Scientists say honey bee populations continue a serious, mysterious decline around the world, and that’s a problem for the agriculture industry, which relies on bees for pollination. Now a study suggests that glyphosate, the world’s most widely used weed killer, may be harming the insects.

According to the study, published Sept. 24 in the Proceedings of the National Academy of Sciences, glyphosate disrupts microbes in the bees’ digestive system, making them vulnerable to deadly infections. Previously, researchers did not consider the chemical a threat to insects and animals because it targets a cellular pathway that only plants and some bacteria possess.

In the PNAS study, researchers gave hundreds of bees a syrup containing glyphosate doses that mimicked the environmental levels bees would encounter if foraging among flowering weeds. They then compared those bees to another group of bees that received syrup without glyphosate.

After three days, the scientists found significantly lower levels of S. alvi, a bacterium that appears to protect bees from dangerous infections, in the bees that received glyphosate. Only 12 percent of the bees that ingested the chemical survived an infection caused by a bacterium commonly found in trace amounts in beehives. By comparison, 47 percent of the glyphosate-free bees survived the infection.

What about glyphosate and human microbiomes? According to Science magazine, humans likely encounter only very low exposure to glyphosate, and their guts harbor different microbes than bees’.

Brain drain?

American children spend, on average, 3.6 hours per day looking at phone, television, and computer screens for recreational purposes—and that is linked to poor cognitive performance, according to a new study.

Researchers studied 4,524 U.S. children ages 8-11 years and assessed the amount of time the children spent looking at screens, engaging in physical activity, and sleeping. They used expert guidelines that say children should get between nine and 11 hours of sleep, one hour of exercise, and no more than two hours of recreational screen time per day. Only 5 percent of the children in the study met all three guidelines (and 29 percent met none).

The study results, published Sept. 26 in The Lancet Child & Adolescent Health, showed that kids who spent less than two hours on screens scored about 4 percent higher on tests of memory, language, and thinking skills than children who met none of the recommendations. Children who achieved the guidelines for both screen time and sleep performed significantly better on the cognitive tests. —J.B.

Powerhouse repair

Genetic defects in the mitochondria, the power generators within cells, are a common cause of diseases that can affect the nervous system, muscles, heart, liver, or other organs. But so far no treatment exists for those born with mitochondrial diseases. A popular gene editing tool, CRISPR, cannot modify DNA in the mitochondria.

Now in two independent studies, published Sept. 24 in Nature Medicine, researchers used two older gene-editing tools to cut out defective mitochondrial DNA and counteract the effects of mutations in lab mice. A safety trial with humans could begin as early as next year.

Researchers have previously attempted to prevent mitochondrial disease with the “three-parent baby” approach, but that technique is controversial because it produces babies with the genetic material of three people. —J.B.