title: Herbivory mitigation through increased water-use efficiency in a leaf-mining moth-apple tree relationship.
abstract: Herbivory alters plant gas exchange but the effects depend on the type of leaf damage. In contrast to ectophagous insects, leaf miners, by living inside the leaf tissues, do not affect the integrity of the leaf surface. Thus, the effect of leaf miners on CO2 uptake and water-use efficiency by leaves remains unclear. We explored the impacts of the leaf-mining moth Phyllonorycter blancardella (Lepidoptera: Gracillariidae) on light responses of the apple leaf gas exchanges to determine the balance between the negative effects of reduced photosynthesis and potential positive impacts of increased water-use efficiency (WUE). Gas exchange in intact and mined leaf tissues was measured using an infrared gas analyser. The maximal assimilation rate was slightly reduced but the light response of net photosynthesis was not affected in mined leaf tissues. The transpiration rate was far more affected than the assimilation rate in the mine integument as a result of stomatal closure from moderate to high irradiance level. The WUE was about 200% higher in the mined leaf tissues than in intact leaf portions. Our results illustrate a novel mechanism by which plants might minimize losses from herbivore attacks; via trade-offs between the negative impacts on photosynthesis and the positive effects of increased WUE.
authors.affiliation: Institut de Recherche sur la Biologie de l'Insecte (IRBI, CNRS UMR 6035), Université François Rabelais, Faculté des Sciences et Techniques, 37200 Tours, France. sylvainp@biol.sc.edu
authors.forename: Sylvain
authors.initials: S
authors.lastname: Pincebourde
authors.forename: Ela
authors.initials: E
authors.lastname: Frak
authors.forename: Hervé
authors.initials: H
authors.lastname: Sinoquet
authors.forename: Jean Luc
authors.initials: JL
authors.lastname: Regnard
authors.forename: Jérôme
authors.initials: J
authors.lastname: Casas
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D005740:Gases / Q000378:metabolism; D006790:Host-Parasite Interactions; D007814:Larva / Q000502:physiology; D008027:Light; D027845:Malus / Q000469:parasitology* / Q000502:physiology* / Q000528:radiation effects; D009036:Moths / Q000502:physiology*; D010788:Photosynthesis / Q000528:radiation effects; D018515:Plant Leaves / Q000469:parasitology* / Q000528:radiation effects; D018526:Plant Transpiration / Q000528:radiation effects; D012119:Respiration / Q000528:radiation effects; D014867:Water / Q000502:physiology*
chemical_list: D005740:Gases; D014867:Water; D002245:Carbon Dioxide