How to stop the voracious beetles killing SA’s trees

A South African company has developed unique nanotechnology to take care of the polyphagous shot hole borer beetle (PSHB) currently eating its way through South Africa, Israel, California, Japan, South Korea and more.

There’s a two million hectare Kruger National Park-shaped smorgasbord awaiting the PSHB – and for the first time since its arrival there is a solution to stop it.

It is believed the beetle travels in the wood of pallets and packing crates.

Imagine a tennis ball, made of rubber, covered in green fuzz, and hollow, said Pan African Farms CEO Piet Meyer. Now imagine your tennis ball was 10 nanometres big.

“These little vessicles are similar in structure. It is covered in an oil base made up of essential fatty acids and inside it can hold active ingredients,” said Meyer.

“Every living organism needs those oils for survival and normal functioning. Now, there are special mechanisms inside each cellular structure which allows it to absorb these oils almost freely, which enables the Amphiphilic Nano Oil Delivery System (Anods) to act like a Trojan Horse.”

Inside the Anods is the “active ingredient”, which is a naturally occurring fungicide to which the fungus carried by the beetle has no defence.

Tests had shown the Anods could penetrate trees through bark (up to 10cm) and bare tree trunks (up to 10.7cm) in 24 hours.

As Anods are made from natural products with fungus as its specific target, the tree is not harmed.

Because the fungus was killed off both in the tree and on the beetle, even if the beetle managed to escape, it would still starve to death because it no longer had the capability to grow more fungus, Meyer said.

And do not believe the adaptable 2mm-long tree-killing monster only likes alien or exotic tree species. With about 400 tree species in Kruger, it is unlikely the beetle won’t find a tree it likes.

“What is really worrying about this species is that it attacks our indigenous as well as exotic species,” said Kruger National Park conservation manager Navashni Govender. “It is now gaining momentum and becoming of national importance. It’s going to be a listed invasive species, and is now found in all provinces except Limpopo.”

Govender said one infested tree had been found in Nelspruit. The tree has since been removed.

To help monitor the possible future presence of the tree slayer in Kruger, an insect trap had been developed with the beetle’s favourite nectar as bait, and 35 of them placed along the western border at various entrances and strategic spots.

A polyphagous shot hole borer beetle.

Hilton Fryer is a member of the Southern African Tree Care Association and a data scientist who has been using technology to raise PSHB awareness and to generate PSHB national distribution data.

“Preventative treatment has the best outcomes given damage from the shot hole borer can’t be undone within the tree,” Fryer said. “Don’t chop down your trees prematurely just because you have been told that you have the shot hole borer. Get informed first, and take your time when making a decision. You do have numerous options to save your trees.”

Its presence in South Africa was first realised in 2017 by Dr Trudy Paap of the Forestry and Agricultural Biotechnology Institute (FABI) while conducting routine testing of mature London plane trees planted on the street outside the KwaZulu-Natal Botanical Gardens.

One thing led to another and we now know “the female beetle carries several fungal species, one of which is Fusarium euwallaceae, with it when it infests new trees,” a descriptor on FABI stated.

“It bores through the bark into the sapwood of the tree and inoculates the fungus into the living wood. The fungus grows in the galleries (tunnels) of the beetle and serve as ‘vegetable garden’ for the beetle larvae, but in susceptible trees the fungus can spread through the sapwood causing disease or even death of the tree.”

– amandaw@citizen.co.za

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