A team of scientists led by the Indian Institute of Spices Research (IISR), Kozhikode, have discovered a new species of insect pathogenic fungus with potential biocontrol application. The fungus, isolated from leafhopper pest of Malabar tamarind (Garcinia gummi-gutta), has been named Metarhizium indicum to indicate its Indian origin.
It is found to cause natural epizootics in the leafhopper pest of Malabar tamarind, an evergreen tree spice native to South and Southeast Asia. The discovery of this insect pathogenic fungus against leafhopper is expected to open new vistas of biological control against this pest group.
The scientists’ team behind the latest discovery comprises C.M. Senthil Kumar, T.K. Jacob, and S. Devasahayam from IISR Kozhikode, and K.C. Rajesh Kumar from Agharkar Research Institute, Pune. The finding has been published in the Journal of Invertebrate Pathology, a premier international journal that publishes findings on the diseases of invertebrates, including insects.
The team members point out that the leafhoppers cause significant economic damage directly as crop pests or indirectly as vectors of diseases across a variety of crops. According to them, fungi belonging to the genus Metarhizium are regarded as generalist insect pathogens with worldwide distribution and commonly known as green Muscardine fungus. Several commercial biocontrol formulations based on this fungus are available in the market for organic crop production, they add.
The scientists say the earlier characterisation and identification of Metarhizium species relied mainly on morphological traits, which in general, overlap the species of this genera which had resulted in underreporting of several cryptic species. With the advent of molecular tools, the diversity of this genus was exposed and many cryptic species were elevated as new species and added to the repository of Metarhizium fungi across the world.
Dr. Senthil Kumar, principal scientist with the team, says there is an urgent need for taxonomic re-evaluation of the reported species using modern molecular tools apart from exploiting the latent potential of the fungi. According to him, the focused explorations for identifying cryptic and unreported species can unravel the hidden diversity of Metarhizium in India and lay the foundation for development of several biocontrol formulations for the management of various crop pests, thereby reducing the reliance on harmful insecticides.
Further research in the area proves to be crucial as India has one-third of the global fungal diversity with more than 27,000 reported fungal species. However, taxonomic work on entomopathogenic fungi, especially those belonging to that of Metarhizium lineage, is very minimal, considering the diverse soil and climatic conditions of the Indian sub-continent. Kozhikode IISR Director R. Dinesh says the institute has plans to conduct further studies on the host range of the newly identified fungus against pests of global importance.