| Summary: | <i>Conotrachelus nenuphar</i> Herbst (Coleoptera: Curculionidae) is a key pest of stone and pome fruits in the United States. Application of certain entomopathogenic nematode (EPN) species has shown efficacy in some crops when targeting the larval stage of <i>C. nenuphar</i> in soil. To date, however, no EPNs have been tested for the control of this pest in highbush blueberries. In 2020, laboratory and field studies were conducted to: (1) determine the persistence of <i>Steinernema riobrave</i>, <i>S. carpocapsae</i>, <i>S. feltiae</i>, and <i>Heterorhabditis bacteriophora</i> in acidic blueberry soil; (2) compare the virulence of these EPNs to <i>C. nenuphar</i> larvae and pupae; and (3) compare the efficacy of these EPN species to control this pest in blueberry fields. The greatest persistence in blueberry soil was exhibited by <i>S. riobrave</i> followed by <i>S. carpocapsae</i>. Superior virulence was observed in <i>S. riobrave</i> against <i>C. nenuphar</i> larvae and pupae. Promising levels of virulence were also observed in <i>S. carpocapsae</i> and <i>S. feltiae</i> against the larvae, but <i>S. scarabaei</i> had low virulence. In the field, <i>S. riobrave</i> provided significantly higher levels of <i>C. nenuphar</i> suppression (90%) than the other EPNs. The field efficacy of <i>S. riobrave</i> against <i>C. nenuphar</i> at low and high rates was confirmed in 2021. <i>Steinernema riobrave</i> has the potential to become an important component in the management of <i>C. nenuphar</i> in highbush blueberry.
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