Constraints associated with taxonomy of biocontrol fungi

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Abstract
An increasing number of fungi are being collected and screened for the biological control of pests, but nomenclature, taxonomy, and correct identification of many of them remain problematic. Trichoderma spp. and the rust fungi are promising candidates for biocontrol agents, yet they present serious taxonomic problems. Several groups of entomopathogenic fungi are also potential biocontrol sources of agents. Genera such as Cordyceps, Aschersonia, Verticillium, Beauveria, and Metarhizium are in need of urgent revision. Before their release can be considered, all details of their complex life cycles and taxonomy have to be elucidated to satisfy quarantine authorities. Formerly, the taxonomy and identification of biocontrol fungi has been based largely on morphological structures, but molecular techniques have been introduced to provide more objective criteria. Beauveria and Metarhizium spp. have been subjected to several molecular techniques that have resolved phylogeny and species concepts. In Metarhizium, a high degree of genetic diversity is present. Incorrect typification, lack of holotypes, and poorly resolved life cycles and unclear teleomorph – (syn)anamorph connections are serious taxonomic contraints. Only a small fraction of the fungi that can be used for biological control has been examined. The destruction of habitats and ecosystems for these fungi will result in the disappearance of fungal germ plasm of potential value, not only for biological control but also as a source of novel metabolites. This loss and the decline of taxonomic expertise in the fungi are major problems. Key words: biocontrol, taxonomy, Trichoderma, Beauveria, Metarhizium, Cordyceps.