Development of PVC-resin-controlled release formulation for pheromones and use in mating disruption of yellow rice stem borer, Scirpophaga incertulas

Half lives of a range of Lepidopteran sex pheromone components incorporated into plasticized polyvinylchloride (PVC)-resin formulations were determined under a range of conditions in a laboratory wind tunnel and in the field in Egypt, Pakistan and India. Increasing aliphatic chain length by two methylene groups increased half lives by a factor of approximately 7.5 at 27 °C. Half lives of saturated aliphatic acetates decreased with increase in temperature by 79.2%, 85.5% and 95% for dodecyl acetate, tetradecyl acetate and hexadecyl acetate, respectively, between 22 and 34 °C. Addition of the polymer-soluble dye, Waxoline Black, improved the stability of labile aldehydes and polyunsaturated compounds incorporated into plasticized PVC under field conditions, although the antioxidant BHT had no effect. Studies confirmed that the formulation was ideally suited for the release of 14-carbon acetates and 16-carbon aldehydes with typical field lives of 70-100 days. A PVC-resin formulation of sex pheromone was tested for mating disruption of yellow rice stem borer, Scirpophaga incertulas, in replicated 1 ha plots in India over two seasons. Even at an application rate of 10 g a.i./ha/season there was a significant reduction in damage relative to that in plots treated with insecticides. However, application rates of 30-40 g a.i./ha/season are recommended for general use by farmers.