Antibiotics linked to bee population dive

The mystery around increasing bee deaths and colony collapse disorder may be linked to antibiotics.

Researchers from the University of Texas found that honeybees treated with tetracycline, a common antibiotic, were half as likely to survive the following week compared with a group of untreated bees. The antibiotics killed beneficial gut bacteria, allowing elevated levels of Serratia, a genus of bacteria, to gain a foothold.

Professor Nancy Moran, from the University of Texas in Austin, who led the study, said: “We aren't suggesting people stop using antibiotics. Antibiotics save lives. We definitely need them. We just need to be careful how we use them. Our study suggests that perturbing the gut microbiome of honeybees is a factor, perhaps one of many, that could make them more susceptible to decline and to the colony collapsing. Antibiotics may have been an underappreciated factor in colony collapse."

Colony collapse disorder created confusion amongst beekeepers a decade ago when millions of bees began disappearing from their hives for no apparent reason. Previous explanations included pesticide exposure, habitat loss and bacterial infections. Researchers now believe antibiotics are also linked to this, but are unsure how. In large scale agriculture, beekeepers apply antibiotics to their hives to prevent bacterial infections such as foulbrood that can wipe out bee larvae.

Researchers removed hundreds of bees and fed them either syrup with antibiotics or just syrup. After differentiating the bees using small dots they were released after five days. About two thirds of the untreated bees were still present three days after being reintroduced to the hive, compared to a third of antibiotic treated bees.

A follow-on study was also carried out with researchers exposing antibiotic-treated bees to Serratia, and observing higher mortality rates compared to untreated bees. The study was published in PLOS Biology. https://www.youtube.com/watch?v=fhaVvW_YKps