Thursday, September 23, 2021

Honey bees, eusocial by their genes, still perish


Upon reading the paper over a breakfast of blueberry yogurt, I came across a quote: “If you’ve ever eaten a strawberry or a blueberry, you ought to thank a bee,” the Baltimore Sun quoted Toni Burnham, president of the Maryland State Beekeepers Association, as saying.

A new study explains genetic changes accompanying the evolution of social complexity in bees. (L Brian Stauffer)

The story showed how bees are dying off, a phenomenon that has been in the news for some time, drawing the attention of lawmakers across the country, with at least one in Maryland promising a renewed scrutiny of the widely used group of pesticides known as neonicotinoids.

In Maryland, beekeepers lost nearly 61 percent of their colonies on average in the past year, one of the highest declines in the nation, according to an annual survey released on May 13 by the US Department of Agriculture:

Total annual losses [for the US] were 42.1 percent for April 2014 through April 2015. The new figure is up from 34.2 percent for 2013-2014.

And for the first time since the government started keeping track of bees dying off, losses during the summer months exceeded losses during the winter months. The summer losses have scientists concerned, even though the winter losses have gone down two years in a row.

  • 2012: 25.3% loss during the summer, 30.5% during the following winter
  • 2013: 19.8% loss during the summer, 23.7% during the following winter
  • 2014: 27.4% loss during the summer, 23.1% during the following winter

“The winter loss numbers are more hopeful especially combined with the fact that we have not seen much sign of Colony Collapse Disorder (CCD) for several years, but such high colony losses in the summer and year-round remain very troubling,” said Jeff Pettis, a senior entomologist at USDA’s Agricultural Research Service Bee Research Laboratory in Beltsville, Md. He added that the growing need for pollination services in agriculture will require scientists to learn more about the stresses on bees that lead to both summer and winter colony losses.

The life of honey bees

Such is the “eusocial” life of bees: Some of their workers forego reproduction to care for their siblings. This can lead to an elaborate and sophisticated “superorganism” of thousands of individuals. Now thousands of bees, whether they’re superorganisms or individuals, are dying.

A class of second graders from Hillcrest Elementary School in Catonsville, Md., recently heard about bees from a naturalist at the Benjamin Banneker Historical Park and Museum in Oella, the Baltimore Sun reported in March.

To a second-grade mind, taking part in the “Bee-ing an Engineer with Wisconsin Fast Plants” program, the eusocial tendency bees have has a kid-friendly explanation: Bees are “really good at pollinating” and “really friendly” because “they’re not going to sting you unless you try to swat them,” one student was quoted as saying.

To a scientist, the “friendliness” we know bees show is attributable to their genetic make-up. Scientists at the University of Illinois, Urbana, published a paper in the journal Science last week showing that as social complexity increases, so does the speed of changes to parts of the genome involved in regulating gene activity, located in the promoters of the genes.

“It appears from these results that gene networks get more complex as social life gets more complex, with network complexity driving social complexity,” said Gene Robinson, a lead on the study, a professor of entomology, and director of the Carl R Woese Institute for Genomic Biology at the university.

Researchers also said the parts of the genome that code for the sequence of amino acids in proteins don’t evolve as much when social complexity increases in bees. Rather, the regulation of gene expression, brought about mainly through DNA methylation, steps up. The proteins themselves don’t really change, in other words; their expression is more regulated, though.

Paul Katula
Paul Katula is the executive editor of the Voxitatis Research Foundation, which publishes this blog. For more information, see the About page.

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