Field Pathogenicity and Persistence of Heterorhabditid and Steinernematid Nematodes (Nematoda) Infecting Black Vine Weevil Larvae (Coleoptera: Curculionidae) in Cranberry Bogs

Abstract

The entomogenous nematode, Heterorhabditis heliothidis (Khan, Brooks and Hirschmann), when applied to a cranberry bog in April at 160 nematodes per cm2, reduced numbers of black vine weevil, Otiorhynchus sulcatus (F.), larvae and pupae >70% in the spring of application and a year later. Bioassays with greater wax moth larvae, Galleria mellonella (L.), of soil samples taken periodically for 10 mo after treatment showed that the nematodes persisted in the soil for at least 10 mo. Bioassays indicated lateral movement of H. heliothidis at least 1 m into untreated control plots. The efficacy of Heterorhabditis sp. (HP88 isolate) and Neoaplectana carpocapsae Weiser (= Steinernema feltiae Filipjev) (All strain) was compared, and all treatments were shown to be efficacious with HP88 giving complete control. A later date of application seemed to improve the efficacy of Heterorhabditis and Neoaplectana against O. sulcatus larvae, probably because of warmer temperatures.