Investigating the molecular basis of cleptobiosis in eusocial stingless bees (Apidae: Hymenoptera)

Cleptobiosis, the act of raiding other species to obtain food or resources, is widespread among animals but rarely obligatory. The eusocial stingless bee Lestrimelitta limao is one of the few species that depend entirely on cleptobiosis, raiding other stingless bee colonies for survival. To investigate the molecular basis and putative evolutionary adaptations associated with this specialized lifestyle, we compared the transcriptomes of non-raiding foragers of L. limao and of three non-robber stingless bees - Nannotrigona testaceicornis, Scaptotrigona aff. depilis, and Tetragonisca angustula. Our analysis revealed that differentially expressed orthologs were predominantly downregulated in L. limao workers, suggesting reduced transcriptional activity during foraging in this species. These downregulated genes fall into three major functional categories potentially linked to cleptobiotic adaptations: (1) detoxification and chemoreception genes, including cytochrome P450s and odorant receptors, indicating decreased exposure to phytochemicals; (2) neuronal and synaptic genes, such as para and Dys, possibly reflecting neurophysiological modifications; and (3) mitochondrial and carbohydrate metabolism genes, suggesting lower energetic demands. These findings provide novel insights into the molecular mechanisms associated with cleptobiotic behavior in eusocial bees.