Experimental evidence for the costs and hygienic significance of the antibiotic metapleural gland secretion in leaf-cutting ants

  title={Experimental evidence for the costs and hygienic significance of the antibiotic metapleural gland secretion in leaf-cutting ants},
  author={Michael Poulsen and Adrianne N. M. Bot and Mogens Gissel Nielsen and Jacobus J. Boomsma},
  journal={Behavioral Ecology and Sociobiology},
Abstract. The paired exocrine metapleural glands present in the large majority of ant species produce compounds with antibiotic properties. In the leaf-cutting ant, Acromyrmex octospinosus, the secretion consists of more than 20 different compounds and it has generally been assumed that the glands serve as a general defence against various infectious microbes of fungal and bacterial origin. We present results illuminating the direct costs and benefits of these metapleural gland defences in A… 

Variable sensitivity of fungi and bacteria to compounds produced by the metapleural glands of leaf-cutting ants

The mutualistic fungus was sensitive to all classes of compounds, which suggests that defence via metapleural gland secretion is under constraint when the protection of the fungus garden is concerned.

The effect of metapleural gland secretion on the growth of a mutualistic bacterium on the cuticle of leaf-cutting ants

The age-dependent abundance of the bacterium and its partial dependence on metapleural gland secretion support the hypothesis that the abundance of this mutualist is actively regulated.

Regulation and specificity of antifungal metapleural gland secretion in leaf-cutting ants

The MG defence system of leaf-cutting ants has characteristics reminiscent of an additional cuticular immune system, with specific and non-specific components, of which some are constitutive and others induced.

Functional role of phenylacetic acid from metapleural gland secretions in controlling fungal pathogens in evolutionarily derived leaf-cutting ants

It is hypothesized that changes in Atta ants form larger colonies with more extreme caste differentiation relative to other attines, in societies characterized by an almost complete absence of reproductive conflicts, are associated with unique evolutionary innovations in chemical pest management that appear robust against selection pressure for resistance by specialized mycopathogens.

Active use of the metapleural glands by ants in controlling fungal infection

Ants selectively groom their MGs when disease agents are present, suggesting that they also selectively use their MG secretions, which has important implications for understanding the evolution of hygienic behaviour in social groups.

Differential resistance and the importance of antibiotic production in Acromyrmex echinatior leaf-cutting ant castes towards the entomopathogenic fungus Aspergillus nomius

Results of this study indicate that the relatively large glands in small workers makes this caste particularly well adapted to preventing pathogenic microorganisms from entering the colony.

Weaving resistance: silk and disease resistance in the weaver ant Polyrhachis dives

The results in combination suggest that silk in P. dives is unlikely to provide protection against parasites and that it is also not a hygienic substrate, and alternative explanations may be needed for the loss of the metapleural gland in weaver ants.

Antimicrobial Defense Shows an Abrupt Evolutionary Transition in the Fungus-Growing Ants

A comparative analysis of the size of the gland reservoir across the fungus-growing ants suggests that the relationship between leaf-cutting ants and their parasites is distinctly different from that for other attine ants, in accord with the hypothesis that multiple mating by queens evolved to improve colony-level disease resistance.

The metapleural gland of ants

A synthetic approach integrating functional morphology, phylogenetic transitions and chemical ecology of the MGs of both the derived and the unstudied early‐branching (basal) ant lineages is needed to elucidate the evolutionary origin and diversification of the MG of ants.



Metapleural Gland Secretion of the Leaf-cutter Ant Acromyrmex octospinosus: New Compounds and Their Functional Significance

A comprehensive analysis of metapleural gland secretions of Acromyrmex octospinosus using a recently developed method for the analysis of polar compounds by gas chromatography and mass spectrometry shows that the chemical identity and quantitative recovery of different compounds in the metapeural gland secretion depends upon the method used and the type of colony from which the samples are taken.

Antibiotic Production: a Possible Function for the Metapleural Glands of Ants (Hymenoptera: Formicidae)

In this species, experimental and control spores germinated at approximately equal rates, but the secretions significantly reduced subsequent hyphal growth, which is consistent with the hypothesis that the metapleural gland is a source of antibiotic.

Mutualistic bacteria and a possible trade-off between alternative defence mechanisms in Acromyrmex leaf-cutting ants

Two sympatric species investigated, Acromyrmex octospinosus and A. echinatior, have quantitatively different combinations of these defence mechanisms, suggesting that the optimal investment in alternative defence mechanisms in different ant species depends on differences in caste allocation or parasite pressure.

Vergleichende Untersuchungen zur Funktion der Ameisenmetathorakaldrüse

It is concluded that the metapleural gland contents function as an antiseptic, with the exception of the gland fluid of Cremastogaster inflata, which was found to suppress the growth of Escherichia coli.

The epizootiology of a Metarhizium infection in mini‐nests of the leaf‐cutting ant Atta sexdens rubropilosa

The results suggest that the social stress caused by even such a short‐lived Metarhizium epizootic was sufficient to cause the decline and ultimate death of the mini‐nests, and demonstrates how important the social homeostasis of the colony is to leaf‐cutting ants.

Variable metapleural gland size-allometries in Acromyrmex leafcutter ants (Hymenoptera: Formicidae)

Variation in the relative size of the metapleural gland (bulla) was analyzed for workers of two sympatric but genetically differentiated species from the Acromyrmex octospinosus species complex, showing that a significant proportion of the individual variation was due to among colony differences.

Fungus-growing ants use antibiotic-producing bacteria to control garden parasites

A new, third mutualist in this symbiosis is described, a filamentous bacterium (actinomycete) of the genus Streptomyces that produces antibiotics specifically targeted to suppress the growth of the specialized garden-parasite Escovopsis.


The differences in growth trajectories between spined and less-spined colonies detected in the field were small relative to those predicted from short-term laboratory experiments, emphasizing the importance of field studies to evaluate the costs of defense in nature.

Waste management in leaf-cutting ants

Evidence is provided for the importance of effective waste management in colonies of several Panamanian species of Atta and Acromyrmex leaf-cutting ants, differing in colony size and typical mode of waste accumulation (external or internal dumps).