Friday, June 29, 2018

PRO/AH/EDR> Varroa mite, apis - Australia: (VI)

VARROA MITE, APIS - AUSTRALIA: (VICTORIA)
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Date: Thu 28 Jun 2018 23:00
Source: ABC [edited]
<http://www.abc.net.au/news/rural/2018-06-29/varroa-mite-detected-in-melbourne/9923972>


The potentially devastating varroa mite, which could wipe out the
Australian beekeeping industry, has been detected in Victoria.

A bee colony infested with the varroa mite was detected on [Wed 27 Jun
2018] at the Port of Melbourne on a ship from the United States.

A colony was found in a wooden crate and tests revealed some bees were
infested with varroa mite, but the exact variety of the varroa mite is
yet to be determined.

Australia is one of the last remaining countries in the world to be
free of the blood-sucking varroa destructor, which has already
devastated bee colonies in New Zealand, the United States, and
Europe.

_Varroa destructor_ is the breed of mite that affects European honey
bees, which agriculture industries around the world rely on for
pollination.

However, north Queensland has had recent incursions of the less
dangerous _Varroa jacobsoni_, which only infects Asian honey bees.

Agriculture Victoria chief health plant officer Nigel Ainsworth said
the master of the ship reported seeing dead bees on the ship, which
was immediately investigated by Agriculture Victoria and the
Commonwealth Department of Agriculture and Water Resources (DAWR) upon
docking at the Port of Melbourne.

Mr Ainsworth said the colony had been destroyed and Agriculture
Victoria was "confident" the situation was contained to the single
colony.

He said 3 other wooden crates on the ship from Texas had also been
secured.

"We haven't had final confirmation as it's a fairly specialised area
to formally ID them, but unfortunately we're fairly sure that it's
going to be _Varroa destructor_," Mr Ainsworth said.

"[That is] the bad varroa mite, given that it came from the US where
that's the form of varroa that is prevalent."

Mr Ainsworth said cold weather conditions meant the bees were
lethargic and "pretty unlikely" to have flown beyond the ship.

Laboratory tests of the established sentinel hives at the port
returned negative readings for varroa.

As a precaution, more sentinel hives have been installed and floral
sweep netting has been undertaken within the port precinct and the
adjacent parkland.

Biosecurity officers are also inspecting gardens within a 2-kilometre
[1.24 miles approx.] radius of the port.

"[This is] an example of how the system should work."

Australian Honey Bee Industry Council chairman Lindsay Bourke said the
industry was "very concerned" about the detection.

"We are on the lookout for this all the time," Mr Bourke said.

"The only thing in our advantage is that it arrived in Victoria,
because Victorians are the most proactive in this department."

Mr Bourke said it was likely the variety was varroa destructor, which
is considered more serious than _Varroa jacobsoni_.

He said _Varroa destructor_ had been detected in Australia on "a
number of occasions".

Mr Bourke said New Zealand, which carries _Varroa destructor_,
typically posed the biggest threat to Australia.

It has been reported that hived bees in the United States dropped by
about 30 per cent when it was found there, and native bee populations
in New Zealand dropped by 90 per cent when it hit NZ.

Last year [2017] it was reported bees in the United States and Europe
were starting to evolve through natural selection to survive the mite
decimating their populations.

At the time, Professor Stephen Martin, chair of animal ecology at
Salford University in the United Kingdom, said in some instances bees
were living with varroa mites and an associated virus, without any
other treatment.

Professor Martin said although the process of evolution was slow, it
gave the industry hope and sparked an interest in better beekeeping
methods, with people entering the industry to try to save the bees.

He said while the varroa mite sucked the blood of the bee, it was the
transmission of a virus into the bee that really caused the damage.

"In areas where there is no virus, the bees and the mites can live
together, but this is extremely rare," he said.

"The mite is simply the vector for the virus to get into the bee.

"In Europe and America almost every single bee has got the virus."

[Byline: Meagan Rooth]

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Communicated by:
ProMED-mail
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[There are 2 species of _Varroa_ mites. These species were once listed
as one. The more damaging _Varroa destructor_ was previously included
under the name _V. jacobsoni_, until DNA sequencing revealed a
difference in the mites. Based on DNA sequencing, and close
observation _Varroa jacobsoni_ is the species of mite which
parasitises _Apis cerana_ (Asian honey bees).

