Two-Spotted Spider Mite
Tetranychus urticae
📖 Description
Two-Spotted Spider Mite (Tetranychus urticae) is one of the most destructive and widely distributed mite pests worldwide, attacking over 200 plant species including cotton, vegetables, ornamentals and fruit crops across the Indian subcontinent. The pest is particularly severe in cotton belts of Maharashtra, Gujarat, Andhra Pradesh, Telangana and Tamil Nadu, and in vegetable belts of Karnataka, West Bengal, Odisha and Bihar. The pest is a classic example of ‘secondary pest outbreak’ — in IPM programs where broad-spectrum insecticides are avoided, natural predatory mites (Amblyseius, Phytoseiulus) and the Stethorus ladybird beetle keep T. urticae populations below economic threshold. However, when pyrethroids or broad-spectrum insecticides are applied (often for other pests), predatory mites are killed and T. urticae populations explode — a phenomenon called ‘pest resurgence’. The pest is also notoriously prone to developing resistance — populations have evolved resistance to virtually all major acaricide classes (organophosphates, pyrethroids, dicofol, abamectin, hexythiazox), making resistance management through mode-of-action rotation critical. The pest produces characteristic fine webbing on leaf undersides that protects mites from natural enemies and contact acaricides. IPM with conservation of native predatory mites, release of Phytoseiulus persimilis (a specialist predator of Tetranychus), neem-based sprays, and need-based acaricide rotation provides effective and sustainable control. The pest is most severe in warm dry conditions (25-35°C, low humidity) — overhead irrigation and maintaining field humidity can suppress populations naturally.
⚠️ Symptoms to watch for
- Fine stippling (whitish-grey spots) on upper leaf surface from feeding, leaf bronzing and yellowing, characteristic fine webbing on leaf undersides, premature leaf drop, reduced photosynthesis and yield, yield loss 30-60% in heavy infestations, complete defoliation in severe outbreaks
🩹 Treatment
- Release predatory mites (Amblyseius, Phytoseiulus) @ 5000-10000/ha, apply neem oil 1% with sticker, use need-based acaricide when 5-10 mites per leaf, conserve native predatory mites by avoiding pyrethroids
🌿 Organic treatments
- Release predatory mites Phytoseiulus persimilis @ 5000-10000/ha (highly effective), Amblyseius californicus @ 5000/ha, spray neem oil 1% + 5 g/L soap, apply wettable sulphur 80 WP @ 3 g/L (avoid in high temperatures), apply Verticillium lecanii @ 5 g/L, conserve native predatory mites
🧪 Chemical treatments
- Spiromesifen 240 SC @ 0.5 ml/L, Abamectin 1.9 EC @ 0.5 ml/L, Etoxazole 10 SC @ 1 ml/L, Propargite 57 EC @ 2 ml/L, Diafenthiuron 50 WP @ 1 g/L, Fenpyroximate 5 SC @ 1 ml/L — rotate to avoid resistance (cross-resistance common)
🛡️ Prevention
- Avoid pyrethroids and broad-spectrum insecticides (trigger mite resurgence by killing predatory mites), maintain balanced nutrition (avoid excess nitrogen), maintain field humidity (overhead irrigation suppresses mites), monitor with 20x hand lens, plant resistant varieties, conserve native predatory mites (Amblyseius, Phytoseiulus, Stethorus ladybird beetle)
🪴 Affected plants
- Cotton, Brinjal, Tomato, Cucumber, Pumpkin, Rose, Hibiscus, Apple, Strawberry, Beans, Numerous Ornamentals and Vegetables (over 200 hosts)
🦋 Natural predators
- Phytoseiulus persimilis (specialist predator), Amblyseius californicus, Amblyseius swirskii, Stethorus punctillum (ladybird beetle), Scolothrips sexmaculatus, Feltiella acarisuga (predatory midge)
🌱 Host plants
- Gossypium hirsutum, Solanum melongena, Solanum lycopersicum, Cucumis sativus, Cucurbita pepo, Rosa spp., Hibiscus rosa-sinensis
🔄 Lifecycle
- Female lays 50-100 eggs on leaf underside, often under webbing.
- Eggs hatch in 3-5 days.
- Larvae (6 legs) feed for 1-2 days, then protonymph (8 legs, 2-3 days), deutonymph (8 legs, 2-3 days), adult.
- Adult lifespan 15-30 days.
- Total life cycle 7-12 days at 30°C; 20-30 overlapping generations per year.
- Diapauses as orange-red adult in winter.
📅 Season
- Year-round in tropical India, peaks Mar-Jun and Oct-Dec during warm dry months
🔎 Appearance
- Adult female is a tiny, pale yellowish-green mite with two characteristic dark spots on either side of the body (visible through translucent body wall); turns orange-red in diapause (winter).
- Adult male is smaller and narrower.
- Eggs are spherical, translucent.
- Produces characteristic fine webbing on leaf undersides.
💥 Damage level
- Severe
🔁 Reproduction rate
- Very Rapid
🗺️ Geographic regions
- Indian Subcontinent
- Cosmopolitan Worldwide
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