Semi-natural habitats benefit the community of diurnal floral visitors of canola ( Brassica napus L.) in the Argentine pampas

Abstract

Canola is the second most important oilseed crop. Several studies have suggested that habitats adjacent to canola fields affect the abundance and richness of floral visitors, which could impact their yield. To characterize the community of flower-visiting insects associated with canola and its possible temporal variation, we performed trials (2020–2022) on canola crops, in two contrasting habitats (agricultural: A; semi-natural: SN). The abundance and richness of flowering plants and insect visitors were determined using entomological nets and traps. The floral visitation rate was estimated through plant observations. The results indicated a lower abundance of floral visitors in A (542) than in SN (764), with 23 and 31 species, respectively, with Apis mellifera, Lasioglossum spp., and Toxomerus duplicatus being the most abundant. The censuses revealed 442 floral visitors in habitat A and 593 in habitat SN, with A. mellifera being the most frequent. Wild Hymenoptera and Diptera also exhibited a high floral visitation rate, particularly in SN. These contrasting habitats affect canola insect visitors differently, with wild Hymenoptera and Diptera being the most affected in the agricultural habitat. We discuss the need to adjust agricultural management so that the maximum productive potential of the crop is reached while maintaining the stability of ecosystems.