Brassica screening for cabbage stem flea beetle (Psylliodes chrysocephala) larval antibiosis

Scientific protocol associated with: Brock, RE, Courtney, C, Penfield, S, and Wells, R, Larval antibiosis to cabbage stem flea (Psyllides chrysocephala) is absent within (Brassica napus), bioRxiv DOI: 10.64898/2026.01.22.694425 (2026). Abstract The cabbage stem flea beetle (Psylliodes chrysocephala) is a major economic pest of oilseed rape (Brassica napus), with host plant resistance now representing a key breeding target. Here, we present a protocol for screening Brassica plants for CSFB larval antibiosis (defined as reduced larval survival and development), allowing large-scale resistance phenotyping across diverse Brassica populations. This method has been used to demonstrate CSFB larval development across time within B. napus, an absence of antibiosis across a large B. napus diversity panel, and consistent antibiosis in white mustard (Sinapis alba), a relative of B. napus. Access to this protocol will allow other research groups and crop breeders to conduct larval screening experiments, with the goal of better understanding genes and traits that confer resistance or susceptibility to CSFB larvae. This protocol should be cited alongside: Brock, RE, Courtney, C, Penfield, S, and Wells, R, Larval antibiosis to cabbage stem flea (Psyllides chrysocephala) is absent within (Brassica napus), bioRxiv DOI: 10.64898/2026.01.22.694425 (2026).