Pheromone release rate determination

New methods and apparatus are described for evaluating the pheromone release characteristics of controlled release formulations of All-tetradecenal both in the laboratory and following aerial application in the field. Laboratory release rates determined by these methods correlate well with rates observed in the field. 

Early experiments in our laboratory were concerned with methods for sampling and analysis of TDAL from formulations (6), insects (7) and from the forest atmosphere (8). This work was largely founded upon concepts developed previously by Beroza e t al. (9, 10, 11). Since then, several other groups have applied these concepts to the measurement of a number of different insect pheromone release rates (12, 13). On the basis of our early findings, we were convinced that the existing laboratory techniques for release rate determination from formulations were inadequate. Laboratory tested formulations did not experience the extremes of climatic variation which are the norm in the field and consequently the release rate results were not transferable to field performance. 

To determine the versatility of the apparatus for measuring release rates in general, the release of (acetyl-l-1 C)-gossy-plure was measured from rubber septa, a pheromone release device frequently used in field experiments. After 21 days of measurements, the septa were extracted and any residual activity in the apparatus was measured. The average recovery, detailed in Table II, was 97% indicating that the usefulness of the mini-airflow device was not limited to hollow fibers alone. 

A dynamic flow method was used to determine the rate of pheromone release from the various matrices. A vacuum manifold was constructed for multi-sample analysis. The sample chambers were modeled after the design of CrossQ) and consisted of a glass chamber fitted with a charcoal pre-filter and absorbent column. 

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