This agrees with work done in North America over many years, by Karl Leius
in Ontario in the 1960s for example.
Wild carrot/Queen Anne's Lace has been found effective, and Virginia
Mountaim Mint (Pycnanthemum virginianum) and hairy mountain mint
(Virginianum pilosum) have been recommended.
Boneset (Eupatorium perfoliatum) and Joe-Pye-Weed (Eupatorium maculatum
and others) have been found to attract beneficials. They will grow on many
soils that do not dry out in summer (especially if competition is limited)
despite being considered wetland plants.
I have observed parasitic wasps on cultivated sunflowers, and I speculate
that the related false sunflower Heliopsis helianthoides and cup-plant
Silphium perfoliatum, as well as the wild sunflowers of the genus
Helianthus, would be useful.
Generally, wildflowers for butterflies should also attract beneficials.
Small flowers are good for the egg-laying adults of the important
parasitic wasps. Indiangrass has extra-floral nectaries.