NEW MORPHOLOGICAL VARIANTS OF INFECTIVE JUVENILES ASSOCIATED WITH MUTATIONS IN 4 SEX-LINKED GENES OF STEINERNEMA-FELTIAE (FILIPJEV) (NEMATODA, STEINERNEMATIDAE)

The research reported here provides a detailed genetic and morphologic al characterization of the first eight mutations artificially induced in Steinernema feltiae. All newly identified alleles proved to be sex- linked and recessive to wild-type counterparts. They define four indep endent genes designated as Sfdpy-1, Sfdpy-2, Sfseg-1, and Sfvab-1. All mutations affected the morphology of the nematode infective juveniles and except for the pn32 allele they showed complete penetrance. Modif ications of the gross morphology observed among identified mutants inc luded visible reduction of infective juvenile length to width ratio (d umpy phenotype), regular serial swellings present along the nematode b ody line (segmented phenotype), and distinct constrictions of the juve nile body which occurred irregularly on its dorsal side (variable abno rmal phenotype). A number of other minor modifications such as helical twist of the nematode body, transverse foldings of its cuticle, Vario us changes of head and tail region, rearrangements of lateral fields a nd others have also been associated with individual mutations. The wid e range of distinctive phenotypes produced in this research provides e xcellent comparative material for detailed study on the significance o f morphological characters to the entomopathogenic activity of S. felt iae infective juveniles.