Floral strips adjacent to Manitoba crop fields attract beneficial insects shortly after establishment regardless of management type or landscape context

Abstract

Insects provide valuable ecosystem services to agriculture, but their populations are often lower in these areas. We established floral strips on the edges of eight organic and seven conventional crop fields in southern Manitoba. We then compared the capture rates of ground beetles, syrphid flies and bees in floral strips; control (unmodified) field edges; nearby semi-natural sites; and within the strip and control fields at six distances away from field borders (5–150 m). The effects of farm management and landscape context on insect abundance, diversity and associated species traits were investigated. Capture rates of bees and beetles were significantly higher within the floral strips than the control treatment. However, capture rates of syrphids were significantly higher in the control. Beetles and bees responded positively to blooming forb cover and edge density (0.5 km), whereas syrphids responded positively to non-rewarding agriculture and negatively to the semi-natural areas (1 km). We found no significant difference in insect abundance or diversity between organic and conventional management types, and no differences in insect abundances within the fields were detected. No significant associations between insect traits and landscape variables were identified. These results show that floral strips are effective at attracting ground beetles and bees shortly after establishment, but these communities are functionally similar to those present in control fields. Longitudinal studies are needed to determine whether populations continue to increase over time and become more functionally diverse in fields with floral strips.