Tolerances of hybridized entomopathogenic nematode Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) strains to heat and desiccation

Heat and desiccation are two major problems of entonnopathogenic nematodes (EPNs) for outdoor applications. The factors decrease their survival and effectivity in the field. Thus, the success ratio drops dramatically especially in hot and drought prone regions. Hybridization of EPNs is a way to overcome these major stress problems. In the present study, heat and desiccation tolerances of ten hybrid strains, which were hybridized from six domestic strains isolated from different climatic regions in Turkey, were determined. The heat tolerance experiments were performed at 32, 34, 36, 38, 40 and 42 degrees C and desiccation tolerance experiments were performed at Poly Ethylene Glycol (PEG) concentrations of 10, 20, 30, 40, 50, 60, 70 and 80 %. The results of the tolerance experiments are shown as mean temperature tolerated by 50% of the population (MT50) and mean temperature tolerated by 10% (MT10) of the strains for heat testing, and as Lethal Concentration (LC50 and LC90) for the desiccation test. For the heat tolerance experiments, the results showed that hybrid strains had slightly higher heat tolerance levels than their parents. In the desiccation experiments, it was determined that most of the hybrid strains had greater tolerances than their parents. The outcome of the study was promising for conducting further research and trials.