The importance of wild pollinators for indigenous crop pollination: the case of Cyclopia (honeybush)

Abstract

Pollination is an important ecosystem service. Animal-mediated pollination (mostly insects) increases the production of 35% of global crops. Honey bees (Apis mellifera) are considered important crop pollinators globally, but are under pressure and therefore the value of wild pollinators for crop production is receiving more attention. The importance of pollinators (including non-Apis) has been extensively studied in the agricultural sector of South Africa, however little research is available on the pollination of indigenous crops. With the considerable value of the indigenous honeybush (Cyclopia Vent.) in the tea industry, it is important to determine the pollinators since Cyclopia is widespread across the fynbos biome and the pollinators are largely unknown. Here we ask whether carpenter bees (xylocopid bees) are the only pollinators of commercially important Cyclopia species, or if honey bees contribute to pollination. Floral observations and camera trapping confirmed that six species of xylocopid bees were the only pollinators of four commercially important Cyclopia species. Honey bees were observed to be ineffective pollinators of Cyclopia owing to their inability to trip Cyclopia flowers and gain access to the floral reproductive parts. Similarly, an additional seven species including Diptera, Apidae and Lema sp. were unable to gain access to Cyclopia flowers, although were observed visiting. Nectar measurements revealed the highest nectar volume in C. genistoides, while C. intermedia had the highest nectar sugar concentration (above 35% for all species). The value of native non-Apis insects for crop pollination in a changing world is highlighted in Cyclopia, an indigenous legume gaining traction in the global tea market and therefore in cultivation.