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<p><i>Spodoptera frugiperda</i> (J. E Smith) (Noctuidae: Lepidoptera) is a highly invasive pest of maize, known for its prolific reproduction and efficient dispersal. This study examined the effects of seasonal temperature and maize plant age on oviposition behaviour and larval dispersal. Field-cage assays were used to assess monthly fecundity and larval movement, while field experiments evaluated oviposition preference at different plant ages and inter-plant dispersal. The effect of temperature on <i>S. frugiperda</i> reproductive traits was significant, with fecundity highest in July (732.05 eggs/plant) and lowest in January (90.31 eggs/plant), and egg viability ranging from 26.75% to 77.74%, both positively associated with maximum (fecundity: <i>r</i> = 0.94, R² = 0.89; egg viability: <i>r</i> = 0.84-0.97, R² = 0.71-0.95) and minimum temperatures (fecundity: <i>r</i> = 0.96, R² = 0.93). Host plant age significantly influenced oviposition, with 20&#xa0;day old maize receiving maximum egg masses (4.27/plant), followed by 10&#xa0;day old plants (3.03/plant), while older plants attracted fewer eggs; females consistently preferred the abaxial leaf surface, depositing more eggs than on the adaxial side (13.50 vs. 7.83 on 20-day-old and 8.33 vs. 6.83 on 10-day-old plants). A negative correlation was observed between oviposition and increasing plant age (<i>r</i> = -0.81), trichome density (<i>r</i> = -0.90), and trichome length (<i>r</i> = -0.63), with regression analysis indicating a weak negative relationship with host age (R² = 0.66). Larval dispersal studies revealed ballooning behaviour immediately after release, which declined sharply after 1.5&#xa0;h. Larval settling in the central whorl increased with time, reaching a maximum of 35.67% at 4&#xa0;h post-infestation. Under field conditions, 14.66% and 22.14% of larvae dispersed to neighbouring plants within 2 and 7 days, respectively, while over 71.06% were lost within the first week. Dispersal was mainly restricted to plants within the same row, particularly within 60&#xa0;cm of the initially infested plant. These results reveal how host traits and environmental conditions shape the oviposition and dispersal patterns of <i>S. frugiperda</i>. The findings enhance understanding of its spatiotemporal behaviour and provide valuable insights for developing targeted, stage-specific monitoring and integrated pest management (IPM) strategies in maize cultivation systems.</p>

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Oviposition preference and larval dispersal of the invasive Spodoptera frugiperda (J.E Smith) on maize under North Indian conditions

  • 期刊论文

  • 发表日期：

    2025年11月27日

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  • Oshin Bhargav,
  • Naveen Aggarwal,
  • Jawala Jindal

摘要

Spodoptera frugiperda (J. E Smith) (Noctuidae: Lepidoptera) is a highly invasive pest of maize, known for its prolific reproduction and efficient dispersal. This study examined the effects of seasonal temperature and maize plant age on oviposition behaviour and larval dispersal. Field-cage assays were used to assess monthly fecundity and larval movement, while field experiments evaluated oviposition preference at different plant ages and inter-plant dispersal. The effect of temperature on S. frugiperda reproductive traits was significant, with fecundity highest in July (732.05 eggs/plant) and lowest in January (90.31 eggs/plant), and egg viability ranging from 26.75% to 77.74%, both positively associated with maximum (fecundity: r = 0.94, R² = 0.89; egg viability: r = 0.84-0.97, R² = 0.71-0.95) and minimum temperatures (fecundity: r = 0.96, R² = 0.93). Host plant age significantly influenced oviposition, with 20 day old maize receiving maximum egg masses (4.27/plant), followed by 10 day old plants (3.03/plant), while older plants attracted fewer eggs; females consistently preferred the abaxial leaf surface, depositing more eggs than on the adaxial side (13.50 vs. 7.83 on 20-day-old and 8.33 vs. 6.83 on 10-day-old plants). A negative correlation was observed between oviposition and increasing plant age (r = -0.81), trichome density (r = -0.90), and trichome length (r = -0.63), with regression analysis indicating a weak negative relationship with host age (R² = 0.66). Larval dispersal studies revealed ballooning behaviour immediately after release, which declined sharply after 1.5 h. Larval settling in the central whorl increased with time, reaching a maximum of 35.67% at 4 h post-infestation. Under field conditions, 14.66% and 22.14% of larvae dispersed to neighbouring plants within 2 and 7 days, respectively, while over 71.06% were lost within the first week. Dispersal was mainly restricted to plants within the same row, particularly within 60 cm of the initially infested plant. These results reveal how host traits and environmental conditions shape the oviposition and dispersal patterns of S. frugiperda. The findings enhance understanding of its spatiotemporal behaviour and provide valuable insights for developing targeted, stage-specific monitoring and integrated pest management (IPM) strategies in maize cultivation systems.