Predicting sex bias in mobility from functional traits in flying insects

Understanding the movement patterns of organisms is crucial for effective biodiversity conservation in the increasingly dynamic and fragmented landscapes. Since the colonization of habitat patches relies largely on females, sex differences in movement capability must also be considered. However, obtaining direct measurements of mobility and dispersal, and sex biases in these traits, is often challenging. This underscores the importance of predicting sex‐specific estimates of mobility based on species' functional traits. Our phylogenetic comparative study aims at identifying species traits that could serve as proxies for sex bias in mobility in flying insects. We rely on a comprehensive dataset on the sex ratios of 454 moth species (Lepidoptera: Macroheterocera), captured by light traps of the Finnish national moth monitoring scheme. We first demonstrate that, in the vast majority of species, males outnumber females among the captured individuals. Our phylogenetic regression models reveal that species‐specific sex ratios correlate with traits typically predicted to be associated with sex differences in mobility. Female proportions decrease as sexual dimorphism in wingspan becomes more male‐biased and female wing loading relative to males increases. Proportions of females are also lower in larger species. Females are particularly scarce in trap samples of species in which the reproductive output of females is primarily determined by larval‐derived resources (i.e. capital breeders). These associations suggest that the observed variations in sex ratios do indeed mirror the variation in sex bias in mobility across species. Our findings highlight the potential of trait‐based approaches to identify meaningful indicators of insect mobility, including sex biases in movement patterns. The availability of such proxies facilitates predictions about how different species might respond to contemporary challenges, such as light pollution and habitat loss and fragmentation. The detected associations also advance ordination schemes of insect life histories by integrating mobility measures into relevant analyses.