Litchi Fruit Borer
Conopomorpha sinensis
📖 Description
Litchi Fruit Borer (Conopomorpha sinensis) is the most destructive pest of litchi across the Indian subcontinent, particularly severe in the major litchi-growing belts of Bihar (Muzaffarpur, Samastipur, East Champaran — India’s largest litchi-producing region), West Bengal (Murshidabad, Malda), Jharkhand (Ranchi, Lohardaga), Uttar Pradesh (Saharanpur, Dehradun) and Tripura where India is the world’s second-largest producer of litchi (after China, over 80,000 hectares cultivated). The pest is particularly damaging because (a) the larvae tunnel inside the fruit — the most valuable plant part for litchi cultivation, (b) infested fruits are completely unsaleable for fresh market or export (even a single larva inside makes a fruit unsaleable), (c) the pest preferentially attacks fruits at the colour-break stage (when fruits begin to turn red) — exactly the stage when fruits are maturing and most valuable, (d) the pest has a very short life cycle (25-30 days) with multiple overlapping generations (8-10 per year), allowing rapid buildup during the fruiting season, and (e) once a larva enters the fruit, no insecticide can reach it — control must focus on preventing egg-laying on the fruit. The pest is most severe in monocropped litchi orchards and in orchards with poor sanitation. IPM with fruit bagging (the single most effective control — paper bags applied 15-20 days after fruit set prevent all egg-laying), pheromone trap monitoring, neem-based sprays, Trichogramma egg parasitoid releases, Bt sprays during peak adult flight, and need-based insecticide rotation with strict pre-harvest intervals provides effective and sustainable control. The pest is a particular concern for export-oriented litchi growers (litchi is exported from India to UAE, UK, EU and other markets) because even a single infested fruit in a consignment can lead to rejection of the entire shipment.
⚠️ Symptoms to watch for
- Tiny pinhead-sized punctures on fruit skin (egg-laying sites), brownish frass extruding from small bore holes on fruit, internal fruit flesh tunnelled and contaminated with frass, premature fruit drop (especially young fruits), fruit splitting and rotting from secondary fungal infection (Anthracnose, Rhizopus), complete loss of market value for infested fruits (even a single larva inside makes a fruit unsaleable for fresh market or export), yield loss 20-50% in commercial litchi orchards, export-quality downgrading
🩹 Treatment
- Bag fruit clusters with paper bags 15-20 days after fruit set (very effective), install pheromone traps @ 4/ha for adult monitoring, spray neem oil 1% with sticker on fruit clusters, use need-based systemic insecticide at first sign of egg-laying, prune and destroy infested fruits before larval emergence
🌿 Organic treatments
- Bag fruit clusters with paper bags 15-20 days after fruit set (the single most effective organic control — prevents egg-laying on the fruit), install pheromone traps @ 4/ha for adult monitoring and mass trapping, spray neem oil 1% + 5 g/L soap on fruit clusters weekly from fruit set to harvest, apply Bacillus thuringiensis (Bt) @ 1 g/L on fruit clusters, spray NSKE 5%, release Trichogramma chilonis @ 50000/ha (egg parasitoid — highly effective against the tiny eggs), apply Beauveria bassiana @ 5 g/L, prune and destroy infested fruits before larval emergence (breaks the lifecycle), maintain orchard sanitation by removing fallen fruits (pupation sites)
🧪 Chemical treatments
- Emamectin benzoate 5 SG @ 0.3 g/L (very effective against young caterpillars before they enter the fruit), Chlorantraniliprole 18.5 SC @ 0.3 ml/L, Lambda-cyhalothrin 5 EC @ 0.5 ml/L (broad-spectrum — use as last resort and observe pre-harvest interval of 14 days), Spinosad 45 SC @ 0.2 ml/L, Novaluron 10 EC @ 1 ml/L (chitin synthesis inhibitor — effective against eggs and young larvae), Azadirachtin 10000 ppm @ 2 ml/L — apply 2-3 sprays at 10-12 day intervals from fruit set to 2 weeks before harvest, observe pre-harvest intervals strictly
🛡️ Prevention
- Bag fruit clusters with paper bags 15-20 days after fruit set (the single most effective preventive measure — prevents egg-laying on the fruit), maintain orchard sanitation by removing fallen fruits and debris (pupation sites), prune and burn infested fruits before larval emergence (breaks the lifecycle), install pheromone traps @ 4/ha from March onward for monitoring adult moth activity, plant litchi orchards away from old or abandoned litchi and longan trees (which serve as reservoirs), balanced fertilization and irrigation (vigorous trees are less attractive to egg-laying moths), avoid monocropping — intercrop with non-host species to disrupt adult movement, observe pre-harvest intervals strictly for any insecticide used (litchi is consumed fresh with no processing), use light traps @ 1/ha to monitor adult activity at night, conserve native parasitoids and predators by avoiding broad-spectrum insecticides
🪴 Affected plants
- Litchi (Litchi chinensis), Longan (Dimocarpus longan), Occasionally Rambutan
🦋 Natural predators
- Trichogramma chilonis (egg parasitoid — highly effective against the tiny eggs), Anthocorid Bugs (Orius — against eggs and young larvae before they enter the fruit), Spiders, Lacewing Larvae (Chrysoperla), Predatory Bugs (Reduviid), Birds (Bulbul, Babbler — important predators of pupating larvae on fruit surface)
🌱 Host plants
- Litchi chinensis, Dimocarpus longan (longan), Nephelium lappaceum (rambutan — occasionally)
🔄 Lifecycle
- Female lays 50-150 eggs singly on the fruit surface (often near the stem end or in skin depressions).
- Eggs hatch in 3-5 days.
- Larvae tunnel into the fruit and feed for 8-12 days through 4-5 instars, then emerge and pupate in silken cocoons on the fruit surface, leaf litter or bark crevices for 6-10 days.
- Adult lifespan 7-15 days.
- Total life cycle 25-30 days; 8-10 overlapping generations per year in tropical India, with peak activity during the fruiting season (Apr-Jul in Bihar, Mar-Jun in West Bengal).
📅 Season
- Active Mar-Jul (litchi fruiting season in India); peaks Apr-Jun (most damaging during fruit maturation)
🔎 Appearance
- Adult is a tiny, slender, dark brown moth with silvery-white patches on the forewings and characteristic long fringed scales on the wing margins; at rest, the moth holds its wings tent-like over the body and looks like a small dark speck on the fruit or leaf surface.
- Larva is a tiny, slender, creamy-white to pale pink caterpillar with a dark brown head capsule; found tunneling inside litchi fruits.
- Pupa is dark brown, 5-6 mm long, in a silken cocoon on the fruit surface, leaf litter or bark crevices.
💥 Damage level
- Severe
🔁 Reproduction rate
- Rapid
🗺️ Geographic regions
- Indian Subcontinent
- South China
- Southeast Asia
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