Wound-induced response and methyl-jasmonate treatment in potato plants: specific effect on Macrosiphum euphorbiae

Plant responses induced by different biotic or abiotic stresses may severely modify plant physiology, which in turn may have consequences on phytophagous insects. Jasmonate plays a central role in controlling responses induced by both biotic and abiotic wounding. The aim of our work was to investigate the effects of the potato response to mechanical wounding, Colorado potato beetle (CPB) damage, and direct treatment with volatile methyl-jasmonate (MeJA) on the aphid Macrosiphum euphorbiae. Dual-choice olfactometry showed that plants treated with MeJA lost their attractiveness for the potato aphids, while both abiotic and biotic wounding did not alter the orientation of aphids. Electropenetrography (EPG) revealed that the feeding behaviour of aphids was slightly disturbed by a previous CPB wounding, while their phloem ingestion phases were significantly reduced by mechanical wounding and MeJA treatment. Aphid nymph survival was reduced on mechanically wounded plants, the pre-reproductive period was lengthened and the fecundity reduced on plants treated with MeJA. Both mechanical and CPB wounding led to slighter effects than those induced by a direct MeJA treatment. Interestingly, Me-JA induced an antixenosis resistance towards M. euphorbiae, previously shown to induce antibiosis. These findings are discussed with regard to their consequences on the aphid colonization processes.