Honey Bee Lifespans are 50% less than 50 Years ago.
In a recent publishing of their work, entomologists at the University of Maryland have discovered honey bees living in a lab are also dying at a higher rate (50%) than they had 50 years ago.
What is Causing Honey Bee Declines?
Researchers in the study isolated the bees from the colony just before they emerged as adults. And according to the University of Maryland who wrote one of the reports, they stated:
"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."
Up until this study, the main causes of the decline have been hypothesized as being from Colony Collapse Disorder, which has been identified as several factors, such as habitat reduction, nutritional availability, diseases, parasites, pesticide exposure, and the varroa mite. And it is very likely those stressors from CCD are still a major factor, if not still the cause.
More research needs to be done to determine if these stressors are passed down through the brood in their development stages. And as this study identified, these bees were brood in an active hive, but no details on those hive conditions were revealed in the report.
How the Study was Performed (Cited directly from the report)
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 were 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.
"When I plotted the lifespans over time, I realized, wow, there's actually this huge time effect going on," Nearman said. "Standardized protocols for rearing honey bees in the lab weren't really formalized until the 2000s, so you would think that lifespans would be longer or unchanged because we're getting better at this, right? Instead, we saw a doubling of mortality rate."
They did go on to identify that the lab-kept bees could be experiencing a higher mortality rate due to their pesticide exposure during their development within the hive before being pulled out and incubated within the lab.
I would assume that the hives these test bees were pulled out of are hives within a standard agricultural area or an area with human development. There certainly are trace elements from around the area of the hive (bees can forage up to 5 miles from their hive), and there is likely a very high chance the wax frame and capping that the developing brood sat in during its 21-day incubation period, most certainly has a pesticide exposure.
What is Next?
The story goes on to say:
The next steps for the researchers will be to compare trends in honey bee lifespans across the U.S. and in other countries. If they find differences in longevity, they can isolate and compare potential contributing factors such as genetics, pesticide use and presence of viruses in the local bee stocks.
It would seem obvious that another next step would be to control the study a bit more and raise bees from egg to honey bees in a controlled setting with low to no contaminated wax and see if the lifespan changes.
What can Beekeepers do?
Beekeepers can start by helping educate their neighbors and friends on CCD and discuss how using fewer pesticides or none and help make more habitat for the bees. Beekeepers can also buy package bees that offer a better genetic profile to overcome the stressors introduced by CCD potentially. As a company that sells honey bees in the Spring, we have focused on a better bee package that has been raised off of breeder queens that have survived into their 5th productive year and have done so without any treatments.
The full study can be found here -> https://www.nature.com/articles/s41598-022-21401-2