Sesame Stem and Leaf Webber
Antigastra catalaunalis
📖 Description
Antigastra catalaunalis, the sesame leaf webber and capsule borer, is a specialist Gelechiid moth that is the single most important entomological constraint on sesame production in India. Sesame is grown on ~16 lakh hectares in India producing ~7 lakh tonnes annually, and A. catalaunalis causes estimated losses of ₹400–600 crore per year. The species has 4–6 overlapping generations per year synchronised to the sesame cropping cycle. Females oviposit on tender leaves, flower buds, and young capsules; larvae initially web leaves and flowers at the top of the plant before boring into stems and capsules. The combined webbing-and-boring habit makes this pest particularly damaging: webbed flowers fail to set capsules, bored stems cause shoot death, and bored capsules shed or yield partially consumed seeds. Because sesame is a minor crop in terms of research investment, fewer resistant varieties and IPM tools are available compared to major crops.
⚠️ Symptoms to watch for
- Webbed leaves and flowers at the top of sesame plants, bored stem holes with frass, wilting and drying of the top shoot ('dead heart' symptom), shed flowers and young capsules, and bored capsules with partially consumed seeds.
- Severe infestation causes 30–60 % yield loss
- the combined leaf-webbing and stem-boring habit makes this pest particularly damaging because it destroys both vegetative tissue and reproductive structures simultaneously.
🩹 Treatment
- Monitor adult activity with light traps or pheromone traps where lures are available.
- Spray neem oil 2 % or azadirachtin 1 % (2 ml/L) at the first sign of leaf webbing.
- Apply Bt kurstaki @ 1 g/L at egg-hatch.
- If larvae have bored into stems, apply chlorantraniliprole 18.5 SC @ 0.3 ml/L or emamectin benzoate 5 SG @ 0.4 g/L — both have translaminar and systemic activity.
- Always target sprays at the top third of the plant where the pest is most active.
🌿 Organic treatments
- Neem oil 2 %
- azadirachtin 1 % (2 ml/L)
- Bt kurstaki @ 1 g/L at egg-hatch
- Beauveria bassiana 1×10^8 cfu/mL @ 5 g/L
- light-trap mass-trapping of adults
- manual removal of webbed shoots
- sowing of trap crops of sesame around the main field to concentrate oviposition.
🧪 Chemical treatments
- Chlorantraniliprole 18.5 SC @ 0.3 ml/L
- emamectin benzoate 5 SG @ 0.4 g/L
- indoxacarb 14.5 SC @ 0.5 ml/L
- flubendiamide 39.35 SC @ 0.2 ml/L
- quinalphos 25 EC @ 1.5 ml/L (last resort — broad-spectrum).
🛡️ Prevention
- Time sowing to escape the peak moth activity window — early sowing (June–July for kharif, January–February for rabi) reduces infestation.
- Practice crop rotation with non-host crops (pulses, cereals) for at least one season.
- Destroy crop residues after harvest by burning or deep ploughing.
- Avoid late-maturing varieties that extend the vulnerable flowering window.
- Maintain field sanitation — wild Sesamum spp. and Pedalium murex act as reservoirs.
- Encourage intercropping with pigeonpea or green gram to disrupt host-finding.
🪴 Affected plants
- Sesame (Sesamum indicum) is the sole economic host.
- In India it is the most destructive pest of sesame in all sesame-growing states — Gujarat, Rajasthan, Madhya Pradesh, Uttar Pradesh, West Bengal, Andhra Pradesh, and Tamil Nadu.
🦋 Natural predators
- Predatory bugs (Eocanthecona furcellata, Nesidiocoris tenuis)
- lacewing larvae
- predatory beetles
- egg parasitoids (Trichogramma spp.)
- larval parasitoids (Cotesia spp., Bracon hebetor, Apanteles spp.)
- and entomopathogenic fungi (Beauveria bassiana, Metarhizium anisopliae).
🌱 Host plants
- Sesame (Sesamum indicum) is the sole economic host
- wild Sesamum spp. (S. laciniatum, S. radiatum) and Pedalium murex are occasional reservoirs.
🔄 Lifecycle
- Eggs hatch in 3–5 days; larvae web leaves/flowers/bore stems for 12–18 days (4–5 instars); pupation in soil, leaf litter, or inside webbed material for 7–10 days; adult lifespan 5–10 days.
- Total lifecycle 25–40 days; 4–6 generations per year.
📅 Season
- Active year-round across sesame tracts; peaks during kharif (July–September) and rabi (January–March) sesame crops.
🔎 Appearance
- Larvae are slender, pale greenish-yellow to pinkish-cream caterpillars with a shiny brown head capsule, scattered dark setae, and faint pinkish dorsal stripes — found inside webbed leaves, flowers, or bored stems.
- Adults are small, slender, brownish-orange moths with darker brown scales at the wing tips and a paler band along the costa; at rest they hold their wings roof-shaped over the body.
💥 Damage level
- High
🔁 Reproduction rate
- Fast
🗺️ Geographic regions
- Indian Subcontinent (pan-India in sesame tracts)
- Africa
- Middle East
- Southeast Asia
- South China
- Philippines
- Australia
- Central America.
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