Efficacy of native isolates and commercial products of two entomopathogenic nematode species on model host, Tenebrio molitor (Coleoptera: Tenebrionidae) larvae

Entomopathogenic nematodes are valuable biocontrol agents of pests. The use of indigenous isolates compared to imported isolates has advantages including compatibility with the environment and native pests and not causing adverse effects on indigenous species. In the present study, the effect of native isolates of Steinernema carpocapsae and Steinernema feltiae on model host, Tenebrio molitor was compared with exotic commercial products by two bioassay methods (in Petri dishes and soil). Probit analysis showed a significant correlation between the nematode concentrations and the insect mortality (R2 ≥ 0.90). The Iranian S. carpocapsae isolate showed the lowest LC50 value (5 IJ Larva-1) and the commercial S. feltiae isolate showed the highest LC50 value (7 IJ Larva-1). However, based on the LC50 ratio values there was no significant difference between the four nematode isolates. The comparison of the mortality percentage of the pest in soil bioassay showed a similar effect of native isolates with commercial isolates (P ≤ 0.01). The impact of native nematode isolates on par with commercial isolates which had been selected among numerous isolates, showed their high potential Therefor, basic research with the aim of developing the practical application of these valuable agents is suggested.