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 tetra decenyl acetates in Shin Etsu polyethylene tubing pheromone dispensers . Change in pheromone column length in the polyethylene tubing was mod eled by dl/dt = l . (a + bT)/dt (where l is column length, t is time i nterval, and T is average temperature for that time interval). Regress ion of the natural log of relative change in liquid length against tim e interval and accumulated day degrees in orchards produced the coeffi cients a and b. The model was validated by comparing predicted and act ual liquid length remaining in field-aged dispensers, as well as measu ring release rates by using gas chromatography. Mean daily orchard tem peratures and measurement of column length of dispensers on a single d ate were used to accurately predict column length within 15%, after si x months. Predictions of instanteous release rate were also made from this model, and other possible model uses and limitations are discusse d.