Chaba wipes out weevils

The insects that were released on Saipan to curb the population of the noxious ivy gourd have been exterminated.

Thousands of weevils vanished after supertyphoon Chaba unleashed its fury on the islands sometime in August, temporarily halting the campaign to reduce the ivy gourd population on the island. Fortunately the college managed to keep a few, which it is now nurturing for future release.

Isidoro T. Cabrera, agricultural assistant to the Northern Marianas College’s Cooperative Research, Extension and Education Service, said the series of typhoons that hit the islands, especially Chaba, completely wiped out Saipan’s weevil population.

“They just disappeared after the typhoon,” Cabrera said.

The weevil, which is scientifically known as Acythopeus cocciniae, is a type of beetle that feeds on ivy gourd. The larvae of weevils mine through the leaves, while adult weevils feed on the leaves, producing a “shot-hole” appearance. By defoliating the ivy gourd leaves, weevils weaken the vine’s growth ability.

The Department of Land and Natural Resources saw the need to curb the ivy gourd population, saying that the invasive vine destroys plant life and any other living matter underneath it. An African vine of the melon family Cucurbitacae, ivy gourd was believed to be smuggled to Saipan in the 1990s, according to the department.

Before the weevils’ first release on Saipan in May 2003, the DLNR estimated that the vine already covered about 35 percent of the island’s vegetation. The DLNR disclosed then that small patches of the vine were already spotted on Tinian, Rota and even on Sarigan in the Northern Islands.

The DLNR first released weevils last year after securing final approval from the U.S. Department of Agriculture. The department then released 75 weevils each in Susupe and Kagman to allow the biocontrol agent to propagate and feed on ivy gourd leaves.

In July last year, the DLNR released on the island another batch of weevils numbering about 300.

Cabrera said the weevils’ population grew to thousands before Chaba wiped them out. As the weevil population grew, Cabrera said the CREES took 40 weevils and brought them to the NMC’s nursery. The weevil population at the nursery has grown to about 3,000 to 5,000.

“We are fortunate that we have these at the NMC,” Cabrera said. About two weeks ago, he said the DLNR got about 200 weevils from the NMC’s nursery, with the plan of allowing them to propagate and releasing them on the island.

CREES said that it would take several years before the weevil population significantly reduces the local ivy gourd population.