Tuesday, February 07, 2017

Bumblebees Are Dying Out Because They’re Too Fat to Mate

Before the 1990s, the rusty-patched bumblebee could be found in 28 states throughout the Midwest and the New England region. Then, it vanished mysteriously. Within a few decades, 90 percent of rusty-patched bumblebees were gone in an ecological poof . Even more troubling, several other closely related bumblebee species also died-off. Now it’s almost unheard of to see the rusty-patched bumblebee. Last month it became the first bee in the continental U.S. listed under the Endangered Species Act. Pesticides, climate change, habitat destruction, stress from competition, or a combination of these might all be to blame. Most recently, however, entomologist have been investigating a parasitic fungus found on the bumblebee called Nosema bombi, and the more they learn the more they’ve become concerned. Before the 1990s, the rusty-patched bumblebee could be found in 28 states throughout the Midwest and the New England region. Then, it vanished mysteriously. Within a few decades, 90 percent of rusty-patched bumblebees were gone in an ecological poof . Even more troubling, several other closely related bumblebee species also died-off. Now it’s almost unheard of to see the rusty-patched bumblebee. A queen bumblebee can birth males—called drones—on her own. But only after a male fertilizes her eggs can she produce female bees. This is crucial, because drones are essentially layabouts. It’s the women, the worker bees, that do all the foraging to sustain a colony. So inside a mating cage, Strange places a queen bumblebee, and on the other side a drone infected with Nosema bombi. Already this fungus has spreads down the bee’s throat, has rooted itself in the gut where the spores “proliferate like crazy,” according to Strange. There the fungus swells in the soft tissue between the bumblebee’s organs until the drone grows so plump it can’t bend its abdomen to mate with the queen. Without fertilization, the queen can only birth more males. Without females, future colonies starve...more

No comments: