Management of Wireworms in Sweet Potatoes with Persistent NY Entomopathogenic Nematodes

Abstract

Wireworms are the larval stages of click beetles (Coleoptera: Elateridae) and common polyphagous soil dwelling pests feeding on different plant parts including seeds, roots, stems, and tubers inhibiting plant growth eventually leading to plant death. With the ban of persistent synthetic insecticides such as lindane in 2009 due to negative effects on the environment, no effective control tactics (chemical or biological) are available for wireworms. Some entomopathogenic nematode species/strains have been reported to attack wireworms in the soil, causing death. Non-native EPN species have the advantage of being easily available commercial products for insect pest control. However, these strains do not persist and require annual application as a biopesticide. Native species provide an advantage because application is a single event with multi-year persistence and pest suppression. In the first harvest, the EPN combination of Steinernema feltiae × Heterorhabditis bacteriophora had significantly less wireworm feeding damage than the untreated check irrespective of whether the plants were located in the outside rows or the inside rows. The EPN combination of S. carpocapsae × S. feltiae were numerically different from the untreated checks, but the fewer wireworm feeding wounds were not statistically different from the untreated check. Inoculated EPNs were still present in 30% of the soil samples in all treated plots 1076 days after application/inoculation.