Comparison of beneficial traits among strains of the entomopathogenic nematode, Steinernema carpocapsae, for control of Curculio caryae (Coleoptera: Curculionidae)

Our objective was to compare beneficial traits among strains of Steinernema carpocapsae to identify or develop a superior biocontrol candidate for suppression of the pecan weevil, Curculio caryae. Virulence, environmental tolerance to heat and desiccation, and reproductive capacity were compared among eight strains. Fitness (in vitro growth) of the symbiotic bacteria, Xenorhabdus nematophila isolated from six of the nematode strains, was also compared. Significant differences were detected among nematode and bacteria strains for each trait. All nematode strains were more virulent to C. caryae adults than to larvae. No single S. carpocapsae strain was superior for all beneficial traits measured. Overall, Breton, DD136, Italian, and Kapow strains were ranked inferior to other strains. Agriotos, All, and Sal strains were superior when desiccation was a factor. When desiccation tolerance was removed as a factor, the Mexican strain also tended to fall into the superior rankings.