Endophytes and mycoparasites associated with an indigenous forest tree, Theobroma gileri, in Ecuador and a preliminary assessment of their potential as biocontrol agents of cocoa diseases

The main constraint and continuing threat to cocoa production in Latin America is disease caused by two basidiomycete fungi belonging to the genus Crinipellis (Agaricales), both of which are currently on an invasive front. Classical biological control, in which coevolved natural enemies are considered to offer the most potential for sustainable control of invasive alien organisms, is investigated as a management strategy. Our initial approach has been to search for the suspected coevolved host (Theobroma gileri) of one of these pathogens, Crinipellis roreri, the causal agent of frosty pod rot, in the mesic forests of north-west Ecuador; to isolate the endophytes and mycoparasites associated with both host and pathogen; to screen selected fungi in the greenhouse and laboratory, in order to determine their biocontrol potential. Endophytes were isolated directly in the field from healthy tree boles and pods, and over 40 genera were recorded, mainly representing anamorphs of Hypocreales in the genera Acremonium, Clonostachys, Trichoderma and Verticillium, as well as basidiomycetes belonging to the Agaricales and Polyporales. Of the endophytic fungi tested, most can be inoculated into and recovered from asymptomatic cocoa seedlings. Twenty-eight mycoparasitic species were isolated from diseased pods and selected mycoparasites as well as endophytes were screened against C. roreri using the pre-colonised plate method. Consistently high mycoparasitism of the C. roreri pseudostroma was demonstrated, particularly by a complex of Clonostachys and Trichoderma species.