Comparative study of element contents in seven isolates of entomopathogenic nematodes

Little is known about element contents in the entomopathogenic nematodes despite their vital role in the growth and development of all organisms. Ten element contents of seven nematode isolates were determined. No significant differences were observed in concentrations of aluminum (Al), chromium (Cr), and lead (Pb) among all the studied nematode isolates, while significant differences of cadmium (Cd), selenium (Se), zinc (Zn), and manganese (Mn) concentrations among isolates were found. All isolates related to Heterorhabditidae family contained significantly higher copper (Cu), iron (Fe), and cobalt (Co) concentrations than isolates related to Steinernematidae family of entomopathogenic nematode (EPN). In all of tested isolates, the content of Cu was the highest and that of Se was the lowest. The concentrations of the studied elements were in the following descending order: Cu > Fe > Co > Mn > Zn > Pb > Cr > Cd > Al > Se. It is suggested that Photorhabdus bacteria associated with Heterorhabditis spp. of EPN accumulate Cu, Fe, and Co for activation of their metalloenzymes to enhance their virulence potential.