Screening Brassicaceae plants for cabbage stem flea beetle (Psylliodes chrysocephala) larval antibiosis

Scientific protocol associated with: This protocol should be cited alongside: Brock RE, Courtney C, Penfield S, and Wells R (2026), Larval antibiosis to cabbage stem flea beetle (Psylliodes chrysocephala) is absent within oilseed rape (Brassica napus), bioRxiv DOI: 10.64898/2026.01.22.694425. 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 Brassicaceae plants (Brassica and Sinapis species) for CSFB larval antibiosis (defined as reduced larval survival and development), allowing large-scale antibiosis phenotyping across genetically diverse Brassicaceae populations. This method has been used to demonstrate CSFB larval development across time within B. napus, an absence of antibiosis across a large, genetically diverse B. napus population, 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 (2026), Larval antibiosis to cabbage stem flea beetle (Psylliodes chrysocephala) is absent within oilseed rape (Brassica napus), bioRxiv DOI: 10.64898/2026.01.22.694425.