In the first comprehensive study concerning the health of migratory bee populations, NC State researchers uncovered newfound importance in food sources.
When considering an insect’s lifespan, it goes without saying that a reliable food source is vital. Beyond a food source, however, are factors that seem to hold an almost equal responsibility in longevity. For one, environmental stressors can offset a delicate equilibrium, especially for a more vulnerable insect like a honeybee.
Most beekeepers in the U.S. are hobbyists, maintaining personal hives in backyards and gardens. But the largest numbers of hives — meaning some of the most substantial groups of bee populations — are used for commercial scale agricultural purposes. Hives are transported from crop to crop in order to pollinate. When one crop’s season concludes, the hives are transported via truck to a different site.
The study examined bee colonies in varying degrees of mobility in different environments. By partnering with a commercial beekeeper, researchers studied bees used for pollination services and a stationary hive in Raleigh. Bees were marked and monitored to indicate variances in mortality patterns.
One may expect to find that constant movement leads to a drop in life expectancy. This held true within the experiment: as compared to stationary bees, migratory populations lived for about a day less.
“One day may seem trivial, but when a normal forager bee lifespan is only around 20 days, one day is significant,” said Michael Simone-Finstrom, an NC State postdoctoral researcher during this research.
What the researchers didn’t expect was the significant influence the abundance of foraging potential in the bees’ environment had on the hives’ well-being.
“We found that migratory beekeeping influences the lifespan of bees, but how this impacts health and honey bee aging is more complicated and often more influenced by the environment these colonies are in,” Simone-Finstrom said.
The main component supporting bee health seemed to be the profusion of food, unrelated to location. Bees used for commercial pollination seemed better off in this respect, which may seem unusual for a couple of reasons. In an agricultural setting, the nutrition available to bees would be unnaturally analogous; little plant diversity is found in crops. Additionally, an agricultural food supply may contain pesticides. Despite this, the sheer reliability of foraging opportunity seemed to outweigh the factors marked by the researchers as negative. For stationary bees, food scarcity during dry summers, for example, was a clear source of distress for the insects.
“It’s better to have little diversity than nothing at all in different times of the year,” said David Tarpy, a professor of entomology and plant pathology, and co-author of the study. “It comes down to making sure the bees have adequate food to eat. In hindsight it’s not all that surprising, but it was necessary to tease those things apart.”
Identifying the main stressor within a honeybee colony means further defining what keeps hives healthy.
“We need to be focusing on nutrition, habitat restoration, adequate pollinator plantings and habitats, [and] having buffer zones to have plants blooming … when crops are in transition,” Tarpy said.
