Pheromone dispenser

Rubber septa were used as the pheromone dispensers. A practical problem was that components of multi-component pheromones sometimes varied greatly in volatility. Therefore, the amounts of the less volatile components were increased so that the septa would release... 

Over the years, many types of such controlled-release formulations have been evaluated, such as cotton wicks, rubber septa, polyethylene in various forms, cigarette filters, plastic tablets, cork, wax, molecular sieve, etc. (2). In recent years, commercial production of controlled-release formulations has provided an economical and reproducible source of pheromone dispensers and small particles for aerial dispersion. At the present time, many of the insect pheromone programs involving commercially produced, controlled-release products use one of the formulations listed in Table I. 

Figure 1. The Hereon Disrupt pheromone dispenser. Controlled amounts of active agent move from reservoir layer to surface and subsequent diffusion.

The Pheromone Dispensers and their use. Two kinds of dispensers were used, both marketed by Borregaard Ind. Ltd., Sarpsborg, Norway. 1. A plastic bag formulation produced by Celamerck, In-gelheim, West-Germany. 2. A laminated plastic-tape formulation produced by Herculite Products Inc., New York, N.Y., U.S.A. One dispenser contained 1500 mg methylbutenol, 70 mg (S)-c- s-verbenol and 10 mg (1979) or 15 mg (1980) ipsdienol. 

Pheromone Dispenser and Trap Design Much Technological Development Needed... 

Fadamiro HY, Cosse AA, Baker TC (1999) Mating disruption of European com borer, Ostrinia nubilalis by using two types of sex pheromone dispensers deployed in grassy aggregation sites in Iowa cornfields J Asia-Pacific Entomol 2 121-132... 

Several applications based on biodegradable plastics that end up directly in soil after their useful life are under development and experiencing rapid market growth. Examples are mulch films, strings, hooks and clips, slow release pheromone dispensers and drip irrigation pipes. Furthermore, mature industrial compost, obtained from a feedstock that includes biodegradable polymers, also ends up in soil because of its application as a soil improver. 

Release rates of acetate esters of (2S,3S,7S)-3,7-dimethylpentadecan-2-oll and (2S,3R,7R)-3,7-dimethyltridecan-2-ol 3 from polyethylene and cotton dispensers have been measured at different temperatures and loadings. Adjustment of the initial pheromone load on polyethylene for expected temperatures should permit the formulation of a constant release rate during the entire flight period. Successful field trapping trials for N. sertifer were carried out in Sweden, the Czech Republic, Italy, and Greece [29]. 

In early studies, the criterion for pheromonal activity was designated as the lowest concentration (ppm) of the candidate compound in a 10-fold dilution series that elicited a demonstrable response from test mites. Activity was expressed in terms of the dose of the test compound applied to the filter paper dispenser. More recently, more sophisticated bioassays using arenas have been developed, in which the movements of mites toward or away from test stimuli can be quantified (Nishimura et al., 2002). 

Large scale use of pheromones cal dispenser system which must re continuously over the prescribed p same time, being able to withstand ment. 

Practical use of pheromones started in 1978. That year we used 110.000 trap-trees sprayed with an insecticide (Lindane). The first year we used one dispenser with an initial loading of 70 mg cis-verbenol and 10 mg ipsdienol. A second dispenser was loaded with 100 mg methylbutenol. In 1979 we adjusted the loading and used only one dispenser containing all 3... 

Evaluation of Controlled Release Laminate Dispensers for Pheromones of Several Insect Species... 

With the formulations described here (namely the laminate dispensers), we had previously determined that the same pattern of release was obtained by either of two methods of measurement collection of pheromone emitted under controlled conditions of temperature and air speed (9, 10) or determination of residual lure content by extraction and gas chromatographic (GC) analysis. Since the latter method is simple and rapid and provides reproducible data for the comparison of formulations, it was used to obtain the data presented in this paper. 

In another experiment, a mixture of C °al (5%), (Z)-ll-Cjg al (90%) and (Z)-ll-Cj ol [( Z)-ll-hexadecen-l-ol] (5%) was Incorporated Into 3 other types of laminate dispensers at approximately 1.6 mg/cm BHT was again added as an antioxidant. The alcohol was Included since It Is a component of the pheromone of the tobacco budworm. The laminates were cut into 4 x 20 mm dispensers and again were aged In 2 locations at room temperature In a laboratory In Maryland and outdoors In Arizona (October-December). At selected Intervals, sample dispensers from each location were extracted and GC analyses performed for all 3 components as well as for acid formed through oxidation. Again, no acid was detected In any of the formulations. The tj values for the laboratory and field aged dispensers are given In Table III. 

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. 

In a second test conducted to evaluate a dispenser that would release lure more slowly, the CIMB pheromone was formulated in both 16-mil polymeric PVC and 3-mil acrylic films. The dispensers (50 x 12 mm), containing 10 mg of pheromone, were aged in a greenhouse in California at temperatures ranging from 21 to 36°C. Analyses for residual lure content over a 7-week period gave 1/2 values of 19 days for the polymeric PVC and 44 days for the acrylic dispensers. 

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. 

---