The metapleural glands of fungus-growing and non-fungus-growing ants: Ultrastructural study

Abstract

The metapleural glands are considered an autapomorphic structure to ants and probable have an antibiotic or antifungal function. The present study was aimed at investigating the ultrastructural mor phology of the metapleural glands in ants which have different feeding types: from fungus-growing ants, the higher and lower attine, and non-fungus-growing ants from the tribes Blepharidattini and Ectatommini analyzed by transmission electron microscopy. Plasma membrane invaginations in secre tory cells of both fungus-growing and non-fungus-growing ants facilitate absorption of extracellular material from hemolymph. Higher and lower attines differed slightly from non-fungus-growing ants, by the presence of oval secretory cells and well-developed RER in the metapleural glands, which indi cates a higher production of secretion in attines. Also, well-developed Golgi regions in the leaf-cutting ants and Ectatommini probably modify the secretions, produced by the secretory cell or coming of the hemolymph, into pheromone or antimicrobial compounds, the latter mainly in leaf-cutting ants. Still, the secretory cells of the metapleural gland of leaf-cutting ants exhibited several mitochondria near microvilli of the intracytoplasmic portion of the canaliculus, indicating an important role of the meta pleural gland in the production and transport of secretion in metapleural gland of leaf-cutting ants. Thus, our work corroborates other findings, however our results add that the slight ultrastructural dif ference in the metapleural glands of leaf-cutting ants can be due to the feeding type (fungus-growing ants), resulting in greater secretory capacity and antimicrobial properties to combat pathogens (for example, micro-fungi parasites Escovopsis).

The effects of social environment and the metapleural gland on disease resistance in acorn ants

“…Larger colonies may have more reliance on the MG [34], whereas T. curvispinosus colonies often containing under 100 workers. Previous research has also suggested more general importance of MG for fungal growing ant species, due to stronger pathogen pressure [43]. Perhaps removing MG gland function within a larger, fungal-growing species, would show stronger effects to social pathogen resistance.…”