Agriculture Reference
In-Depth Information
When on adult bees (see Photograph 13 in the colour photograph section of this
book), the mite sucks the bees' blood by piercing their cuticles. It is then that the bees
are thought to be more prone to infections from existing bee pathogens. With the
exception of some resistance in the Russian Primorskiy bee, Apis mellifera is defenseless
against these parasites and, unless the beekeeper intervenes with treatment, the colony
will have died out by the autumn.
Identifying Varroa destructor
On adult bees the mites look like small, crab-shaped, red/brown blobs 1.5 mm wide
and 1.1 mm long. They can be missed because they tend to blend in with the colour of
the bee, so look carefully. Mites can be seen, however, more easily by uncapping drone
brood and lifting them out.
Assessing colony infestation
The natural daily mite fall can be employed to assess varroa infestation (see below).
In severely infested colonies, there will be a rapid reduction in the number of adult
bees, and some or many of the adults will have deformed, ragged wings and deformed
abdomens. In severely infested colonies, foul brood-type symptoms may be also seen,
and this may lead to a diagnosis of parasitic mite syndrome, which is described later in
this chapter.
The following methods should help to determine varroa infestations in your hives. It
is also worth checking to see if the mites have become resistant to the usual chemical
treatments. Such resistance has occurred in many countries as a result of abusing the
chemicals, and it has taken many beekeepers by surprise (an easy way to check this is
also shown below).
Drone brood inspection
Test 100 cells. If there are, say, 5% with varroa, you have a low infestation. If there are,
say, 25% with varroa you have a high infestation.
Natural mite-fall inspection
This method involves counting the mites that fall off the bees naturally during the
normal course of the day. You can do this by inserting what is known as a 'sticky board'
Search WWH ::




Custom Search