Morphological variation between allopatric populations of Steinernema kraussei (Steiner, 1923) (Rhabditida : Steinernematidae)

Morphometrics of four Canadian, three US and two European isolates represen ting distinct geographic populations of Steinernema kraussei (Steiner, 1923 ) were compared and analysed by multivariate analysis. A total of 540 indiv iduals (270 males and 270 third-stage infective juveniles) representing the nine populations was measured. Fourteen morphometric variables were select ed and subjected to principal component and canonical analyses. Results fro m both analyses indicate that there are morphological differences among the studied isolates, and that these differences are congruent with their geog raphic origin. The European isolates were shown to be distinctly different from the North American isolates. Within the North American isolates, the w estern isolates were distinguished from the eastern one (Parishville). No s ignificant differences were observed between the two European isolates stud ied.