🦟 Crop-Specific Pests
Wheat stem borer, pomegranate butterfly, ber fruit fly, mustard aphid — life cycles, damage, management, and comparative pest summary for CUET Agriculture
Unlike polyphagous pests that attack many crops, the pests covered in this lesson are more restricted in their host range. Some are oligophagous (feeding on a few related crops) while one is monophagous (feeding on a single crop). Understanding these pests alongside their specific crop associations is essential for CUET.
VII. Wheat Stem Borer (गेहूँ का तना छेदक)
Wheat Stem Borer / Pink Borer (Sesamia inferens) — Source: Wikimedia Commons (CC)
| Feature | Detail |
|---|---|
| Scientific Name | Sesamia inferens |
| Phylum | Arthropoda |
| Class | Insecta / Hexapoda |
| Order | Lepidoptera |
| Family | Noctuidae |
This pest is also called the "Pink Borer" (गुलाबी तना छेदक) because the caterpillar has a distinct pink colouration. It is an important Rabi season pest of cereal crops.
Host Plants
- Wheat, Rice, Maize — all major cereals can be attacked, but wheat is the most commonly damaged crop during Rabi season
Nature of Damage
The caterpillar enters the stem and bores inside, feeding on the internal tissue. This internal feeding produces two characteristic symptoms:
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Unlike polyphagous pests that attack many crops, the pests covered in this lesson are more restricted in their host range. Some are oligophagous (feeding on a few related crops) while one is monophagous (feeding on a single crop). Understanding these pests alongside their specific crop associations is essential for CUET.
VII. Wheat Stem Borer (गेहूँ का तना छेदक)
Wheat Stem Borer / Pink Borer (Sesamia inferens) — Source: Wikimedia Commons (CC)
| Feature | Detail |
|---|---|
| Scientific Name | Sesamia inferens |
| Phylum | Arthropoda |
| Class | Insecta / Hexapoda |
| Order | Lepidoptera |
| Family | Noctuidae |
This pest is also called the "Pink Borer" (गुलाबी तना छेदक) because the caterpillar has a distinct pink colouration. It is an important Rabi season pest of cereal crops.
Host Plants
- Wheat, Rice, Maize — all major cereals can be attacked, but wheat is the most commonly damaged crop during Rabi season
Nature of Damage
The caterpillar enters the stem and bores inside, feeding on the internal tissue. This internal feeding produces two characteristic symptoms:
- "Dead Heart" — When the caterpillar bores into the growing point during the vegetative stage, the central shoot dries up and turns brown. It comes out easily when pulled — this is the diagnostic test for dead heart.
- "White Ear" — When boring occurs during the reproductive stage, the ear/panicle emerges but remains empty (no grain filling) because the vascular connection has been severed. The ear turns white, standing out conspicuously against healthy green ears.
TIP
Dead Heart = vegetative stage damage (central shoot dies). White Ear = reproductive stage damage (empty panicle). These two symptoms are diagnostic for all stem borers across cereals, not just the wheat stem borer.
Life Cycle
| Stage | Duration |
|---|---|
| Egg | ~400 eggs per female; incubation 7-10 days |
| Caterpillar/Larva | 20-30 days (damaging stage); distinctly pink coloured |
| Pupa | Inside the bored stem; 7-12 days |
| Adult moth | Brown/grey coloured; nocturnal; female lays eggs on leaf sheaths near the stem |
Management
- Crop rotation (फसल चक्र अपनावे) — breaking the pest cycle by not growing cereals in the same field consecutively
- Egg parasitoid: Bracon sp. — a wasp that parasitises the borer inside the stem
- Chemical: Chlorpyrifos 20 EC or Quinalphos 25 EC @ 0.05% as foliar spray — most effective when applied at the egg-hatching stage before larvae enter the stem
VIII. Pomegranate Butterfly (अनार की तितली)
Pomegranate Butterfly (Virachola isocrates) — Source: Wikimedia Commons (CC)
| Feature | Detail |
|---|---|
| Scientific Name | Virachola isocrates |
| Phylum | Arthropoda |
| Class | Insecta / Hexapoda |
| Order | Lepidoptera |
| Family | Lycaenidae |
This is a fruit borer that specifically targets developing fruits. The adult is a beautiful butterfly (not a moth), which is unusual since most agricultural pests in Lepidoptera are moths.
