Natural Resistance to and Attraction of the Cabbage Root Fly (Delia radicum) in Oilseed Rape Accessions

Winter oilseed rape
(OSR, Brassica napus) is an important
crop and frequently attacked by the cabbage root
fly larvae (Delia radicum). They damage
the taproot, cause plant death, and negatively impact yield. Options
to control D. radicum with synthetic
pesticides are limited, and no tolerance in OSR has been described.
We aim to identify natural resistance in OSR accessions to D. radicum as a starting point for plant breeding.
We tested OSR accessions for differences in larval feeding damage,
larval performance, female attraction, and oviposition preference.
Using a subset of the most and least resistant accessions, we analyzed
volatile profiles and leaf traits and assessed root metabolic fingerprints.
Resistance to larval damage was related to lower aliphatic glucosinolates
and higher lignin-related compound levels. Oviposition preference
was linked to higher trichome density. Our results suggest breeding
efforts should focus on increasing lignin and decreasing specific
glucosinolates in OSR roots.