East Java Caterpillar Plague Has Experts Guessing

Fidelis E. Satriastanti Jakarta Globe 30 Mar 11;

At least 10 villages in the East Java district of Probolinggo are seeing attacks of wormlike invaders, according to media reports and entomologists.

Thousands of caterpillars started appearing in villages there on Saturday, creeping into homes and fields and forcing some to go around with umbrellas, media reports said on Monday.

“I haven’t figured out what type [of caterpillar] these are. Generally, a population explosion is caused by a rise in temperatures,” said Hari Sutrisno, entomologist at the Indonesian Institute of Sciences (LIPI).

Hari added that the outbreak might also have been caused by an imbalance resulting from the disappearance of a species’ natural predators.

“One of the natural enemies of hairy caterpillars is the wasp. However, their population is declining because of the increasing use of pesticides and herbicides,” he said.

“Intensive agriculture is not only dangerous to humans. It will disrupt nature’s balance and can cause a population explosion of pests, such as snakes, flies and plant hoppers. All of those outbreaks occur because of ecosystem imbalance.”

Siti Nuramaliati Prijono, director of the Research Center for Biology at LIPI, said simple food chain theory was at play.

“You disrupt one chain, it will affect the others,” Siti said. “People tend to think it’s not a big deal when a certain species goes extinct. They say, ‘It’s gone, so what?’ But then, when we see such outbreaks [like in Probolinggo], we have to realize it’s difficult to predict the impact of a species’ extinction.”

In explaining the caterpillar outbreak, she said species such as birds that specifically feed on caterpillars may no longer exist in the area. Climatic conditions, she added, could also trigger species to breed faster.

“Ecosystem imbalance is usually triggered by natural aspects. Because of there being no predators, caterpillar populations become bigger and turn into butterflies. Then come the outbreak,” she said. “Most of the outbreaks cannot be predicted, but we can pay attention to the signs, such as why there are so many butterflies all of a sudden. They should have captured those butterflies to prevent them from breeding.”

Antung Deddy Radiansyah, assistant deputy for biodiversity and land damage control at the Environment Ministry, said the outbreak was indicative of low biodiversity.

“Those areas are dominated by monoculture. This makes crops much more vulnerable to pests,” Antung said.

“It could also be that they were too late in spraying their plants [in Probolinggo]. However, in the future, multiple plants should be introduced rather than just one type.”