1Department of Entomology, Sugarcane Research Station, Cuddalore-607 001, Tamil Nadu (India).
2, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore-641 003, Tamil Nadu (India).
*Address for correspondence: 273-A, Anna Salai, Pondicherry-605 001, Pondicherry State (India).
The effect of biopathogens, viz., Bacillus thuringiensis var. kurstaki (B.t.) 0.25% suspension, and the white muscardine fungus, Beauveria bassiana Vuillemin >(2 x 108 conidia/cm2) was studied on different stages of spotted beetle, Henosepilachna vigintioctopunctata (Fab.) infesting egg plant, Solanum melongena Linn. B.t. used as a leaf dip casued a maximum mortality of 68.9% in the first instar grubs and a minimum of 13% in the prepupal stage of egg plant spotted beetle. The adults were less susceptible to B.t. The per cent egg hatchability was respectively 12.2, 11.7, 17.9, 12.9 and 18.7 when freshly laid, 1, 2, 3 and 4-day old eggs were treated with 0.25% B.t Direct spraying of the white muscardine fungus killed 58.1% first instar grubs and 35.2% pre-pupal stage grubs. The adults were not susceptible to this fungus, the maximum mortality being 10.3% in the case of newly emerged adults. This fungus caused 54.6% hatchability of one-day old eggs of the spotted beetle.
