Conspecific pheromone extracts enhance entomopathogenic infectivity

Entomopathogenic nematodes (EPNs) provide economic control of various insect pests. However, field efficacy can be inconsistent. The ability of a nematode to find and infect (invade) a host insect is critical to successful pathogenesis. Thus, behaviors including dispersal and infectivity play important roles in improving efficacy. Previously, we discovered that EPN-infected host substances enhance nematode dispersal. Later we found that a mixture of pheromones in the infected host induced dispersal and improved EPN efficacy. In this study, we determined if dispersal-inducing pheromone extracts also increase nematode infectivity (the propensity to invade a host insect). Two nematode species, Steinernema carpocapsae and Steinernema feltiae, and two insect hosts, Galleria mellonella and Diaprepes abbreviatus, were tested. We discovered that conspecific dispersal pheromone extracts of each EPN species enhanced infectivity. These results indicate that the utility of dispersal pheromone extracts for enhancing EPN activity and biocontrol efficacy is improved not only due to increased nematode movement, but also due to increased host infection.