Insects have developed a vast diversity of relationships with microorganisms. Phytophagous species, in particular, often rely on their gut microbiota to acquire essential nutrients, adapt to abiotic conditions, defend against natural enemies, or detoxify insecticides. Moreover, the composition of their gut bacterial community can vary, sometimes over very short time scales, in response to a new environment or a new host—situations that may arise during biological invasions.

​

This project will focus on the study of Spodoptera frugiperda, a lepidopteran native to the American continent that is highly polyphagous and causes significant damage to food crops. It can rapidly develop resistance to control methods, making its management particularly challenging. The microbiota of S. frugiperda can vary depending on the host plant on which the larvae feed or on agricultural practices. However, the role of microbial symbioses in this species remains poorly understood.

This thesis aims to determine whether microbiota modulations, similar to those previously described in S. frugiperda, occur during invasion and are associated with increased tolerance to environmental stresses in the insect. We will also seek to describe the reciprocal interactions between the composition and diversity of the gut microbiota and resistance to abiotic stresses such as extreme temperatures and insecticide exposure.