New Study: Honey Bees Are Protected From the Varroa Mite by Selective Breeding

According to a new study, a new breed of honey bees has made a significant contribution to the global fight against the parasitic Varroa mite.

Since its first growth 50 years ago, the aggressive mite, which has expanded to every continent except Australia and Antarctica, has been the primary danger to honey bees.

The danger of mites to honeybees

(Photo : DAMIEN MEYER/AFP via Getty Images)

"Pol-line" bees, selected for mite resistance in a rigorous 20-year conventional breeding, were trialed alongside a regular type in a large-scale pollination operation in the study by the universities of Louisiana and Exeter, as well as the USDA's Agricultural Research Service.

The mite-resistant bees had a greater chance of surviving the winter with 60% survival compared to 26% in standard honey bees.

Standard honey bees, on the other hand, suffered significant losses unless intensive pharmacological miticide treatments were utilized.

According to Dr. Thomas O'Shea-Wheller of the Environment and Sustainability Institute at Exeter's Penryn Campus in Cornwall, the Varroa mite is the biggest threat to regulated honey bee colonies across the world, as per ScienceDaily.

Commercial beekeepers transport tens of thousands of colonies annually to provide pollination for large-scale agriculture in three US states, namely, Mississippi, California, and North Dakota, according to the research.

Because Varroa mites originated in Asia, European honey bees, the most prevalent pollinator species, have not developed alongside them and hence lack effective defense.

Managed bees, like people, are mainly "decoupled" from natural selection, so they cannot evolve resistance as they could in the wild, according to Dr. O'Shea-Wheller.

Managed bees, on the other hand, occasionally respond to mites, which proliferate in bee larval cells, by expelling contaminated larvae, killing both the larvae and the mites, in a behavior known as Varroa-sensitive hygiene (VSH).

Colonies may be generated to automatically protect themselves from infection while retaining enormous colony numbers and abundant honey output by selecting breeding for this characteristic.

"The wonderful thing about the current trait is that we've understood that honey bees of all types convey it at some level, so we know that it can be promoted and selected for in everyone's bees with the right tools," said USDA Agricultural Research Service research molecular biologist Dr. Michael Simone-Finstrom.

Because honey bees are in great demand in the early spring for pollinating high-value crops like almonds, colony survival during the winter is especially crucial for beekeepers.

The researchers also looked at the number of viruses linked to Varroa mites in bee colonies.

Surprisingly, when these viruses were studied apart from mite infection levels, they were not good predictors of colony losses.

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What is selective breeding?

Selective breeding is pairing together parents with similar features in order to create kids with more desired traits. The mix of gene variations handed down through the ages determines some of an organism's features.

Children of tall parents, for example, may inherit a mix of "tall" gene variations and become tall themselves.

Selective breeding frequently produces a colony of animals or plants with genetics that are quite similar. Because the group has similar DNA, it will have similar strengths and limitations.

But since they are susceptible to the same illnesses, viral infections are more likely to spread among genetically identical populations.

Inbreeding is a type of selective breeding that includes breeding individuals who are closely related.

Since they are more likely to inherit two copies of recessive gene variations, one from each parent, inbred populations are more prone to suffer from genetic conditions caused by recessive gene variants.

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