Potential of Lecanicillium spp. for management of insects, nematodes and plant diseases

Fungi in the genus Lecanicillium (formerly classified as the single species Verticillium lecanii) are important pathogens of insects and some have been developed as commercial biopesticides. Some isolates are also active against phytoparasitic nematodes or fungi. Lecanicillium spp. use both mechanical forces and hydrolytic enzymes to directly penetrate the insect integument and the cell wall of the fungal plant pathogen. In addition to mycoparasitism of the plant pathogen, the mode of action is linked to colonization of host plant tissues, triggering an induced systemic resistance. Recently it was demonstrated that development of Lecanicillium hybrids through protoplast fusion may result in strains that inherit parental attributes, thereby allowing development of hybrid strains with broader host range and other increased benefits, such as increased viability. Such hybrids have demonstrated increased virulence against aphids, whiteflies and the soybean cyst nematode. Three naturally occurring species of Lecanicillium, L. attenuatum, L. longisporum, and an isolate that could not be linked to any presently described species based on rDNA sequences have been shown to have potential to control aphids as well as suppress the growth and spore production of Sphaerotheca fuliginea, the causal agent of cucumber powdery mildew. These results suggest that strains of Lecanicillium spp. may have potential for development as a single microbial control agent effective against several plant diseases, pest insects and plant parasitic nematodes due to its antagonistic, parasitic and disease resistance inducing characteristics. However, to our knowledge, no Lecanicillium spp. have been developed for control of phytopathogens or phytoparasitic nematodes.