Natural Incidence Of Hirsutella Thompsonii Fisher on the Coconut Eriophyid Mite, Aceria Guerreronis Keifer in Certain Districts of Karnataka and Tamil Nadu in India

Abstract

Hirsutella thompsoni Fisher was found to be widespread in the three districts of Karnataka (Bangalore Rural. Mandya and Kolar) and one in Tamil Nadu (Coimbatore) during the surveys conducted. The incidence of the pathogen was the highest in Coimbatore where 17.19 per cent of mite-infested coconut samples yielded the fungus. The presence or the fungal pathogen was the lowest in Bangalore rural district. where only 1.37 per cent of the samples showed the occurrence. The average incidence of H.thompsonil in mite-infested coconuts was 6.85 per cent. In Kamataka. only Mandya district showed significant presence (6.22 %) of the fungus. Overall, 7.03 per cent of the population of mites was infected with H.thompsonii. The nymphal stages (9.34%) were found to be more susceptible than the adults (4.72%). The consistent association ofthe fungus with the mite in the two states surveyed indicates that augmentation of the pathogen in the form of a rnycoacaricide may result in artificial epizootics.