Controlled release of insect sex pheromones from paraffin wax and emulsions

Paraffin wax and aqueous paraffin emulsions can be used as controlled relea se carriers for insect sex pheromones for mating disruption of orchard pest s. Paraffin can be applied at ambient temperature as an aqueous emulsion, a dheres to tree bark or foliage, releases pheromone for an extended period o f time, and will slowly erode from bark and biodegrade in soil. Pheromone e mulsions can be applied with simple spray equipment. Pheromone release-rate s from paraffin were measured in laboratory flow-cell experiments. Pheromon e was trapped from an air stream with an adsorbent, eluted periodically, an d quantified by gas chromatography. Pheromone release from paraffin was par tition-controlled, providing a constant (zero-order) release rate. A typica l paraffin emulsion consisted of 30% paraffin, 4% pheromone, 4% soy oil, 1% vitamin E, 2% emulsifier, and the balance water. Soy oil and vitamin E act ed as volatility suppressants. A constant release of oriental fruit moth ph eromone from paraffin emulsions was observed in the laboratory for more tha n 100 days at 27 degrees C, with release-rates ranging from 0.4 to 2 mg/day , depending on the concentration and surface area of the dried emulsion. Th e use of paraffin emulsions is a viable method for direct application of in sect pheromones for mating disruption. Sprayable formulations can be design ed to release insect pheromones to the environment at a rate necessary for insect control by mating disruption. At temperatures below 38 degrees C, ze ro-order release was observed. At 38 degrees C and higher, pheromone oxidat ion occurred. A partition-controlled release mechanism was supported by a z ero-order pheromone release-rate, low air/wax partition coefficients, and p heromone solubility in paraffin. (C) 1999 Published by Elsevier Science B.V .