Cry Proteins from Bacillus thuringiensis Active against Diamondback Moth and Fall Armyworm

Area of Science:

• Microbiology
• Insect Toxicology
• Biotechnology

Background:

• Bacillus thuringiensis (Bt) biopesticides and genetically modified crops are vital for controlling Plutella xylostella and Spodoptera frugiperda.
• Insect resistance to Bt toxins necessitates exploring novel strains and toxin combinations to maintain effective pest management.

Purpose of the Study:

• To characterize the protein and toxin gene content of 20 Bacillus thuringiensis isolates from Northeast Brazil.
• To identify potent Bt isolates effective against Plutella xylostella and Spodoptera frugiperda.

Main Methods:

• Protein profiles were analyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).
• Toxin gene presence was determined through polymerase chain reaction (PCR) assays.
• Insecticidal activity was quantified using lethal concentration 50 (LC50) values.

Main Results:

• Most isolates produced Cry1, Cry8, and Cry9 proteins (approx. 130 kDa).
• Isolates LIIT-4306 and LIIT-4311 exhibited high efficacy against both pests, with low LC50 values.
• These potent isolates harbored a wide array of cry genes, including multiple cry1A variants, cry2, cry8, and cry9C.

Conclusions:

• The identified Bacillus thuringiensis isolates possess diverse toxin gene profiles with significant potential for controlling Plutella xylostella and Spodoptera frugiperda.
• The presence of multiple cry1A genes in effective isolates highlights their importance for pest control strategies.
• This study provides valuable insights for developing sustainable biopesticide solutions against key agricultural pests.