In a major study, the researchers from the University of Marylandfound that the lifespan of honey bees is 50% shorter than it was in the 1970s.
This is the first study to show an overall decline in honey bee lifespan potentially independent of environmental stressors, hinting that genetics may be influencing the broader trends seen in the beekeeping industry. The researchers concluded the findings after studying the individual honey bees kept in a controlled, laboratory environment.
Bee colonies naturally age and die off, making colony turnover an accepted factor in the bee keeping business. However, U.S. Bee keepers had reported high loss rates over the past decade.
“We’re isolating bees from the colony life just before they emerge as adults, so whatever is reducing their lifespan is happening before that point,” said Anthony Nearman, a Ph.D. student in the Department of Entomology and lead author of the study. “This introduces the idea of a genetic component. If this hypothesis is right, it also points to a possible solution. If we can isolate some genetic factors, then maybe we can breed for longer-lived honey bees.”
Nearman first noticed the decline in lifespan while conducting a study with entomology associate professor Dennis van Engelsdorp on standardized protocols for rearing adult bees in the laboratory. Replicating earlier studies, the researchers collected bee pupae from honey bee hives when the pupae were within 24 hours of emerging from the wax cells they are reared in. The collected bees finished growing in an incubator and were then kept as adults in special cages.
Nearman was evaluating the effect of supplementing the caged bees’ sugar water diet with plain water to better mimic natural conditions when he noticed that, regardless of diet, the median lifespan of his caged bees was half that of caged bees in similar experiments in the 1970s. (17.7 days today versus 34.3 days in the 1970s.) This prompted a deeper review of published laboratory studies over the past 50 years.
Although a laboratory environment is very different from a colony, historical records of lab-kept bees suggest a similar lifespan to colony bees, and scientists generally assume that isolated factors that reduce lifespan in one environment will also reduce it in another. Previous studies had also shown that in the real world, shorter honey bee lifespans corresponded to less foraging time and lower honey production. This is the first study to connect those factors to colony turnover rates.