Myco-Biocontrol of Red Spider Mite (Oligonychus Coffeae,Nietner) Using Metarhizium Anisopliae.

Abstract

The red spider mite Oligonychus coffeae, Nietner is considered to be one of the major pest of tea in North East India which leads to considerable loss of crop yield. Considering ill effects of chemical pesticides on human health and environment it is essential for exploration of biological solution to solve the problem of tea red spider mite. Entomopathogenic fungi are a group of fungal organisms associated with insects and extensively used in various parts of the world as biopesticides against economic important insect pests. The present study is intended to find potential indigenous entomopathogenic fungi from highly diverse tea growing area and further to develop as a biocontrol agent. Entomopathogenic fungi were isolated from Tea growing soil by using Insect Bait technique. Further, from the isolated entomopathogenic fungus Metarhizium anisopliae was selected for its wide availability and prior knowledge as the natural enemies of a number of different pests. In this study, laboratory evaluation was made on the impact of the entomopathogenic biocontrol agent Metarhizium anisopliae on various stages of red spider mite. In the pathogenicity experiments, Oligonychus coffeae were exposed to fungal spore concentrations (10 6 , 10 7 , 10 8 , and 10 9 spores/ml). The isolate of Metarhizium anisopliae shows higher degree of virulence against tea red spider mite. The total mortality percentage of red spider mite caused by Metarhizium anisopliae ranged from 60% to nearly 90% in all the stages within 2 to 3 days. After the application of Metarhizium anisopliae spore suspension, the highest percentage of egg 90.4%, nymph 92% and adult 90% mortality was recorded within 2-2.6days at the spore load of 10 8 spores/ml. Dose dependent variability also observed in the mortality of Oligonychus coffeae. Metarhizium anisopliae spore load 10 8 has detrimental effects on mortality of Oligonychus coffeae. The laboratory findings confirms the biocontrol properties of the tarhizium anisopliae against all stages of tea red spider mite and suggested the feasibility for effective biocontrol of the pest in Tea crop. The Metarhizium anisopliae considered to be a most valuable biocontrol agent in the tea growing region of North East India. FTIR studies show the position of the hydroxyl group and carbonyl (C=O) groups play important roles in insecticidal activity of Metarhizium anisopliae.