Impact of some entomopathogenic nematode isolates on the mortality and penetration rate of Rhyzopertha dominica and Tenebrio molitor

Entomopathogenic nematodes (EPNs) are widely used as a biological control agent in pest management. The purpose of this study was to determine the effectiveness and penetration rates of certain EPNs. Three different EPN species were utilized in the study: Heterorhabditis bacteriophora HBH hybrid strain, Steinernema carpocapsae TUR-S4 isolate, Steinernema feltiae TUR-S3 and S-Bilecik isolates. These isolates were applied at different doses (50, 100, 150, 200, 250, 300, 350, and 400 Infective Juveniles (IJs)/Petri) on larvae of Tenebrio molitor and adults of Rhyzopertha dominica. Additionally, the penetration rates of the mentioned EPN species on T. molitor larvae and R. dominica adults were determined. As a result, the highest mortality rate observed in R. dominica adults was 93.33% when treated with the HBH isolate at the dose of 400 IJs/Petri dishes. For T. molitor larvae, the highest mortality rate was 100% at doses of 8.85 IJs/cm2, 10.60 IJs/cm2, 12.40 IJs/cm2, 14.15 IJs/cm2 for HBH and TUR-S3, 10.60 IJs/cm2, 12.40 IJs/cm2, 14.15 IJs/cm2 for TUR-S4, and 7.10 IJs/cm2, 8.85 IJs/cm2, 10.60 IJs/cm2, 12.40 IJs/cm2, 14.15 IJs/cm2 for S-Bilecik. When examining the penetration rates, the highest rate of 23.33% was observed in R. dominica adults treated with HBH, while for T. molitor, this rate was 22.67% in individuals treated with HBH. These findings underscore the importance of continued investigation into the potential of these EPNs for sustainable pest management strategies.