Control of the Oriental Fruit Moth, Grapholita molesta, Using Entomopathogenic Nematodes in Laboratory and Fruit Bin Assays.

The oriental fruit moth (OFM), Grapholita molesta (Busck), which is among the most important insect pests of peaches and nectarines, has developed resistance to a wide range of insecticides. We investigated the ability of the entomopathogenic nematodes (EPN) Steinernema carpocapsae (Weiser), S. feltiae (Filipjev), S. riobrave (Cabanillas et al.), and Heterorhabditis marelatus (Liu and Berry) to control OFM under laboratory and fruit bin conditions. At a dosage of 10 infective juveniles (IJ)/cm(2) in the laboratory, S. carpocapsae caused 63%, S. feltiae 87.8%, S. riobrave 75.6%, and H. marelatus 67.1% OFM mortality. All four nematode species caused significant OFM larval mortality in comparison to the nontreated controls. Steinernema feltiae was used for the bin assays due to the higher OFM mortality it caused than the other tested EPN species and to its ability to find OFM under cryptic environments. Diapausing cocooned OFM larvae in miniature fruit bins were susceptible to IJ of S. feltiae in infested corner supports and cardboard strips. Treatment of bins with suspensions of 10 or 25 S. feltiae IJ/ml water with wetting agent (Silwet L77) resulted in 33.3 to 59% and 77.7 to 81.6% OFM mortality in corner supports and cardboard strips, respectively. This paper presents new information on the use of EPN, specifically S. feltiae, as nonchemical means of OFM control.