In Vivo Production of Heterorhabditis bacteriophora ‘Oswego’ (Rhabditida: Heterorhabditidae), a Potential Biological Control Agent for Soil-Inhabiting Insects in Temperate Regions

Abstract

The ‘Oswego’ strain of Heterorhabditis bacteriophom has been demonstrated to be effective against several soil-inhabiting pests. This study examined factors affecting in vivo production of this entomopathogenic nematode in greater wax moth, Galleria mellonella , larvae. Timing of emergence of infective juveniles and total production was studied in relation to inoculum rate and host crowding. Nematode establishment increased with increasing inoculum rate in the range of 20–500 infective juveniles per host. However, total production per host was insensitive to inoculum rate within this range. Average number of infective juveniles produced was 336,000 per host. Production within environmental chambers was not influenced by crowding of hosts within production dishes, or crowding among dishes within the chamber. There was some evidence of a crowding effect within production dishes on total production when nematodes were reared in moderately fluctuating ambient laboratory temperatures (mean = 23.8°C). Large, late stage wax moth larvae produced 567,000 infective juveniles per host, twice as many as produced from small, late stage, wax moth larvae. Infective juveniles were produced in at least 3 emergence cycles, but the greatest proportion emerged in the 1st production cycle (82%). Median emergence time from inoculation to the midpoint of the 1st production cycle was 17 d at an inoculation rate of 20 infective juveniles per host. Median emergence time was 1-2 d faster at doses of 200 infective juveniles per host. Median emergence time also varied with location within the environmental chamber.