Sucrose as an apple tree resistance inducer against Cydia pomonella L.

Abstract: The studies of plant insect relationships are necessary for research of new control methods. We showed that the soluble carbohydrates and sugar alcohols exuded on the leaf surface influence Cydia pomonella L. egg-laying and neonate larval behaviour. The metabolite pattern and quantities can explain apple tree resistance to egg-laying. The plant resistance can be obtained by modifying the pattern with spraying sucrose solutions on apple tree. This was done in several orchards and varieties, over three years alone and/or in association with chemical or biological controls.The spraying of 100 ppm sucrose or 10 ppm did not differ, and the addition of sucrose to treatments, leads to increase the practical efficacy and the ABBOTT one. The practical efficacy = (% of damage on the treatment reference – % of damage with sucrose addition)/% of damage on the treatment reference, was 30% over three years and several varieties. These results open a research field on pesticide alternatives and on improvement of biological controls. Enhancement of this technology should be obtained by studies of dose effects, duration and time period efficacy. Knowledge of genes concerned in this induction would be helpful for resistance selection.