Seasonality and life histories of two endemic New Zealand carabid beetles (Coleoptera: Carabidae): Mecodema oconnori Broun and Megadromus capito (White)

Abstract

Seasonal activity and life histories of two large endemic carabid beetles, Mecodema oconnori Broun and Megadromus capito (White), were investigated in two lowland forest remnants in the Horowhenua region, North Island, New Zealand. Seasonal activity was estimated from manual searches of surface refuges, plus pitfall trapping from October to March. Adults of both species were present throughout the year, although M. oconnori was much more abundant in spring. Megadromus capito larvae were caught from October to March, and the three instars overlapped temporally, implying a long period of larval emergence and development. Adult females were dissected to investigate their reproductive phenology. Both species carried eggs for at least 6 months of the year. M. oconnori females contained very few eggs, with a maximum of three eggs each and a mean of 1.6 eggs per female. Mg. capito females had up to 28 eggs each and a mean of 10.5. Both species appear to have low egg loads, a relatively long period of reproductive activity and long life spans, but longer‐term studies on the pre‐adult stages and reproductive activity of adults are required to complete understanding of their life cycles.