Beekeepers have reported large losses of bee colonies worldwide in recent years. The issue is attracting public attention because bees and other insect pollinators are key contributors to maintaining ecosystems and biodiversity.
One of the biggest threats to them is not much bigger than the head of a pin. It is a parasite of the tick family that, left unchecked, could kill enough bees to doom an entire colony.
Therefore, science has harnessed efforts to fight the pest by creating new species of bees capable of resisting it.
The absence of bees threatens many plant species, as well as the organisms that are directly or indirectly associated with these plants. Many agricultural crops are also at risk. All this represents a problem, the solution of which is particularly important for the future of the planet.
The main reasons for the decline of bees are pesticides, changes in land use (urbanization of agricultural areas) and the effects of climate change. They endanger bees and their role as pollinators of the world’s food crops.
Of all the threats, however, the varroa jacobsoni mite is the main concern of beekeepers, says Elina Niño, a honey bee entomologist at the University of California, Berkeley. The parasites in question attach themselves to the backs of insects, sucking their blood and laying in their larvae and eggs.
Mites originate from the Indonesian island of Java and are now spread all over the world. They are small, 1-1.5 mm in size and affect all bees – queen, drones and workers, leading to a disease called varroatosis.
“It’s a big problem worldwide and it can cause huge losses,” Niño says.
To combat the scourge, most beekeepers rely on poisonous preparations called miticides. The problem is that mites are increasingly developing resistance to them, which in turn leads to the use of increasingly stronger poisons.
A significantly more sustainable and ecological approach is to raise special bees that deal with the problem themselves. Through selection and modification, new species can be made that are fully predisposed to care for themselves and others in the hive, killing the mites during the natural grooming process. The same bees can also clean the brood cells, removing any infected larvae.
Most species of honey bees that are raised commercially do not have similar instincts because they produce less honey or have fewer workers in the colony.
So for the past 14 years, USDA researchers have been working to create improved species that are both productive enough and able to fend off the dangerous mites.
Scientists create hundreds of colonies and test how they will perform in different conditions, comparing them to regular bees. Both species are treated with two courses of preparations in one season, and at the end of it, it turns out that the improved bees have 30% higher productivity and 15% less mortality due to mites.
What’s more, the researchers also tested some colonies with just one dose of miticide each. Thus an even more dramatic difference is established. Commercial bee colonies collapse, with only 9% of the bees in them surviving at the end of the season, while colonies of improved bees show a 56% survival rate.
This shows that beekeepers who want to reduce chemical use – and are willing to accept greater losses – would benefit greatly from using mite-resistant bees.
The survey also contained another surprise.
The scientists examined the levels of four key viruses spread by mites, and in most cases their levels did not significantly affect the chances of survival of any of the insect species studied. This unexpected result suggests that the mites are more harmful than the viruses they spread, says University of Georgia honey bee expert Keith Delaplan.
“This is important to know because so much of our efforts so far have focused on viruses,” he says, adding that although there are no cures for them, a positive outcome in the fight against mites will also have an impact on the spread of viruses.
If mite-resistant bees become more popular, there is a good chance that herd immunity will also develop. This will reduce overall parasite levels and reduce their spread between hives.
According to Delaplan, the success of the improved bees could prove to be a milestone in the fight against varroatosis.
And from there to the salvation of bees.