Diversity of entomopathogenic bacteria associated with the white grub, Brahmina coriacea
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ORIGINAL PAPER
Diversity of entomopathogenic bacteria associated with the white grub, Brahmina coriacea Anupam Sharma • D. R. Thakur • Sarika Kanwar V. K. Chandla
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Received: 16 March 2012 / Accepted: 9 August 2012 / Published online: 26 September 2012 Ó Springer-Verlag 2012
Abstract A survey of potato fields located in the southeastern region of Himachal Pradesh (India) was carried out in order to find out the natural pathogens infecting the white grub, Brahmina coriacea. About 88 % population of the infected grubs were found to exhibit symptoms of natural bacterial infection during the years 2007–2008. Hence, we attempted to isolate and characterize the most potent bacteria for the management of B. coriacea and tested their insecticidal activity. In this study, ten different bacterial isolates belonging to genera Bacillus, Psychrobacter, Paracoccus, Paenibacillus, Mycobacterium, Staphylococcus and Novosphingobium were isolated from B. coriacea. Bacterial species were identified based on morphology, biochemical tests and homologies of 16S rRNA gene sequences. Pathogenicity tests for all isolated bacteria at 1.0 9 108 cfu/ml of broth were performed on late first instar grubs. Among the bacteria tested, Bacillus cereus induced highest mortality
Communicated by ‘‘Communicated by M. Traugott’’ . A. Sharma (&) S. Kanwar V. K. Chandla Division of Plant Protection, Central Potato Research Institute, Shimla, India e-mail: [email protected] S. Kanwar e-mail: [email protected] V. K. Chandla e-mail: [email protected] Present Address: A. Sharma Department of Agronomy, CSKHPKV, Palampur, HP, India D. R. Thakur Department of Biosciences, Himachal Pradesh University, Shimla, India e-mail: [email protected]
level of 51.85 % within 7 days of treatment followed by Psychrobacter pulmonis (33.33 %), Bacillus psychrodurans (25.93 %), Bacillus pumilus (25.93 %), Paenibacillus tylopili (22.22 %) and Novosphingobium capsulatum (18.52 %). Mortality levels were further increased up to 100 % by B. cereus followed by 88.89 % by P. pulmonis after 30 days of treatment. Our results indicate that B. cereus, P. pulmonis, B. psychrodurans, B. pumilus, P. tylopili and N. capsulatum may be valuable biological control agents for white grubs, B. coriacea. Keywords Entomopathogenic bacteria 16S rRNA genes Biochemical test White grub Potato
Introduction The geographical range of potato (Solanum tuberosum L.) is worldwide and is grown as a major source of food in most countries in temperate climates. Since potato is not a native crop of the sub-tropical region, it is therefore susceptible to many diseases and pest attacks prevalent in abundance in such agro-climates. Potato growing areas located in the north-western hills of India suffer serious damage by soil-dwelling pests belonging to the order Coleoptera including Brahmina coriacea (Hope) (Coleoptera: Scarabaeidae) (Sushil et al. 2008). Initially, first instar grubs of B. coriacea feed on the mother tuber and roots of developing plants. Second instar grubs tend
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