Australia has either just completed an exercise dealing with this mite
or is still in the exercise. So based upon the exercise to heighten
awareness and methods of dealing with this tiny invader, they should
be well prepared for the situation and likely did not expect to put
their practice into action so rapidly.

Varroa is a reportable disease according to OIE. Manual of Diagnostic
Tests and Vaccines for Terrestrial Animals Chapter Part 2, Section
2.9, Chapter 2.9.5.

This mite can be very destructive to naive colonies of bees.

An excerpt from that chapter includes:
"The mite _Varroa destructor_ (formerly _Varroa jacobsoni_) is a
parasite of adult bees and their brood. It penetrates the
intersegmental skin between the abdominal sclera of adult bees to
ingest haemolymph. It can sometimes be found between the head and
thorax. The number of parasites steadily increases with increasing
brood activity and the growth of the bee population, especially late
in the season when clinical signs of infestation can first be
recognised. The life span of the mite depends on temperature and
humidity but, in practice, it can be said to last from some days to a
few months.

Identification of the agent: The clinical signs of varroosis can only
be recognised at a late stage of infestation, so that diagnosis
entails the examination of the hive debris. The debris produced during
the summer is especially useful for diagnosis. The earliest and most
precise diagnosis can be made only after the application of a
medication that forces the mites to drop off the bees or kills them
directly. Larger amounts of debris can be examined using a flotation
procedure. Bees are washed in petroleum spirit, alcohol or detergent
solution. However, this method is less accurate due to the unequal
distribution of mites and the usually small sample sizes.

In heavily infested bee colonies, clinical signs of varroosis can
often first be seen in the latter part of the season when the brood is
reduced. Heavy infestations are usually reached 3-4 years after the
primary invasion, but can occur within weeks if infested by bees from
nearby colonies that are collapsing.

Essentially, the brood is damaged by the parasitic mites. Bees and
their offspring that have been infected during the brood phase by only
one parasitic mite show various ill effects, such as a shortened life
span, changes in behaviour and an increased disease susceptibility.
The parasitism is critical if more than one mite enters the brood cell
for reproduction. Only in the lethal stage immediately before the
collapse of the colonies do clinical signs, such as shrunken wings and
shortened abdomen, appear. This is due to an increased susceptibility
to deformed wing and acute paralysis virus, as well as to the
infection of wounds and loss of haemolymph. If the brood dies shortly
before or after sealing, clinical signs of European foulbrood appear
without the presence of the specific agent _Melissococcus pluton_. If
the brood survives, the emerging bees show various behavioural changes
and their life span is considerably shortened."

Although there are many tests to verify the presence of the mite,
there appears to be little in the way of treatment for the colonies.
There are some products providing limited success. From the OIE
chapter cited above:

"There are no biological products and vaccines available. Formic acid,
oxalic acid, lactic acid and thymol can be used to control Varroa
mites (<http://www.apis.admin.ch/english/Themes/Varroa.htm>). Some
hygienic strains are less susceptible to Varroa parasites."

A map of Victoria, Australia: <http://healthmap.org/promed/p/288>. -
Mod.TG]

[See Also:
2017
----
Varroa mite, apis - USA: (NY)
http://promedmail.org/post/20170711.5166540
2016
----
Deformed wing virus, varroa mite, apis: manmade global spread, RFI
http://promedmail.org/post/20160208.4001320
Varroosis, apis - Australia (04): (QL)
http://promedmail.org/post/20160718.4352558
Varroosis, apis - Australia (03): 1st report, _V. jacobsoni_ Java/PNG
haplotype http://promedmail.org/post/20160708.4333269
Varroosis, apis - Australia (02): 1st report, OIE, _V. destructor_
excluded http://promedmail.org/post/20160707.4331364
Varroosis, apis - Australia: 1st report, OIE
http://promedmail.org/post/20160704.4325486
2006
----
Varroa mite, bee - New Zealand
http://promedmail.org/post/20061216.3537
2004
----
Varroa mite, bees - New Zealand (S. Island): alert
http://promedmail.org/post/20040607.1531
2000
----
Bronze bee mite - New Zealand
http://promedmail.org/post/20000415.0537]
.................................................mhj/tg/ec/dk
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