According to a new study conducted by entomologists, the individual honey bee’s longevity housed in a controlled laboratory setting is 50% shorter than it was in the 1970s.
When scientists predicted the effect of today’s shorter lifespans, the results matched the increased colony loss and decreased honey output experienced by US beekeepers in recent decades.
As bee colonies mature and die off naturally, colony turnover is an established issue in the beekeeping industry. However, throughout the last decade, beekeepers in the United States have reported significant loss rates, necessitating the replacement of more colonies in order to maintain operations profitably. To figure out why, scientists have looked at environmental factors, infections, parasites, pesticide exposure, and nutrition.
This paper suggests that genetics may be driving the larger trends of increasing colony turnover rates reported in the beekeeping industry as the first study to indicate an overall loss in honey bee longevity potentially independent of environmental stresses.
The study, Water provisioning increases caged worker bee lifespan and caged worker bees are living half as long as observed 50 years ago was published in the journal Scientific Reports.
Researchers’ Explanation of this study
“We’re separating bees from colony life right before they emerge as adults. So, whatever is limiting their longevity is happening before that moment,” said Anthony Nearman. He is the study’s primary author and a PhD student in the Department of Entomology. “The concept of a genetic component is introduced here. If this hypothesis is correct, it may also hint at a solution. We may be able to breed for longer-lived honey bees if we can extract some genetic characteristics.”
Nearman initially noted the drop in longevity while working on standardised techniques for growing adult bees in the laboratory with entomology associate professor Dennis van Engelsdorp. In order to replicate the previous study, the researchers collected bee pupae from honey bee hives when the pupae were within 24 hours of emerging from the wax cells in which they are nurtured. The captured bees were grown in an incubator before being housed as adults in special cages.
Nearman was examining the effect of replacing the caged bees’ sugar water diet with plain water to better replicate natural settings when he discovered that, regardless of diet, the median longevity of his caged bees was half that of caged bees in comparable tests in the 1970s. (17.7 days presently, compared to 34.3 days in the 1970s). This prompted a more thorough examination of published laboratory experiments over the previous 50 years.
“I noticed, wow, there’s actually this tremendous temporal impact going on when I plotted the lifespans across time,” Nearman said. “Standardized techniques for lab-raised honey bee rearing were not actually codified until the 2000s, so you’d assume that lifespans would be longer or unchanged because we’re getting better at it, right? Instead, the death rate more than doubled.”
The Results of the Study
Despite the fact that a laboratory environment is extremely different from a colony. Historical records of lab-kept bees imply that they have similar longevity to colony bees. And, scientists typically believe that isolated variables that lower lifespan in one setting would similarly reduce it in another. Previous research has also demonstrated that shorter honey bee lifespans are linked to less foraging time. And reduced honey output in the real world. This is the first study to establish a link between those variables and colony turnover rates.
When the researchers simulated the impact of a 50% decrease in longevity on a beekeeping business. Whereas lost colonies are replaced annually, the resulting loss rates were roughly 33%. This is remarkably comparable to the average overwinter and yearly loss rates recorded by beekeepers over the last 14 years of 30% and 40%, respectively.
Nearman and vanEngelsdorp speculated that their lab-kept bees may have been exposed to low-level virus contamination or pesticides. During their larval period when they are brooding in the hive and being fed by worker bees. However, no overt signs of such exposures have been observed in bees. And a genetic component to lifespan has been observed in other insects such as fruit flies.
The researchers’ next step will be to examine trends in honey bee lifespans throughout the United States and other nations. If they discover disparities in longevity, scientists can identify and evaluate probable contributing factors. Such as genetics, pesticide usage, and virus prevalence in local bee populations.