A temperature-dependent model for predicting release rates of pheromone from a polyethylene tubing dispenser.

A model was developed to describe release of two formulations of tetradecenyl acetates in Shin Etsu polyethylene tubing pheromone dispensers. Change in pheromone column length in the polyethylene tubing was modeled bydl/dt=l ... (a+bT)/dt (wherel is column length,t is time interval, andT is average temperature for that time interval). Regression of the natural log of relative change in liquid length against time interval and accumulated day degrees in orchards produced the coefficientsa andb. The model was validated by comparing predicted and actual liquid length remaining in field-aged dispensers, as well as measuring release rates by using gas chromatography. Mean daily orchard temperatures and measurement of column length of dispensers on a single date were used to accurately predict column length within 15%, after six months. Predictions of instantaneous release rate were also made from this model, and other possible model uses and limitations are discussed.