18.104.22.168. Phoretic phase
After emerging from the brood cell the varroa mite enters the phoretic phase, that is spent on adult bees and lasts until a new brood cell is invaded for reproducing. Bioassays have been used by several authors to work on the chemical cues affecting the mite on the adult bees. Kraus (1994) used a simple two-choice bioassay to test several chemicals for their effect on the mite as a screening procedure to identify possible substances to be used in biological control methods. He and others used laboratory bioassays to investigate the stimuli affecting the host choice by the mite (Hoppe and Ritter, 1988; Kraus, 1990, 1994; Del Piccolo et al., 2010). These bioassays are all based on the same kind of setup. Here the bioassay described by Del Piccolo et al. (2010), that was used to study the preference of the varroa mite for pollen and nurse bees, is presented.