Null Hyper-Parasitism, a Threat for Successful Biological Control Management

Abstract

Null hyper-parasitism, a new term is coined by the author to define the hyper-parasitism by a microbial agent on another hyper-parasite. The novel phenomenon of null hyper-parasitism was discovered in the in vitro and in vivo experimentation, where the bio-control agent Trichoderma hamatum hyper-parasitic on Sclerotium rolfsii, a foot rot pathogen of groundnut, was hyper-parasitiosed by a microbial strain of Aspergillus niger and Bacillus thermophillus. Here A. niger and B. thermophillus as null hyper-parasite nullified the bio-control action of hyper-parasite Trichoderma hamatum on Sclerotium rolfsii. The in vivo experimentation suggest that such type of null hyper-parasitism exist in soil ecosystem, may be to maintain the natural microbial equilibrium and extinction of a microbial species from nature due to presence of hyper-parasite and its antagonistic or bio-control activity as evident in the above case of parasite/pathogen S. rolfsii, its hyper-parasite T. hamatum and null hypersite A. niger and B. Thermophillus. Now, therefore the success of the bio-control or hyper-parasitism of soil borne fungal plant pathogen by Trichoderma sp may be dependent on the non- existence of null hyper-parasite in the soil ecosystem where the hyperparasite has to be used.