Bioefficacy of Indian strains of entomopathogenic nematodes against different homopterans under laboratory conditions.

The virulence of four Indian strains of entomopathogenic nematodes Steinernemac thermophilum (New Delhi strain), S. meghalayensis (Meghalaya strain), S. riobrave (Gujarat strain), S. harryi n. sp. (Tamil Nadu strain) were evaluated against third instar nymphs of solenopsis mealybug (Phenacoccus solenopsis), adult cotton aphid (Aphis gossypii) and second instar nymphs of cotton whitefly (Bemisia tabaci) in two doses (50 and 500 IJs/ml) in sand well and leaf disc assays under laboratory conditions. S. thermophilum caused significant mortality of mealybugs which was 83% within 72 h after inoculation at 50 IJ/ml and 100% within 48 h at 500 IJs/ml. S. riobrave and S. harryi n. sp. produced intermediate mortality of about 66% within 60 h at 500 IJs/m1. Against aphid, S. thermophilum caused 66 and 83~’O mortality at 50 and 500 IJs/ml, respectively within 3 days post inoculation. None of the Steinernema spp. caused significant mortality of whitefly at 50 IJs/ml; only the higher concentration produced mortality. At 5(J0 IJs/ml S. riobrave caused maximum mortality of about 66% within 72 h after inoculation. S. meghalayensis was the least effective strain as it caused only 33% mortality of all tested insects at both low and high doses. Emergence was observed only in 16.6% of the mealybug cadavers infected with S. thermophilum and S. harryi n. sp, while no emergence was observed from whitefly and aphid cadavers.