DISTRIBUTION AND BIOCONTROL POTENTIAL OF ENTOMOPATHOGENIC NEMATODES AGAINST SOME LEPIDOPTEROUS PESTS

Abstract

newline ABSTRACT newlineSurvey for entomopathogenic nematodes (EPNs) was conducted in ten districts of Himachal newlinePradesh during 2011-13. In all, 930 soil samples from 131 locations were analysed for the newlineoccurrence of the nematodes. The frequency of occurrence of these nematodes was very low newline(3.82%). The nematodes were found in five locations i.e. Sangla (Distt. Kinnaur), Kamand newline(Distt. Kullu), Rajgarh (Distt Sirmour), Rajour and Sutkar (Distt. Chamba). These localities newlineare situated in mid hill/high hill zones of the state. The nematodes were recovered from fruit newlineorchards only having lighter soils. The nematodes from all the locations were identified as newlineHeterorhabditis. Nematode cultures from different locations were considered as isolates and newlinewere designated as Sangla isolate, Kamand isolate , Rajgarh isolate , Sutkar isolate and newlineRajour isolate . Former three isolates, along with one commercial isolate i.e. H. indica newline(procured from NBAII, Bangluru) were evaluated for their pathogenic effects against newlineSpodoptera litura, Helicoverpa armigera, Plutella xylostella and Agrotis segetum in Petri newlineplates/soil/screen house. All these three local isolates including the commercial isolate newlineproved pathogenic variably to different insect-pests. In screen house testing on cabbage, newlineRajgarh isolate was found highly effective against S. litura, H. armigera and P. xylostella. newlineThe virulence of these isolates was considered of the medium level. The bacterium, newlinePhotorhabdus luminescence was associated with all the isolates and proved non pathogenic newlineto Achroia grisella when tested alone. Besides, host invasion studies in A. grisella revealed newlinemaximum penetration through natural openings, other than mouth. For in vivo mass newlineproduction of local EPNs, Corcyra cephalonica, A. grisella and Bombyx mori were used. newlineThe average yield of IJs/larva was minimum (23020-26030) in C. Cephalonica and newlinemaximum in B. mori (463080-546840) for different EPNs. For in vitro production, chicken newlineoffal medium was used. The yield was maximum for Rajgarh isolate (17.70 x 106 newlineIJs/flask).