Enhancing plant resistance at the seed stage: low concentrations of methyl jasmonate reduce the performance of the leaf miner Tuta absoluta but do not alter the behavior of its predator Chrysoperla externa.

Abstract

Plants express inducible direct and indirect defenses in response to herbivory. The plant hormone jasmonic acid (JA) and related signaling compounds referred to as jasmonates play a central role in regulating defense responses to a wide range of herbivores.We assessed whether treating tomato seeds with 0.8mM of methyl jasmonate (MeJA) affected the performance of the leaf miner Tuta absoluta, and whether possible changes in volatile profiles altered the behavior of its predator Chrysoperla externa. MeJA-treatment significantly lengthened larval development and decreased the pupal weight of T. absoluta. Herbivory alone increased the emissions of α-pinene, 6-methyl 5-hepten-2-one, β-myrcene, (E)-β-ocimene, isoterpinolene, TMTT, (Z)-3-hexenyl butyrate, and hexyl salicylate. MeJA seed treatment significantly decreased the emissions of α-cubebene from undamaged and herbivore-infested plants. In addition, the emissions of several compounds were lower in the absence of herbivory. Chrysoperla. externa preferred odors from herbivore-infested plants over those from control plants, regardless of the MeJA-treatment, and they did not show any preference for herbivore-infested plants for any of the MeJA-treatments. Our results show preliminary evidence that the treatment of tomato seeds with MeJA can reduce the performance of Tuta absoluta, and that the chemical differences observed in plant VOC profiles do not alter the behavior of the model predator.