The irregular developmental duration mainly caused by the broad-complex in Chilo suppressalis.

Area of Science:

• Entomology
• Molecular Biology
• Pest Management

Background:

• Chilo suppressalis is a major rice pest with overlapping generations and irregular development, complicating control strategies.
• The Broad-Complex (Br-C) gene is known to regulate development in insects, but its specific role in C. suppressalis was unclear.

Purpose of the Study:

• To investigate the role of the Broad-Complex (Br-C) gene in regulating the developmental duration of Chilo suppressalis.
• To identify specific isoforms of Br-C involved in larval development and pupation.

Main Methods:

• Identification of four Broad-Complex (Br-C) gene isoforms (CsBr-C Z1, Z2, Z4, Z7) in C. suppressalis.
• RNA interference (RNAi) using dsRNA targeting CsBr-Cs and specific isoforms (e.g., dsCsBr-C Z2).
• CRISPR/Cas9-mediated gene mutagenesis to create CsBr-Cs knockout individuals.

Main Results:

• RNAi of CsBr-Cs significantly extended larval development duration and altered pupation instars, with dsCsBr-C Z2 showing the longest delay.
• CRISPR/Cas9-induced knockout of CsBr-Cs also significantly prolonged developmental duration and delayed pupation.
• Pupation rates were significantly reduced in most dsCsBr-Cs treated groups compared to controls (dsGFP).

Conclusions:

• The Broad-Complex (Br-C) gene, specifically CsBr-Cs, is essential for regulating pupal commitment in Chilo suppressalis.
• CsBr-Cs plays a significant role in controlling the overall developmental duration of this critical rice pest.
• Understanding CsBr-Cs function offers potential targets for novel pest management strategies against C. suppressalis.