Pest responsible for food crisis in Africa reaches Karnataka

The fall armyworm, an exotic pest from the Americas, has been reported from India for the first time. Scientists are concerned that the pest could pose a serious threat to maize crops in Karnataka. This is the first time these pests are being reported anywhere outside the Americas and Africa.

Field surveys in early July this year by a team from the Indian Council of Agricultural Research – National Bureau of Agricultural Insect Resources (ICAR-NBAIR) revealed that pest incidence in the Chikkaballapur area was more than 70 percent. The first pest alert in Karnataka was issued by the Indian Council of Agricultural Research on July 30.

Based on field surveys and molecular analyses, scientists from the University of Agricultural Sciences, Dharwad (UAS) and the ICAR have confirmed that the pest is indeed the fall armyworm, Spodoptera frugiperda. Molecular identification of the larvae confirmed a 100 percent match with populations from Canada and Costa Rica, said a note from ICAR-NBAIR.

“These pests are prevalent between 20 percent and 70 percent in maize fields in districts like Hassan, Haveri, Shimoga, Chikkaballapur, and Davanagere in Karnataka. In Dharwad, the number stands at around 10 percent,” said an entomologist from UAS, A.S. Vastrad. He was part of a team that carried out studies in these regions. “Pest invasions don’t happen overnight. Once they arrive, they need some time to establish themselves. And by this time, it is already too late,” he said.

Since the species has been reported in India for the first time, scientists are still understanding its bio-ecology to come up with management tactics. Fall armyworms have developed resistance to several insecticides and a lack of natural predators makes it difficult to control them.

In individual fields, damaged crops constitute between 5 percent and 60 percent. “India does not have any natural predators against these pests, and they are having a free run. The only pesticides that can contain them are very expensive,” said Vastrad. The pests reached sub-Saharan countries in 2016 and threatened the food security of at least 44 countries.

Combatting a hardy pest

“There is no certain way of knowing how they could have reached India. They could have come to India through imports from Africa and have slipped through quarantine measures. But they are very tough and are capable of flying long distances,” he said. “Instances of Spodoptera frugiperda infestation have already been reported in Telangana and Tamil Nadu,” he added.

Earlier this month, scientists from the ICAR-NBAIR met officials from the Karnataka state agriculture department to discuss the way forward. “There are a few predators that can be used to mitigate the spread of these pests. We are augmenting a few fungi species, along with bacteria like Bacillus thuringiensis, along with eggs of parasitoids,” said A.N. Shylesha, principal scientist at the Division of Insect Systematics of ICAR-NBAIR who first noted the presence of these pests on the field.

“We are giving them [agriculture department] cultures which can be mass produced. It will be in powder form, which farmers can mix it in the ration of 3 gm to 5 gm per litre of water and spray it on their crops,” he added.

Officials from the state agriculture department hope that the incidents of damage will come down when the new sowing begins. “In Hassan, we had some 1,700 ha area of maize crops being damaged by fall armyworms. It has now reduced to 700 ha,” said Madhu Sudha, the joint director of the agriculture department in Hassan .

“We have been telling farmers what kind of pesticides to use in what dosage to bring these pests down. Scientists from agricultural universities also visited farmlands to educate farmers how to identify this particular type of pest,” he added.

Africa’s winged invader makes landfall in India

According to the Food and Agriculture Organisation of the United Nations (FAO), note on the fall armyworm, it is native to tropical and subtropical regions of the Americas. It was first detected outside its native region in 2016 in Central and Western Africa, quickly spreading all across sub-Saharan Africa.

By late 2017, the pest had swarmed 12 maize-producing countries, leaving devastation in its wake: 22 million square kilometres of crops infested, with about 15 million tonnes (8.319 million tonnes to 20.55 million tonnes) of yield lost, and economic loss amounting to 4 billion USD (2.48 billion to 6.18 billion USD).

“The pest in its native range and in the recently invaded areas is known to have caused extensive crop damage threatening farmers’ livelihood and food security,” said Vastrad. “There are already armyworms in India but the arrival of fall armyworm is particularly ominous since it is ravenous, polyphagous and spreads fast,” he added.

The pest has a life cycle of between one and three months. “With the right up-winds, these pests can fly 100 kms a day, or 1,000 kms in their life. Which means they can spread far and quickly,” said Vastrad. The real damage, however, comes when the pest is in its larval stage.

“It can cause significant damage to crops, if not well managed. It prefers maize, but can feed on more than 80 additional species of plants, including rice, sorghum, millet, sugarcane, vegetable crops and cotton,” according to the FAO report.

A recent study in the preprint journal BioRxiv has reported that there is a very high chance of the pest spreading widely in India, southeast Asia and Australia – areas with climatic conditions similar to its native habitat in tropical America.

Farmers will need great support through Integrated Pest Management (IPM) to sustainably manage the fall armyworm in their cropping systems. “However, use of biopesticides, botanicals and alternating sprays of old and newer insecticides is advocated in the absence of the IPM strategies,” said Vastrad.

Banner image: Fall armyworm. Photo by Ernani Zimmermann/Wikimedia Commons.