Frangipani trees across Darwin are getting “hammered” by an exotic pest called papaya mealybug.
Since its discovery last year, the pest has spread across Darwin suburbs, impacting a range of host plants such as papaya, hibiscus and frangipanis.
The NT government and Darwin City Council has just released hundreds of native ladybirds, in a trial that will hopefully reduce mealybug numbers and slow their spread.
Principal entomologist Dr Brian Thistleton, said the ladybirds love to “feast” on mealybugs.
“It’s native to Australia and has actually been used world-wide. Overseas they call it the mealybug destroyer,” he said.
“There’s populations of this ladybird already in Darwin, but what we’ve done is get extra from a biological-control supplier to boost numbers.”
He said the papaya mealybug arrived in Australia last year along with an exotic parasitoid, which also attacks the pest.
“Between the parasitoid and the ladybird, the two together will hopefully bring the populations [of mealybug] down,” he said.
Hopes rest on tiny insects
Darwin Lord Mayor and former NT Agriculture Minister, Kon Vatskalis, hopes the ladybird trial works.
“The franipani’s have been absolutely hammered and I’m really worried because we’ve got beautiful frangipanis in this city,” he told ABC Radio Darwin.
“Especially down in the [Botanical Gardens] where there’s different species and different colours of frangipani — I don’t want to lose them.”
“The mealybugs have completely destroyed the hibiscus in my house too, it’s so sad, but hopefully getting the ladybirds here might be effective.”
Farmers ready
As the name suggests, the papaya mealybug loves papaya and Dr Thistleton said the pest had been killing papaya trees in peoples backyards.
NT Farmers Association president Simon Smith said the pest had spread south to Palmerston, but he was not aware of any farmers in Darwin’s rural area being affected yet.
“Farmers have to control [other types of] mealybugs anyway and already use predators like the ladybird,” he said.
“So at this stage we’re not overly concerned and thankfully the current protocol for sending [produce and plants] interstate, will not be impeded by this and shouldn’t be an issue.”
He said the NT sold a lot of potted frangipanis and he felt for home gardeners in Darwin who were battling the pest.
How far could it spread?
Dr Thistleton said the pest could spread through the transportation of plant materials.
“I’m sure this is something that State biosecurity departments are looking at,” he said.
“Obviously if it gets into a state [like Queensland] that has a big paw paw industry, it’s [impact] could be quite significant.”
He said the pest originated from Central America and research suggested it would most likely stick to tropical climates only.
If you see any damage that you suspect to be papaya mealybug call the Exotic Plant Pest Hotline on 1800 084 881.
