Tea Aphid
Toxoptera aurantii
📖 Description
Toxoptera aurantii, the camellia or black citrus aphid, is a tropical and subtropical aphid with an exceptionally broad host range (>90 plant families) but is most economically damaging on tea in India’s hill tracts. It reproduces almost entirely by parthenogenesis year-round in warm, humid tea agro-ecosystems, producing 30–70 live nymphs per female in 10–15 days. Unlike many aphids it does not produce sexual morphs in most of its range; winged alates develop under crowding or declining host quality and colonise new flush. The aphid’s damage is twofold: direct phloem feeding that depletes the bush of soluble nitrogen and potassium needed for polyphenol synthesis, and indirect sooty-mould growth that reduces leaf photosynthetic area. Its broad host range makes it a chronic reservoir on shade trees (Erythrina, Gliricidia) and weeds, from which it re-invades tea each season.
⚠️ Symptoms to watch for
- Curling and downward cupping of tender flush leaves, yellow mottling, sticky honeydew deposition on the upper surface of lower leaves, and sooty mould growth that blocks sunlight.
- Heavy infestations stunt young bushes, delay tipping and plucking cycles by 10–15 days, and downgrade made-tea quality by raising theaflavin and reducing aroma volatiles.
- Ant activity around the bushes is a tell-tale sign of an active colony.
🩹 Treatment
- Conserve natural enemies (lacewings, syrphids, coccinellids) by avoiding broad-spectrum sprays during their peak.
- Spot-spray neem oil (1 %) or azadirachtin 1500 ppm (2 ml/L) on infested flush during early morning.
- If colonies persist on young tea, apply imidacloprid 17.8 SL (0.3 ml/L) or thiamethoxam 25 WG (0.2 g/L) as a foliar spray
- observe a 7–10 day plucking withhold.
- Always rotate neonicotinoids with other modes of action to delay resistance.
🌿 Organic treatments
- Neem oil 1 % emulsion with sticky-trapper sticker
- azadirachtin 1 % (2 ml/L)
- release of lacewing larvae (Chrysoperla zastrowi sillemi) at 5,000/ha
- spray of Verticillium lecanii (now Lecanicillium lecanii) 1×10^8 cfu/mL at 5 g/L during humid weather.
🧪 Chemical treatments
- Imidacloprid 17.8 SL @ 0.3 ml/L
- thiamethoxam 25 WG @ 0.2 g/L
- acetamiprid 20 SP @ 0.2 g/L
- pymetrozine 50 WG @ 0.3 g/L (selective to aphids, safe to predators).
🛡️ Prevention
- Maintain balanced shade (35–40 %) to discourage excessive flush softness.
- Promote weed-free but groundcover-rich aisles for predator refugia.
- Avoid nitrogen overdose that attracts aphids.
- Tip young bushes regularly to remove colonised flush.
- Inspect nursery plants before field planting — aphids often arrive on infested seedlings.
🪴 Affected plants
- Tea (Camellia sinensis), cocoa, coffee, citrus, mango, pear, and many other evergreen plantation hosts.
- In India it is the most consistent aphid pest of young tea in Darjeeling, Assam, and the Nilgiris.
🦋 Natural predators
- Ladybird beetles (Coccinella transversalis, Menochilus sexmaculatus)
- green lacewings (Chrysoperla zastrowi sillemi)
- syrphid fly larvae (Ischiodon scutellaris)
- predatory midges (Aphidoletes aphidimyza)
- parasitoid wasps (Aphidius colemani, Lysiphlebus testaceipes)
- and entomopathogenic fungi (Lecanicillium lecanii, Beauveria bassiana).
🌱 Host plants
- Tea (Camellia sinensis)
- coffee (Coffea spp.)
- cocoa (Theobroma cacao)
- citrus
- mango
- pear
- Erythrina indica (shade tree)
- Gliricidia sepium
- and many broadleaf evergreens.
🔄 Lifecycle
- Anholocyclic (continuous parthenogenesis) in tea agro-ecosystems.
- Viviparous female produces 30–70 nymphs over 10–15 days; nymphs pass through 4 instars in 7–10 days; adult lifespan 20–30 days; up to 30 generations per year in warm humid conditions.
- Winged alates develop when colonies become crowded or when host quality declines, allowing dispersal to new flush.
📅 Season
- Peak infestations during the main flushing seasons: March–May (spring flush in Darjeeling and Assam) and September–November (autumn flush in south India).
- Severe in cool, dry periods that follow rains; populations crash during heavy monsoon.
🔎 Appearance
- Soft-bodied, pear-shaped, dark brown to almost black aphid with black cornicles and pale legs.
- Winged alates have a shiny black thorax and transparent wings with dark veins; wingless parthenogenetic females dominate the colonies.
- Nymphs are smaller, flatter, and reddish-brown with shorter cornicles.
- Adults often crowd the tender flush and underside of young tea leaves in dense, ant-attended colonies.
💥 Damage level
- Moderate
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Indian Subcontinent (Darjeeling, Assam, Dooars, Nilgiris, Anaimalai, Munnar)
- Southeast Asia
- China
- Japan
- East Africa
- South America.
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