A study conducted in American laboratories at the University of Maryland shows that honey bee lifespan has halved since the 1970s. The laboratory worker bee would live an average of 17.7 days today, compared to 34.2 days in 1969.
As always, these laboratory results can be applied to bees living in a colony. How then can they be explained? Are environmental factors alone responsible for this? Not necessarily…
Mortality, disease and pesticides
These are breeding bees and not wild bees, the decline of which is already known. These brood bees are not only living shorter lives, but mortality rates have in some cases doubled between the 1970s and 2000s. The threat is serious as these honeybees, raised by beekeepers in artificial hives, are the main pollinating insects for many food crops.
This mass extinction due to reduced life expectancy is accompanied by reduced honey production and sometimes the loss of entire bee colonies. The first explanation put forward by the researchers is the spread of a disease in honey bees: the deformed wing virus, carried by an increasingly common parasite called the Varroa mite. which looks like a spider and sucks fat from the bees, thus weakening them.
Another possible explanation is the weakening of honey bees by new generations of pesticides, which did not exist in the 1970s. The contamination of the bees would occur through the transfer of pollen, which itself is contaminated, to the larvae of the queens. A worrying situation as bees exposed to the highly toxic neonicotinoids can become more susceptible to disease. Such a vicious cycle…
Have the bees’ genes changed?
Surprisingly, another explanation is gaining traction: This is said to come from the bees’ own genetics. The bees’ genes may have changed, as their lifespan is directly related to these genes. When exposed to today’s stressors such as disease and pesticides, these genes may have undergone some kind of evolution. So the bees made a conscious decision to “live fast, die young” following the example of other species such as the cod (which due to overfishing matures faster but remains smaller).
However, the researchers seem to rule out that the conditions in the laboratory itself can explain the decline in life expectancy. If conditions in the study have changed over the past 50 years, advances in breeding standards should have at least stabilized or even extended bees’ lifespans.
The suspicion of a genetic component must therefore be taken very seriously, which prompted the scientists to already considered the possibility of isolating certain genetic factors to be able to breed longer-lived bees. To do this, the genetic factors, the presence of diseases and Viruses and the use of pesticides in agriculture are weighed against each other on site.