Identification of Bacillus thuringiensis Strains for the Management of Lepidopteran Pests

Abstract

Bacillus thuringiensis (Bt)-based bioinsecticides and transgenic plants expressing proteins with insecticidal activity (Cry and Vip) have been successfully used in several integrated pest management programs worldwide. Lepidoptera comprise some of the most economically important insect pests of the major agricultural crops. In this study, the toxicity of 150 Bt strains was evaluated against Helicoverpa armigera (Hübner) larvae. Eight strains (426, 520B, 1636, 1641, 1644, 1648, 1657 and 1658) showed high insecticide activity against H. armigera and were therefore tested against Anticarsia gemmatalis (Hübner), Spodoptera cosmioides (Walker), Chrysodeixis includens (Walker), and Diatraea saccharalis (Fabricius) larvae. Our results showed that most of the Bt strains were also toxic to these lepidopteran species. The biochemical and molecular analyses of these strains revealed that they had a similar protein profile; however, their cry and vip gene contents were variable. In addition, the median lethal concentration (LC 50 ) of the selected strains indicated that the strains 1636, 1641, and 1658 were the most effective against H. armigera, showing LC 50 values of 185.02, 159.44, and 192.98 ng/cm 2 , respectively. Our results suggest that the selected Bt strains have great potential to control the lepidopteran pests H. armigera, A. gemmatalis, D. saccharalis, S. cosmioides, and C. includes.

Complete genome sequence of Bacillus thuringiensis BR145, a strain with insecticidal activity against Lepidoptera pests

“…The strain showed insecticidal activity against H. armigera (LC50 of 0.294 µg.cm-2) and to C. includens from both origins, with LC 50 0.277 µg.cm -2 , and 0.398 µg.cm -2 , respectively ( Table 1 ). This LC 50 of in both species is comparable to previous bioactive B. thuringiensis isolates with potential use in microbial control ( Ignoffo et al, 1977 ; Pinheiro and Valicente, 2021 ).…”

Bacillus thuringiensis strains to control Noctuidae pests

“…(2009) used selective bioassays to show that seven of 100 Bt strains, in addition to HD‐1, showed high toxicity to S. eridania larvae. Pinheiro and Valicente (2021) demonstrated that eight of 150 Bt strains caused mortality rates higher than 75% to H. armigera . These results corroborate our findings that Bt could be a viable alternative for insect pest control.…”

“…Some studies have reported high mortality levels after Bt ingestion by S. frugiperda larvae(Monnerat et al, 2007;Valicente et al, 2010). dosSantos et al (2009) used selective bioassays to show that seven of 100 Bt strains, in addition to HD-1, showed high toxicity to S. eridania larvae Pinheiro and Valicente (2021). demonstrated that eight of 150 Bt strains caused mortality rates higher than 75% to H. armigera.…”

Expression of Pinellia pedatisecta Agglutinin PPA Gene in Transgenic Sugarcane Led to Stomata Patterning Change and Resistance to Sugarcane Woolly Aphid, Ceratovacuna lanigera Zehntner

“…The second approach is crop breeding to develop insect−resistant cultivars, mainly via genetic engineering. Bacillus thuringiensis (Bt) crystal protein genes have been widely used in crops to resist chewing pests [1,2]. Nevertheless, transgenic Bt crops can resist only limited types of pests.…”