How wild honeybees survive the cold winter

Date:
February 16, 2022
Source:
University of Wu"rzburg
Summary:
In northern Spain, wild honeybees use hollow electricity poles as
nesting cavities. Natural areas in the surroundings promote the
colonies' chances to survive the winter.



FULL STORY ========================================================================== Until recently, experts considered it unlikely that the honeybee had
survived as a wild animal in Europe. In a current study, biologists
Benjamin Rutschmann and Patrick Kohl from Julius-Maximilians-Universita"t Wu"rzburg (JMU) in Bavaria, Germany, show that wild honeybees still
exist in the region of Galicia in the northwest of Spain.


==========================================================================
The researchers describe where to find the bees' nests and under which conditions they can survive in Biological Conservation, a journal for conservation biology.

136 square kilometres searched for power poles Rutschmann and Kohl are
doctoral students at the JMU Chair of Animal Ecology and Tropical Biology
in the group of Professor Ingolf Steffan-Dewenter.

They started their studies in Galicia in October 2019 at the suggestion
of their Spanish colleague Alejandro Machado. The latter had observed
swarms of honeybees occupying the inside of hollow electricity poles
and apparently thriving there. In order to find out whether the region
would support an entire population of wild bee colonies, the researchers searched a 136 square kilometre area for hollow power poles.

"We discovered 214 poles," says Rutschmann. For each one, the researchers checked if a honeybee colony lived inside. "In the first year of
our investigation, we found 29 colonies." On a second visit in March
2020, they found that 17 of these colonies had survived the winter --
"even though they had neither been fed nor treated against parasites."
Galician honeybees are not imported breeds


==========================================================================
Now, it could have been that the wild honeybee colonies were the feral descendants of foreign honeybee strains imported by beekeepers. In
Germany, according to Rutschmann, the native honeybee subspecies (Apis mellifera mellifera) was displaced in this way a long time ago by imported subspecies, first and foremost by the Carnica bee (A. m. carnica).

But this was not the case in Galicia. By analysing wing venation pattern
the JMU researchers discovered that all the colonies living in power poles
were members of the Iberian honeybee, Apis mellifera iberiensis. It is
thus conceivable that in Spain the honeybee has existed both as a wild
and as a livestock animal up to the present day. "Whether the population
under study can be stable in the long term, however, must be shown by
further years of observation," says Kohl.

First data on survival rates "After two years of study and a total of
52 observed bee colonies, we see that around 40 percent of the colonies
survive the winter," reports Alejandro Machado, who himself lives in
the region. This is the first data ever reported on the survival rates
of wild honeybee colonies in Europe.

An analysis of the landscape around the power poles showed that the
survival of the Galician honeybees strongly depends on how natural the surroundings are. In power poles surrounded by shrubland, heathland
or forests many more colonies survive the winter than in power poles
located in intensively cultivated fields.



==========================================================================
For colonies surrounded by more than 50 per cent semi-natural habitats, at least every second colony survived the winter. In contrast, in landscapes
with less than 25 per cent semi-natural habitat and therefore little
supply of food, the probability of survival was close to zero.

Striking landscape contrasts in Galicia provided insights In Galicia,
the researchers found strong contrasts between contiguous semi- natural
areas with no or traditional, extensive use (heathland, coppice) and large areas of intensive agriculture with high pesticide and fertiliser inputs.

"It was this stark contrast between quasi-nature and agricultural desert
that made it possible for us to realise that the landscape context plays
such an important role in the survival of honeybees," says Rutschmann.

The study shows the fundamental importance of extensive forms of land use
and the restoration of near-natural landscape features such as hedgerows
for insect conservation. "Without sufficient nesting and feeding habitats,
even the banning of pesticides or the halt of climate change will not
help insects," concludes Kohl.

========================================================================== Story Source: Materials provided by University_of_Wu"rzburg. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Benjamin Rutschmann, Patrick L. Kohl, Alejandro Machado, Ingolf
Steffan-
Dewenter. Semi-natural habitats promote winter survival of
wild-living honeybees in an agricultural landscape. Biological
Conservation, 2022; 266: 109450 DOI: 10.1016/j.biocon.2022.109450 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220216103021.htm

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