Presumably polylectic: Terzo et al. (2000) have recorded the species at the flowers of Rubus sp. (Rosaceae) where it nests.
In Cyprus, Mavromoustakis (1948, 1951; 1954) observed it at Eryngium creticum (Apiaceae), Dittrichia (=Inula) crithmoides, Cichorium pumilum, Pulicaria dysenterica (Asteraceae) Lotus sp. (Fabaceae), Mentha longifolia, Ballota nigra, (Lamiaceae) and Rubus ulmifolius anatolicus (Rosaceae).
Ceratina mandibularis is reported to visit the female flowers of Ecballium elaterium (Cucurbitaceae) at the beginning of each foraging day and stay longer in these flowers (Reuyen, Dukas 2004).