Selective breeding sustainably safeguards honey bees from Varroa mite.
A new type of honey bees offers a significant advance in the international fight versus the parasitic Varroa mite, new research programs.
The invasive mite, which has actually infected all continents except Australia and Antarctica, has actually been the prime danger to honey bees given that its initial expansion 50 years back.
In the study– by the universities of Louisiana and Exeter, and the Agricultural Research Service of the US Department of Agriculture (USDA)– “Pol-line” bees, bred for resistance to the mite in an extensive 20-year breeding program, were trialed alongside a basic variety in a massive pollination operation.
The mite-resistant bees were more than two times as most likely to make it through the winter season (60% survival compared to 26% in standard honey bees). While the basic honey bees experienced high losses unless extensive chemical miticide treatments were utilized.
Beekeepers transport nests to support large-scale agriculture. Image taken in South Dakota. Credit: Thomas OShea-Wheller
” The Varroa mite is the greatest danger to handled honey bee nests internationally,” said Dr. Thomas OShea-Wheller, of the Environment and Sustainability Institute at Exeters Penryn Campus in Cornwall.
” So far, new approaches to manage the mites– and the diseases that they bring– have had restricted success, and the termites are becoming increasingly resistant to chemical treatments. Its a ticking time-bomb.
” By selectively breeding bees that recognize and remove termites from their nests, our study discovered a considerable reduction in mite numbers, and most importantly, a two-fold increase in colony survival.
” While this is the very first large-scale trial, continued breeding and use of these bees has revealed regularly promising results.
” This type of resistance supplies a natural and sustainable solution to the hazard positioned by Varroa termites, and does not depend on chemicals or human intervention.”
Bees in California. Credit: Thomas OShea-Wheller
The research study happened across three US states (Mississippi, California, and North Dakota), where commercial beekeepers move tens of countless colonies every year to offer pollination for large-scale agriculture.
Varroa mites came from Asia, so European honey bees (the most common species kept for pollination) have not progressed along with them, and for that reason do not have effective resistance.
Like humans, managed bees are mostly “decoupled” from natural choice, Dr. OShea-Wheller said, so they can not develop resistance like they might in the wild.
Managed bees often react to termites (which recreate in the cells of bee larvae) by expelling infested larvae– killing both the larvae and the mites, in a behavior known as Varroa-sensitive hygiene (VSH).
By selectively breeding for this trait, nests can be produced that immediately secure themselves from invasion, while preserving large colony sizes and sufficient honey production.
” The great feature of this particular quality is that weve found out honey bees of all types reveal it at some level, so we know that with the right tools, it can be promoted and chosen for in everyones bees,” said research molecular biologist Dr. Michael Simone-Finstrom, of the USDA Agricultural Research Service.
Nest survival over the winter season is especially essential for beekeepers, because honey bees remain in high need in the early spring– an essential time for pollinating high-value crops such as almonds.
The study likewise taken a look at levels of viruses connected with Varroa termites in bee colonies.
The colonies reproduced for Varroa resistance showed lower levels of 3 major infections (DWV-A, cbpv, and dwv-b).
Remarkably however, when taken a look at individually from levels of mite invasion, these viruses were not strong predictors of colony losses.
” A great deal of research study is focussed on the infections, with possibly insufficient focus on the mites themselves,” Dr. OShea-Wheller said.
” The viruses are clearly important, however we require to take a step back and be rigorous in providing the very best practical outcomes, since if you manage the termites, you immediately control for the infections that they send.”
Dr. OShea-Wheller stated bee breeding and screening is costly and takes some time, however that reproducing mite-resistant bees is cost-effective in the long term, and is likely to be the only sustainable service to handle the Varroa pandemic.
Reference: “An obtained honey bee stock confers resistance to Varroa destructor and associated viral transmission” 7 April 2022, Scientific Reports.DOI: 10.1038/ s41598-022-08643-w.
The study was moneyed by USDA.