A Alaphilippe, S Derridj

Primary metabolites (sugars) of the phylloplane stimulate the egg laying of the codling moth, Cydia pomonella. By modifying ratios and quantities of these metabolites we can decrease the number of eggs laid on the plants and could modify the development of pathogens. We thus spray apple trees with an epiphytic microorganism, which may modify the phylloplane composition by its metabolism and/or by inducing plant resistance mechanism, and as a consequence, modify the insect egg laying. We first screened epiphytic microorganisms able to survive on apple plant parts and to cover the whole foliage. Then we treated apple trees with one of the selected microorganisms (a yeast), and looked at the effect on egg laying. The preliminary results show that the egg repartition within trees is not changed by the presence of introduced microorganisms, but the egg number laid on trees is reduced up to 60% by the treatment. The first results of the phylloplane chemical analyses showed that the treatment changed the ratios within the sugar blend.