Significance of Achromobacter nematophilus Poinar and Thomas (Achromobacteraceae: Eubacteriales) in the development of the nematode, DD-136 (Neoaplectana sp. Steinernematidae)

Abstract

By culturing Galleria mellonella, Neoaplectana sp. (DD-136) and Achromobacter nematophilus separately under axenic conditions in the laboratory, it was possible to study the relationship between the bacterium and nematode during nematode parasitism of the insect. The infective-stage juveniles of the nematode were able to penetrate and kill the insect host without the presence of A. nematophilus or any other bacterium. However, without accompanying bacteria the nematode was unable to reproduce. Only when A. nematophilus or a possible replacement, such as Pseudomonas aeruginosa, was added to the blood did reproduction occur. The relationship between A. nematophilus and the nematode is considered a mutualistic one, since the bacterium lives and is protected inside the intestine of the free-living stage of the nematode and is transported and released by the nematode to the haemolymph of a host insect. The nematode, in turn, is dependent on the bacterium for reproduction.