Unknown influences halved the lifespan of honey bees, study says

(CN) — Anthony Nearman first noticed that lab-kept honey bees died sooner than expected during an adult bee rearing study. The Ph.D. student in the University of Maryland’s department of entomology and entomology associate professor Dennis van Engelsdorp took bee pupae from honey bee hives, completed their growth using an incubator, and then watched the bees’ progress as adults.

Then, Nearman said that regardless of what diet he and van Engelsdorp put the honey bees on, their lifespans remained relatively short. Specifically, Nearman reported that while caged bees from studies in the 1970s lived an average of 34.3 days, his caged bees lived for an average of 17.7 days.

His study published Monday in Scientific Reports says that it did not take long for Nearman to realize that it was not because of a laboratory-related environmental stressor.

“The protocols and conditions for maintaining bees in a laboratory setting haven’t changed much over the past 50 years, so whatever is causing a reduction in lifespan is happening before we remove baby bees from the colony,” wrote Nearman via email.

According to Nearman, one possibility is that his lab-kept bees suffered pesticide exposure or low-level viral contamination during the larval stage.

“Adult bees feed the young as they develop so viruses can transmit in this way,” wrote Nearman. “Also, parasites, such as Varroa, feed on developing bees, providing another transmission route. Often honey bee viruses can have the effect of a shorter overall lifespan. Pesticides are something commonly found in bee’s wax, which have been shown to make their way into bees developing in that wax.”

However, the study notes that the lab-kept bees did not show overt symptoms of such exposures, so Nearman considered potential genetic influences.

“Given that queens can mate with over a dozen drones, honey bee genetics are extremely complex,” wrote Nearman. “Identifying a gene or set of genes that contribute to length of life has proven elusive, but I think that’s true for all organisms. I suspect selective breeding programs could reveal if breeding for longer lived bees is even possible. As for the effect, we’ll have to wait and see.”

While Nearman hopes that future research will isolate the cause of this issue, it could create problems with current productivity.

Colony turnover is a natural facet of beekeeping, as bee colonies naturally age and die off with replacements taking over. However, the study says that over the past decade, U.S. beekeepers reported high loss rates in their bee colonies. This means that beekeepers must replace more colonies more regularly to keep operations viable.

Nearman noted that while a direct link is associative at this point, there are strong correlations between shorter lifespans and reductions in actual honey production figures from the same years.

“It is well documented in individual colonies that average bee lifespan is positively correlated to the amount of honey a colony produces,” wrote Nearman. “Honey bees are more than our most critical pollinator. They are also the livelihood of so many people for which colony loss is a very real issue. Honey bee health isn’t a science experiment. It’s an investment in food security and each other.”

Follow @kndrleon

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