Vegetos

Abstract

The fall armyworm (FAW) Spodoptera frugiperda is originally from the tropical and subtropical regions of America and has been present in the United States since 1797. However, FAW was first reported in India in May 2018 by the University of Agricultural and Horticultural Sciences, Shivamogga, Karnataka (Sharanabasappa et al., First report of fall armyworm Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), an alien invasive pest on maize in India). By the 2019 monsoon season, FAW had spread to the northwestern parts of India, and by 2019-20, it had affected a total of 214,339 hectares across the country (Suby et al. Invasion of fall armyworm (Spodoptera frugiperda) in India: nature, distribution, management and potential impact). Yield loss by the FAW had been attempted by artificial infestation in screen house since a systematic investigation of yield loss had not yet been reported. Artificial infestation was done at V2, V5, V8, and V12 phrenological stages of the maize crop using known numbers of S. frugiperda neonates applied near the leaf whorl with a camel brush during morning hours between 8.00 to 11.00AM. Observations on Leaf Injury Rating (LIR) were recorded 15 days after the artificial infestation, Observations on ear damage rating was recorded after harvesting on 20 plants in each replication. Percent yield loss was computed comparing with the yield obtained in control. A field experiment was conducted at Maize Research Centre in Rajendranagar, Hyderabad during rabi 2021-22 to evaluate the impact of fall armyworm (FAW) on maize yield. The experiment was designed as a Split Plot, with the main plots representing different phenological stages of the crop (V2, V5, V8, and V12), and the subplots representing the number of larvae released per plant (5, 10, 15, 20, and 0 larvae/plant). The study recorded data on leaf injury rating, ear damage rating, the quantity and percentage of cob and grain yield loss. The results showed that the highest leaf injury rating (8.80) and ear damage rating (8.77) were observed at the V₂ stage with 20 larvae/plant. The lowest leaf injury rating (1.83) and ear damage rating (1.40) were observed at the V₁₂ stage with 5 larvae/plant. Control 0 larvae/plant resulted in the lowest leaf injury rating (1.00) and ear damage rating (1.00) across all the stages. The highest cob yield (9799.07 kg ha-1) and grain yield (8769.14 kg ha-1) were recorded at the V₁₂ stage with 0 larvae/plant, while the lowest cob yield (2012.58 kg ha-1) and grain yield (1620.31 kg ha-1) were recorded at the V₂ stage with 20 larvae/plant. The highest cob yield loss (7520.79 kg ha-1) and grain yield loss (6926.70 kg ha-1) were recorded at the V₂ stage with 20 larvae/plant, while the minimum cob yield loss (289.03 kg ha-1) and grain yield loss (543.96 kg ha-1) were observed at the V₁₂ stage with 5 larvae/plant. The highest percentage of cob yield loss (78.88%) and grain yield loss (81.04%) were recorded at the V₂ stage with 20 larvae/plant, while the lowest percentage of cob yield loss (2.94%) and grain yield loss (6.20%) were recorded at the V₁₂ stage with 5 larvae/plant.