Acarine Disease

Signs and Symptons

Acarine disease is something to look for in the spring when colonies may fail to build up properly. Look out for large numbers of crawling bees on the ground and/or a pile of dead bees beneath the entrance – these are signs of chronic bee paralysis virus (CBPV) which is often present when the bees have Acarine. They may also have ‘K wings’. This is where the bees hold their fore-wings at strange angles so they look like a letter K. The bee has has four wings, two on each side; they are zipped together for flight and unzipped but folded together in a relaxed sort of way otherwise. With K wings it’s as if the wings are broken and the fore-wings are held out at right angles.

Life Cycle

Acarine itself is a disease of adult honey bees and is caused by a parastitic mite Acarapis woodi.  As such, It is related to Varroa as they are both mites. Mites have eight legs and are members of the spider family.

Acarine mites invade and infest the main thoracic trachea, or wind pipe, of honey bee where they feed on bee blood (haemolymph) and eggs are laid. These hatch in 5 days and larvae develop into adult mites after another 9 days. The young mites are then filled with the urge to travel and emerge blinking and twittering from the trachea and onto the hairy backs of the bees. They pass from bee to bee when they touch then they follow vibrations to the wing root and from there follow moving air to invade trachea via first spiracle. Presumably they mate during their time in the great outdoors and once inside the host bee, the cycle repeats itself.

The mite burden shortens the life of individual bees but there are no outward signs of disease itself. The presence of biting mites may increase vectoring and susceptibility to paralysis virus, symptoms of which are – crawling moribund bees and/or a heap of dead bees below entrance. The effect on the colony must depend on the number of mites present and the spring weather – if the weather be kind their rate of colony expansion might outrun the mites otherwise the mite-load and the increasing age of the bees will wear the colony down.

Diagnosis and Treatment

Microscopic examination is needed for confirmation or a sample of bees can be sent away for expert analysis.

As for treatment – if you are treating your bees with thymol for Varroa this will also help to control the numbers of Acarine but the best thing is to find resistant bees. Roger Patterson, writing on Dave Cushman’s website believes that the native bee is at least partially resistant to Acarine as the guard hairs around the spiracles are much stiffer than in other races of bees and this helps to keep the little feckers out.

A spiracle is a hairy little pore which leads into the branching system of tubes which act as the lungs of insects such as bees and wasps. When you add that little squirt of washing-up liquid to the water of your wasp traps (you do do that don’t you?) its effect is to break down the surface tension of the water which allows it to flow in through the wasp spiracles so they drown.

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