Study on the optimum pheromone release rate for attraction of Chilo suppressalis (Lepidoptera: Pyralidae)

Traditional chemical control against Chilo suppressalis Walker is currently being replaced in Spain by new methods based on pheromones. A key step to improve the efficacy of these methods is the determination of the optimum pheromone release rate, which is still uncertain for this pest. In this work, the pheromone release profile and the field performance of a new mesoporous dispenser was compared with a standard commercial dispenser. For this purpose, pheromone loads were extracted from field-aged dispensers and quantified by gas chromatography with flame ionization detector. In addition, a field trial was carried out with traps baited with one, two, or three mesoporous dispensers per trap, as well as with traps containing one standard dispenser. We found that the highest number of field catches did not correspond to the highest pheromone emission rate, which suggests a repellent effect of the insect if the emission is excessive. The results suggest that the attractant activity was maximized by emitting approximately 34 microg/d. The efficacy of the mesoporous dispenser and its possible improvements are discussed.