Estimation of entomopathogenic nematode population density in soil by correlation between bait insect mortality and nematode penetration

We present a method for estimating entomopathogenic nematode densities in soil samples based on repeated sampling with wax moth, Galleria mellonella larvae as bait hosts. This method has a very high extraction efficiency and is less time consuming than other methods. Ten bait insects are added per sample and are replaced every 3 days with fresh insects until nematode infections cease. The estimation of nematode density is based on a strong linear relationship between the log(10) of the number of nematode-infected bait insects and the log(10) of the number of nematodes found in these bait insects. This relationship was tested for two nematode species in field samples of natural populations and for three nematode species and three soil types in the laboratory. The slope of the linear regression line varied only slightly among trial, species, and soil type.