Investigation on comparison of heat and drought tolerances of the entomopathogenic nematode Heterorhabditis bacteriophora HBH hybrid strain after in vivo and in vitro productions

Studies and commercial productions on entomopathogenic nematodes (EPN), which have an important place in biological control, have progressed significantly since the 1970s. The wide range of pests it affects, the ability to search for its host under the ground, and the fact that it is not harmful to the environment and human health have caused it to be among the alternative methods. Although EPNs can be as effective as pesticides when suitable environmental conditions are provided, abiotic factors such as temperature, oxygen content and soil moisture affect their lives in open field applications. Temperature and drought are the most important environmental factors affecting the survival of nematodes. EPNs are generally produced by two different methods, in vivo and in vitro. In this thesis, infective juveniles (IJs) of Heterorhabditis bacteriophora (HBH) strain obtained by in vivo or in vitro production methods were exposed to different heat and drought values in order to determine their tolerance. Mortality rates (about 2%) obtained by exposing IJs obtained by in vivo and in vitro production method to temperatures of 32, 34 and 36°C for 2 hours were found to be at the same statistical level. Mortality rates increased as the exposure temperature rose above 37°C. To determine drought tolerance, PEG 600 was applied against IJs at ten different concentrations (10, 20, 30, 40, 50, 55, 57.5, 60, 70 and 80) over a 24-hour period. When IJs obtained by in vivo or in vitro production method were exposed to PEG 600 concentration of 50% and above, mortality rates started to increase statistically.