Laminated polymeric dispenser

Traps. The racemic form of the pheromone has been used for a long time In survey traps placed throughout the United States. The (+) enantiomer Is now available In sufficient quantity to provide a bait for many thousands of traps. Only one-half a milligram Is needed In each trap throughout a season because dlsparlure Is formulated In a long-lasting, controlled-release device, usually a Hereon laminated polymeric dispenser. 

The longer t 2 values for the laboratory-aged samples reflect the lower average temperature and air movement In the laboratory as compared to the field situation. As expected, the vinyl laminate released the aldehydes much too rapidly but could be suitable for the alcohol component. The acrylic laminate might also be useful for the alcohol. The polymeric PVC and acrylic laminates produced a greater difference In the release of the C] and aldehydes than did the Mylar-coated vinyl dispensers evaluated In the previous test. If the Insect behavior requires that all of the components of the pheromone blend be released in a constant ratio and a rate proportional to their original concentration, then it Is likely that the alcohol would have to be be formulated in one dispenser (e.g. in 3-mll acrylic) and the Cj al and C. al in another (e.g. in Mylar-coated vinyl). Both of the dispensers could then be deployed at each location In the field. 

The optically active citrus mealybug (CIMB) pheromone was intially formulated in laminate dispensers (13 x 13 mm) made of 9-mil vinyl and 16-mil polymeric PVG films. The dispensers, containing 1 mg of pheromone, were aged outdoors in California in late 1980 at temperatures ranging from 27-38°C in the day and 7-16°C overnight. Analysis for residual pheromone showed that over 98% of the lure was released by the vinyl dispensers in the first week (t /2 = 2 days), while the polymeric PVC formulations gave a slower release with a t, <2 of 11 days. 

A similar set of experiments was conducted for the development of a laminate dispenser for the Comstock mealybug (COMB) pheromone. Initially, 2-octyl acetate, which has a volatility and polarity similar to that of the pheromone, was used as a model and was incorporated in 3 types of laminate dispensers 16-mil polymeric PVC, 6-mil acrylic and 9-mil vinyl films were used. Dispensers (13 x 13 mm) containing 2.7 mg of compound were aged in a greenhouse in California at temperatures ranging from 21-36°C and then analyzed. The 2-octyl acetate contents gave two values of 1 day for the 9-mil vinyl, 8 days for the 16-mil polymeric PVC and greater than 40 days for the 6-mil acrylic film. On the basis of this experiment, the 9-mil vinyl and the 6-mil acrylic films were eliminated from consideration. 

The final dispenser evaluation with COMB pheromone again compared dispensers made of 3-mil acrylic film with those of 16-mil polymeric PVC the 13 x 13 mm laminate dispensers each contained 1 mg of racemic pheromone. Also included in this test were rubber septa baited with 1 mg of compound. All of the dispensers were aged outdoors in California at temperatures ranging from 32-39°C in the daytime to 15-21°C overnight. Analyses of residual lure contents showed a tof just 2 days for the rubber septa and approximately 15 days for the 16-mil polymeric PVC laminate the 3-mil acrylic dispensers lost pheromone so slowly that tj/2 could not be measured, but it was much greater than 70 days. On the basis of these tests, laminate dispensers made of 16-mil polymeric PVC were selected for the COMB monitoring program and have been successfully used in 1980 and 1981. 

As in the case of the Comstock and citrus mealybug pheromones, the release data for the California red scale pheomone showed that the laminate formulation made with 16-mil polymeric PVC film gave a long-lasting and suitable dispenser for the monitoring program. The results of these dispenser evaluations are summarized for citrus insect pheromones in Table IV. 

As with trapping, the delivery mechanisms for the pheromones are important. They must be able to provide a nominated dose over an extended period, often under adverse weather conditions. Thus, various slow-release methods have been devised for field use and incorporated into the delivery systems. These have involved the use of hollow fibres as reservoirs which can be applied aerially on to the canopy of plants twisted rope formulations consisting of wire-based sealed polyethylene tubes filled with disruptant that are twisted around the base of plants other polyethylene or rubber tube or polymeric ampullae dispensers, multilayered laminates of acrylic polymer flakes, resin-treated filter paper and micro-encapsulated formulations. 

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