Laboratory studies on larval feeding habits of Amara macronota (Coleoptera: Carabidae: Zabrini)

Abstract

Many studies have suggested that some carabids (tribes Zabrini and Harpalini; Coleoptera: Carabidae) feed on seeds during their adult stage (i.e., granivore or omnivore with a tendency toward granivory), but relatively few studies have investigated the larval feeding habits of those species. In the present study, larval development on different diets was examined in a Zabrini carabid Amara (Curtonotus) macronota. Six diet types were tested: Solidago altissima seeds, Bidens frondosa seeds, Setaria spp. seeds, mixed seeds, insect larvae (Diptera), and insect larvae+mixed seeds. Because of the high mortality during larval overwintering under laboratory-rearing conditions, survival and developmental duration through pre-overwintering stages (1st and 2nd instars) were compared. The insect larvae+mixed seeds diet showed high survival (85%), followed by the insect larvae diet (40%). All seed diets showed low survival rates (0–10%). Developmental durations were not significantly different, although some diets could not be compared due to a small sample size. These results suggest that A. macronota larvae are omnivores with a tendency toward carnivory. Larval morphometry, which is useful in determining the instars of field-collected larvae, was used.