Worker Body Size Drives Cuticle Thickness and Higher Relative Intensity of the Lipid Reaction in the Leaf-Cutting Ants Atta laevigata and Atta sexdens.

The body size of insects influences the surface-area-to-volume ratio and can affect the thickness of the cuticle and relative intensity of the lipid reaction particularly in eusocial species such as leaf-cutting ants of the genus Atta, which exhibit pronounced worker polymorphism. In this study, we evaluated the relationship between body size, relative intensity of the lipid reaction, and cuticle thickness in workers of Atta laevigata (Smith, 1858) (Hymenoptera: Formicidae) and Atta sexdens (Linnaeus, 1758) (Hymenoptera: Formicidae). Small, medium, and large workers, defined according to the width of the cephalic capsule, were compared regarding relative cuticle thickness and relative intensity of the lipid reaction. Both traits varied among worker size classes. Small workers showed higher relative intensity of the lipid reaction and greater relative cuticle thickness, while medium and large workers exhibited lower values for both traits, indicating that different cuticle components respond similarly to body size, regardless of the species. Although the relative intensity of the lipid reaction was not differentiated between species, cuticle thickness was consistently greater in A. sexdens than in A. laevigata in all size classes. Overall, our findings suggest that differences in cuticular characteristics between A. laevigata and A. sexdens are not solely associated with body size and may also be related to the specific functions performed by workers within the colony.