The sweet potato whitefly has in recent years begun invading farmland in Sidodadi village, Beringin district in Deli Serdang regency, North Sumatra.
The insects are proving a headache because they carry viruses that attack crops, says Deli Serdang Farmers Learning Forum head Toegiran.
He says many farmers are still not aware of the danger these insects pose, despite the fact they have been infecting crops since 2005.
Toegiran adds the whiteflies have of late broadened their target range for crops to infect.
“They’ve multiplied rapidly lately,” Toegiran tells The Jakarta Post.
“About four years ago they’d only attack chili pepper crops, but they’ve started appearing on corn and soybean crops since planting season last year.”
He speculated the rapid spread of the whiteflies is most likely due to the impact of climate change: the insects thrive in cooler climates, he points out, but have recently begun migrating to warmer areas and attacking a wider variety of crops.
“When the rainfall is high, the pests multiply slowly, but they pick up the pace on warmer days and seek protection in cool places because they can’t take the heat,” Toegiran says.
He adds the viruses carried by the whiteflies doesn’t live long in hot climates, but thrives in cool places. He also says the virus usually develops in the morning, when the air is cooler.
Affected plants are easily recognized by their wilted leaves, he goes on, the shady undersides of which the whiteflies deposit their eggs.
Toegiran adds that with affected chili plants, the leaves turn yellow and wither, similar with affected corn and soybean plants.
“The insects’ food comes from the leaf network, so every affected plant has yellowing leaves,” he says, adding he’s concerned the pests will later turn to the all-important rice crops.
Farmers in the area are growing increasingly concerned that the virus will attack other valuable cash crops, he says, and although they can often fend off other pests, the whiteflies pose a challenge to them.
Several attempts have been made to control the insects here, says Toegiran, such as fumigation, but with little success.
Jemingan, a chili farmer in Sidodadi village, says he only became aware of the threat posed by the whiteflies after almost 30 years of growing chili plants. He says the virus spreads quickly across the crops, particularly in hot weather, adding the insects only began attacking his crops four years ago.
Jemingan says farmers in the area lose around 25 percent of their crops to the viruses brought by the whiteflies.
“In previous years I’d harvest 250 kilograms of chili from my land, but now I’m only getting 200 or so,” he adds.
Around 30 farmers in the area still keep growing chili plants, despite the threat, for lack of a suitable alternative.
“We hope the government can help us overcome the problem with a swiftness,” Jemingan says.
“We don’t know how long these insects will keep posing a threat to farmers here.”
