Nematode allies? Investigating potential non-target effects of persistent entomopathogenic nematodes on pest and beneficial arthropods

Entomopathogenic nematodes (EPNs) are obligate generalist parasites of insects that can be used for biological control of soil-dwelling insect pests. Persistent strains of EPNs, with multi-year survival, are now commercially available as biocontrol agents for controlling pests, including corn rootworms. Although previous studies have focused on the efficacy of persistent EPNs for pest control, little is known about their potential non-target effects on other arthropod species. Assessing potential non-target effects is an important step in developing pest management approaches, for example, testing pesticide effects on beneficial arthropods. The goal of this study was to evaluate whether persistent EPNs influence the abundance or composition of non-target pest and beneficial arthropods in Texas corn fields. We hypothesized that generalist persistent EPNs would decrease the abundance of beneficial ground-dwelling arthropod predators, as well as lepidopteran pests that pupate in soil. For this study, persistent EPNs were applied to producer-operated cornfields at two sites in Texas (Comanche and Goliad). We conducted pitfall samplings to evaluate the abundance and composition of ground beetles (Carabidae) and spiders (Araneae), and soil emergence assays to assess the influence of EPNs on the survival of fall
armyworm (Spodoptera frugiperda) and corn earworm (Helicoverpa zea). Results from the first growing season in 2024, at Comanche, indicated that the abundance of beneficial arthropods was not affected by EPNs. However, persistent EPN treatment reduced fall armyworm survival, suggesting producers may gain additional benefits of EPN biocontrol. This study provides new insights concerning the ecological impacts of persistent EPN strains in corn agroecosystems.