Efficacy of <i>Steinernema carpocapsae</i> as a biological control agent for <i>Ostrinia furnacalis</i> pupae: Effects of distance, developmental stage, and soil depth

Asian corn borer, <i>Ostrinia furnacalis</i> Guenée (Lepidoptera: Crambidae), is a major pest in corn production, and its management remains a significant challenge. Current control methods, which rely heavily on synthetic chemical pesticides, are environmentally detrimental and unsustainable, necessitating the development of eco-friendly alternatives. This study investigates the potential of the entomopathogenic nematode <i>Steinernema carpocapsae</i> as a biological control agent for <i>O. furnacalis</i> pupae, focusing on its infection efficacy and the factors influencing its performance. We conducted a series of laboratory experiments to evaluate the effects of distance, pupal developmental stage, soil depth, and light conditions on nematode attraction, pupal mortality and sublethal impacts on pupal longevity and oviposition. Results demonstrated that <i>S. carpocapsae</i> exhibited the highest attraction to pupae at a 3 cm distance, with infection declining significantly at greater distances. Younger pupae (<12 h old), were more attractive to nematodes than older pupae, and female pupae were preferred over males. Nematode infection was highest on the head and thorax of pupae, with a significant reduction in infection observed after 24 h. Infection caused 100% mortality in pupae within 2 cm soil depth, though efficacy was reduced under light conditions. Sublethal effects included a significant reduction in the longevity of infected adults and a decrease in the number of eggs laid by infected females compared to controls. These findings underscore the potential of <i>S. carpocapsae</i> as an effective biocontrol agent for sustainable pest management in corn production, offering a viable alternative to chemical pesticides.