Insecticidal Activity of Primary, Secondary and Maternally Linked Mutant Form Variants of Photorhabdus luminescens Cells on Galleria mellonella

Pathogenicity of P, M and Phase II form variants of Photorhabdus luminescens was tested by injecting 1, 10, 100, 500 and 1000 cells/4^th instar Galleria mellonella. Comparing the mortality between the P and M form cells, though it was relatively faster in P form cells with respect to all the 5 doses tested, there was no statistical difference between the two. Higher bacterial doses of 100, 500 and 1000 cells/larva were at par in their mortality pattern, whereas, the lower two doses of 1 and 10 cells/larva were found to be significantly different. Hundred per cent mortality was recorded with 100 cells/larva within 24 h in both the P form and M form variants. Injection with 1 cell/larva resulted in a maximum of 40% mortality after 42h in both the forms, while injection of 10 cells/larva resulted in a maximum 80% mortality after 48 h in P form and after 36 h in M form variant. In comparison to P and M form variants, the P II cell variants resulted in significantly poor mortality.