Table 1 Comparison of index of aggregation (I_a) (the observed value of distance to regularity/the mean randomized value (Perry 1995)) values of four different studies on entomopathogenic nematode distributions using different approaches in various regions

Heterorhabditis bacteriophora-infective stage juveniles (IJs) applied uniformly, in one or nine patches on Kentucky bluegrass

EPN-infected Galleria mellonella larvae over time

All mean values were less than one but differed (P ≤ 0.05) until 20 weeks, no more, after EPN application

The values suggest a more even distribution than a random one (New Jersey/USA)

Wilson et al. 2003

Natural populations of Steinernema feltiae and S. affine in grassland plots

IJs assigned to one of 4 groups of increasing physiological age

The values ranged 1.27–1.45 with group II as the most aggregated one

All values indicate aggregated distribution (Merelbeke/Belgium)

Spiridonov et al. 2007

H. bacteriophora- or S. carpocapsae-infected G. mellonella larvae applied within 24 h of initial IJ emergence to cultivated fields and adjoining grassy border plots

H. bacteriophora and S. carpocapsae-IJs recovered from G. mellonella larvae baits applied several times after the cadavers

Range < 1 to >2. Mean values differed between EPN species in bait traps and between soil management regimes at 48 h and 16 days after placing the cadavers, respectively

Spatial distributions after dispersing from a grassy border into the adjacent cultivated field plots were more aggregated for H. bacteriophora than for S. carpocapsae (Ohio/USA)

Bal et al. 2017

Natural populations of H. indica in citrus and mango grove

EPN-infected G. mellonella larvae

0.913

I_a refers to even distribution (Giza/Egypt)

Abd-Elgawad (unpublished)