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Extension News Releases - Shelter Design is Essential to Leafcutter Bee Survival - February 26, 2003 Manitoba Ag

                                                                                                            February 2003

Extension News Releases
Shelter Design is Essential to Leafcutter Bee Survival

A recent study points to new management techniques that could help growers get larger numbers of healthy bees
from three types of leafcutter bee shelters.

Leafcutter bee shelters can be seen throughout southern Manitoba, where they house bees that pollinate alfalfa seed
fields. These shelters are key to leafcutter bee production because they allow beekeepers to collect the cocoons for
the next generation of bees in the fall.

Rheal Lafreniere, Manitoba Agriculture and Food extension apiarist, said shelter design could have an impact on how
many healthy cocoons and eggs are collected and survive.

"Manitoba leafcutter bee producers lose between 10 and 15 per cent of their developing bees every year due to
mortality from moulds and other diseases," stated Lafreniere. "Past studies show that this type of mortality fluctuates
with temperature and relative humidity. We wanted to look at how shelter design affects temperature and humidity
and, ultimately, bee brood development."

Supported by the Covering New Ground program, Lafreniere worked with the Manitoba Forage Seed Producers
Association to monitor the environments within three types of leafcutter bee shelters: a plastic dome, a wooden four
by eight-foot shelter and a tarped structure, all used to some extent by Manitoba leafcutter bee producers.

Team members then measured the mortality rate of the developing bee broods and looked for links with temperature
and humidity. Lafreniere's team set up data loggers which recorded temperature and humidity inside 14 shelters
during the pollination season. During July and August, workers counted the number of healthy and dead larvae in
each of the three types of shelters.

The data suggests that the blue plastic domes were consistently hotter than the two other types of shelters. "The
tarped and wooden shelters were two to three degrees Celsius warmer than outside temperatures and the blue domed
shelters were up to nine degrees warmer than outside temperatures," said Lafreniere.

"There was 13.6 per cent bee mortality in the blue poly domes compared to a range of 4.3 to 6.8 per cent in the
wooden and tarped structures respectively."

Lafreniere noted that temperatures in the dome hit the low 40s on some days. He also pointed out that this type of
shelter's ability to capture warmth may also have advantages. Warmer temperatures inside the domes could benefit
bee producers on moderate or cool days when bees need additional warmth.

Lafreniere had some additional advice for growers who want to monitor or manage temperature and humidity inside
the leafcutter bee shelters. "Ideally, you want temperatures inside the shelter to be between the high 20s and the low
30s. You also want moderate humidity. Producers who use the poly dome shelters have been adding vent holes and
enlarging the opening at the top. This increases air circulation and keeps temperature and humidity down."

Team members expect additional data to come in over the winter. They submitted the dead larvae to a laboratory to
examine the causes of mortality. They are particularly interested in examining disease trends to see if there are
significant differences in bee disease levels in the three shelter types. They expect to report on this data this winter.

http://www.gov.mb.ca/agriculture/research/covering/newsrelease/leafcutterbee-feb26.html                       2003-08-19
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Extension News Releases - Shelter Design is Essential to Leafcutter Bee Survival - February 26, 2003 Manitoba Ag

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This is the 23rd in a series of news releases on agricultural sustainability produced by Covering New Ground, a
program that funds local projects to help find economical solutions to environmental challenges in Manitoba's
agricultural community.

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http://www.gov.mb.ca/agriculture/research/covering/newsrelease/leafcutterbee-feb26.html                        2003-08-19

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