Linn Vassvik
Forsker
(+47) 482 68 342
linn.vassvik@nibio.no
Sted
Ås - Bygg O43
Besøksadresse
Oluf Thesens vei 43, 1433 Ås (Varelevering: Elizabeth Stephansens vei 21)
Forfattere
Linn Vassvik Anders Nielsen Michael P. D. Garratt Bjørn Arild Hatteland Joseph Chipperfield Erik Trond AschehougSammendrag
Apples are dependent upon pollinators for the transfer of pollen between cultivars to ensure high quality fruit production. Agricultural intensification has reduced the availability of stable floral resources for wild bees, leading to widespread declines of important pollinators of apples. Managed honeybees are commonly used to supplement pollination services in apple orchards, but honeybees are less efficient pollinators compared to wild bees. We investigated whether increased flower abundance in the understory vegetation of apple orchards can increase pollinator activity to apple flowers. We compared bee visitation in five orchards in Eastern Norway: three unmowed orchards, and two mowed orchards. In unmowed orchards, dandelions ( Taraxacum spp.) dominated the understory vegetation. Bee observations were conducted on the understory vegetation and apple trees, via manual observations and time-lapse cameras. Wild bees preferentially visited apple flowers over dandelions, while honeybees did not differ in their visits to apple flowers and dandelion flowers. We also found that the abundance of dandelion flowers in the understory increased visits by wild bees to apple flowers. Taken together, this suggests that within orchard floral resources do not compete for pollinators but instead increase apple visitation and improve pollination success. Our results highlight the importance of managing apple orchards for wild bee populations and the potential short-term benefits of understory floral resources on apple production. Implications for insect conservation Our results show that understory vegetation should be left unmowed to increase pollination of apple flowers and provide pollinators with alternate floral resources before, during, and after apple flowering.
Sammendrag
ASO er Norges første nasjonale, arealrepresentative overvåking av semi-naturlig eng, en truet naturtype med stort artsmangfold. I perioden 2021–2025 ble 713 enger registrert over hele landet. Estimert areal av seminaturlig eng er 2 200–4 500 km² (0,7–1,5 % av Norges landareal), betydelig mer enn tidligere kartlagt. 40 % av engene er intakte, men majoriteten er ikke i bruk og i ferd med å gro igjen. Problemarter og fremmede arter utgjør viktige påvirkningfaktorer, og 32 % av engene har fremmedartsinnslag. Artsmangfoldet er størst i slåttemark og naturbeitemark, og 35 rødlistede arter ble funnet. Rapporten gir anbefalinger for videre overvåking, inkludert justering av metoder, bedre datalagring og overgang til NiN 3.0. ASO gir viktig kunnskap for forvaltning og bevaring av semi-naturlig eng og dens artsmangfold i Norge.
Forfattere
Linn Vassvik Anders Nielsen Michael Garratt Bjørn Arild Hatteland Joseph Chipperfield Jørund Johansen Silje Maria Midthjell Høydal Erik Trond AschehougSammendrag
Insect pollinators are important drivers of fruit quality and yield in horticultural systems. The global reduction in wild bee populations has increased the demand for managed honeybees, despite honeybees relatively low pollination efficiency. Here, we assessed how bee communities, bee behaviour, and orchard design in Norwegian apple orchards affects apple pollination success, an important determinant of apple quality. We placed pan and vane traps in 18 apple orchards, in six distinct locations, within the two main apple growing regions in Norway. We also tracked individual bees (honeybees, bumblebees, and solitary bees) throughout the apple flowering season, and recorded their flower handling time, number of flower visits, stigma contact, and movement between apple flowers. Finally, we calculated the seed set rate (ovules developed into seeds / total number of ovules) from 908 harvested apples to estimate pollination success. Our key finding is that pollination success was driven by the abundance of wild bees and overall orchard planting design. We found lower pollination success in block design orchards where a single cultivar is planted continuously over a large area, compared to orchards with an integrated design where compatible cultivars are planted within the orchard. We also found that stigma contact decreased as apple flowering progressed, and that solitary bees visited fewer flowers per foraging event but were potentially more thorough foragers. Our results highlight the importance of promoting wild bees in apple orchards while also ensuring there is compatible pollen in the orchards for optimal pollination.