Herbivore secretes gut bacteria to suppress plant defenses

Plants elicit defenses in response to insect attacks. As plants have evolved strategies to defend themselves against attackers, some insect herbivores secrete effectors in their oral secretions (OS) to overcome plant defenses. Herbivores harbor diverse microbes in their guts and the microbial symbionts provide essential nutrients or protection from natural enemies. In addition, some of these microbes may modify plant-insect interactions. However, the role of herbivore-associated microbes in manipulating plant defenses remains unclear. Here, we demonstrated that gut bacteria secreted by larvae of Colorado potato beetles (Leptinotarsa decemlineata) during herbivory suppress anti-herbivore defenses in tomato (Solanum lycopersicum). Three microbial symbionts isolated from OS of the larvae were responsible for defense suppression. Beetles benefit from down-regulated plant defenses through enhanced larval growth. Our findings indicate that beetles secrete gut bacteria to evade anti-herbivore defenses of its host.