Comparative Efficacy of Bacillus thuringiensis Commercial Formulations against Leaf Worm, Spodoptera litura Fabricius under Laboratory Conditions.

A study was carried out in the Bio-control Laboratory, Department of Entomology at Pir Mehr Ali Shah, Arid Agriculture University Rawalpindi to check the efficacy of commercial biopesticides under controlled environmental conditions. Bio pesticides are important alternates for chemical control of economically damaging insect pests like leaf worm, Spodoptera litura Fabricius. In this study, two commercial products including Dipel with Bt sub speciess kurstaki and Turex with Bt sub speciess kurstaki and aizawai were tested against three early larval instars of S. litura under laboratory conditions using leaf dip method. Mortality was recorded after three and seven days of exposure. The results indicated that larval mortality increased with time and Turex (Bt sub speciess kurstaki and aizawai) after 3 days of exposure caused significantly higher mortality i.e 46.43, 43.45 and 38.69 % as compared to Dipel (Bt sub speciess kurstaki) that caused 19.05, 6.55 and 4.76 % mortality for 1^st, 2^nd and 3^rd instar, respectively. The data for 7^th day also showed significantly higher mortality as 64.29, 60.71 and 45.24 % by Turex (Bt sub speciess kurstaki and aizawai) in comparison with 55.95, 57.74 and 42.86 % mortality by Dipel (Bt sub species kurstaki) for 1^st, 2^nd and 3^rd instar, respectively. Susceptibility to both bio pesticides increased with increase in their concentration and decreased with increase in larval instar. Similarly LC50 values suggested Turex (Bt sub species kurstaki and aizawai) to be more toxic with less LC₅₀ values as compared to Dipel (Bt sub species kurstaki). These results indicated that these bio pesticides if used at early insect stage can help to control this pest. [ABSTRACT FROM AUTHOR]