An easy method for estimating the efficacy of mating disruption in the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae).

An easy method for estimating the efficacy of mating disruption was designed for the Oriental fruit moth, Grapholita molesta because this moth is too small to prepare tethered females and the estimation of the efficacy of mating disruption is rather important when the field population is low. Four virgin females were confined together with six males in a globular net cage (mating cage, about 21 cm dia.) made by combining two sieve baskets of stainless steel commercially available at a low price. The mating cages were placed overnight in pear orchards treated and untreated with synthetic sex pheromone. On the following morning, the females were dissected to examine the spermatophore in the abdomen. Mating rates were significantly reduced in the pheromone treated orchards as compared to in the untreated orchards. More than five cages (20 females) were necessary to evaluate the mating rate in a single orchard. Merits of this method are considered that can be applied to small moths such as G. molesta and the mating rate is not influenced by the wild population density.