Success of Grapholita molesta (Busck) reared on the diet used for Cydia pomonella L. (Lepidoptera: Tortricidae) sterile insect release

The survival of Grapholita molesta (Busck) on the synthetic diet currently used by the Okanagan Sterile Insect Release Programme in British Columbia to rear Cydia pomonella L. was compared to that on a synthetic diet normally used to rear G. molesta and crab apples as a control. Development of G. molesta on the three diets was followed from egg to adult. The fitness of the resulting moths was compared using metrics of survival to pupation and pupal weight, survival to adulthood and female fecundity. More G. molesta reached the pupal stage and had a significantly greater pupal mass when reared on the G. molesta diet than on the C. pomonella or crab apple diets. There was no difference among the number of moths surviving to adulthood on any of the diet types. Although pupal mass was affected by larval diet, G. molesta females had a statistically similar number of offspring regardless of the diet they were reared on as larvae. Grapholita molesta can be reared on the diet currently used to mass rear C. pomonella for sterile insect release but may require a period of adaptation to the novel food source. If G. molesta becomes established in the Okanagan Valley of British Columbia, a similar sterile insect release approach to that currently used against C. pomonella may be a feasible approach