Chem. Engg. Seminar Series: Shantanu P Shukla

Microbial symbionts as a source of metabolic innovation and host adaptation

Insects demonstrate remarkable evolutionary associations with microbial symbionts. In their most extreme form, these mutualistic relationships involve endosymbiotic bacteria and fungi residing directly within host cells or tissues that supply essential metabolites that insects cannot synthesize de novo. This interdependency has driven the evolution of obligate symbiosis, rendering both partners incapable of surviving independently. Maintaining such obligate relationships requires highly coordinated genetic and physiological adaptations in both organisms to guarantee the successful vertical transmission of symbionts to offspring and facilitate efficient metabolic exchange.

In this presentation, I will share our findings on scale insects—a specialized lineage of sap-feeding insects that rely exclusively on plant phloem. While phloem sap is rich in carbohydrates, it is deficient in essential nutrients such as amino acids and vitamins. We demonstrate that microbial symbionts synthesize these missing nutrients not only during the adult stage but also during early embryonic development. Furthermore, we reveal that these symbionts produce diverse metabolites that regulate host growth, influence broader phenotypic traits, and ultimately drive the ecological success of these insects.