Evaluating Entomopathogenic Nematodes as Biocontrol Agents Against Two Major Cockroach Species, and , in Antalya, Türkiye.

Cockroaches, particularly the German cockroach ( Linnaeus, Blattodea: Ectobiidae) and the American cockroach ( (Linnaeus), Blattodea: Blattidae), are major public health pests due to their ability to transmit pathogens and develop resistance to chemical insecticides, including synthetic pyrethroids, which are widely used worldwide. Given the increasing resistance, entomopathogenic nematodes (EPNs) have emerged as a potential biological control alternative. This study evaluates the efficacy of three EPN species, (Weiser), (Filipjev), and Poinar, against and collected from different regions of Antalya, Türkiye. Laboratory bioassays were conducted under controlled conditions, testing five EPN concentrations (100, 250, 500, 750, and 1000 IJs/mL). The results showed that was the most effective, causing mortality rates of 46.7% to 100% in adult German cockroaches and 20% to 66.7% in nymphs, while and exhibited lower efficacy. American cockroaches showed higher resistance, with achieving a maximum mortality of 33.3% at the highest concentration, whereas and had no significant lethal effect. These findings suggest that could be a promising biological control agent for , particularly in pyrethroid-resistant populations.