ed nurse bees kept in a controlled environment. Head space of an empty jar kept under the same conditions was used as control. Each foreleg was used to test all the treatments. To prepare EP cartridges of the potential disrupting compounds, 1 ml of the compound dissolved in hexane was pipetted onto a piece of filter paper which is placed in a glass Pasteur pipette and exposed to air for 30 s to allow solvent to evaporate. Three different stimuli were tested: a “positive stimulus”, a “positive stimulus+compound”, a control stimulus- “Air” and hexane. In all experiments, the stimuli were given in the same order on the same forelegs as presented in Fig. 3A. When more than one compound was tested, the experiments with the different compounds were done in a random order. At least six different Varroa forelegs were tested for each experiment. The EP MedChemExpress TL32711 response was amplified and recorded by a PC via an IDAC-232 for data acquisition using the “EAG 2000″and “GCEAD-2000″softwares. For the organ to recover and to prevent adaptation, we allowed intervals of 30 s between each stimulus unless specified otherwise. The response amplitude was normalized relative to the response of the same organ to the control stimulus. Only individuals PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19661824 that showed a higher response to the “positive stimulus”than to the control stimulus prior to the exposure to the compounds were used for statistical analysis. The effect of the compounds was evaluated relative to the response to the “positive stimulus”before the exposure to the tested compound. According to previous studies, two kinds of effect were evaluated: the effect that occurred in the presence of the compound termed “short term effect”, and the effect following the administration of the compound but not in its presence termed “long term effect”. N~ ) response to stimulus 100 z 100 Normalization Equation 1. N- Response amplitude normalized relative to the response to air. Behavioral bioassays The effect of the compounds on Varroa host preference was tested in a two-choice bioassay based on Kraus. In the bioassay, a single mite was placed in the center of the arena and was presented with a choice of a freshly killed forager and a nurse placed on opposite sides of the arena. The experiments were conducted in a controlled dark environment, at 3435uC and 6070% RH. The Varroa choice was examined in the presence of 0.01 
mg, 0.1 mg and 10 mg of the compound dissolved in 1 ml hexane or in the presence of 1 ml pure hexane, as control. The compound or hexane, were placed right above the Varroa on the Electrophysiology bioassay Electrophysiological recordings were carried out on the olfactory sensory organ on the Varroa foreleg. The foreleg was dissected at the base and mounted between two glass capillaries filled with KCl solution, each containing a silver recording Disruption of Host Recognition by Varroa Mites inner side of the cover plate, on a piece of parafilm for slow release. Each dose was tested at least in 2 replicates; in each replicate 10 to 19 mites were tested for each treatment. The mite position on a nurse, a forager or elsewhere was documented after 180 minutes. Varroa host preference between a forager and a nurse bee was calculated as the percentage of total mites reaching each of the hosts. Varroa ability to reach any of the hosts was calculated as the percentage of viable mites by the end of the experiment out of the total tested mites. procedures were carried out with the SAS JMP Start statistic progra