Production of viable and infective inoculum of Coccodiella miconiae (Ascomycota: Phyllachoraceae) for the biological control of Miconia calvescens

Abstract

Miconia calvescens is a small tree from the Neotropics that has become an aggressive invader of forest ecosystems in the Pacific. Classical biological control is the sole sustainable method for controlling such invasions. Among the numerous pathogens that have been found on miconia, the fungus Coccodiela miconiae stands out as a very promising biocontrol agent. It is often found in native situations causing a severe disease (yellow pustule) despite being commonly intensively attacked by a series of mycoparasites. However, the fungus is not easily manipulated and is difficult to preserve under controlled conditions because it is a strict biotroph. Elucidation of details of the biology of C. miconiae is needed to allow for its use in biological control. Herein results of a broad range of tests that were performed are presented. Such tests aimed at determining: (1) an efficient method for obtaining viable and infective ascospores; (2) effect of temperature, light and other factors on ascospores; (3) a protocol for plant inoculation. It was concluded that ascospores are efficiently obtained when mature stromata are detached from leaves and agitated in water for 3–4 h and that such suspension is infective when used immediately. Ascospore germination was favored by incubation at 25 °C under a 12 h of light/12 h dark regime. A protocol for inoculation of C. miconiae is described. These findings indicate that it may now be possible to manipulate C. miconiae as a classical biocontrol agent.