Evaluating the ecological impact of synthetic predator pheromone on pest and non-target species in a potato field

Recent studies suggest that semiochemicals, such as predator odors, can protect crops by deterring pests, but their effects on large agricultural scales and non-target organisms remain unclear. Agroecosystems include diverse pests and natural enemies, making it essential to assess unintended impacts, which could disrupt ecological balance and predator-prey dynamics. Our previous research demonstrated that a synthetic aggregation pheromone from Podisus maculiventris, a predator of the Colorado potato beetle (Leptinotarsa decemlineata), reduced prey larval abundance through non-consumptive effects. However, the broader effects on non-target predators and herbivores in potato cropping systems remain unknown. We tested a synthetic blend containing alpha-terpineol, terpinen-4-ol, benzyl alcohol, linalool, and (E)-2-hexenal. Linalool and (E)-2-hexenal are herbivore-induced plant volatiles known to influence a variety of herbivores and predators. Field experiments assessed insect abundance and predation rates on sentinel L. decemlineata eggs in potato plots treated with the synthetic predator pheromone, using D-vac sampling and visual counts. Additionally, greenhouse assays were performed to evaluate the pheromone’s effect on the consumption of L. decemlineata eggs by predators. Field results indicated a reduction in L. decemlineata larval abundance in pheromone-treated plots, while the herbivore community remained unaffected, and the overall predator community was only weakly influenced by the pheromone. However, predation rates in pheromone-treated plots were higher compared to controls. In greenhouse assays, increased egg consumption was observed in two key L. decemlineata predators. These findings suggest that the synthetic predator pheromone may influence predator behavior, reducing L. decemlineata populations without affecting non-target species.