マルハナバチの女王バチ、水中で７日間生存 科学者に驚き

【パリＡＦＰ＝時事】マルハナバチの女王バチが、水中で数日間生き延びたとする実験結果が１７日、英国王立協会の科学誌バイオロジー・レターズに発表された。気候変動によって増加している洪水が地面の下の巣穴を脅かしても、冬眠中のハチが生き延びる可能性を示唆しているという。（写真は資料写真）
　論文の筆頭著者を務めたカナダ・オタワ大学博士研究員のサブリナ・ロンドー氏は、土壌中の残留農薬が冬眠中のマルハナバチの女王バチに及ぼす影響を調べていたが、その際にハチを入れていたチューブに水が入ってしまい、そこで女王バチが生き延びていることに偶然気が付いた。
　より詳しく調べるため、同氏はさらなる実験を行った。研究チームは冬眠中のマルハナバチの女王バチ１４３匹をチューブに入れ、水に完全に沈めたグループ、水に浮かべたグループ、水をまったく入れないグループに分けた。水に沈めた期間は、８時間から７日間と幅を持たせた。
　すると驚くべきことに、水没させた女王バチの８１％が７日間生き延びた上に、乾燥状態に戻してから８週間後も生存していた。
　健康状態への長期的な影響やコロニーへの影響については、さらなる研究が必要だとした。
　この研究で使われたマルハナバチは特に丈夫な北米の固有種で、他の種のハチほど個体数の減少は見られないという。この形質がどの程度一般的なものなのかを調べるためには、他の種のマルハナバチで同じ実験を行う必要がある。
　「少なくとも（洪水が）考慮すべき別の大きな脅威の一つではないということが分かったのは心強い」と同氏は語った。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2024/04/18-19:11）

Bumblebees can surprisingly withstand days underwater, according to a study published Wednesday, suggesting they could withstand increased floods brought on by climate change that threaten their winter hibernation burrows.
The survival of these pollinators that are crucial to ecosystems is encouraging amid worrying global trends of their declining populations, the study's lead author Sabrina Rondeau told AFP.
With global warming prompting more frequent and extreme floods in regions around the world, it poses an unpredictable challenge for soil-dwelling species, particularly bees nesting or overwintering underground, co-author Nigel Raine of the University of Guelph said in a statement.
Rondeau said she first discovered queen bumblebees could withstand drowning by accident.
She had been studying the effect of pesticide residues in soil on queen bumblebees that burrow underground for the winter when water accidentally entered the tubes housing a few of the bees.
I freaked out, said Rondeau, who had been conducting the experiment for her doctoral studies. It was only a small proportion... so it was not that big of a deal, but I didn't want to lose those bees.
To her shock, she said, they survived.
I've been studying bumblebees for a very long time. I've talked about it to a lot of people and no one knew that this was a possibility, she said.
She launched another experiment to better understand what happened.
Researchers placed 143 hibernating queen bumblebees in tubes -- some with no water as a comparative group, some floating in water and some fully submerged using a plunger for a period ranging from eight hours to seven days, according to the study published in the journal Biology Letters.
Remarkably, 81 percent of the hibernating queens that were submerged not only survived seven days, but once returned to dry conditions remained alive eight weeks later.
The long-term impact on the bees' health and the effects it could have on a colony still needs further research, Rondeau noted.
The common eastern bumblebees used in the study are found in North America and are particularly hardy, not showing the same degree of population declines as other bee species, she said.
So we are also wondering whether this resistance to flooding can be part of why they're doing so well, said Rondeau, now a postdoctoral fellow at the University of Ottawa.
The study would have to be replicated on other species of bumblebees to determine how common the trait is.
But it's encouraging to know that at least (flooding) is not another big threat that we have to consider, she said.