Cowpea Aphid
Aphis craccivora
📖 Description
Cowpea Aphid is a major pest of pulses and legumes across the Indian subcontinent, attacking cowpea, chickpea, pigeon pea, mung bean, urd bean, groundnut, and many other legumes. Dense colonies of aphids suck sap from tender shoots, leaves, and inflorescences, causing distortion, stunting, and reduced pod formation. The pest is particularly damaging because it transmits over 30 plant viruses, including Bean Common Mosaic Virus, Cowpea Aphid-Borne Mosaic Virus, and Groundnut Rosette Virus. Outbreaks are favored by cool, dry conditions and excessive nitrogen fertilization. The pest reproduces entirely by parthenogenesis in tropical conditions, allowing populations to explode within days. Conservation biological control with ladybird beetles (Coccinella, Menochilus), syrphid fly larvae, and parasitic wasps (Aphidius, Lysiphlebus) is central to sustainable management.
⚠️ Symptoms to watch for
- Curling and distortion of leaves, stunted plant growth, sticky honeydew on leaves, sooty mold growth, flower and pod drop, reduced pod and grain formation, transmission of over 30 plant viruses including Bean Common Mosaic Virus, yield loss 30-50%
🩹 Treatment
- Spray neem oil 5ml/L with sticker, apply 5% NSKE, release ladybird beetles, apply recommended insecticides at early infestation, conserve natural enemies
🌿 Organic treatments
- Spray neem oil 5 ml/L with sticker, apply 5% NSKE, release Coccinella septempunctata @ 5000/ha and Menochilus sexmaculatus, apply Lecanicillium lecanii @ 5 g/L, spray 5% verticillium lecanii, intercrop with marigold or mustard as trap crop, conserve syrphid fly larvae
🧪 Chemical treatments
- Imidacloprid 17.8 SL @ 0.3 ml/L, Thiamethoxam 25 WG @ 0.4 g/L, Acetamiprid 20 SP @ 0.2 g/L, Dimethoate 30 EC @ 1.5 ml/L, Pymetrozine 50 WG @ 0.5 g/L (rotate; resistance common)
🛡️ Prevention
- Plant early to escape peak aphid activity, use resistant varieties where available, balanced fertilizer use (avoid excessive nitrogen), inspect crop weekly for early colonies, conserve ladybird beetles and syrphid flies by avoiding broad-spectrum insecticides, remove virus-infected plants promptly, intercrop with trap crops, destroy crop residues after harvest
🪴 Affected plants
- Cowpea, Chickpea, Pigeon Pea, Green Gram, Black Gram, Beans, Groundnut, Lucerne, Many Legumes (over 50 host plants)
🦋 Natural predators
- Coccinella septempunctata, Menochilus sexmaculatus, Syrphid Fly Larvae, Green Lacewings, Aphidius Wasps
🌱 Host plants
- Vigna unguiculata, Cicer arietinum, Cajanus cajan, Vigna radiata, Vigna mungo, Arachis hypogaea
🔄 Lifecycle
- Reproduces entirely by parthenogenesis in tropical conditions, with females giving birth to 50-100 live nymphs.
- Nymphs mature in 7-12 days and begin reproducing immediately.
- Winged forms appear when colonies are crowded, dispersing to new plants.
- Adults live 15-30 days.
- Total life cycle 8-15 days; 20+ overlapping generations per year.
📅 Season
- Year-round in tropical climates, peaks Nov-Mar during cool dry Rabi season
🔎 Appearance
- Small, pear-shaped, shiny black or dark brown aphids with black cornicles.
- They form dense colonies on tender shoots, leaves, and inflorescences of pulses and other legumes.
- Winged forms appear when colonies become crowded.
💥 Damage level
- High
🔁 Reproduction rate
- Rapid
🗺️ Geographic regions
- Indian Subcontinent
- Africa
- Southeast Asia
- Worldwide Tropics
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