Chemical Cues from Entomopathogenic Nematodes Vary Across Three Species with Different Foraging Strategies, Triggering Different Behavioral Responses in Prey and Competitors

Abstract

Chemical cues play important roles in predator–prey interactions. Semiochemicals can aid predator foraging and alert prey organisms to the presence of predators. Previous work suggests that predator traits differentially influence prey behavior, however, empirical data on how prey organisms respond to chemical cues from predator species with different hunting strategies, and how foraging predators react to cues from potential competitors, is lacking. Furthermore, most research in this area has focused on aquatic and aboveground terrestrial systems, while interactions among belowground, soiling-dwelling organisms have received relatively little attention. Here, we assessed how chemical cues from three species of entomopathogenic nematodes (EPNs), each with a different foraging strategy, influenced herbivore (cucumber beetle) and natural enemy (EPN) foraging behavior. We predicted these cues could serve as chemical indicators of increased predation risk, prey availability, or competition. Our findings revealed that foraging cucumber beetle larvae avoided chemical cues from Heterorhabditis bacteriophora (active-foraging cruiser EPNs), but not Steinernema carpocapsae (ambusher EPNs) or Steinernema riobrave (intermediate-foraging EPNs). In contrast, foraging H. bacteriophora EPNs were attracted to cues produced by the two Steinernema species but not conspecific cues. Notably, the three EPN species produced distinct blends of olfactory cues, with only a few semi-conserved compounds across species. These results indicate that a belowground insect herbivore responds differently to chemical cues from different EPN species, with some EPN species avoiding prey detection. Moreover, the active-hunting EPNs were attracted to heterospecific cues, suggesting these cues indicate a greater probability of available prey, rather than strong interspecific competition.

Bioactive compounds from bacterial and fungal agents for the control of phytopathogenic nematodes: mechanisms of action, interactions, and applications

“…Mecanismo de acción. Los nematodos son organismos que pueden generar feromonas, conocidas como ascarósidos, esenciales para diversas actividades, como atracción, agregación, repulsión y búsqueda de alimento (Grunseich et al, 2021). Estas feromonas tienen la capacidad de activar múltiples vías de traducción de señales e inducir la morfogénesis en la formación de estructuras de captura, tales como redes adhesivas, botones, columnas, anillos constrictivos y no constrictivos (Jiang et al, 2017).…”

What Is More Important to Host-Seeking Entomopathogenic Nematodes, Innate or Learned Preference?

“…To locate host insects, IJs rely on cues such as insect-produced odors [4,5], CO 2 [6], and nematode-produced pheromones or kairomones [7]. These cues can be utilized individually or in combination to enhance host finding [8]. EPNs can also utilize plant-produced compounds to find hosts, especially herbivore-induced plant defense compounds [9][10][11].…”