Egyptian Journal of Plant Protection, 9(2): 11-20.2014 © Egyptian Society of Plant Protection.2014 INFLUENCE OF TWO PASTEURIA PENETRANS ISOLATES AT DIFFERENT APPLICATION TYPE ON ROOT-KNOT NEMATODES (Meloidogyne spp.) Mahdy, M. E. 1 ; Mousa, E. M. 1 and Heba Y. Al-Sisi 2 1 Dept. of Agric. Botany ,Fac. Of Agric., Minufiya Univ., , Shebin El-Kom, Egypt 2 Dept. Of Nematode Res., Inst. Of Plant Pathol., Agric. Res. Centre, Giza, Egypt ABSTRACT Two P. penetrans isolates namely: Pp Japanese and Egyptian were used at different three types: pp infected root powder, spore suspension and attached larvae as a biocontrol agent against root-knot nematodes, Meloidogyne spp. on tomato plants under greenhouse conditions. Results revealed that the effective treatment obtained with Pp Japanese isolate as a pp root infected powder, where all nematode parameters significantly reduced compared to plants treated with nematode alone. Egyptian isolate appeared promise result when applied also as a pp root infected powder and as a spore suspension. The lowest effect was noticed with Pp Japanese isolate when applied as attached larvae. Results indicate that the highest Pp infected females recorded with Pp Japanese isolate as a root powder, followed by Pp Egyptian isolate as a spore suspension, whereas the lowest Pp infected females recorded with Pp Japanese isolate as a attached larvae. Key words: Root-knot nematodes Meloidogyne spp.; Pasteuria penetrans; Tomato (Lycopersicon esculentum Mill). INTRODUCTION The root-knot nematodes (Meloidogyne spp.) are sedentary endoparasites and are among the most damaging agricultural pests, attacking a wide range of crops (Sikora and Grico, 1993). The infection starts with root penetration of second stage juveniles hatched in soil from eggs encapsulated in egg masses laid by the females on the infected roots (Barker et al., 1985). Chemical control is becoming more and more expensive because of increased costs in the synthesis of new compound and their use is increasingly undesirable because of environmental hazards associated with their application. Now some attention has been given to biological control of plant-parasitic nematodes with the use of natural enemies as a safe and cheap alternative method to chemical control (Gowen and Ahmed, 1990). Encouraging results were obtained with the use of Pasteuria penetrans as a biological control agent of nematodes on different crops (Zaki and Maqbool, 1991 a). P. penetrans is an endospore-forming, gram-positive bacterium that is considered an important parasite of several of the agriculturally important Meloidogyne spp. Within this bacterial species exist strains that are specific to species within the genus Meloidogyne even down to the host race level of the nematode (Chen and Dickson, 1998). The bacterium is an obligate parasite of root-knot nematode, and so it has not been successfully cultivated on artificial media although numerous researchers have made such attempts (Chen and Dickson, 1998). The Pp infected females was distinguished by their opaque dull creamy white to amber color compared to white healthy females of Meloidogyne spp. as described by Mankau and Imbriani (1975); Mankau and Prasad (1977). Infected females of Meloidogyne spp. can contain up to 2.5 million non- motile endospores (Hewlett and Dickson, 1993) that are released into the soil *corresponding author e-mail:Mahdymagdy@yahoo.com