The pathogenicity of entomopathogenic nematodes from the genera Stetnernema and Heterorhabditts against Heliothts armigera Hiibner was tested under laboratory conditions. Complete mortality was achieved with 200 infective juveniles (IJ) of S. feltiae Filipjev, strain ‘All,’ The LD50 was 54 IJ per insect. Similar results were obtained with other nematode strains. The youngest instars were the most susceptible to nematode infection. Eight hours of insect exposure to the nematode were needed to induce >80% mortality. Survival of S. feltiae ‘All’ strain on the foliage of bean plants under glasshouse conditions (50-70% RH, 25°C, natural illumination, 14:10[L:D]photoperiod) was reduced to 20% within 4 h and to 0% after 8 h exposure. A comparative bioassay of the survival of several steinernematid and heterorhabditid nematodes on foliage of bean plants under glasshouse conditions indicated that S. feltiae ‘Mexican’ and ‘Pye’ strains have a higher capability to withstand the experimental conditions than S. feltiae ‘All’ strain. Foliage application of the S. feltiae ‘Pye’ strain, mixed in solutions of the anti desiccants glycerol (1% wt/wt) or Folicote (6% wt/wt), resulted in 75 and 95% control of H. armigera larvae, respectively. When the same solutions were applied with the ‘All’ strain, which is less tolerant to desiccation, only 10 and 40% control control were achieved, respectively.
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Glazer et al. (1990) studied this question.