Microorganisms for sustainable tea cultivation in the north east India: recent advances

Sustainable tea cultivation rely more on adopting alternative control strategies for effective pest management in an environment-friendly way which could replace some insecticides and thereby reduce the amount of pesticide residues in made tea. Hence, entomopathogens can play a vital role by providing effective control of target pests, conservation of natural enemies and biodiversity in tea ecosystem, an attempt has been made to isolate Beauveria spp and Metarhizium spp from Darjeeling and Dooars tea plantations and identified two potential isolates namely (BKN 1/14 as Beauveria bassiana and (MET 5/1) as Metarhizium anisoplae. Stock suspension was prepared at concentration 1 x 108 CFU/ml, further diluted to 0.25%, 0.5%, 0.75% and 1% using distilled water were sprayed on different life stages of tea mosquito, as well as red spider mite. A Baculovirus, belonging to the group Nucleopolyhedrosis Virus (NPV) which infects the Hyposidra talaca larvae has been isolated, identified, and characterized. Based on the findings of the laboratory studies, these beneficial microbial were developed in to a 5% AS formulations by the industry partner, following standard protocol. The developed 5% AS formulations were evaluated their field bio-efficacy under in vivo conditions following the standard operational procedure (SOP) in three different locations against tea mosquito, red spider mite and lopper with encouraging results in comparison to commercial samples. All the three formulations were found to be non-phytotoxic to the tea plants, safer to the insect natural enemies, there is no tainting effect on made tea and were found to have a longer shelf life at room temperature without any change in their bio-efficacy. These strains could be commercialized after fulfilling the requirements for its registration and label claim on tea for the benefit of the tea industry.

Author(s): Azariah Babu

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