Pathogenicity of Aspergillus Niger and Aspergillus flavus on red spider mite (Oligonychus coffeae Nietner), a serious pest of tea

Abstract

Red spider mite, Oligonychus coffeae Nietner is one of the most serious pest of tea plantation in Northeast India. In order to evaluate the pathogenicity of entomopathogenic fungi against this pest, mite populations were maintained in the laboratory by detached leaf culture method. Aspergillus niger and Aspergillus flavus were isolated from dead spider mites collected from Tongani tea garden located in Mangaldai, Assam and identified. The bioassay was carried out by spraying the mites with three different conidial concentrations of 1x10 6 , 1x10 7 , 1x10 8 conidia/ml and 0.01% Tween 80 which was used as blank control. Each concentration was replicated three times comprising of 20 mites in each replicate. Results showed that A. niger was highly pathogenic and recorded highest mortality of 91.11% after 96 hrs. LC50 and LT50 values for A. niger was recorded to be lower than that of A. flavus thereby indicating that A. niger was more pathogenic to red spider mite population.