How bees help mimicking flies with pollination


Bees and butterflies are perhaps the most famous pollinators, but they’re not the only ones. Bats, birds, beetles, wasps and flies also play an important role.

Rae Olsson, a postdoctoral fellow at Washington State University (WSU), has been working on pollinating insects since 2014. While her job was to collect data on bee populations, Olsson found that the flowers received a wide variety of visitors.

“As I stood and stared at flowers and watched insects come and go, I noticed that many of the insects that were visiting weren’t bees,” says Olsson.

Discouraged by the lack of interest in alternative pollinators such as flies and wasps, they set out to research the category on their own. “People overlook the fly pollinators and the wasp pollinators and the beetles because they’re just not that cute,” says Olsson. “Bees, butterflies, and hummingbirds are all charismatic and cute, but people just aren’t that into flies and wasps and ants. We have very limited knowledge about them. “

The resulting study, recently published in Food webs, highlights the importance of non-bee insect pollinators in gardens and farms. Over the course of two years, Olsson observed more than 2,400 pollinator visits to flowers on 19 rural farms and 17 urban farms and gardens in West Washington. They found that, unsurprisingly, the majority of the visits were made by bees, accounting for 61 percent of the visits. But nearly 35 percent were made from flies, most of which were hoverflies, flies mimicking black and yellow bees, commonly referred to as hoverflies. Olsson also observed that other insects such as wasps, lacewings, spiders, butterflies, dragonflies, beetles and ants visited the flowers, although they made up less than four percent of all visits.

“Bees are definitely still important and will generally be more efficient pollinators,” says Olsson. This is because bees purposely collect pollen to feed their offspring. They also have dense patches of hair that act as Velcro that pollen easily sticks to. Syrphid flies, on the other hand, are not as hairy and pollinate almost randomly, carrying pollen from one flower to another while they feed and forage for nectar.

But more breeders should watch out for hoverflies, which are also beneficial in that they eat unwanted pests like aphids. “There are many negative connotations that humans have with these organisms, even though they are really very diverse and have many benefits for the ecosystem,” says Olsson.

Hoverflies were the only pollinators observed on some of the plants observed, including peas, kale and lilies – an important detail for farmers of these plants to know if they want to ensure a successful harvest.

“My recommendation for anyone working in agriculture is to make sure that as many flowers as possible are in bloom during the season, and ideally more than one flower,” says Olsson. “Because food and living space are made available, access to water and a kind of undisturbed area on the farm provide habitat, nesting sites and food resources for these alternative pollinators.”


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