A self-fertile species of Steinernema from Indonesia: further evidence of convergent evolution amongst entomopathogenic nematodes?

More than 20 species of the entomopathogenic nematode Steinernema have been described; to date, all reproduce exclusively by cross-fertilization of ma le and female individuals. Steinernema sp. strain T87 from Indonesia was fo und to consist largely of self-fertile hermaphrodites. Progeny rr-ere produ ced bq morphological females both in insects (Galleria mellonella) and in h anging drops of insect haemol)mph inoculated with a single infective juveni le. Sperm were present in the oviduct of unmated morphological females. App roximately 1% of infective juveniles developed into males, and males were a lso present in the second generation where they constituted 1-6%, of the po pulation. Under the same conditions the related species Steinernema longica udum strain CB2B displayed typical steinernematid reproduction: cross-ferti lization and a 1:1 sex ratio. It is argued that the development of hermaphr oditism in Steinernema sp. T87 represents convergent evolution with Heteror habditis, the other major genus of entomopathogenic nematode.