Why is the Varroa destructor so successful?

The BeeHolder, Summer 2013

The Varroa mite has developed a wide array of Some insects such as ants will never allow a features to make it successful as a parasite of stray ant from another colony to enter their the honey bee, including ‘chemical camouflage’. nest when they identify their different chemical profile. While bees are much less fussy, there are marked differences in the chemical profiles of different colonies.

Crab like varroa miteIn the same way, both to bees, and to mites, the chemical signatures of adult bees and larvae are clearly and obviously different. Research work by Rickarda Kather explains how a Varroa mite, when it first arrives ‘camouflaged’ to be ‘invisible’ on an adult bee, can then alter and adapt her chemical profile so the bees in the new colony don’t ‘see’ her.

This microscope photograph highlights some of these features, which include:-

  • A flattened crab like shape – which enables the mite to fit between the bees segments.
  • Stiff ventral hairs – which helps prevent its removal from the bee.
  • The shape of the peritreme surrounding the spiracles in their surface – which aids respiration whilst submerged in brood fluid.
  • A thick cuticle skin – which prevents water and moisture loss.
  • Retractable lobed suckers – which aid attachment to the bee.
  • Specialised piercing mouthparts – which allow the mite to the mite to penetrate the bee’s cuticle (the surface covering of the bee.)
  • The chemical pattern of the mite’s own cuticle – which is similar to that of the honey bee and provides a ‘chemical camouflage’.

This chemical camouflage is further enhanced by the ability of the mite to adapt its chemical profile to becPupa chemical profileome Adult Bee Chemical Profilesimilar to that of the bee colony and make her invisible. The rapidity of this adaption can be demonstrated by comparing the profile of an adult bee to a pupa bee, the main difference is in the ‘red compounds’ (methylalkanes). When a mite is taken from an adult bee, the mite’s red compounds are low (as in the adult bee) but when transferred to a pupa, the first change in compounds can already be recorded after twenty minutes and will be almost complete after three hours. The mite just absorbs them and becomes essentially invisible.

thanks to Ipswich & East Suffolk Beekeepers and Ricky Kather