m witnessing its disappearance. It’s happened so quickly,” he says.

The cause of the catastrophe was eventually identified, in the form of a creature far smaller than the golden giant. Each year more than 2 million bumblebee colonies are exported from factories in Europe to greenhouses in more than 60 countries. These industrial bumblebees are bred and sold for their fantastic pollination skills: their plump, hairy bodies are perfect to shake the pollen of the male part of the plant to the female. This buzz pollination – so-called because of the sound it makes – can lead to a 30% increase in the yield of tomatoes, compared with pollination by hand, with a wand.

Around the world the industrial bees travel, pollinating fruits and vegetables, including tomatoes, aubergines, peppers and blueberries. More than a third of the world’s crop production is reliant on pollinators whose annual services are estimated to be worth up to $577bn (£440bn) to the global economy.

But the growth of the bumblebee trade for agricultural pollination since the 1980s has been identified as one of the top emerging environmental issues likely to affect global diversity.

“Just as European settlers accidentally wiped out native populations in the Americas with a host of European diseases such as measles, which they had no defences against, the European bumblebees can transmit pathogens that kill native bees,” says Cecilia Smith-Ramírez, a researcher in pollination and bumblebees at the University de Los Lagos and Institute of Ecology and Biodiversity (IEB) in Chile.

Since 1997, Chile has imported more than 1.2m bumblebee colonies from factories in Belgium, Slovakia and Israel. In 2015 alone, 200,000 were imported. Over the years, they have escaped the greenhouses and spread more than 2,000km (1,200 miles) to the southernmost tip of South America, across the Andes into Argentina and from the Pacific to the Atlantic coast.------