Pathogenicity, development, and reproduction of Heterorhabditis bacteriophora and Steinernema carpocapsae under axenic in vivo conditions

Galleria mellonella larvae cultured axenically were treated with axenic dau er juveniles of Heterorhabditis bacteriophora and Steinernema carpocapsae, After 3 days S. carpocapsae had killed all insects, with 9.4 +/- 4.3 nemato des per larva. H. bacteriophora were unable to kill G. mellonella, although 13.3 +/- 6.4 nematodes per Galleria were found in the hemocoel. Invading n ematodes of both strains recovered from the dauer stage. H. bacteriophora d eveloped into hermaphrodites with eggs and J1 in the uterus and in the hemo lymph of the living insects. Development beyond the J1 stage was not record ed. An. injection of supernatants from different Photorhabdus luminescens c ultures killed the insects but could not provide nutrients to support a fur ther development. Only the injection of bacterial cells supported productio n of dauers in the axenic insects. Axenic S. carpocapsae developed to adult s and produced offspring. After 3 weeks an average of 5275 nematodes per la rva were counted, of which 6.7% were dauer juveniles, 39.2% other juvenile stages, 11.9% males, and 42.2% females. Compared to in vivo reproduction in the presence of the symbiotic bacterium Xenorhabdus nematophilus the dauer juvenile yields were low. Even after 5 weeks the percentage of dauer juven iles did not surpass 10%. (C) 200 Academic Press.