Host Plants
- Pomegranate (अनार), Guava (अमरूद), Ber (बेर), Apple (सेब), Loquat (लोकाट) — primarily attacks fruit crops
Nature of Damage
- The caterpillar enters the fruit and feeds on the seeds and pulp inside, causing extensive internal damage
- Up to 8 caterpillars can be found feeding inside a single fruit
- Frass (excreta) is visible at the entry hole, which is the external sign of infestation
- Infested fruits often develop secondary fungal and bacterial rot
Life Cycle
| Stage | Duration |
|---|---|
| Egg | Laid on the surface of developing fruits; incubation 7-10 days |
| Caterpillar/Larva | 18-47 days (damaging stage) — relatively long larval period |
| Pupa | In soil near the base of host trees; 7-34 days |
| Generations/year | 4 |
Management
- Bag fruits with paper or cloth covers — this is the most effective method as it physically prevents the butterfly from laying eggs on the fruit. Bags are applied when fruits are small and removed before harvest.
- Spray Dimethoate 30 EC or Quinalphos 25 EC @ 2 ml/litre of water as foliar spray, timed when adult butterflies are first seen
IX. Ber Fruit Fly (बेर की फलमक्खी)
Fruit Fly (Tephritidae) — Source: Wikimedia Commons (CC)
| Feature | Detail |
|---|---|
| Scientific Name | Carpomyia vesuviana |
| Phylum | Arthropoda |
| Class | Insecta / Hexapoda |
| Order | Diptera |
| Family | Tephritidae |
The Ber fruit fly is a monophagous pest — it feeds exclusively on Ber (Indian jujube), making it unique among the pests studied in this unit. The female fly punctures the fruit skin with her sharp ovipositor and lays eggs inside the fruit. The developing maggots (larvae) feed on the fruit pulp, causing it to rot and drop prematurely. Multiple maggots (up to 18 per fruit) can develop inside a single Ber fruit.
Life Cycle
| Stage | Duration |
|---|---|
| Egg | Deposited inside fruit through ovipositor puncture; incubation 2-3 days |
| Maggot | 7-10 days (damaging stage) — feeds on fruit pulp, causing brown discolouration and decay |
| Pupa | In soil beneath host trees; 14-30 days |
| Generations | 2-3 per year |
Management
- Collect and destroy all fallen fruits regularly — fallen fruits contain developing maggots that would otherwise pupate in the soil and produce the next generation
- Apply Dimethoate 30 EC @ 1 ml/litre as foliar spray at the time of fruit setting
X. Mustard Aphid (मैथी एवं सरसों का मोयला)
Aphids (Aphididae) — Source: Wikimedia Commons (CC)
| Feature | Detail |
|---|---|
| Scientific Name | Lipaphis erysimi |
| Phylum | Arthropoda |
| Class | Insecta / Hexapoda |
| Order | Hemiptera |
| Family | Aphididae |
The mustard aphid is the most important pest of mustard and rapeseed crops in India. These tiny, soft-bodied insects form dense colonies on tender plant parts and can build up enormous populations in a very short time due to their unique reproductive strategy.
Nature of Damage
- Both nymph and adult stages suck sap from tender leaves, shoots, flowers, and developing pods, weakening the plant and reducing seed set
- Aphids secrete honeydew — a sugary, sticky substance that drops onto lower leaves. A black fungus called sooty mould grows on this honeydew, forming a dark coating that blocks sunlight and significantly reduces photosynthesis
- Heavy infestations cause leaf curling, stunted growth, and flower/pod drop, leading to severe yield losses
NOTE
Aphids cause dual damage: (1) Direct damage through sap sucking that weakens the plant, and (2) Indirect damage through honeydew-based sooty mould that reduces photosynthesis. Additionally, aphids are important virus vectors — they transmit several plant viruses while feeding.
