Maize Aphid (Corn Leaf Aphid)
Rhopalosiphum maidis
📖 Description
Maize Aphid or Corn Leaf Aphid is the dominant aphid pest of maize and sorghum across the Indian subcontinent, particularly severe in kharif maize of Karnataka, Andhra Pradesh, Telangana, Maharashtra and Bihar. The pest colonises the leaf whorl before tasseling and migrates to tassels and ear tips at flowering, where copious honeydew interferes with pollination and grain filling. Beyond direct feeding damage, R. maidis is the most important vector of Maize Dwarf Mosaic Virus and Sugarcane Mosaic Virus in Indian maize, capable of transmitting viruses in a single probe. Outbreaks are favoured by warm dry weather, excessive nitrogen and continuous cereal cropping. IPM focuses on conserving natural enemies (especially syrphid flies, coccinellids and aphidiid wasps), avoiding broad-spectrum insecticides and planting virus-free seed in areas with high MDMV pressure.
⚠️ Symptoms to watch for
- Yellowing and curling of leaves
- sooty mold growth on honeydew
- deformation of tassels and ears
- poor grain filling
- transmission of Maize Dwarf Mosaic Virus (MDMV)
- Sugarcane Mosaic Virus (SCMV) and Maize Leaf Fleck Virus
- yield loss 10-30% in early infestations
🩹 Treatment
- Conserve natural enemies (coccinellids, syrphids)
- apply neem oil 5 ml/L when 50+ aphids per plant
- use need-based systemic insecticide when whorls are saturated with aphids
🌿 Organic treatments
- Neem oil 5 ml/L + 5 g/L soap sprayed into whorls
- release Menochilus sexmaculatus @ 5 grubs/m2
- apply Verticillium lecanii @ 5 g/L
- spray NSKE 5%
- apply Beauveria bassiana @ 5 g/L
- conserve syrphid flies by flowering border crops
🧪 Chemical treatments
- Imidacloprid 17.8 SL @ 0.3 ml/L (foliar or seed treatment)
- Dimethoate 30 EC @ 1 ml/L
- Acephate 75 SP @ 1 g/L
- Thiamethoxam 25 WG @ 0.2 g/L
- Pymetrozine 50 WG @ 0.5 g/L (selective to aphids)
🛡️ Prevention
- Plant early to escape peak aphid buildup
- balanced nitrogen application
- intercrop with legumes to encourage natural enemies
- destroy weed hosts (Sorghum halepense, Cynodon)
- use yellow sticky traps @ 10/ha for monitoring
- plant tolerant hybrids (Pioneer 30V92, NK 6240)
🪴 Affected plants
- Maize
- Sorghum
- Pearl Millet
- Barley
- Wheat
- Finger Millet
- Foxtail Millet
- Wild Grasses
🦋 Natural predators
- Ladybird Beetles (Menochilus, Coccinella, Cheilomenes)
- Syrphid Flies (Ischiodon, Episyrphus)
- Lacewing Larvae
- Aphidiid Wasps (Lysiphlebus, Diaeretiella)
- Spiders
🌱 Host plants
- Zea mays
- Sorghum bicolor
- Pennisetum glaucum
- Hordeum vulgare
- Triticum aestivum
🔄 Lifecycle
- Parthenogenetic viviparous reproduction — females produce 50-100 nymphs each.
- Nymphs pass through 4 instars in 5-8 days.
- Adult lifespan 15-25 days.
- Total life cycle 7-12 days in summer.
- 20-30 overlapping generations per year.
- No egg stage in tropical lowlands.
📅 Season
- Year-round, peaks Jun-Sep (kharif maize) and Feb-Apr (rabi maize)
🔎 Appearance
- Small oval aphid, dark bluish-green to nearly black, with short dark cornicles and pale legs.
- Winged forms have a dark head and thorax with green abdomen.
- Colonies cluster inside leaf whorls, on tassels and ear tips, often covering developing grain with sticky honeydew.
💥 Damage level
- Moderate
🔁 Reproduction rate
- Very Rapid
🗺️ Geographic regions
- Indian Subcontinent
- South Asia
- Africa
- Tropics and Subtropics Worldwide
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