Cashew Nut Borer
Cydalima laticostalis
📖 Description
Cashew Nut Borer (Cydalima laticostalis) is an important pest of cashew across the Indian subcontinent, particularly severe in the major cashew-growing belts of Kerala (Kollam, Kasaragod), Karnataka (Dakshina Kannada, Udupi, Uttara Kannada — India’s largest cashew-producing state), Goa, Maharashtra (Ratnagiri, Sindhudurg), Andhra Pradesh (Srikakulam, Vizianagaram), Odisha (Gajapati, Koraput), Tamil Nadu (Cuddalore, Villupuram) and West Bengal where India is the world’s second-largest producer of cashew (after Côte d’Ivoire, over 1 million hectares cultivated). The pest is particularly damaging because (a) the larvae tunnel inside the cashew apple and developing nut — the most valuable plant part for cashew cultivation, (b) infested apples fall prematurely with the nut inside failing to develop or becoming shrivelled, (c) the entry wounds created by larvae allow secondary fungal pathogens (Botryodiplodia, Pestalotia) to cause rapid rotting — often more damaging than the direct pest injury, (d) the pest has multiple overlapping generations per year (6-8 in tropical India), allowing rapid buildup during the fruiting season, and (e) once a larva enters the apple, no insecticide can reach it — control must focus on preventing egg-laying and removing fallen apples. The pest is most severe in monocropped cashew orchards and in orchards with poor sanitation (where fallen apples accumulate). IPM with weekly collection and destruction of fallen apples (the single most effective control — kills larvae and pupae inside and breaks the lifecycle), light trap monitoring of nocturnal adults, Bt sprays during peak fruiting, Trichogramma egg parasitoid releases, fruit bagging for high-value trees, and need-based insecticide rotation provides effective and sustainable control. The pest is a particular concern for smallholder cashew farmers (the dominant production system in India) because the crop provides annual income through raw nut sales, and even moderate infestations can reduce nut yield and quality enough to significantly affect household income.
⚠️ Symptoms to watch for
- Bore holes on cashew apples with frass extruding, tunnelled and rotten cashew apples, premature fruit and nut drop, nuts inside affected apples fail to develop or are shrivelled, secondary fungal infection (Botryodiplodia, Pestalotia) entering through wounds causing rapid rotting, yield loss 15-35% in severely infested cashew orchards, especially damaging to young orchards (3-8 years old)
🩹 Treatment
- Collect and destroy fallen cashew apples weekly (kills larvae and pupae inside), install light traps @ 1/ha for adult monitoring, spray neem oil 1% with sticker on cashew apples, apply Bacillus thuringiensis (Bt) @ 1 g/L on apple clusters, use need-based insecticide when 5% of apples are infested
🌿 Organic treatments
- Collect and burn fallen cashew apples weekly (the single most effective organic control — kills larvae and pupae inside, breaks the lifecycle), install light traps @ 1/ha for adult monitoring and mass trapping (adults are nocturnal), spray Bacillus thuringiensis (Bt) @ 1 g/L on apple clusters weekly from fruit set to harvest, spray neem oil 1% + 5 g/L soap on apple clusters, apply Beauveria bassiana @ 5 g/L, spray NSKE 5%, release Trichogramma chilonis @ 50000/ha (egg parasitoid), conserve native predators (spiders, lacewings, predatory bugs, ants), bag young cashew apple clusters with paper bags (very effective for high-value trees)
🧪 Chemical treatments
- Emamectin benzoate 5 SG @ 0.3 g/L (very effective against young caterpillars before they enter the apple), Chlorantraniliprole 18.5 SC @ 0.3 ml/L, Lambda-cyhalothrin 5 EC @ 0.5 ml/L (broad-spectrum, use as last resort), 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 sprays at 15-day intervals during peak fruiting
🛡️ Prevention
- Plant cashew orchards away from old or abandoned cashew trees (which serve as reservoirs), collect and destroy fallen cashew apples weekly (breaks the lifecycle by killing larvae and pupae inside), maintain orchard sanitation by removing debris and weeds (pupation sites), prune and burn infested apple clusters before larval emergence, install light traps @ 1/ha from February onward for monitoring adult activity, plant early-maturing varieties (Vengurla, Ullal) to escape peak pest pressure, balanced fertilization (avoid excess nitrogen), bag young cashew apple clusters with paper bags (very effective for high-value trees), intercrop with non-host species (mango, coconut) to disrupt adult movement, conserve native predators and ants (which are important natural enemies) by avoiding broad-spectrum insecticides
🪴 Affected plants
- Cashew, Occasionally Other Anacardiaceae (Mango, Pistasia)
🦋 Natural predators
- Trichogramma chilonis (egg parasitoid), Spiders (LYS, Salticid), Lacewing Larvae (Chrysoperla), Predatory Bugs (Reduviid, Anthocorid), Ants (important predators of pupating larvae on fallen apples), Birds (Bulbul, Babbler — important predators in orchards)
🌱 Host plants
- Anacardium occidentale, Mangifera indica (occasionally), Pistacia spp. (occasionally)
🔄 Lifecycle
- Female lays 100-200 eggs singly on the cashew apple surface (often near the stem end).
- Eggs hatch in 3-5 days.
- Larvae tunnel into the apple and feed for 10-15 days through 5 instars, then emerge and pupate in silken cocoons in soil debris or between fallen apples for 7-12 days.
- Adult lifespan 7-15 days.
- Total life cycle 25-35 days; 6-8 overlapping generations per year in tropical India, with peak activity during the fruiting season (Feb-Jun in South India).
📅 Season
- Active Feb-Jul (cashew fruiting season in India); peaks Mar-May (most damaging during fruit maturation)
🔎 Appearance
- Adult is a small, slender, brownish-yellow moth with darker brown markings on the forewings; wings held tent-like over the body at rest, giving a slender appearance.
- Larva is a slender, smooth, pale yellowish-green to pinkish caterpillar with a dark brown head capsule and small dark spots along the body; found tunneling inside cashew apples and developing nuts.
- Pupa is dark brown, 8-10 mm long, in a silken cocoon in soil debris or between fallen cashew apples.
💥 Damage level
- Moderate
🔁 Reproduction rate
- Rapid
🗺️ Geographic regions
- Indian Subcontinent
- South Asia
- Southeast Asia
- East Africa
- Brazil
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