Influence of Intercropping Canola or Pea with Barley on Assemblages of Ground Beetles (Coleoptera: Carabidae)

Pitfall traps were used to compare assemblages of ground beetles (Coleoptera: Carabidae) among treatments of two intercrop trials replicated at each of two sites in each of three years. The first trial comprised canola (Brassica napus L.) and barley (Hordeum vulgare L.) in monoculture and three intercrop treatments of canola and barley. The second trial comprised pea (Pisum sativum L.) and barley in monoculture and three intercrop treatments of pea and barley. Treatment had little effect on species richness. For taxa combined, a significant effect of treatment was detected in 3 of 11 cases, reflecting greater captures of beetles in canola or pea than in barley. Captures of individual taxa were compared among canola or pea versus each of the three intercrops versus barley. For 14 of 15 cases showing significant differences between monocultures, more beetles were captured in canola or pea than in barley. For 12 of 14 cases showing significant differences between monocultures and intercrops, captures of beetles were highest in canola or pea. These cases primarily reflected different captures of Amara spp. and Bembidion spp. across treatments. Results show that under the experimental conditions of the current study in Alberta, Canada, intercropping barley into canola or pea did not increase the activity abundance of populations above that observed in the latter two crops.