Effects of rain and sunlight on oriental fruit moth (Lepidoptera: Tortricidae) pheromone microcapsules applied to apple foliage


The effect of rain and sunlight on the number of Phase I, III, or V microcapsules containing oriental fruit moth (OFM), Grapholita molesta (Busck) (Lepidoptera: Tortricidae), pheromone was determined on apple leaves with microscopy. Rainfall >10 mm reduced the number of microcapsules on field-exposed leaves by up to 76% relative to control leaves. One week of cloudless exposure to mid-July sunlight caused a significant decrease (79-94%) of Phase I and III microcapsules but not Phase V microcapsules. Decreases of microcapsules after field exposure were greater on the top than the bottom surfaces of leaves. With one exception, the number of Phase I and III microcapsules with and without Nu-Film 17 was not significantly different on apple leaves exposed to field conditions. Leaf surface (top or bottom) and exposure to sunlight were the most important variables influencing the number of pheromone microcapsules on apple leaves in the field. Overall, there were more Phase III microcapsules per cm leaf surface area than Phase I and V microcapsules before and after exposure to field conditions. The Phase III sprayable pheromone formulation may be better suited for growing conditions in Michigan and related climates, whereas the Phase V formulation may be better suited for climates where sunlight is more intense.


Environmental Plant Science and Natural Resources

Document Type



Apple, Grapholita molesta, Mating disruption, Microencapsulation, Sprayable pheromone

Publication Date


Journal Title

Journal of Agricultural and Urban Entomology