Digestion of chitin by the labial glands of Acromyrmex octospinosus Reich (Hymenoptera: Formicidae)

Abstract

The capability of the attine ant, Acromyrmex octospinosus, to digest chitin was studied. β-N-Acetylglucosaminidase, chitobiase, and chitinase activities of labial gland extracts were demonstrated. The biochemical characteristics (pH optimum, Michaelis constant, temperature influence) were investigated and the results are discussed in comparison with published data. The absence of microflora in the labial glands suggests the direct production of the chitinolytic system by labial glands. Its function in the digestion of the chitinous symbiotic fungus walls was examined. Effective degradation of this fungal material has been demonstrated in the infrabuccal pocket. Acromyrmex octospinosus appears to have adapted to a fungus diet by synthesis of specific enzymes. This result is discussed in relation to a previous hypothesis concerning mycophagous insects. Some hypotheses regarding the role of the chitinolytic activities are formulated.