Evaluation of persistent versus commercial nematode strains for management of Curculio caryae (Horn)

Pecan weevil, Curculio caryae (Horn) (Coleoptera: Curculionidae), is a pest of pecans in both southeastern and southwestern pecan orchards. Entomopathogenic nematodes are effective in controlling ground-dwelling stages of C. caryae. However, development of new nematode strains that allow for less frequent application while still allowing for optimal control can be beneficial to growers. This study will evaluate the effectiveness and persistence of two nematode strains, NY04 (Steinernema feltiae) and NY01 (Steinernema carpocapsae), that are hypothesized to be more persistent than other strains. The NY04 and NY01 strains will be compared with their commercial strain counterparts, SfSn and ScAll (respectively) in both field and lab tests. Field studies will be conducted in pecan orchards in both Georgia and Oklahoma. Nematodes will be applied at a rate of 12,500 ijs/m² (=approximately 50 million per acre per strain). Mesh circle traps will be used to quantify and evaluate adult C. caryae that emerge from each treatment. In addition, soil samples will be collected monthly from each treated area and nematodes will be baited with Galleria mellonella (L.) in the lab to check for virulence. Lab studies will also be performed to evaluate the longevity of each nematode strain. This study is currently ongoing.