ENTOMOPATHOGENICITY OF PHOTORHABDUS BACTERIA AGAINST PULSE BEETLE, CALLOSOBRUCHUS CHINENSIS L. (BRUCHIDAE: COLEOPTERA) IN CHICKPEA GRAINS

Abstract

Pulse beetle, being cosmopolitan is responsible for severe losses in lentil, maize, cowpea, mung bean and sorghum. In chickpea, 50 to 60 percent losses in seed weight and 46 to 66 percent protein losses have been recorded due to severe attack of Callosobruchus chinensis. Indiscriminate use of pesticides and fumigants to control pulse beetle has resulted in insecticide resistance, environmental hazards, residual toxicity and pest resurgence so the control trends have been changed and particularly biological control measures have attained high significance like entomopathogenic bacteria were used as alternate bio-control agents against this serious pest. During this research the pathogenicity of entomopathogenic bacteria Photorhabdus temperate was observed against pulse beetle at different concentrations. Bacterial culture was grown in Luria broth agar at 25°C in incubator, and then it was multiplied in neutralized distilled water medium to get single colonies of bacteria on this medium. Initially, concentrations 8×107 and 5.6×107 cells/ml of P. temperate were obtained by counting no. of cells using spectrophotometer. After that we diluted these bacterial concentrations into required concentrations like 1×106, 1×107 and 1×108 cells/ml. The concentration 1×108 cells/ml was reported as the highly efficient in controlling the fecundity with the minimum 4.82 eggs/grain. The least number of F1adults (12.1) was observed at this bacterial concentration. The same concentration showed minimum damage in terms of holes development in grains. Results revealed that the higher concentrations were more effective than the lower concentrations of entomopathogenic bacteria. The findings of the research provided an effective and safe biological control measures and in future will lead to an effective IPM programme for this economic pest.