This is an Accepted Article that has been peer-reviewed and approved for publication in the Insect Science but has yet to undergo copy-editing and proof correction. Please cite this article as doi: 10.1111/1744-7917.12475. This article is protected by copyright. All rights reserved. Author running head: M. Coppola et al. Title running head: Trichoderma helps tomatoes attacked by aphids Correspondence: Maria Cristina Digilio. Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, Portici, 80055, Italy. Tel: +39 0812539194; email: digilio@unina.it *MC and PC contributed equally. ORIGINAL ARTICLE Trichoderma harzianum enhances tomato indirect defense against aphids Mariangela Coppola 1,* , Pasquale Cascone 2,* , Maria Luisa Chiusano 1 , Chiara Colantuono 1 , Matteo Lorito 1 , Francesco Pennacchio 1 , Rosa Rao 1 , Sheridan Lois Woo 1 , Emilio Guerrieri 2 and Maria Cristina Digilio 1 1 Department of Agricultural Sciences, Via Università 100, Portici, 80055, Italy and 2 CNR – IPSP, Via Università 133, Portici, 80055, Italy Abstract Many fungal root symbionts of the genus Trichoderma are well-known for their beneficial effects on agronomic performance and protection against plant pathogens; moreover, they may enhance protection from insect pests, by triggering plant resistance mechanisms. Defense barriers against insects are induced by the activation of metabolic pathways involved in the production of defense-related plant compounds, either directly