Eberl, FranziskaDe Bobadilla, Maite FernandezReichelt, MichaelHammerbacher, AlmuthGershenzon, JonathanUnsicker, Sybille B.2020-10-022020-10-022020-07Eberl, F., Fernandez de Bobadilla, M., Reichelt, M. et al. 2020, 'Herbivory meets fungivory : insect herbivores feed on plant pathogenic fungi for their own benefit', Ecology Letters, vol. 23, no. 7, pp. 1073-1084.1461-023X (print)1461-0248 (online)10.1111/ele.13506http://hdl.handle.net/2263/76312Plants are regularly colonised by fungi and bacteria, but plant-inhabiting microbes are rarely considered in studies on plant–herbivore interactions. Here we show that young gypsy moth (Lymantria dispar) caterpillars prefer to feed on black poplar (Populus nigra) foliage infected by the rust fungus Melampsora larici-populina instead of uninfected control foliage, and selectively consume fungal spores. This consumption, also observed in a related lepidopteran species, is stimulated by the sugar alcohol mannitol, found in much higher concentration in fungal tissue and infected leaves than uninfected plant foliage. Gypsy moth larvae developed more rapidly on rust-infected leaves, which cannot be attributed to mannitol but rather to greater levels of total nitrogen, essential amino acids and B vitamins in fungal tissue and fungus-infected leaves. Herbivore consumption of fungi and other microbes may be much more widespread than commonly believed with important consequences for the ecology and evolution of plant–herbivore interactions.en© 2020 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License.Gypsy mothMycophagyNutritional ecologyRust fungusSalicaceaeTripartite interactionArticle