Submitted to: Journal of Nematology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/23/2006
Publication Date: 8/15/2006
Citation: Riga, E., Lacey, L.A., Guerra, N., Headrick, H.L. 2006. Control of the oriental fruit moth, Grapholita molesta, using entomopathogenic nematodes in laboratory and fruit bin assays. Journal of Nematology. 38(1): 168-171. Interpretive Summary: Oriental fruit moth, a native insect of China, has spread throughout the world and is considered the most important insect pest of peaches. The moth spends the winter as a cocooned larva in the orchard. The successful control of overwintering oriental fruit moth larvae would result in substantial reduction in fruit damage in the subsequent growing season. Insect-specific nematodes can target overwintering larvae in their cryptic habitats when conditions are favorable for infectivity. In cooperation with nematologists at Washington State University, in Prosser, WA, researchers at the USDA-ARS, Yakima Agricultural Research Laboratory are conducting studies to develop and evaluate insect-specific nematodes for control of cocooned oriental fruit moth larvae in orchards and fruit bins. It was found that infective stages of four species of nematodes were highly effective at controlling cocooned larvae in laboratory assays and tests condicted in infested fruit bins. These findings indicate that insect-specific nematodes could provide a non-chemical means of control that could be applied in the fall or spring when all of the oriental fruit moth population is overwintering in the orchard.
Technical Abstract: The oriental fruit moth (OFM), Grapholita molesta, is among the most important insect pests of peaches, and nectarines and it has developed resistance to a wide range of insecticides. We investigated the ability of the entomopathogenic nematodes (EPNs) Steinernema carpocapsae, S. feltiae, S. riobrave, and Heterorhabditis marelatus to control OFM under laboratory conditions and in fruit bins. In the laboratory, all four nematode species infected OFM larvae and caused significantly higher larval mortality. However, S. feltiae was the most effective of all tested nematodes, resulting in 80% OFM mortality. Diapausing cocooned OFM larvae in miniature fruit bins were susceptible to infective juveniles (IJs) of S. feltiae in infested corner supports and cardboard strips. Treatment of bins with S. feltiae 10 or25 IJs/ml suspensions of water with wetting agent (Silwet L77®) resulted in 33.3-59% and 77.7-81.6% OFM mortality in corner supports and cardboard strips, respectively. The highest OFM mortality was observed in infested cardboard strips after treatment of bins with S. feltiae at 10 and 25 IJs/ml. Cocooned OFM larvae are significantly more susceptible to infection than are pupae (true but this is not really covered in this paper). Our results indicate that S. feltiae provides an additional non-chemical means of OFM control.