Impact of camelina (Camelina sativa (L.) Crantz, Brassicaceae) on the diversity of pollinators (Apidae & Syrphidae) in camelina-pea mixed crop cultivation

Abstract

The decline in insects forces the establishment of insect-friendly cultivation systems in agricultural landscapes in order to support pollinating insects and preserve ecosystem services. The study aims to clarify whether the additional cultivation of camelina in pea crops increases the diversity of wild bees and hoverflies. Abundance and diversity were considered and evaluated in camelina-pea mixed crop cultures, pea cultures and camelina cultures in three consecutive years by using standardized methods such as pan traps and visual catches. Aphid infestation, aphid predators as well as butterflies were also recorded. The comparison of pollinators shows an increase in species numbers in all three years of collection as well as in the number of individuals in 2020 and 2021 in mixed crops compared to pea crops. Calculated diversity indices (Shannon-Wiener-Index H_s and Evenness E) averaged H_s = 2.86 with E = 0.72 for mixed crops and thus higher than for pea crops, with H_s = 2.39 and E = 0.65. In camelina crops, also butterflies benefit visibly from the additional offer of flowers. The study demonstrates that additional cultivation of camelina provide necessary flowering resources, that have been shown to be used by a more diverse pollinator community, thereby supporting biodiversity in agricultural landscapes.