Department of Entomology, CSKHPKV, Palampur-176062
National Symposium on Strategic Issues in Plant Pathological Research held at Department of Plant Pathology, CSK HP Krishi Vishvavidayalaya, Palampur on November 24–25, 2011
White grubs are most destructive and troublesome soil insects being highly polyphagous and capable of causingserious damage to a wide variety of agricultural crops. The white grubs are difficult to control by soil application of insecticides because they go deep into the soil. Entomopathogenic fungi are considered as the novel candidates for white grub management, because good moisture is available in soil during rainy season which helps in regular multiplication of fungus under natural field conditions. In Himachal Pradesh, Beauveria bassiana (Bals.) is frequently found to infect white grubs. During 2009–2010, large numbers of samples were collected to isolate local entomo-pathogens from white grubs. In total, 1730 grubs were collected from 12 locations of Himachal Pradesh, out of which 11.16 per cent grubs were found to be infected with B. bassiana maximum at Kheradhar. Most of the infected white grubs were identified as that of Brahmina coriacea (Hope). The infected grubs on incubation at 26±1°C showed the presence of white mycelia growth of fungus on their body. In potato dextrose agar medium culture, white fungal growth was observed in grub infected samples and pathogenicity tests on healthy grubs proved the pathogenic behavour of the isolated The morphology of the fungus was studied under compound microscope and identified as Beauveria bassiana (Bals.) based on standard descriptive keys. Growth pattern on insect body was usually characterized by formation of loose or tough mycelial mat with cushions or areas of conidial structures. Sympodial conidium development was found in B. bassiana. The conidia were formed solitarily on a laterally proliferating conidiogenous cells, often showing a geniculate or “zig-zag” type of elongation. Conidia were globose to subglobose (2.0–3.0x2.0–2.5µm) and conidiogenous structures formed dense clusters. This fungus seems to hold considerable potential to contain population of white grubs in endemic areas.
