OCCURRENCE IN THE SOIL AND DISPERSAL OF Lecanicillium lecanii, A FUNGAL PATHOGEN OF THE GREEN COFFEE SCALE (Coccus viridis) AND COFFEE RUST (Hemileia vastatrix)

Abstract

The fungus Lecanicillium lecanii attacks the green scale (Coccus viridis), a pest of coffee, and is also a hyperparasite of coffee rust (Hemileia vastatrix). Knowledge of the epizootiology of this fungus is potentially important for conservation biological control in coffee agroecosystems. The presence of viable propagules of L. lecanii in the soil, a possible environmental reservoir, was assessed using two baiting methods: the standard Galleria mellonella bait method and a C. viridis bait method. Infectious propagules of L. lecanii were detected in soil samples taken from a 45 ha study plot, both nearby and far from recent epizootics of L. lecanii. To test the potential for the transmission of L. lecanii conidia from the soil via rain splash or wind, coffee seedlings with populations of C. viridis were placed near L. lecanii-inoculated soil and then subjected to artificial rain and wind treatments. Rain splash was shown to be a potential transmission mechanism. Dispersal of L. lecanii conidia by the ant Azteca instabilis was tested using field and laboratory ant-exclusion experiments. Azteca instabilis was shown to transport conidia of L. lecanii; however, dispersal by A. instabilis may not be important under field conditions.