CHARACTERIZATION OF CHEMICALS INVOLVED IN HONEYBEE-PLANT INTERACTIONS

To characterize plant chemicals cueing honeybees preferences between s unflower genotypes selected to produce hybrid seeds, combined behavior al and chemical analyses were undertaken. From observations of the for aging behavior under field conditions, bees' preferences between femal e and male parent lines were shown. Since bees' attraction to plants i s based upon an associative conditioning between food, provided by nec tar and pollen, and plant volatiles, these components were compared be tween genotypes. Sugar composition of nectars was analyzed by gas chro matography: glucose, fructose and sucrose were identified, with sucros e inducing bees' preferences. Pollen production was quantified on pare nt lines and resulting hybrid varieties, using a coulter-counter devic e. Differences among parent lines and heredity effect were found. Howe ver, there were strong interaction between parental lines and high var iability within genotypes. Pollenkitt analysis using thin layer chroma tography was undertaken to separate the main classes of lipids (hydroc arbons, sterols, mono-, di- and triglycerids). Fatty acids composition was analyzed by gas chromatography, the main components being two uns aturated fatty acids. Comparison of volatile components collected by a ir-entrainment method showed differences between male and female genot ypes. Discriminative components were limited to 10% of the volatile bl ends and were identified by coupled gas chromatography-mass spectromet ry.