What is more important to host seeking entomopathogenic nematodes, innate or learned preference?

For successful reproduction, entomopathogenic nematodes (EPNs) must identify, move towards, and successfully infect a suitable insect hosts in chemically complex soil environments. EPNs appear to have an innate host insect preference and, in addition, can develop a strong preference for host related volatile compounds due to prior exposure. The importance of these innate vs learned preferences were investigated. Steinernema diaprepesi, that are innately attracted to their laboratory host Galleria mellonella, were raised on Tenebrio molitor until they exhibited a preference for T. molitor larva over G. mellonella. Infective juveniles (IJ) of both host strains were then subsequently trained on three plant produced compounds: pregeijerene, caryophyllene, and pinene. Previous studies have identified pregeijerene to be innately attractive to untrained S. diaprepesi, while caryophyllene is neither attractive nor repellent and B-pinene deter untrained nematodes. IJs demonstrate positive chemotaxis to all compounds once trained. After training to the plant compounds, the behavior of IJs were assayed in sand column choice tests where the two host insects were presented with and without the plant compounds. This presentation will compare and contrast the response of S. diaprepesi IJs to their innate and learned preferences.