Abstract: The tolerance of six commercially produced entomopathogenic nematodes, namely Steinernema carpocapsae All, S. feltiae SN, S. longicaudum X-7, S. glaseri KG, Heterorhabditis bacteriophora H06, and H. indica LN2, to abiotic stresses(high temperature, low temperature, low humidity, osmotic pressure, UV-B radiation, and hypoxia) was evaluated through measuring their survival and pathogenicity. The results showed that S. longicaudum X-7 and S. glaseri KG exhibited strong tolerance to temperature stress, with survival rates exceeding 97.92% after exposure to 40 ℃ for 2 h or -5 ℃ for 36 h. In contrast, the two Heterorhabditis species displayed poor temperature tolerance, with survival rates dropping to below 6.93% under 40 ℃ for 2 h and -5 ℃ for 12 h. Regarding desiccation stress, S. carpocapsae All demonstrated favorable adaptability to high humidity, achieving a survival rate of 57.09% after 24 h exposure to 85% relative humidity. Under osmotic stress, H. indica LN2 showed the weakest tolerance, with a survival rate of merely 2.57% after 96 h treatment in osmotic solution. Following UV-B radiation exposure, S. carpocapsae All and S. longicaudum X-7 exhibited relatively strong resistance. After 120 h of hypoxia treatment, the survival rates of S. feltiae SN and H. bacteriophora H06 decreased to 23.46% and 15.72%, respectively. Additionally, both high temperature and UV-B radiation negatively affected the nematodes' pathogenicity to varying degrees. In conclusion, the six nematode species display distinct tolerance profiles to abiotic stresses, and these findings provide a scientific basis for optimizing storage and transportation conditions during industrial production and for guiding the precise field application of these nematodes as commercial formulations.

Key words: entomopathogenic nematodes, biological control, abiotic factors, environment