Some flower visitors would never enter your mind as being potential pollinators.
Dr Romina Rader
Australian Research Council Discovery Early Career Research (DECRA) Fellow
School of Environmental and Rural Science.
The animal kingdom is a diverse place, with many different orders of weird and wonderful animals. Australia is well known for its fair share of invertebrate animal oddities that maintain its dangerous animal image – massive centipedes the size of dinner plates, bulldog ants with huge biting mouthparts and parasitic flies that shoot their eggs into the nests of unsuspecting hosts. However, we actually know very little about the diversity of animals that visit the flowers that are among the thousands of plant species across the globe. Pollination is an essential part of the flowering plant life cycle and most wild plants benefit from animal-mediated pollen movement. Many of the world’s food crops also benefit from animal pollination by way of increased yield and quality of the crops produced. Understanding the importance of pollination processes also means understanding the food, nesting and other habitat needs for pollinators, so research being undertaken by Dr Romina Rader on wild pollinators, ultimately feeds back into issues of food security and the preservation and enhancement of vital ecosystems.
Bees are the most famous flower visitors but a whole range of insects and other arthropods also use flowers in different ways. Many fruit crops are effectively pollinated by non-bee insects including oil palm (weevil), figs (wasps) and jackfruit (flies). Others, such as the tropical durian fruit, have flowers that dehisce at night when bees are generally not in flight.
Flies are especially important pollinators and visit many wild and crop plants. For example, midges are small flies that pollinate cocoa flowers, and cocoa yields are greatest when growers place additional fruit husks or decomposing leaf litter under the flowers to make additional habitat for the midge pollinators.
Native flies, not bees, have also come out as one of the top pollinators of mango trees according to a study on 10 farms in the Mareeba region in Queensland. Dr Rader and her team found that native flies visited mango flowers 20% more frequently than bees and they were among the top transporters of pollen. “If growers want to attract and keep these pollinators they need to give them the resources needed to see out their life cycle. This may include planting native plants close to the orchard that produce lots of nectar and pollen at times when the mango tree isn’t in flower”, says Dr Rader.
Flies are also effective pollinators of carrot, cauliflower and onion flowers. These flowers need pollen to produce the seed that is then grown to produce the root vegetables we eat. These examples show, as Dr Romina Rader explains, that effective pollination is a complex phenomenon determined by both species-level and community-level factors. While pollinator communities are constituted by interacting organisms in a shared environment, these factors are sometimes overlooked when quantifying species-level pollinator effectiveness alone.
Pollinators are not just small insects either. Many vertebrate animals visit flowers and some are effective pollinators, including hummingbirds, honey possums and flying foxes.
Some flower visitors would never enter your mind as being potential pollinators. Spiders and mites have been recorded visiting flowers, and earwigs and thrips have been recorded as contacting floral reproductive parts while visiting flowers for other reasons. Thrips have been implicated in the pollination of at least 24 crop species but their effectiveness has not been well studied.
As an Australian Research Council DECRA Fellow, Dr Rader now hopes to expand her work to include to better understand how to maintain the life history and nutritional needs of all pollinators to inform management strategies that integrate wild and managed pollinators into farming system land management practices.