"Brassica White"

[PhilBJohnson]

Is there a Brassica species, which the Small White butterfly species (Pieris rapae) never uses to complete it's Life Cycles?

Dyke bank in Lincolnshire growing Rapeseed (Brassica napus) near vegetable allotments May 4th 2020

i did not know enough about rapeseed and what pest control sprays (insecticides), some farmers might use on their crops, that might also be unsuitable for, or less appropriate for use on river banks, draining water into a water course in close proximity. In my picture, not knowing the land owner, I thought that the Environment Agency, (or Anglian Water) might have been responsible for what was growing there.