Interaction of Xenorhabdus nematophilus subsp. nematophilus with the haemolymph of Galleria mellonella

The lethal dose (LD)₅₀ values and probit-mortality regression slopes of the primary and secondary forms of Xenorhabdus nematophilus subsp. nematophilus for Galleria mellonella were equal. The two bacterial forms grew at equal rates in larval serum-supplemented media. The secondary form grew less well in larval serum-supplemented media than in synthetic larval serum.The secondary bacteria adhered to the haemocytes to a greater extent than did the primary bacteria. Both types of bacteria did not produce metabolites suppressing the ability of the haemocytes to respond to Bacillus cerues.Differences were observed in the rate of clearance of the primary and secondary bacteria from and their subsequent re-entrance into the haemolymph in vivo. This appeared to be independent of bacterial metabolism. Evidence is presented showing multiplication of the primary bacteria during their association with the haemocytes.The total haemocyte counts increased during bacterial infection. All the haemocytes were killed. The rate and pattern of change of the total haemocyte counts was influenced by the form of bacteria and independent of bacterial metabolism.