Flying Ant Day: When Virgin Queens and Male Drones Mate on the Wing | insects

A steady stream of black ants rush in and out of a crevice in the patio. They have been living there peacefully for weeks. You may have tried to get rid of them, especially if they were taking sugar from the kitchen or crawling through your bedroom. Perhaps you ignored them, or marveled at their ability to navigate seemingly inconspicuous paving stones back to their nest.

Then we have a period of warm weather, a summer downpour, and when it stops, winged explorers come out of the ground – welcome to flying ant day!

But what exactly is flying ant day? For starters, it’s not just one day. Recent studies have shown that winged ants appear over several weeks, although there are usually several large spikes. Here’s what happened in 2016, with many synchronized events in early August.

The Royal Society of Biology recently began working with entomologist Adam Hart of the University of Gloucester (who studies insects). He said: “A lot of people tend to think that there is one National Flying Ant Day, and the media is eager to report it, but our research has shown that there is absolutely no such thing. As in previous years, we also have this summer seen many ‘flying ant days’ across the country.”

Because temperature-induced swarming often occurs after summer rains, ants can appear over a wide area on the same day if conditions are similar everywhere. Millions can be on the wing and after a short or much longer flight can land anywhere – on trees, cars and clothing. There is much more to eat.

Flights of fantasy

Flying Ant Day is a mating event or nuptial flight, and in Britain a common participant is the little black ant, Lasius niger (Formicidae). Lasius niger builds its nests in soil, stumps or under paving stones, so patios are a favored choice.

The colony starts with one or more mated queens. These nurse the larvae until enough workers (less than half the size of the queen and all sterile females) have developed. Usually only one queen survives and she will reproduce until the colony is 4,000-7,000 strong, which can take several years. Some large nests can have more than 20,000 workers, living only a few months. Intriguingly, queens can survive for two decades or more and are considered the longest-lived of all adult insects.

With abundant food, the colony grows every spring and summer. Fertilized eggs normally develop into workers, but virgin queens are produced at a high colony density, in a process determined by the queen. These new queens are winged, just like the males produced from unfertilized eggs. Males do not work, their only role is to fertilize a virgin queen, and this is often done on the wing.

Unlike honeybees, where the new queen takes over the colony and the old queen leaves with a swarm of workers, Lasius niger and other ants, the old queen remains. Instead, hundreds of reproductive males and females (drones and “princesses”) emerge from the nest – hence flying ant day.

Safety in numbers: Mass prey reduces the chance of one organism being eaten. Photo: Smithore/Getty Images

What are the advantages?

In short: maximizing genetic mixing, minimizing losses to predators and overcoming a low success rate. All ensure survival and spread of the species.

Genetic mixing is enhanced by virgin queens and drones proliferating for the first time. This is to maximize the chances of mating between different colonies to reduce inbreeding – something Charles Darwin commented on regarding plants. (Remember that all colony ants were produced by one queen, so they have a high genetic similarity.)

After dispersing, the “princesses” release pheromones to attract drones, but often play hard to get – they fly to escape converging males, allowing only the fastest and strongest to mate.

Mass emergence provides a rich food source, which can attract predators. Mass prey, however, benefits from safety in numbers, reducing the chances of an organism being eaten. If they are present in small numbers, they are more vulnerable as this can train the predators, which will remain in the area. This is why other insects, such as crickets, behave similarly.

Still, any potential queen has little chance of success. During its lifetime, a large colony of ants can scatter thousands of princesses, but on average only one will succeed. And that’s probably a good thing, otherwise the number of ant colonies would grow very quickly. Many succumb to predators: birds, dragonflies, often other ants, or die from starvation or environmental hazards. The first brood may fail and the young colony may become extinct. Together, these mortality factors create a strong selection that ensures the queen has maximum fitness to produce the next generation. She must also be lucky.

The secret of a long life

Flying ants swarm in grass.
A queen usually mates with several males, which increases the genetic diversity of her offspring. Photo: Andrew Shorey/Alamy

And what about the drones? Mating takes place in flight or on the ground, and since a queen usually mates with several males, this increases the genetic diversity of her offspring. The queen stores a lifelong supply of sperm in an abdominal structure called a spermatheca, from which hundreds of thousands of eggs are fertilized. Meanwhile, the drones die within a day or two.

At the end of the nuptial flight, the fertilized queens land, chew their wings and start a new colony, where – if successful – they will remain for the rest of their lives.

But how do queen ants live so long? Lasius niger queens can live for more than 25 years — and understand why interested researchers have explored the causes of aging. There are well-cataloged environmental reasons for longer life, including a protected environment and a safe food supply without the risks of hunting, but it was recently reported that queens have higher expression of those genes necessary for DNA damage repair and degradation. of proteins than genetically identical workers.

It is fertile ground for further research under a crack in the paving stones.

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