3.6.2. Bioassays in Varroa chemical ecology
Bioassays are a fundamental resource in the study of behaviour modifying chemicals, all the way from the demonstration of their existence, through all steps of isolation, until the final confirmation of their identity. Some of the bioassays used so far in varroa chemical ecology were simple adaptations of those already used for the study of arthropod semiochemicals (Baker and Cardé, 1984). In particular, the response of the varroa mite towards different odour sources and pure compounds was tested using several general purpose setups, including four-arms olfactometers (Le Conte et al., 1989), servospheres (Rickli et al., 1992), Y-mazes (Kraus, 1993), wind-tunnels (Kuenen and Calderone, 2002) and observation arenas (Rickli et al., 1994), in other cases, bioassays were specifically designed for the varroa mite. In this section, we will concentrate on the latter. The chemical stimuli that influence the behaviour of the mite during the following stages of the mite’s biological cycle have been studied by means of bioassays: cell invasion, mating, oviposition, phoretic phase.