New Zealand
February 28, 2007
Scientists are hoping they will be
able to offer good news to New Zealand arable farmers who face
increased pollination costs due to the incursion of the varroa
mite.
Research into native pollinators and other lesser known
pollinators has shown they may be more efficient at pollinating
crops than originally thought. Unlike honey bees, native bees
and flies are not susceptible to varroa and their importance to
agriculture, although small, may increase significantly,
particularly in view of an expected 25% reduction in commercial
hives in the South Island.
Crop & Food Research and
the Foundation for Arable Research are optimistic further study
will give growers vital clues about increasing their local
populations of native pollinators.
Dr Brad Howlett of Crop & Food Research has already identified a
significant number of native and other unmanaged pollinators
visiting crops.
“Up until I started investigating these insects under a project
funded by the Foundation for Research Science and Technology,
there was very little on what else, other than honey bees,
pollinated seed crops like onions, brassica and carrots. In two
years we’ve established that there is a diverse array of insects
visiting these crops and in many instances, they are quite
common across the crops. Better still, some of them are carrying
high pollen loads and move quickly between flowers.
“What we now want to establish is why sometimes these
pollinators are abundant across one field but not another. We
think a lot of it has to do with proximity to their preferred
nesting places, places to shelter and breed, and the timing of
flowering.”
Dr Howlett says it may even be feasible to develop artificial
ways to increase the abundance of these pollinators, such as
developing artificial nesting environments or by doing something
as simple as increasing the amount of nearby hedgerow.
Meantime, Nick Pyke, Chief Executive for the Foundation for
Arable Research (FAR), says growers can take some immediate
action as a result of the establishment of varroa in the South
Island.
“Arable growers need to act now if they want to minimise the
impact that varroa could have on their business. They need to
review the procedures that they currently use on farm when
applying agrichemicals or irrigation to ensure that they refrain
from harming pollinators in and around their property, including
the mowing of sward and flowering of weeds before applying
agrichemicals.”
Mr Pyke says growers could also start to familiarise themselves
with indigenous pollinators and other pollinators on their farms
and look at developing plans to encourage these species.
“It is also important that growers maintain good relationships
with their beekeepers and continue to communicate with them
regarding their pollination requirements. It is without a doubt
that varroa will have a marked impact on the pollination of
crops, therefore FAR will continue to provide research and
extension in this area to assist with minimising the impact that
the arable farming industry may face.”
About Varroa
Varroa (Varroa destructor) is an external parasite of honey
bees. Adult female mites are fairly large – about 1.1 x 1.6mm.
They have a hard reddish to dark brown body that is flattened
and oval in shape.
Varroa mites are transferred to new bee colonies on adult bees.
The mite will then leave the bee and crawl into a brood cell.
Once in the cell the mite submerges itself into the larval food
at the bottom of the cell and begin feeding on the prepupa. The
mite will then lay its eggs. The eggs hatch and go through two
juvenile stages before becoming adults. The adult mites then
leave the cell when the bee emerges. The feeding of the mite
weakens the hive and can cause hive failure if control measures
are not implemented.
A number of other insects can pollinate flowers and could be
important pollinators of crops including bumble bees, leaf
cutter bees, native solitary bees and a number of species of
flies. None of these species are susceptible to varroa. However,
generally these species have not been managed for pollination of
field crops and we are still learning about their ecology. |
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