There is currently no information on the genome size and complexity in the entomoparasitic nematodes Steinernema and Heterorhabditis. DNA reassociation kinetics were used to determine the genome size and complexity in 2 species: Steinernema carpocapsae and Heterorhabditis bacteriophora. C0t curves derived from renaturation kinetics of denatured DNA indicate that the genomes of these entomoparasitic rhabditids are different both in size and complexity. Genome sizes were estimated at 2·3 × 108 bp for S. carpocapsae and 3·9 × 107 bp for H. bacteriophora and repetitive DNA contents were found to represent 39% and 51% of these respective genomes.
