Evaluation of four entomopathogenic nematodes againstSpodoptera littoralis (Lepid., Noctuidae) larvae under different temperatures

The efficacies of four strains of entomopathogenic nematodes on infecting and killingSpodoptera littoralis were tested in the laboratory concerning soil temperature, nematode dose and emergence from the insect cadavers. All the tested nematodes attained almost 100% insect mortality at 4, 10 and 25 °C but at 35 °C,Heterorhabditis bacteriophora (HP88) achieved the least (64%). As soil temperature rise to 35 °C, the most adversely affected nematode in terms of recycling efficiency wasH. bacteriophora (EASD98) followed bySteinernema riobravis, H. bacteriophora (HP88) and finallyH. indicus (EAS59). Although all nematodes could infect and kill the host insects at 35 °C, those ofH. bacteriophora (EASD98) could not emerge from the cadavers. Differences in the numbers of emerging infective juveniles as related to nematode concentration and different degrees of soil temperatures were obvious and may be considered in developing a biocontrol strategy for the management of the cotton leaf-worm.With 4 tablesThis research was supported by the NARP project No. H-035 and is a part of a M. Sc. thesis by Mr. Atwa Ahmed Atwa.