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Table 1 Indices of aggregation (Ia)* values recorded at different countries on entomopathogenic nematode (EPN) populations with various sampling methods and units (Abd-Elgawad 2019)

From: Towards sound use of statistics in nematology

EPN investigated population Method of measuring EPNs Ia value Notes (geographical zone) References
Heterorhabditis bacteriophora-infective stage juveniles (IJs) used in different distribution patterns EPN-infected greater wax moth larvae over time Mean values were less than one but differed significantly until 20 weeks after adding EPNs The values indicate a more uniform distribution than a random one (New Jersey/USA) Wilson et al. (2003)
Natural Steinernema feltiae and S. affine populations in grassland IJs grouped to 4 groups of different physiological ages The values were in the range 1.27–1.45, group II was the most aggregated stage All values showed clumped distribution patterns (Merelbeke/Belgium) Spiridonov et al. (2007)
H. bacteriophora or S. carpocapsae-infected greater wax moth larvae used within 24 h of starting IJ exit to planted fields and grassy plots IJs of H. bacteriophora and S. carpocapsae recovered from greater wax moth larvae baits used after the cadavers Mean values range < 1 to > 2. They differed between nematode species in bait traps and between control methods at 48 h and 16 days after placing the cadavers, respectively Distribution patterns after dispersing from a grassy border plots into the adjacent cultivated field plots were more clumped for H. bacteriophora than for S. carpocapsae (Ohio/USA) Bal et al. (2017)
H. indica natural populations in citrus and mango grove EPN-infected greater wax moth larvae 0.913 Ia refers to uniform distribution (Giza/Egypt) Abd-Elgawad (2020)
  1. *Ia = the observed value of distance to regularity/the mean randomized value (Perry 1995)