Montana native Entomopathogenic Nematode Species against Limonius californicus (Coleoptera: Elateridae)

Authors: SANDHI, RAMANDEEP KAUR - Montana State University; Shapiro Ilan, David; Reddy, Gadi V.P.

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2020
Publication Date: 8/2/2020
Citation: Sandhi, R., Shapiro-Ilan, D., Reddy, G.V. 2020. Montana native Entomopathogenic Nematode Species against Limonius californicus (Coleoptera: Elateridae). Journal of Economic Entomology. 113:1-8. https://doi.org/10.1093/jee/toaa164.
DOI: https://doi.org/10.1093/jee/toaa164

Interpretive Summary: Wireworms are economically damaging pests of wheat in Montana. Due to environmental and regulatory concerns, it is desirable to investigate potential non-chemical control solutions for wireworms. The objective of the study was to determine if Montana native entomopathogenic nematodes species are able to kill and suppress sugar beet wireworm in the Golden Triangle Region of Montana. In addition, we also studied if the efficacy of two Montana native nematode species against wireworms differs depending on different soil types in Montana as well as varied moisture levels. Entomopathogenic nematodes are small round worms that are environmentally-friendly bio-pesticides. Overall results indicate that the native entomopathogenic nematodes that we tested have only limited potential for wireworm control. However, there are many wireworm species, in several genera that are pests in various crops in Montana, and some of these species may be more susceptible to the native EPNs. Perhaps, different commercially available nematode species need to be tested and explored against different wireworm species present in the area instead of the native ones.

Technical Abstract: Wireworms, larvae of click beetles (Coleoptera: Elateridae), are economically important soil-dwelling polyphagous pests in the Pacific Northwest region and Intermountain region of the United States. They have become a serious threat to spring wheat in the Northern Great Plains because of a lack of effective control tactics. There is an urgent need for alternative methods for control of wireworms, such as including biological control agents such as entomopathogenic nematodes (EPNs). Native/indigenous EPN species are expected to have better potential than exotic species to control the local insect pests. Two Montana native EPN species (Steinernema feltiae and Heterorhabditis bacteriophora) were tested against sugarbeet wireworm, Limonius californicus (Coleoptera: Elateridae) in laboratory and shade house studies. In the laboratory bioassay, two isolates of S. feltiae killed 48-50% L. californicus after four weeks when applied at the rate of 28,000 IJs/five larvae. Heterorhabditis bacteriophora was not able to cause >30% L. californicus larval mortality. However, none of the two isolates of S. feltiae performed well against L. californicus when tested in different soil types. Similarly, two isolates of S. feltiae that were tested killed only 20-25% of wireworm larvae in a shade house trial and did not differ significantly from the control. Four weeks after EPN treatment in the shade house trial, the percentage of wheat plant damage from L. californicus ranged from 30-40% in the presence of S. felitae which did not differ significantly from control treatment. These results suggest that S. felitae have might have some potential in targeting wireworm populations.