Journal of Zhejiang University SCIENCE
(ISSN 1009-3095, Monthly)

2005   Vol. 6B   No. 6   p.457-463

Pathogenicity of bacterium, Xenorhabdus nematophila isolated from entomopathogenic nematode (Steinernema carpocapsae) and its secretion against Galleria mellonella larvae

MAHAR Ali Nawaz¹, MUNIR Muhammad^†2, ELAWAD Sami¹, GOWEN Simon Richard¹, HAGUE Nigel Graham Meckenzi¹

(¹Department of Agriculture, University of Reading, Reading RG6 6AT, UK)
(²School of Plant Sciences, University of Reading, Reading RG6 6AS, UK)
^†E-mail: m_munir66@yahoo.co.uk
Received Sept. 16, 2004; revision accepted Dec. 24, 2004

Abstract: The entomopathogenic bacterium, Xenorhabdus nematophila was isolated from the hemolymph of Galleria mellonella infected with Steinernema carpocapsae. The bacterial cells and its metabolic secretions have been found lethal to the Galleria larvae. Toxic secretion in broth caused 95% mortality within 4 d of application whereas the bacterial cells caused 93% mortality after 6 d. When filter and sand substrates were compared, the later one was observed as appropriate. Similarly, bacterial cells and secretion in broth were more effective at 14% moisture and 25 °C temperature treatments. Maximum insect mortality (100%) was observed when bacterial concentration of 4×10⁶ cells/ml was used. Similarly, maximum bacterial cells in broth (95%) were penetrated into the insect body within 2 h of their application. However, when stored bacterial toxic secretion was applied to the insects its efficacy declined. On the other hand, when the same toxic secretion was dried and then dissolved either in broth or water was proved to be effective. The present study showed that the bacterium, X. nematophila or its toxic secretion can be used as an important component of integrated pest management against Galleria.

Key words: Biological control, Bacterial symbionts, Entomopathogenic nematodes, Xenorhabdus nematophila, Galleria mellonella
doi:10.1631/jzus.2005.B0457             CLC number: S43