Evaluating the effect of pheromone extracts on entomopathogenic nematode movement through wood substrates

Entomopathogenic nematodes (EPN) are an established biological pesticide which have been applied in many different agroecosystems. However, susceptibility to environmental conditions and host availability limit the extent to which EPNs are efficacious in the field. To address these vulnerabilities, there are expanding efforts to increase EPN efficacy in the field by manipulating EPN behavior. Previous studies have shown that pheromones produced within EPN-infected hosts can increase efficacy by enhancing behaviors such as the dispersal of infective juveniles. In this study we assessed dispersal of Steinernema feltiae infective juveniles through wooden bolts cut from pecan (Carya illinoinensis) and peach (Prunus persica) trees with and without exposure to EPN pheromones extracts. We hypothesized that the infective juveniles exposed to pheromone extracts would exhibit greater dispersal through an artificially created gallery in wooden bolts compared to infective juveniles that had not been exposed to the pheromones. Infective juveniles were placed by treatment at one end of a 6.72 cm wood bolt and baited by Galleria mellonella on the opposite end. After five hours, the bolts were cut in half and the number of injective juveniles in each half were counted to assess movement. We found that infective juveniles exposed to pheromone extracts exhibited significantly higher rates of dispersal compared to the control. The use of pheromone extracts to increase desirable behaviors such as EPN dispersal may be a valuable component in increasing the consistency and efficacy of EPN as biological pesticides.