Antifungal Activity of Defensive Secretions of Certain Millipedes

ABSTRACT

The defensive secretions of certain polydesmid millipedes exhibited antifungal activity by suppressing mycelial growth and spore germination of ten different fungi isolated from millipedes and adjacent soil. A group of compounds designated as system I, identified from members of the Xystodesmidae, consisted of benzaldehyde, benzoic acid, benzoyl cyanide, and mandelonitrile benzoate. Benzoic acid and benzoyl cyanide were the best inhibitors of mycelial growth and spore germination, usually acting at concentrations of 250, 500, or 1000 μg/ml. A mixture of the four defensive compounds (total of 125 μg/ml) suppressed spore germination more effectively than the individual compounds and appeared to function synergistically. Ethyl benzoate, guaiacol, and phenol were designated as system II as reported for Oxidus gracilis. In spore germination tests, phenol generally caused maximum inhibition at concentrations of 500 to 1000 μg/ml, whereas the other compounds were less effective. A mixture of the defensive compounds did not improve suppression of spore germination.

Key Words:

• cyanogenetic compounds
• defensive secretions
• polydesmid millipedes