Enhancing Lasioglossum (Homalictus) dotatum (Hymenoptera: Halictidae) habitats: The role of rock gravel in bare soil landscapes

Abstract

Native bee populations are generally in decline, and although their conservation needs are recognised, habitat requirements for the majority of species remain unknown. Many bee species construct nests underground, including the native Australian bee Lasioglossum (Homalictus) dotatum. However, like most ground-nesting bees, their nesting ecology, particularly their substrate preferences and soil surface requirements, remains poorly understood. To address this knowledge gap, this study examined whether L. dotatum prefers nesting in bare sand or amid rock gravel and whether soil treatment influences nest-site selection. Experiments were conducted using 24-L pots of Bassendean sand, placed near active L. dotatum nesting aggregations. Ten pots had a layer of rock gravel, while the remaining 10 were left bare. Within each treatment, half of the pots contained untreated sand, and half contained steam-treated sand to remove potential contaminants. This design tested whether L. dotatum prefers certain soil conditions and surface features when selecting nest sites. Results showed that female L. dotatum preferentially nest in pots with rock gravel over those with bare sand, suggesting that rock cover may create a more favourable environment by moderating temperature, retaining moisture, or providing structural stability for nest entrances. Additionally, females preferred steam-treated sand over untreated sand, possibly indicating that factors associated with untreated soil, such as microbial presence or organic residues, may deter nesting. This study advances our understanding of L. dotatum nesting behaviour and provides a framework for creating pollinator-friendly spaces by identifying key soil and surface features that influence nest-site selection. However, the mechanisms driving their preference for steam-treated sand remain unknown, highlighting the need for further research to distinguish the roles of hygiene, soil properties and potential chemical cues in nest-site selection.