Hidden players in plant-insect interactions: effects of third-trophic level symbionts on responses of plants to herbivory


Mutualistic symbionts are increasingly recognized as hidden players in plant-insect interactions. Understanding how symbionts affect plant responses to herbivory provides important insight into the fascinating complexity of terrestrial ecological networks and how we could specifically target symbionts to achieve sustainable pest management. Although the role of herbivore-associated symbionts is gaining increased attention in ecology of plant-insect interactions, how symbionts of members of higher trophic levels affect these interactions is poorly understood. The natural enemies of insect herbivores such as parasitic wasps that are used in biological pest control are associated with mutualistic symbionts (polydnaviruses) that they inject into the herbivore along with eggs in an event of parasitisation. Our exciting unpublished data hint that polydnavirus-genes are expressed in the salivary glands of parasitized caterpillars suggesting that third-trophic level symbionts may alter the herbivore’s salivary composition and consequently, affect the way the herbivore interacts with the plant: a novel ecological phenomenon.
By using a novel multidisciplinary approach that integrates molecular, chemical, behavioral and field ecology, the proposed project aims to manipulate the phenotype of caterpillars to study the effect of symbiotic viruses of third-trophic-level insects at the plant-herbivore interface. We will address this issue at different levels of biological organization, from plant gene expression to plant-mediated ecological consequences. The project will thereby provide novel fundamental insights into the hidden role played by parasitic wasp symbionts in plant responses to herbivory and these insights will generate important knowledge for pest management programs that focus on polydnaviruses as biological control agents.


Project number


Main applicant

Prof. dr. M. Dicke

Affiliated with

Wageningen University & Research, Plantenwetenschappen, Laboratorium voor Entomologie (ENT)


01/01/2018 to 31/12/2021