Scientists discover another cause of bee deaths

Scientists discover another cause of bee deaths, and it's really bad news » Banoosh

So what is with all the dying bees? Scientists have been trying to discover this for years. Meanwhile, bees keep dropping like… well, you know.

Is it mites? Pesticides? Cell phone towers? What is really at the root? Turns out the real issue really scary, because it is more complex and pervasive than thought.

Quartz reports:

Scientists had struggled to find the trigger for so-called Colony Collapse Disorder (CCD) that has wiped out an estimated 10 million beehives, worth $2 billion, over the past six years. Suspects have included pesticides, disease-bearing parasites and poor nutrition. But in a first-of-its-kind study published today in the journal PLOS ONE, scientists at the University of Maryland and the US Department of Agriculture have identified a witch’s brew of pesticides and fungicides contaminating pollen that bees collect to feed their hives. The findings break new ground on why large numbers of bees are dying though they do not identify the specific cause of CCD, where an entire beehive dies at once.


The researchers behind that study in PLOS ONE — Jeffery S. Pettis, Elinor M. Lichtenberg, Michael Andree, Jennie Stitzinger, Robyn Rose, Dennis vanEngelsdorp — collected pollen from hives on the east coast, including cranberry and watermelon crops, and fed it to healthy bees. Those bees had a serious decline in their ability to resist a parasite that causes Colony Collapse Disorder. The pollen they were fed had an average of nine different pesticides and fungicides, though one sample of pollen contained a deadly brew of 21 different chemicals. Further, the researchers discovered that bees that ate pollen with fungicides were three times more likely to be infected by the parasite.

The discovery means that fungicides, thought harmless to bees, is actually a significant part of Colony Collapse Disorder. And that likely means farmers need a whole new set of regulations about how to use fungicides. While neonicotinoids have been linked to mass bee deaths — the same type of chemical at the heart of the massive bumble bee die off in Oregon — this study opens up an entirely new finding that it is more than one group of pesticides, but a combination of many chemicals, which makes the problem far more complex.

And it is not just the types of chemicals used that need to be considered, but also spraying practices. The bees sampled by the authors foraged not from crops, but almost exclusively from weeds and wildflowers, which means bees are more widely exposed to pesticides than thought.

The authors write, “[M]ore attention must be paid to how honey bees are exposed to pesticides outside of the field in which they are placed. We detected 35 different pesticides in the sampled pollen, and found high fungicide loads. The insecticides esfenvalerate and phosmet were at a concentration higher than their median lethal dose in at least one pollen sample. While fungicides are typically seen as fairly safe for honey bees, we found an increased probability of Nosema infection in bees that consumed pollen with a higher fungicide load. Our results highlight a need for research on sub-lethal effects of fungicides and other chemicals that bees placed in an agricultural setting are exposed to.”

While the overarching issue is simple — chemicals used on crops kill bees — the details of the problem are increasingly more complex, including what can be sprayed, where, how, and when to minimize the negative effects on bees and other pollinators while still assisting in crop production. Right now, scientists are still working on discovering the degree to which bees are affected and by what. It will still likely be a long time before solutions are uncovered and put into place. When economics come into play, an outright halt in spraying anything at all anywhere is simply impossible.