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 male and female individuals. Steinernema sp. strain T87 from Indonesia was found to consist largely of self-fertile hermaphrodites. Progeny were produced by morphological females both in insects (Galleria mellonella) and in hanging drops of insect haemolymph inoculated with a single infective juvenile. Sperm were present in the oviduct of unmated morphological females. Approximately 1% of infective juveniles developed into males, and males were also present in the second generation where they constituted 1-6% of the population. Under the same conditions the related species Steinernema longicaudum strain CB2B displayed typical steinernematid reproduction: cross-fertilization and a 1:1 sex ratio. It is argued that the development of hermaphroditism in Steinernema sp. T87 represents convergent evolution with Heterorhabditis, the other major genus of entomopathogenic nematode.
Griffin
C T
CT
Institute of Bioengineering and Agroecology, and Department of Biology, National University of Ireland Maynooth, Co. Kildare. christine.griffin@may.ie
O'Callaghan
K M
KM
Dix
I
I
D000818:Animals; D005075:Biological Evolution; D005260:Female; D005298:Fertility; D007214:Indonesia; D008297:Male; D009348:Nematoda / Q000145:classification* / Q000235:genetics / Q000502:physiology; D012098:Reproduction; D012744:Sex Ratio