The wasps – in various stages of development – being released inside one of the greenhouses at the Yarralumla Nursery. Photo: James Coleman.
Okay, so the work is pretty gross. But in return, the ACT Government’s tiniest workers get paid in their favourite food – aphid innards.
Ladybirds and parasitic wasps are being used at Yarralumla Nursery to protect thousands of plants from pests, reducing the need for chemical pesticides and creating a healthier growing environment.
The tiny workforce comprises ladybirds, which patrol outdoor growing areas through the warmer months, and four species of parasitic wasps that take over inside the nursery’s glasshouses during winter.
Yarralumla Nursery program co-ordinator Kirrilea Cameron. Photo: James Coleman.
Yarralumla Nursery program co-ordinator Kirrilea Cameron said the nursery began experimenting with beneficial insects about three years ago.
“We mainly use ladybirds and the wasps for aphids, they’re sort of the primary pest here, but occasionally, in certain times of each season, we can also buy a predatory pest mite to eat other pest mites,” she said.
“There are several online places that supply these insects, depending on your situation, whether you’re a commercial grower or home gardener.”
The insects are part of an integrated pest management program, helping to tackle aphids and other pests that can damage plant stock.
While the ladybirds are the more obvious ones, it’s the tiny wasps that do much of the heavy lifting in the nursery’s heritage glasshouses.
And the process is not for the squeamish.
“The wasp lays its eggs inside the aphids, and uses the aphid as a host – while it’s still alive,” Ms Cameron explained.
The wasp larvae grow by feeding on the aphid from the inside, before emerging as adults a couple of weeks later and continuing the cycle.
“No chemicals,” Ms Cameron said.
“Typically, in the glasshouses, we might get a bit of an outbreak of aphids here and there, and the wasps take a little bit to catch up, but generally we don’t really see that very often because we’ve got such a population already here that if anything does pop up, the aphids don’t last long. They’re gone pretty quick.”
Just a single vial of wasps can be enough to establish a population in a greenhouse because the insects continue reproducing after release.
The nursery regularly tops up numbers to keep pest populations under control year-round.
Outside, ladybirds take centre stage.
The nursery has even created a beneficial insect garden designed to attract and support the helpful bugs while drawing pests away from valuable plant stock.
When conditions are right, the nursery can become a ladybird hotspot.
The insects are released every few weeks. Photo: James Coleman.
“In fact, there’s one specific fortnight of the year in late summer where they just go crazy here, to the point the propagation team will get cuttings, and they’ve got ladybugs pouring off them,” Ms Cameron said.
“It’s crazy.”
The insects are not only effective but also cheaper than traditional pesticides.
“They’re much cheaper than regular pesticides by far,” Ms Cameron said.
The program has also become a favourite among staff.
“Every time we release more insects, there’s a group of us that come around, and we learn about the bugs – the sales team, everyone … We’re all in this industry because we love it and we love the environment, so to be able to contribute to that in a way that’s chemical-free and sustainable. It’s very important.”
The nursery still uses some chemicals when necessary, but beneficial insects are now one of its first lines of defence.
Ms Cameron said home gardeners could also benefit from learning more about helpful insects before reaching for pesticides.
“There are websites available that have really good tools for identification, so if you’re not sure if something is a pest or a good bug, just look it up,” she said.
Some beneficial species are often mistaken for pests, including ladybird larvae, which look more like a horned alien worm than the familiar red-and-black adults. Despite their small size, they can be voracious hunters of pests.
Ladybird larvae can eat hundreds of aphids before reaching adulthood, while a single adult ladybird can consume up to 75 aphids a day.
That’s going to go down well in the performance review.
