IPM for fall armyworm
Agriculture

Fall Armyworm – a preamble for the Indian chapter of the attack

The larval stage of insect Fall Armyworm (FAW) (Spodoptera frugiperda) moth is a pest that feeds on more than 80 crop species, causing damage to economically important cultivated cereals such as maize, rice, sorghum; cash crops like cotton, sugarcane; and vegetable crops among others. A rapid breeder with a diverse diet, the insect can survive harsh conditions by migrating to different places (across continents) or go into hiding to spring back when conditions are more favorable.

FAW’s first outbreak was detected in Africa in 2016. It has now spread across Asia including India, China, Thailand, Myanmar, Pakistan, Vietnam, Sri Lanka and Bangladesh.

 In India, FAW was first reported in the fields of Chikkaballapur district in Karnataka during a survey conducted in July 2018. The pest has destroyed more than 70 per cent of the crop in Karnataka. The survey was conducted by the National Bureau of Agriculture Insect Resources (NBAIR), which is part of ICAR.

IPM for fall armyworm
Author examining FAW in field

During the annual National Conference on Agriculture on April 25-26 to assess prospects of upcoming Kharif crops, the government recommended use of two chemicals — Cyantraniliprole and Thiamethoxam for the treatment of maize seeds. Though the immediate reaction is to use pesticides, but the FAW is well known for its ability to evolve resistance to these. Moreover, strong general purpose insecticides could kill useful insects that are natural enemies of the pest. Therefore, the scientists who were part of the committee, were surprised over the latest recommendations as these two chemicals were approved to contain Stem-Borer pests, but not FAW.

Around 9.3 million hectares of land is used to grow maize across the country, which produces 28 million tons per year. If the farmers are forced to use these chemicals, then it can potentially damage the crop biodiversity across large swathes of land and also increase farmers’ costs. At the same time, it would be a boon for chemical makers.

Though the farmers used insecticides, they have limited to no impact. So the Agricultural Department of Tamil Nadu suggested the adoption of integrated pest management mechanisms to control the fall armyworm. It would consist of a pheromone trap and a bio-control method of using the fungus Metarhizium anisopliae, which when sprayed would infect the larvae and kill them. Use of Polynecrosis Virus (PNV) to control Spodopteralitura was highly effective in food legume crops and could also be tried.

Other protective measures could include:

– Use of soapy water (a solution of liquid dishwashing detergent and water in lower concentration) as a spray to flush out any harbouring larvae may prove effective. However, the sprayed areas must be watched for about 5 minutes after the application.

The Agricultural Department of Tamil Nadu suggested the adoption of Integrated Pest Management mechanisms to control the Fall armyworm

Management of alternate hosts:

  • Keeping the field and surrounding areas free from grasses.
  • Looking for early signs of infestation. As feeding is more active during the night, at early stages of infestation (between day 3-6 after hatching) it results in semitransparent patches on the leaves called windows. Between days 6-14 the damage becomes explicit with ragged holes in the leaves, chewed away growing point in young plants, and in older plants (in maize) eaten protective leaf bracts and young kernels on the cobs.
  • Trimming the grass short is perhaps the best way to discourage the presence of Armyworms.
  • Engaging natural predators by not scaring away birds that are known to feed on pests in the farm.
  • Using pheromone traps
  • Using biocontrol agents like Metarhizium, PNV, BT (tenibrionis)
  • Spraying Corazen (0.5 ml per lit.) and Sevin (granules)
  • Encouraging Rabi (sown in winter and harvested in the spring) maize as menace of FAW is less (it being susceptible to winter).

Given that the pest, due to its capacity to inflict immeasurable losses to economically important crops, is an extremely serious concern nationwide, the Indian Council of Agricultural Research (ICAR) should think of creating a position of a separate Project Coordinator, All India Coordinated Research Project- Fall Armyworm (PC, AICRP-FAW) to deal with it effectively through integrated pest management in an environmental friendly manner.

Article by Dr. Mukti Sadhan Basu and Dr. shravani Basu, SBSF Consultancy https://sbsf-consultancy.com

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