Measurement by electroantennogram of airborne pheromone in cotton treated for mating disruption of Pectinophora gossypiella following removal of pheromone dispensers

Abstract The presence of pheromone in cotton foliage after removal of pheromone dispensers was assessed by measuring the airborne pheromone concentration with an electroantennogram device. Plots of 0.4 ha in isolated cotton fields were treated with Shin‐Etsu PBW‐Rope® pheromone dispensers for mating disruption of Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae). The dispensers contained (Z,Z)‐ and (Z,E)‐7,11‐hexadecadienyl acetates (gossyplure) in a 49:51 ratio and were applied at a density of 1 000/ha. The 400 pheromone dispensers were removed 1–12 days later. In four experiments involving canopy heights from 30–150 cm, the decay of the pheromone concentration was recorded repeatedly in short intervals for up to 7 h. Decay to undetectable concentrations generally occurred within 1–10 h, depending on plant size and wind conditions. In all four experiments, pheromone concentration 24 h after removal was found to be near or below detection threshold of the electroantennogram. The presence of pheromone within and above the cotton after dispenser removal would be due to re‐entrainment of pheromone that had been adsorbed on cotton foliage or possibly some residual airborne pheromone.