Bacillus thuringiensis kurstaki strains produce vegetative insecticidal proteins (Vip 3) with high potential

Abstract

Bacillus thuringiensis (Bt) produces vegetative insecticidal proteins (Vip) during its vegetative growth stage. Vip3 proteins have a significant role in insecticidal activity of this bacterium. Each new bacterial isolate may encode Vip with different significance. The Vip protein coding by vip genes of two Bt strains (BnBt and MnD) with high insecticidal activity was characterized in this study. Polymerase chain reaction (PCR)-based screening for Vip genes of these Bt isolates expressed the detected Vip gene and tested the protein for insecticidal activity against the cotton leafworm, Spodoptera littoralis larvae. As a result of the screening tests, Vip3 genes were determined in MnD and BnBt isolates. Vip3 genes of both isolates were expressed and confirmed by 90 kDa proteins. Partially purified and trypsin-activated protein samples of BnBt and MnD isolates were tested against the second instar larvae of S. littoralis. The results showed that the highest insecticidal activity of the Vip3 proteins of BnBt and MnD was 86.66% and 83.33% mortality in 10 days, respectively. The median lethal concentrations (LC 50) of BnBt and MnD were determined as 41.860 and 55.154 ng/μl, respectively. The results suggest that Vip3 protein is effective for preventing resistance in various insect-pest species. The expressed proteins may be utilized as a biopesticide against nocuous insects.

Current Insights on Vegetative Insecticidal Proteins (Vip) as Next Generation Pest Killers

“…compared with Vip3Aa16 [ 85 ]. In another study, two Bt strains, BnBt and MnD, were found to produce Vip proteins in isolates of great potential with a high toxicity (LC 50 = 41.860 ng/μL of BnBt and 55.154 ng/μL of MnD) in the second instar larvae of S. littoralis [ 86 ]. Lone and co-workers isolated and expressed a novel Vip3Aa61 gene in Escherichia coli from isolate B. thuringiensis JK37.…”

Vegetative Insecticidal Protein (Vip): A Potential Contender From Bacillus thuringiensis for Efficient Management of Various Detrimental Agricultural Pests

“…The 90 kDa Vip3 protein was expressed and showed 10th-day mortality of 86.66% (Bn Bt ) and 83.33% (MnD) in comparison to 13.33% in control larvae against the second instar stage of S. littoralis . The LC 50 values were obtained as 55.15 and 41.86 ng/μl for MnD and Bn Bt , respectively ( Güney et al, 2019 ). The assessment of the potential of Vip3 protein against whiteflies was done through isolation of complete coding sequence (2.4 kb) of gene from an isolate of Egypt.…”

Pathogenicity of some local entomopathogenic fungus isolates on the cotton leafworm larvae, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

“…Spodoptera littoralis larvae were reared on artificial diet under the laboratory conditions of 25 ± 1 °C and 65 ± 5% (Güney et al 2019). Emerged adults were fed on honey solution in impregnated cotton in plastic boxes (36 × 23 cm).…”