Control of the Oriental Fruit Moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae) by Mating Disruption with Sex Pheromone in Pear Orchards

Abstract

The effect of dispensers containing a 93: 6 : 1 blend of Z8-12: Ac, E8-12: Ac, and Z8–12: OH for mating disruption of Grapholita molesta (Busck) was tested from 1998 to 2000 in pear orchards in Naju, Korea. The permeation of the atmosphere with synthetic sex pheromone significantly reduced the ability of male moths to locate pheromone-baited traps, and reduction of male moths to locate pheromone-baited traps was not significantly different among different pheromone doses. Success in suppression of infestations by pheromone permeation was achieved under the dose rate of 50 g/ha, and increasing pheromone concentration above this dose did not significantly reduce the fruit damage. The efficacy of pheromone treatment could not be predicted using captures of males in traps baited with synthetic pheromone. Apparently, a much lower titer of pheromone was required to reduce trap catch than to reduce damage. The trap catch was influenced by trap position in pheromone plots; significantly more moths were caught at the outer areas than at the inner areas. Also, fruit damage levels in pheromone plots were significantly heavier in the trees located in the outer area. However, the lowered efficacy in the outer areas was partly improved by the application of a high number of dispensers at these areas compared with the inner areas. Assessment of trap catch and damage level over a three-year period showed that the effectiveness of the disruption technique for G. molesta was enhanced through sequential suppression year after year at the same site.