Honey bee life spans are 50% shorter today than they were 50 years ago

The lifespan for individual honey bees kept in a controlled environment is 50% shorter than it was in the 1970s according to a new study. Scientists modeled the effect of shorter lifespans on colony loss and honey production in the U.S.

Bee colonies naturally age and die off so colony turnover is an accepted factor in the business. Over the past 10 years, U.S. beekeepers have had to replace more colonies to keep their operations viable. Environmental stressors, diseases, parasites, pesticide exposure and nutrition are some of the reasons why researchers are trying to understand why.

The first study to show an overall decline in honey bee lifespan potentially independent of environmental stressors suggests that genetics may be affecting the broader trends seen in the beekeeping industry. The study was published in the journal.

Anthony Nearman is a student in the Department of Entomology and the lead author of the study. The idea of a genetic component is introduced. The hypothesis points to a possible solution if it is correct. We might be able to breed for long-lived honey bees if we can isolated some genetic factors.

Nearman noticed the decline in lifespan while conducting a study with an associate professor. The researchers collected bee pupae from honey bee hives when they emerged from their wax cells. The bees were kept in special cages after they were grown in an incubator.

The median lifespan of caged bees in similar experiments in the 1970s was half that of Nearman's bees even though they had the same diet. In the 70s, there were 34.3 days in this day and age. There was a deeper review of published laboratory studies.

Nearman realized that there was a huge time effect when he plotted the lifespans over time. "Standardized protocols for rearing honey bees in the lab weren't really codified until the 2000s, so you would think that lifespans would be longer or unchanged, because we're getting better at this." The mortality rate doubled.

Historical records of lab-kept bees suggest a similar lifespan to colony bees, and scientists assume that isolated factors that reduce lifespan in one environment will also reduce it in another. In the real world, shorter honey bee lifespans correspond to less time spent in the hive and less honey production. The factors are connected to colony turnover rates.

When the team modeled the effect of a 50% reduction in lifespan on a beekeeping operation, it resulted in a loss rate of over 30%. The loss rates for the past 14 years are similar to this one.

When lab-kept bees are brooding in the hive and worker bees are feeding them, they may be exposed to low-level viral or pesticide exposure. The bees have not shown any symptoms of being exposed to those chemicals and a genetic component to longevity has been shown in other insects.

The next step will be to compare honey bee lifespans in the US and other countries. If they find differences in longevity, they can compare factors such as genetics and pesticide use.

Water provisioning increases the life span and lifespan of worker bees.

Journal information: Scientific Reports

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