DETERMINATION OF PROTEOLYTIC ACTIVITY IN VARROA JACOBSONI AN ECTOPARASITIC HEMOPHAGOUS MITE OF HONEY BEES (APIS sp.)

Abstract

SUMMARYIn previous studies, it was demonstrated through immunotechniques that the Varroa resorbs the ingested hemolymph proteins of honey bees (Apis mellifera) into it's own hemolymph. These same proteins are detectable in the eggs of this parasite (T EWARSON , 1981). To check this undegraded resorption of host proteins, a study of proteolytic activity in Varroa was carried out using homogenates of whole female mites in Tris-HCl-buffer (pH 8.2). Low proteolytic activity could be detected only with the help of very sensitive methods (by using synthetic substrates) and also there were indications that a protease inhibitory factor is present in the Apis hemolymph. A possible explanation of macromolecular uptake of host proteins by Varroa due to an inhibitory factor in the host hemolymph, as well as the low proteolytic activity in the mite, is discussed.

Co-adaptation of Apis cerana Fabr. and Varroa jacobsoni Oud

“…Tewarson et al [44] provided evidence that reproducing V. jacobsoni incorporate the host proteins (A. mellifera) directly into the oocytes. According to Tewarson and Jany [46], this type of vitellogenesis is an indication of the high degree of parasitic adaptation which enables the mites to have very rapid oogenesis and a subsequent increase in reproduction efficiency. An additional feature of the accelerated ontogenesis of V. jacobsoni is the phenomenon of larviposition (ovoviviparity).…”

Varroa destructorfeeds primarily on honey bee fat body tissue and not hemolymph

“…The issues with using either isotope for this purpose would be further exacerbated if Varroa employed extraoral digestion like most mesostigmatids, because liquid and semisolid tissues would dissolve together in the host before consumption. Attempts to develop systemic chemotherapeutics during the same period (miticides fed to the bees and consumed by the mites when they feed) consistently ended in failure, and as such, none are currently commercially available (1, 24). This is expected if the target host tissue has not been accurately identified.…”

“…Furthermore, the digestive system and mouthparts of this mite are structured in ways we would expect from an organism that feeds on semisolid tissue via extraoral digestion rather than hemolymph. For example, Varroa have a simple, tube-like gut structuring with no enzymatic activity in the midgut, and a gnathosoma (mouthparts) with well-developed salivary stylets allowing salivary fluid to mix efficiently with internal host tissue (24, 29). While Varroa possess attributes associated with feeding on semisolid tissue, they lack essential adaptations associated with hemolymph feeding.…”

The first gonocycle of the parasitic mite (Varroa juobsoni) in relation to preimaginal development of its host, the honey bee (Apis mellifra carnicar)

“…The reproductive phase is spent in capped bee brood cells on combs which are invaded by female mites a few hours prior to operculation. Reproduction of the parasite occurs only after intake of a number of blood meals, each of approximately 0.1 pl (Tewarson, 1983), of which some bee hemolymph proteins are resorbed without digestion (Tewarson and Engels, 1982;Tewarson and Jany, 1982). All subsequent steps in Varroa reproduction are linked to late larval and pupal preimaginal host stages in capped brood cells.…”