The influence of resource patch condition and size on social interactions, reproductive behaviors, and oviposition in a fungivorous beetle

Abstract

Variation among resource patches can structure spatial patterns of social behavior. Individual preferences and requirements for heterogeneous resources can lead to differences in where behaviors take place and which kinds of individuals interact. In this study we examined whether properties of habitat patches predict presence of and interactions among wild forked fungus beetles (Bolitotherus cornutus). B. cornutus use shelf-like fruiting bodies of wood decaying fungi (brackets) as social arenas, courtship and mating sites, oviposition locations, and food sources. Brackets on a single log vary in size and condition and represent a dynamic resource as individual brackets decay over the years that they persist on a subpopulation. We found that size and condition significantly predicted how a bracket was used by B. cornutus. Both males and females were found more often on larger, living brackets. Larger brackets hosted proportionally more social interactions and mating behaviors relative to the overall visitation by individuals. The relationship between these resource properties and frequencies of behaviors was stronger for reproductive, between-sex social interactions. Live brackets also attracted more oviposition events by females, but bracket size had no effect on this behavior. Our results indicate that the dynamics of growth and aging of a critical resource can impact how social and reproductive behaviors are distributed in time and space, which in turn could affect the social structure of subpopulations.

Significance statement

Species that depend on critical host resources are often faced with a patchy landscape of resource quality. Those patches represent the infrastructure within which social behaviors take place, and can have formative effects on where, when, and how social interactions occur. We demonstrated that the size and condition of a fungal resource predicted male and female forked fungus beetle presence and behavior. Larger, living brackets hosted more beetles overall, while larger brackets in any condition hosted more social interactions and mating behaviors. Female beetles were more likely to lay eggs on living brackets, regardless of size. This study demonstrates how ecological dynamics of aging resource patches can indirectly structure social landscapes by influencing where and how individuals interact.