The categories are quite broad in the table and they mix common names, orders, specific families etc ... not very well put together.Although while looking through the paper, the table that compares carotenoid content wasn't super clear on the claim that drosophila contains significantly less carotenoids than either ants or mites. Maybe someone else could take a look at the paper?
Anyway, according to their table both dipterans and ants have the same mean carotenoid content (120 mg/kg), but it does imply that mites (arachnids) have significantly more (280 mg/kg).
That said, Dugas et al. only cite that paper in regards to the claim that mites are more carotenoid rich than ants. No claim is made as to a comparison between drosophila and either ants or mites (unless I missed it).
Their reference to Olson raises one of my pet peeves ... improper citation. Dugas et al.should have gone back to the original sources listed in appendix A of Olson. The table in Olson is neither a result or conclusion, it is merely introductory material composed of data extracted from other manuscripts of Olson. This is just pure laziness on the part of the authors ...