Evaluation of PDKV Bacillus thuringiensis strains against Spodoptera frugiperda (J.E. Smith)

The present investigation entitled “Evaluation of PDKV Bacillus thuringiensis strains against Spodoptera frugiperda (J.E. Smith)” was carried out during the year 2023-2024 in the Department of Entomology, Post Graduate Institute, Dr. Panjabrao Deshmukh Krishi Vidyapeeth Akola. The aim of the investigation was to evaluate the toxicity of PDKV Bt isolates against Spodoptera frugiperda. During the study eleven local Bt isolates PDKV-SGd-1, PDKV-SY-4, PDKV-SA-6, PDKV-SAk-6, PDKV-I-3, PDKV-SGn-5, PDKV-SAk-9, PDKV-SBn-2, PDKV-SA-18, PDKV-SGn-4 and PDKV-SA-20 along with Btk HD-1 as standard check were used. The endotoxins from these Bt strains were isolated following method of acetone co-precipitation and used for conducting the toxicity bioassays against the third instar larvae of Spodoptera frugiperda. The lowest median lethal concentration (LC50) was exhibited by PDKV-SA-20 of (172.90 µg/ml), followed by PDKV-SGd-1 (177.61 µg/ml) and PDKV-SY-4 (186.17 µg/ml) and these strains were found more effective than standard Btk HD-1 showed the LC50 (191.41 µg/ml). The rest of strains however found at par in toxicity to that of the standard Btk HD-1. Further computation of relative toxicities indicated that Bt isolate SA-20, SGd-1 and SY-4 were 2.08, 2.03 and 1.93-fold more toxic than lowest toxic Bt isolate PDKV-SBn-2.