Evidence for hyperparasitism of coffee rust (Hemileia vastatrix) by the entomogenous fungus, Lecanicillium lecanii, through a complex ecological web

The entomogenous fungus, Lecanicillium lecanii is hyperparasitic on Hemileia vastatrix, the cause of coffee leaf rust in the laboratory, and has frequently been observed attacking it in the field. The existence of a complex ecological web involving the spatially clustered mutualism of an ant (Azteca instabilis) with a scale insect (Coccus viridis), where the scale insect was infected by L. lecanii, prompted a search for a spatial correlation between the attack of L. lecanii on the scale insect and the incidence of rust in a commercial coffee crop. A weak but statistically significant effect of hyperparasitic control of coffee rust was observed on two distinct scales: in a 45-ha plot and on a scale of approximately 10 in. It was concluded that this effect was linked to an indirect effect of the ant-coccid mutualism, where L. lecanii was a parasite of the coccid.