The rusty patched bumblebee was once found in thirty-one states and various parts of Canada before the mid 1900s, but now it's only found in thirteen states and Ontario. Researchers claimed it had an eighty-eight percent decline.
This means the species is vulnerable to extinction, the rule says, even without further habitat loss or insecticide exposure. Canada designated the species as endangered in 2012.
The bees live in large colonies that can be made up of 1,000 individual workers. All types of the species have black heads, the rule states, “but only workers and males have a rusty reddish patch centrally located on the abdomen.”
Habitat degradation may be particularly harmful to these bees because of their feeding habits, as described in the rule:
“The rusty patched bumble bee is one of the first bumble bees to emerge early in the spring and the last to go into hibernation, so to meet its nutritional needs, the species requires a constant and diverse supply of blooming flowers.”
Last October, the Fish and Wildlife Service gave endangered status to seven species of yellow-faced bees native to Hawaii, the first time any U.S. bees received this kind of protection.
According to a recent “major” global assessment sponsored by the U.N. forty percent of pollinator species are facing extinction. They claim this is threatening the future of the global food supply. Is this correct? Who knows.
However, as Wired writes, these are not the kind of bees we should be fretting over:
The bees you should be concerned about are the 3,999 other bee species living in North America, most of which are solitary, stingless, ground-nesting bees you’ve never heard of. Incredible losses in native bee diversity are already happening. 50 percent of Midwestern native bee species disappeared from their historic ranges in the last 100 years. Four of our bumblebee species declined 96 percent in the last 20 years, and three species are believed to already be extinct. A little part of me despairs when I read in a scientific paper: “This species probably should be listed under the Endangered Species Act if it still exists.”
The Bee News You Are Missing
Last week, the big bee news was a suggestion nicotine-derived pesticides can cause honey bee addiction. But you might have missed another important paper that looked at the same group of pesticides on both honey bees and native bees. This massive study paired multiple plantings of seeds coated with a neonicotinoid pesticide with seed treated only with a fungicide. This was one of the largest tests to date of how pesticides and bees interact in a real-world situation, outside a laboratory.
Seeds of all sorts are commonly treated with neonicotinoid pesticides as a preventative treatment. Neonicotinoid pesticides circulate in plant tissues, so any insect munching on the seedlings will be stopped. Unfortunately, the pesticide remains in the plants as they flower, and bees of all types may pick up the chemicals in pollen and nectar. The experimenters used a crop that is attractive to bees — oilseed rape, used to make canola oil — as their test plant.
Honey bees weren’t affected by the seed treatments. But wild bees were affected, and in a big way. Wild bee density in the treated fields was half that of the untreated fields. Bumble bee colonies grew more slowly, and produced fewer queens. Solitary bee nests disappeared from the treated fields completely.
Solitary bees are the most common type of wild bee; they don’t live in a hive. A female bee usually makes a hole in the ground or in a hollow stem, where she lays her eggs and then provisions each grub with a ball of pollen to snack on after they hatch. They are the ultimate single mothers. In this study, no mason bees (Osmia bicornis) began brood cells in the seed treated fields. None.
We don’t know why the mason bees abandoned what should have been an all-you-can-eat yellow flower buffet, but it definitely re-emphasizes the point that all bees are not the same. We can’t keep using commercial honey bees as the measure of what is toxic; while honey bees certainly have bad years, they have a whole crew of beekeepers and researchers providing support to them. But native bees are on their own; they fly solo.
This research used one of the lowest active doses of pesticide that a bee might encounter in a real agricultural field. The seed treatment is applied well before the crop is sown; but the tiny amount of pesticide that remains in the plant is enough to cause problems for female solitary bees.
After several years of intensive research on honey bees and colony collapse disorder, we know a lot about what kills honey bees. We don’t have that broad knowledge base for our native bees. We don’t even know what is a lethal dose of pesticide for many solitary bees.
The 80,000 bees in a honey bee colony create a strong buffering effect. Honey bee colonies can often take a pesticide exposure in stride. Solitary bees can’t.
Photo: Dan Mullen