Functional morphology of the mouthpart sensilla in females of Varroa jacobsoni Oudemans (Acari: Varroidae).

The mouthparts of the Varroa jacobsoni Oudemans adult female (Acari: Varroidae) have been investigated by means of light microscopy, scanning and transmission electron microscopy re- vealing specialised sensory receptors on the chelicerae, corniculi and latera! lips. These receptors are described and a functional interpretation on d1e basis of their ultrastructure is given. Each chelicera bears two uniporous sensilla on each tip of me digitus mobilis (one on the dar- sal part and the other on the ventral one), a dorsal seta and an antiaxial lyrifissure both located on the distai part of each middle artide. The uniporous sensilla could act as a contact chemore- ceptor, the dorsal seta as a mechanoreceptor and the lyrifissure as a mechanosensitive propriore- ceptor. Each corniculus tip bears a supposed uniporous sensillum that could be contact chemorecep- tors. Each latera! lip bears a short cuticular process set on the adorai wall at a slightly distai leve! wim respect to the base of the labrum. Each process is provided with an apical pore. lt could be a contact chemoreceptor.