The duration of development, survivorship and adult size were compared for the larvae of Amara aenea reared in the first generation on pure diets of seeds (Stellaria media, Capsella bursa-pastoris, Tussilago farfara, Plantago major, Urtica dioica, or Potentilla argentela), or a pure diet of yellow mealworms (Tenebrio molitor larvae), and on a mixed diet of seeds and mealworm larvae (T. molitor, S. media and C. bursa-pastoris). To ascertain any long-term effects of pure diets, the beetles were reared on the same pure diet for several generations, or on different pure diets in different generations. The hypothesis that the larvae are primary omnivorous was tested. The evidence that the larvae of A. aenea are primary omnivorous was obtained by revealing that the larvae reared on the mixed diet of insects and seeds survived better, and developed faster in larger adults than those reared on the pure diets of seeds or insects. When the beetles were reared on the same pure diet for several generations, survivorship, and in most cases also the duration of development, did not change. However, when the beetles were reared on a different pure diet each generation, survivorship significantly decreased in successive generations.
Development rates of the eggs of 9 species, larvae of 6 species and pupae of 6 species of the genus Amara (Coleoptera: Carabidae) were recorded at five constant temperatures between 17 and 28°C, and thermal constants for each development stage calculated. The lower development threshold varied between 9.2-13.5°C for different stages and species. Rate isomorphy, which implies the existence of a common temperature threshold for all development stages, was demonstrated in 5 species. The sum of effective temperatures differed between stages. On average the egg stage took 18%, the first larval instar 13%, second instar 13%, third instar 35% and pupa 21% of the total development time. A poor diet increased the SET of the larvae. The results are compared with published data on Carabidae.