Host genetics and pathogen species modulate infection-induced changes in social aggregation behaviour

Abstract

Identifying how infection modifies host behaviours that determine social contact networks is important for understanding heterogeneity in infectious disease dynamics. Here, we investigate whether group social behaviour is modified during bacterial infection in fruit flies ( Drosophila melanogaster ) according to pathogen species, infectious dose, host genetic background and sex. In one experiment, we find that systemic infection with four different bacterial species results in a reduction in the mean pairwise distance within infected female flies, and that the extent of this change depends on pathogen species. However, susceptible flies did not show any evidence of avoidance in the presence of infected flies. In a separate experiment, we observed genetic- and sex-based variation in social aggregation within infected, same-sex groups, with infected female flies aggregating more closely than infected males. In general, our results confirm that bacterial infection induces changes in fruit fly behaviour across a range of pathogen species, but also highlight that these effects vary between fly genetic backgrounds and can be sex-specific. We discuss possible explanations for sex differences in social aggregation and their consequences for individual variation in pathogen transmission.

IMD-mediated innate immune priming increases Drosophila survival and reduces pathogen transmission

“…While the duration of the infectious period is determined to some extent by the infected lifespan of a fly, pathogen transmission is also strongly influenced by host behaviours that impact the contact rates between infected and uninfected individuals [62]. One of the simplest behavioural readouts that is relevant for how frequently individuals may come into contact is locomotor activity [40,41,63]. Highly active individuals are more likely to contact conspecifics and therefore are more likely to spread and to acquire new infections.…”

“…While primed individuals may live longer, thus extending the infectious period, their pathogen burden may be lower, which could lead to lower pathogen shedding and less severe epidemics. Further, behavioural changes in primed individuals may also be likely, if immune deployment during the initial exposure leads to sickness behaviours such as lethargy or reduced social interactions [40,41].…”

Yellow fever outbreak temporarily changes dispersal patterns in an endangered primate

“…They constitute a major threat to wild animal populations but their impacts are hard to predict (Jones et al 2008). One fundamental challenge when examining the dynamics of disease outbreaks is understanding how host movements influence the spread of diseases within and among populations (Dougherty et al 2018), but also reversely, how diseases affect host movements, by changing the behaviour of individuals (Romano et al 2022;Stockmaier et al 2021).…”