A method for culturing the entomopathogenic nematodes Steinernema kraussei and Heterorhabditis brevicaudis mononucleosis nematodes

The present study aimed to develop a method for culturing mononucleosis nematodes (MONO- nematodes) using the symbiotic bacteria (SB) of these nematodes, providing a basis for examining nematode pathogenicity and collecting infective juveniles (IJs). SB were isolated from two EPN strains collected from the Gansu Province: Steinernema kraussei, which is highly resistant to low-humidity stress, and Heterorhabditis brevicaudis, which is sensitive to low-humidity stress. The isolated bacteria were purified and cultured on NBTB. Subsequently, single colonies of SB were transferred to LB medium. Thereafter, the SB were incubated on LB medium with a gravid nematode female, which was collected from the body of an infected wax worm, and cultured to collect IJs. Therefore, the SB of S. kraussei 0657L and H. brevicaudis 0641TY could be isolated using the method described here and IJs could be collected through culture with these SB. The proposed protocol can serve as a simple, rapid, and accurate method to collect IJs of MONO- nematodesdirectly isolating the gravid nematode females from infected wax worms and incubating them with purified SB.