The golden native drone fly (Eristalinus punctulatus) is an effective hybrid carrot pollinator that lives within Australian crop agroecosystems.
Abstract
Native insect flower visitors can be important contributors to crop pollination, yet little is known of their pollination abilities and the resources (habitat) they need to be supported within crop agroecosystems. Here, we compared the abundance and pollination abilities of the golden drone fly (Eristalinus punctulatus) to the European honey bee (Apis mellifera) in hybrid carrot crop fields known to produce variable seed yields in regional New South Wales, Australia. We further observed the egg-laying behaviours of female golden drone flies at a commercial berry orchard to provide insight into the habitat needs of this species. In hybrid carrot crop fields, golden drone flies were far less abundant flower visitors than European honey bees; however, these flies deposited more carrot pollen grains on average (8.21 ± 3.04 SE) onto carrot flowers than European honey bees (3.45 ± 1.06 SE). Both insects also deposited pollen onto a similar number of carrot flowers (pollinated) per visit (about 2 out of 18). Golden drone flies were observed laying eggs within masses of discarded red raspberry plant roots and soil (root balls) at a commercial berry orchard. The natural habitat utilised by these flies, as well as their egg-laying behaviours, were described for the first time. Our results indicate that golden drone flies are effective pollinators of hybrid carrot crop plants. The habitat that these flies utilised to lay eggs (discarded plants and water) is cheap and commonly found in crop agroecosystems. Therefore, we recommend placing this low-cost habitat within, or nearby, crop fields as a potential management practice to support the lifecycle needs of golden drone flies and other non-bee pollinators.