Important Pests

Yellow stem borer (*Scirpophaga incertulas*, Lepidoptera: Pyralidae) is the most important and widely distributed rice pest in India. It causes 'dead heart' (bore hole in tillers at vegetative stage — central leaf dries and pulls out easily) and 'white ear' (unfilled panicle at reproductive stage). ETL: 5% dead hearts at vegetative stage or 1 egg mass/m² for initiating spray. Brown plant hopper (BPH, *Nilaparvata lugens*) is the most serious sucking pest causing 'hopper burn.'

American bollworm (*Helicoverpa armigera*, Noctuidae) — polyphagous; attacks bolls, buds, and flowers; most damaging; controlled by HaNPV and Bt cotton. Pink bollworm (*Pectinophora gossypiella*, Gelechiidae) — larvae bore into bolls and feed on seeds; detected by two holes at boll entry; monitored with gossyplure pheromone traps. Spotted bollworm (*Earias vittella* and *E. insulana*, Noctuidae) — attacks shoots and bolls; causes 'shot hole' symptom on tender shoots. All three are Lepidoptera; HaNPV is specific to *Helicoverpa*.

Wheat aphid (*Sitobion avenae*, *Rhopalosiphum padi*, Hemiptera: Aphididae) — ETL is 10 aphids per tillers or 10–15% infestation before heading. Aphids suck phloem sap, secrete honeydew (promoting sooty mould growth), and transmit barley yellow dwarf virus (BYDV). Management: natural enemies (Coccinellids, Syrphid flies, Chrysoperla) provide significant control; chemical — dimethoate, imidacloprid (seed treatment). Resistant varieties: PBW 343 has some field tolerance.

Khapra beetle (*Trogoderma granarium*, Coleoptera: Dermestidae) is listed as the most serious stored grain pest in India and a major quarantine pest worldwide. It attacks grain in storage, with larvae causing maximum damage (adults do not eat). Grain weevil (*Sitophilus granarius*) and rice weevil (*Sitophilus oryzae*) are primary storage pests (attack whole grain). Lesser grain borer (*Rhyzopertha dominica*) attacks wheat. Management: aluminium phosphide fumigation (3 tablets/tonne of grain) is the standard treatment.

Early shoot borer (*Chilo infuscatellus*, Lepidoptera: Pyralidae) attacks sugarcane from germination to tillering stage — the caterpillar bores into young shoots causing 'dead heart' (central shoot dries while outer leaves remain green). It is the most destructive pest of early-stage sugarcane. The later-stage internode borer (*Chilo sacchariphagus indicus*) bores into internodes causing 'rind hardening' and yield loss. Control: release of *Trichogramma chilonis* (1.5 lakh/acre) is the primary biocontrol measure.

Primary storage pests can attack whole, undamaged grain — they have mouthparts or behaviour to penetrate the grain kernel. Examples: grain weevil (*Sitophilus granarius*), rice weevil (*S. oryzae*), lesser grain borer (*Rhyzopertha dominica*), pulse beetle (*Callosobruchus maculatus* — attacks whole pulses). Secondary storage pests can only attack grain already damaged or broken by primary pests or during threshing. Examples: flour beetle (*Tribolium castaneum*), grain moth (*Sitotroga cerealella* — primary for maize but secondary for wheat). Khapra beetle larvae feed on loose grain and debris.