Life Cycle
- Parthenogenesis (reproduction without mating) is the dominant mode of reproduction — females produce genetically identical offspring without needing males, allowing extremely rapid population buildup
- In plains (warmer climate): Female gives birth to live nymphs (viviparous reproduction) — no eggs are laid, which further accelerates population growth
- In hills (cooler climate): Female lays eggs; nymph emerges in 3-7 days
- Multiple overlapping generations per year — a single female can produce 50-100 nymphs in her lifetime
Management
- Early sowing (अगेती बुवाई) — sowing mustard early helps the crop reach the flowering stage before aphid populations build up, as aphids are most damaging during flowering
- Yellow sticky traps (पीले चिपचिपे पाश) — aphids are strongly attracted to yellow colour; traps help in early detection and monitoring
- Natural enemies: Lady bird beetle (Coccinella sp.) is the most important predator; Diaeretiella rapae is a key parasitoid that lays its eggs inside aphid bodies
- Chemical: Malathion 5% or Quinalphos 5% @ 20-25 kg/hectare as dust
- Spray Dimethoate 30 EC @ 1 ml/litre in 500-600 litres water per hectare
Comparative Summary Table — 6 Major Pests
This comprehensive comparison table covers all the major pests studied in the polyphagous and crop-specific pest lessons. It serves as a quick-revision reference for CUET.
| Feature | 1. Locust (टिड्डी) | 2. White Grub (सफेद लट) | 3. Khapra Beetle (खपरा भृंग) | 4. RHC (कातरा) | 5. Gram Pod Borer (फली वेधक) | 6. Termite (दीमक) |
|---|---|---|---|---|---|---|
| Scientific Name | Schistocerca gregaria | Holotrichia sp. | Trogoderma granarium | Amsacta moorei | Helicoverpa armigera | Odontotermes obesus |
| Phylum | Arthropoda | Arthropoda | Arthropoda | Arthropoda | Arthropoda | Arthropoda |
| Class | Insecta | Insecta | Insecta | Insecta | Insecta | Insecta |
| Order | Orthoptera | Coleoptera | Coleoptera | Lepidoptera | Lepidoptera | Isoptera |
| Family | Acrididae | Scarabaeidae | Dermestidae | Arctiidae | Noctuidae | Termitidae |
| Other Names | Famine insect (महामारी) | Cockchafer, May/June beetle | Cabinet beetle | — | American bollworm, Fruit/Pod borer | White ant |
| Life Cycle Stages | 3 (Egg-Nymph-Adult) | 4 (Egg-Larva-Pupa-Adult) | 4 (Egg-Larva-Pupa-Adult) | 4 (Egg-Larva-Pupa-Adult) | 4 (Egg-Larva-Pupa-Adult) | 3 (Egg-Nymph/Worker/Soldier) |
| Eggs Laid | 50-150 per pod (in soil, 10-15 cm) | 50-60 (in soil at 10-15 cm) | 120-150 (on grain surface or cracks) | On lower leaf surface in clusters | 500-1000 (singly on flowers/pods) | 70,000-80,000/day by queen |
| Egg Incubation | 10-40 days | Summer: 3-5d; Winter: 6-10d | Summer: 3-5d; Winter: 6-10d | 4-5 days | 2-4 days | ~1 week (summer) |
| Larva/Nymph Duration | Nymph: 3-10 weeks | Grub: 82-113 days | Grub: 8-20 days | Caterpillar: 15-23 days | Caterpillar: 15-20 days | Worker from nymph: ~6 months |
| Pupa Duration | — (incomplete metamorphosis) | 2-3 weeks (in soil) | 4-6 days (in grain) | 9-10 months (dormant in soil!) | 6-15 days | — (incomplete metamorphosis) |
| Total Life Cycle | Nymph to adult: ~10 weeks | ~1 year | ~129-150 days | ~26-41 days active + 9-10 months pupa | Multiple overlapping | Queen: 5-10 years |
| Damaging Stage | Nymph (hopper) & Adult | Grub (larva) | Beetle / Grub | Caterpillar | Caterpillar | Workers |
