A study conducted in American laboratories at the University of Maryland shows that honey bee lifespans have 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 only environmental factors responsible for this? Not necessarily…
Mortality, disease and pesticides
These are breeding bees and not wild bees, whose decline is already known. Not only are these breeding bees living shorter lives, but mortality rates have doubled in some cases between the 1970s and 2000s. The threat is serious as these honey bees, raised by beekeepers in artificial hives, are the main pollinating insects for many food crops.
The increase in colony losses and the drop in honey production would be due to a reduction in the lifespan of the bees. The causes of this drop in longevity remain unclear. https://t.co/HFXPIevg6p
— Trust My Science (@TrustMyScience) November 16, 2022
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 would be the spread of a disease in honey bees: the deformed wing virus, carried by an increasingly common parasite called the Varroa mite, which resembles a spider and sucks fat from the bees and thus weakens 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 is itself contaminated, to the larvae of the queens. A worrying situation as bees exposed to the highly toxic neonicotinoids can become more susceptible to disease. So a vicious circle…
Have the bees’ genes changed?
Surprisingly, another explanation gains traction: It is said to come from the bees’ own genetics. The bees’ genes may have changed, since their lifespan is directly related to these genes. When exposed to today’s stressors like disease and pesticides, these genes may have undergone some sort 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).
Honeybees kept under laboratory conditions in the US only live half as long as they did in the 1970s, suggesting that genetics could be contributing to colony losses https://t.co/Qb0z9E5mXN
— New Scientist (@newscientist) November 14, 2022
However, the researchers seem to rule out that the conditions in the laboratory themselves can explain the decline in life expectancy. If conditions in the study have changed over the past 50 years, advances in breeding standards should at least have stabilized or even increased bee lifespans.
The suspicion of a genetic component must therefore be taken very seriously, prompting the scientists to already considering the possibility of isolating certain genetic factors in order 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.