Navigating infection risk during oviposition and larval foraging in a holometabolous insect

11 Deciding where to eat and raise offspring carries important fitness consequences for all 12 animals, especially if foraging, feeding and reproduction increase the risk of exposure to 13 pathogens. In insects with complete metamorphosis, foraging occurs mainly during the larval 14 stage, while oviposition decisions are taken by adult-stage females. Selection for infection 15 avoidance behaviours may therefore be developmentally uncoupled. Using a combination of 16 experimental infections and behavioural choice assays, here we tested if Drosophila 17 melanogaster fruit flies avoid potentially infectious environments at distinct developmental 18 stages. When given conspecific fly carcasses as a food source, larval-stage flies did not 19 discriminate between carcasses that were clean or infected with the pathogenic Drosophila C 20 Virus (DCV), even though scavenging was a viable route of DCV transmission. Adult females 21 however, discriminated between different oviposition sites, laying more eggs near a clean 22 rather than an infectious carcass if they were healthy; DCV-infected females did not 23 discriminate between the two environments. While potentially risky, laying eggs near 24 potentially infectious carcasses was always preferred to sites containing only fly medium. Our 25 findings suggest that infection avoidance can play an important role in how mothers provision 26 their offspring, and underline the need to consider infection avoidance behaviours at multiple 27 life-stages. 28 29 30