Diet affects male gonad maturation, female fecundity, and larval development in the granivorous ground beetle Anisodactylus punctatipennis

1. Granivory is a specialised food habit in the Carabidae and is considered to have evolved from ancestral carnivory. Despite recent investigations, the mechanisms underlying this peculiar feeding shift have not been sufficiently elucidated. In particular, no studies have examined the effects of diet composition on male reproductive traits. 2. This study examined male gonad maturation, female fecundity, and larval development under different diets (insect larvae, mixed seeds, and insect larvae + mixed seeds) for Anisodactylus punctatipennis (Coleoptera: Carabidae). 3. Whereas sperm‐bundle length, the durations of larval stages, and adult weight did not differ among diets, the weights of seminal substance‐producing organs, fecundity, and larval survival were higher with diets containing seeds compared to the pure‐animal diet. These findings provide the first conclusive evidence for granivory in Anisodactylus . 4. This study is the first that demonstrates the effects of diet on male reproductive traits in a granivorous carabid. The results were consistent with similar observations for fecundity and larval performance in this and other studies. Thus, in addition to the female and larval traits, the dietary effects on male reproductive traits may also have played an important role in the evolution of granivory in the Carabidae.