Indirect biological control of the coffee leaf rust, Hemileia vastatrix, by the entomogenous fungus Lecanicillium lecanii in a complex coffee agroecosystem

The entomopathogenic and mycoparasitic fungus Lecanicillium lecanii is known to attack both the green coffee scale, Coccus viridis, and coffee leaf rust, Hemileia vastatrix. Using multi-year surveys of L. lecanii and H. vastatrix prevalence, we demonstrate a previously unreported, one-year time lag between local epizootics (outbreaks) of L. lecanii and significant suppression of H. vastatrix. Epizootics of L. lecanii are associated with large populations of C. viridis, which are in turn associated with colonies of their mutualistic partner, the arboreal-nesting ant Azteca instabilis. Therefore, these results suggest that effective conservation biological control of H. vastatrix using L. lecanii will be enhanced by an understanding of the self-organization process that gives rise to the emergent spatial distribution of the A. instabilis-C. viridis mutualism in this complex coffee agroecosystem. (C) 2012 Elsevier Inc. All rights reserved.