Polyether polyurethane sponge
In sponge after 2 months of storage, the average survival rates of S. ceratophorum, S. pakistanense were 72% and S. siamkayai 71%, S. bifurcatum 77% while H. indica showed 75% survival rate. As the time duration increased, the survival rates of H. indica declined up to 50%, while S. ceratophorum, S. pakistanense showed 45%, S. bifurcatum 42% and S. siamkayai 35% (Fig. 1). S. pakistanense showed a high survival during 2–6 months in sponge medium (ANOVA F = 3.6; df = 3, 15; P < 0.05), whereas S. bifurcatum showed a maximum survival in sponge during 2–6 months (ANOVA F = 3.2; df = 3, 15; P < 0.05), while H. indica showed a minimum survival in sponge during 2–6 months (ANOVA F = 0.2; df = 3, 15; P < 0.05), whereas S. ceratophorum, S. siamkayai showed less significant survival rates in sponge during 2–6 months (ANOVA F = 0.135; df = 3, 15; P < 0.05).
Distilled water
After 2 months of storage in distilled water, the average survival rates of S. ceratophorum were 65%, S. pakistanense 72%, S. bifurcatum 68% and S. siamkayai and H. indica showed 64% of viability. After half year of storage the survival percentage of S. ceratophorum and S. pakistanense was 56 and 60%, respectively. S. siamkayai and H. indica showed 52% and S. bifurcatum 42%. After completion of one year of storage all species survival rates in distilled water were found to be 32–36% (Fig. 1). In water, S. pakistanense showed a significant high survival during 2–6 months (ANOVA F = 8.4; df = 4, 15; P < 0.05), while S. ceratophorum, S. bifurcatum, S. siamkayai and H. indica showed a moderate significance during 2–6 months (ANOVA F = 4.0; df = 3,15; P < 0.05).
Soil medium
In soil medium, viability of nematodes is shown in (Fig. 1) from 2 to 12 months of storage. In soil medium after 2 months of storage less number of nematodes survived of all tested species as compared to other substrate. The survival rates ranged from 35 to 60%at 6 months of storage, declined up to 22–30%. In soil, all type of nematodes showed nonsignificant survival rates during 2–6 months (ANOVA F = 0.1; df = 4, 15; P < 0.05).
Efficacy of EPNs against Spodoptera litura
Isolates of S. bifurcatum, S. ceratophorum, S. pakistanense, S. siamkayai and H. indica were evaluated to find, infectivity and mortality S.litura last stage larvae at different concentrations at 28–30 °C by filter assay in laboratory experiments (Fig. 2). The ANOVA showed significant differences among effectiveness of nematode species on army worm (ANOVA F = 24; df = 4; P = 0.0005). Concentration of nematodes also diverged significantly (RCBD-one-way ANOVA F = 23; df = 4; P < 0.05) and impact of the three concentrations with five nematode species also had the remarkable results on army worm (ANOVA F = 30; df = 4; P < 0.05). Outcome verified that the EPNs could restrain the frequency of S.litura. S. pakistanense, S. bifurcatum and H. indica showed higher mortality rates (87–95%) at high application concentrations than S. ceratophorum and S. Siamkayai (74–78%). Maximum mortality rates were attained at the concentrations of 350 IJs/ml (Fig. 2) after 48 h. At the lowest concentration (150 IJs/ml) 60% of army worms were killed by S. bifurcatum, after 48 h of exposure time showing significant differences with 50% against H. indica and S. ceratophorum. The mortality rates of S. litura increased depends upon the concentrations. At 350 IJs/ml, S. pakistanense showed the highest mortality rates (95%), while the lowest one was (74%) by S. ceratophorum. Nematode juveniles reproduced in the larvae of S. litura, which were clearly seen when dead larvae were transferred to vacant cavity block.