NEW RECORD OF AN ENTOMOGENOUS FUNGUS, Aspergillus niger, ON TEAK LEAF SKELETONIZER, Eutecfona machaeralis (WALKER) AND ITS PATHOGENECITY

摘要

Leaf skeletonizer, Eutectona machaeralis (Walker), is a key pest of teak (Tectona grandis L.f.), responsible for severe defoliation in nurseries, plantations and natural forests. During the recent survey (2008-2009) in teak forests of Madhya Pradesh,larvae of this pest collected from Moiyanala, Mandla Forest Division, were found to be severely (3-8 percentr) infested by a fungus in nature at the time of epidemic outbreak. The infested fungus was isolated on potato dextrose agar (PDA) medium in laboratory and identified as Aspergillus niger Tiegh. (Ascomycetes : Eurotiomycetes : Eurotiales : Trichocomaceae). To confirm the field observations, the native fungus grown on different infested larvae collected from the teak forests were tested for its pathogenecity against the larvae of this insect in laboratory. Results revealed that the fungus is highly pathogenic to induce larval mortality when applied on host plant leaves and larvae together of the insect pest. The minimum concentration for cent percent larval mortality within five days after inoculation was recorded to be 1.5 x 10~7 spore/ml and significantly (P<0.05) different from other treatments including control. The results have been discussed in the light of the pathogenecity of this fungusagainst the target insect pest.