Effects of orchard host plants on the oviposition preference of the oriental fruit moth (Lepidoptera: Tortricidae)

Recently, the oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), has emerged as a major problem on apples (Malus spp.) grown in the mid-Atlantic and midwestern United States, despite its historically important and frequent occurrence as a peach (Prunus spp.) pest. It is possible that host-driven biological phenomena may be contributing to changes in G. molesta population dynamics resulting in outbreaks in apple. Studies were designed to examine the effects of host plants on oviposition behavior, in an effort to clarify the host association status of eastern U.S. populations and also to gain insight into how pest modeling and management efforts may be altered to take into account various host-associated effects. G. molesta adults exhibited ovipositional preference for nonbearing peach trees over nonbearing apple trees in close-range choice tests conducted in the field, regardless of the larval host origin. A significant preference for peach shoots over apple shoots was observed on six of 12 sampling dates with a wild G. molesta population at the interface of adjacent peach and apple blocks. Numbers of eggs found on apple fruit were higher after peach fruit were harvested and apple fruit began to approach maturity (during the flight period for third and fourth brood adults). Possible implications for population modeling and integrated management of G. molesta are discussed.