Viral exposure effects on life-history, flight-related traits, and wing melanisation in the Glanville fritillary butterfly

Infections represent a constant threat for organisms and can lead to substantial fitness losses. Understanding how
individuals, especially from natural populations, respond towards infections is thus of great importance. Little is
known about immunity in the Glanville fritillary butterfly (Melitaea cinxia). As the larvae live gregariously in
family groups, vertical and horizontal transmission of infections could have tremendous effects on individuals
and consequently impact population dynamics in nature. We used the Alphabaculovirus type strain Autographa
californica multiple nucleopolyhedrovirus (AcMNPV) and demonstrated that positive concentration-dependent
baculovirus exposure leads to prolonged developmental time and decreased survival during larval and pupal development, with no sex specific differences. Viral exposure did not influence relative thorax mass or wing morphometric traits often related to flight ability, yet melanisation of the wings increased with viral exposure, potentially influencing disease resistance or flight capacity via thermal regulation. Further research is needed to
explore effects under sub-optimal conditions, determine effects on fitness-related traits, and investigate a potential adaptive response of increased melanisation in the wings due to baculovirus exposure.