| Host Plants | All except Oak, Neem, Jamun, Sheesham | Kharif crops (roots); Trees (adult) | Stored cereals/grains | All Kharif crops | Chickpea, Cotton, Tomato, Maize, Sunflower | All cellulose material |
| Peak Damage Season | Kharif (monsoon) | July-October | July-October | August (monsoon) | Rabi (Nov-March) for pulses | Year-round |
| Generations/Year | Multiple (seasonal) | 1 (univoltine) | Multiple (4-5) | 1 | ~8 | 1 batch of alates/year |
Key Points for CUET
IMPORTANT
- Wheat Stem Borer = Sesamia inferens; causes Dead Heart and White Ear symptoms
- Pomegranate Butterfly = Virachola isocrates; Lycaenidae; fruit borer; best managed by bagging fruits
- Ber Fruit Fly = Carpomyia vesuviana; Diptera; monophagous on Ber only
- Mustard Aphid = Lipaphis erysimi; Hemiptera; sap sucker; honeydew + sooty mould; reproduces by parthenogenesis
- Helicoverpa armigera is the most polyphagous and destructive pest — gram pod borer in pulses, American bollworm in cotton
- Locust Warning Organisation established 1939 at Jodhpur
- White grub is univoltine (1 generation/year); "C" shaped grub is the characteristic identification mark
- RHC pupa stays dormant for 9-10 months — deep ploughing exposes them
Summary Cheat Sheet
| Concept / Topic | Key Details / Explanation |
|---|---|
| Wheat Stem Borer | Sesamia inferens; Order Lepidoptera; Family Noctuidae; also called Pink Borer |
| Dead Heart symptom | Boring into growing point during vegetative stage → central shoot dries, pulls out easily |
| White Ear symptom | Boring during reproductive stage → empty panicle, no grain filling |
| Wheat Stem Borer — Hosts | Wheat, Rice, Maize |
| Wheat Stem Borer — Eggs | ~400/female; incubation 7-10 days; caterpillar 20-30 days |
| Wheat Stem Borer — Management | Crop rotation; Bracon sp. parasitoid; Chlorpyrifos/Quinalphos spray |
| Pomegranate Butterfly | Virachola isocrates; Order Lepidoptera; Family Lycaenidae |
| Pomegranate Butterfly — Hosts | Pomegranate, Guava, Ber, Apple, Loquat |
| Pomegranate Butterfly — Damage | Up to 8 caterpillars per fruit; feeds on seeds/pulp inside |
| Pomegranate Butterfly — Management | Bag fruits (most effective); Dimethoate/Quinalphos spray |
| Pomegranate Butterfly — Generations | 4 per year |
| Ber Fruit Fly | Carpomyia vesuviana; Order Diptera; Family Tephritidae |
| Ber Fruit Fly — Key fact | Monophagous — feeds only on Ber |
| Ber Fruit Fly — Damage | Up to 18 maggots per fruit; fruit rots and drops |
| Ber Fruit Fly — Management | Collect/destroy fallen fruits; Dimethoate 30 EC @ 1 ml/L |
| Mustard Aphid | Lipaphis erysimi; Order Hemiptera; Family Aphididae |
| Mustard Aphid — Damage | Sap sucking → honeydew → sooty mould blocks sunlight, reduces photosynthesis |
| Mustard Aphid — Reproduction | Parthenogenesis; viviparous in plains (live nymphs) |
| Mustard Aphid — Management | Early sowing; yellow sticky traps; Coccinella predator; Malathion/Dimethoate |
| Comparative — Most polyphagous | Helicoverpa armigera (180+ species, ~8 gen/year) |
| Comparative — Univoltine | White grub (1 gen/year) |
| Comparative — Longest pupa | RHC (9-10 months dormant) |
| Comparative — Storage pest | Khapra beetle; native to India |
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