Ljm. Gerritsen et al., PATHOGENICITY OF NEW COMBINATIONS OF HETERORHABDITIS SPP. AND PHOTORHABDUS-LUMINESCENS AGAINST GALLERIA-MELLONELLA AND TIPULA-OLERACEA, Biological control (Print), 13(1), 1998, pp. 9-15
Photorhabdus luminescens isolates were exchanged between four entomopa
thogenic nematode strains; two isolates of Heterorhabditis megidis fro
m The Netherlands and two isolates of H. bacteriophora, one from Austr
alia and one from Moldavia. When cultured on H. megidis symbionts only
few H. bacteriophora infective juveniles retained the symbiotic bacte
rium. These infective juveniles, without symbiotic bacteria, were not
pathogenic to insects. When P. luminescens was injected into insect la
rvae it could kill Galleria mellonella (Lepidoptera: Galleridae) larva
e but it was not pathogenic to Tipula oleracea (Diptera: Tipulidae). T
he combination of nematode and bacterium killed T. oleracea, showing t
hat the nematode is more than just a vector for the bacterium. Small d
ifferences in pathogenicity between the combinations could only be obs
erved in T. oleracea, not in the highly susceptible G. mellonella. The
pathogenicity of a combination depends on the pathogenicity of the ba
cterium, the pathogenicity of the nematode and the interaction between
them. The pathogenicity of H. bacteriophora strains against T. olerac
ea was low, partly because of the low penetration rate of these strain
s. (C) 1998 Academic Press.