Influence of bacterial density and mating on life history traits of Heterorhabditis bacteriophora

Abstract

Heterorhabditis bacteriophora, associated with Photorhabdus luminescens, is commonly used against insect pests. Dauer juveniles (DJ) develop into self-fertilising hermaphrodites that lay eggs until juveniles hatch inside the uterus and feed on the body content of the mother (endotokia matricida). The life history traits of H. bacteriophora were studied at 2.5 × 109, 5 × 109, 10 × 109 and 20 × 109 cells ml−1 of P. luminescens at 25°C using a hanging drop technique. The number of offspring produced per hermaphrodite increased from 50 at 2.5 × 109 cells ml−1 to 269 at 20 × 109 cells ml−1 of P. luminescens. The bacterial density did not influence the beginning of endotokia matricida, hermaphrodite death, DJ release from the maternal carcass and the percentage of juveniles obtained through endotokia matricida. Mating of automictic females could not increase offspring production and survival. Endotokia matricida is an obligatory developmental step in H. bacteriophora.