Modelling of pheromone release from solid matrix dispenser for integrated pest management

Sex pheromones are introduced in the cultivated areas to create mating disruption and thus to protect crops from pests. This article deals with the release characteristics of a model pheromone (dodecyl acetate) encapsulated in a solid matrix developed as a passive dispenser. Released kinetics were obtained both in the field by extracting and quantifying the remaining pheromone in the dispenser over time and in laboratory by emission chamber tests under controlled conditions. Results showed that the release profiles follow pseudo-zero-order kinetics with a quasi-constant release rate of 1.53 mg day^-1 under field conditions for the first sixty days. Emission data showed that two key parameters, i.e., the matrix/air partition coefficient (K_ma) and the convective transfer coefficient in the gas phase (h_m) govern the release rate of the dispenser. Estimates of K_ma varied from 1×10⁶ to 4.55×10⁶ and h_m from 3.2×10^-3 to 5×10^-3 m s^-1 depending on the air velocity and temperature conditions. Temperature dependence of K_ma was most significant and was addressed by estimating the enthalpy of the pheromone partitioning between the matrix dispenser and air ${\Delta H}_{\text{ma}}$ (102 kJ mol^-1). The results led to the development of a model based on K_ma and h_m as the main parameters describing pheromone release from the matrix dispenser. A good agreement was found between the measurements obtained in field and model predictions. This model could be an effective tool for adjusting the release rate of pheromone dispensers under practise conditions.