Profile of ecoregion and management practices impacts on abundance and diversity of native entomopathogenic nematodes in Oklahoma

Entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae are obligate parasites of arthropods, exist naturally in soils worldwide, and have been used to suppress soil-dwelling insect pests. Little has been done to catalogue EPN diversity within Oklahoma. Ranging from east to west, Oklahoma is home to 11 different ecoregions, 9 precipitation zones and 7 soil orders. This study aims to characterize EPN communities throughout these diverse habitats, focusing on a production system that is both common within and unique to the state; simultaneous wheat and beef production. An additional objective of this study will be to compare EPN communities in organic versus conventional beef and wheat production systems within the same ecoregion. A combination of bioassay technique and molecular identification will be used to identify species at all sites. Preliminary soil samples from paired landscapes of organic and conventionally managed wheat fields and pastureland were subjected to bioassay using G. mellonella to ascertain infection rates by EPN. EPN were identified, initially by G. mellonella symptoms, and then confirmed using DNA sequencing. Based on symptomatic indications at least three species and two different genera were represented. Molecular identification is pending. Overall infection rates were 7.70% (n=384) in organic wheat, 2.80% (n=378) in conventional wheat, 10.50% (n=186) in organic cow pasture, and 8.30% (n=192) in conventional cow pasture. Infection rates were higher in the organic fields and pastures.