Waterweed-eating weevils to be set loose in mid-2018

KOTA KINABALU: The plan to unleash weevils to eat up an aquatic plant choking numerous lakes and ponds around Sabah is on track, according to state authorities.

State Agriculture Department director Datuk Idrus Shafie said the weevils, a type of beetle, are being bred for release by mid-2018.

“The breeding rate of these weevils are a bit slow but we hope that there will be enough to be released by then,” he said yesterday.

Idrus said the weevils were being bred in tanks at Tungog on the banks of an oxbow lake in Kinabatangan district in the east coast.

“Our researchers are trying to figure out the factors contributing to the slow birth rate, such as the ambient temperature or water quality,” he added.

The department brought in over 350 weevils from the Durian Tunggal lake in Melaka last year and first started breeding the insects at its research centre in Tuaran.

The weevils, originally brought in from Australia, were used to control a similar infestation in Peninsular Malaysia in the 1980s.

Idrus said increasing the number of weevils was crucial as the department had received reports of even more ponds and lakes around the state being infested by the salvenia molesta aquatic weed, commonly known as the giant salvinia, an aquatic fern native to south-eastern Brazil.

It is a free-floating plant that does not attach to the soil, but instead remains buoyant on the water surface.

Idris said it was believed that the fern had been brought in as an ornamental plant for aquariums and later discarded in drains or lakes where it began to spread rapidly.

At last count, 19 of the 20 oxbow lakes in the Kinabatangan region were infested with the aquatic plant that can double its area from 10 sq metres within three days.

He said the fern was choking ponds and lakes in Paitan, Papar, Kota Belud and Tuaran.

Idrus said due to its rapid growth rate, the plant was disrupting the ecosystems there.

Idrus said there was no fear of the weevils “getting out of control” as it would only eat that particular water fern.