1. Identification, Symptoms, Nature of Damage of Mango Fruit Fly, Stone/Nut Weevil and Pulp weevil
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2. Background
India is the world’s second largest producer of fruits and vegetables.
Mango is known as king of fruits in India and has largest acrage and production in the world but its export is mainly hindered by quarantine concerns.
Fruit flies, stone weevil and pulp weevil infesting mango fruits in India are of quarantine concerns to many countries
viz., Japan (fruit flies) ,USA (fruit flies &
Stone weevil) etc.
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3. Fruit flies (Diptera: Tephritidae)
Fruit flies (Diptera: Tephritidae) are among the world’s most serious pests of horticultural crops due to their direct economic impact as females oviposit inside the fruits and consequently young larvae feed on the pulp thus render them unmarketable.
The fruit flies comprise over 4,000 species distributed globally throughout all the temperate, subtropical and tropical climatic zones. The genus Bactrocera includes about 500 species.
In India, eight species of genus Bactrocera are identified among quarantine pests related to mango.
Fruit fly laying eggs Larvae after hatching
feeding on pulp
Bactrocera dorsalis B. zonata B. cucurbitae
B. Correcta B. diversa B. tau
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4. Important Fruit flies
In India, Oriental fruit fly B. dorsalis Hendel is the most destructive fruit fly of mango, followed by Peach fruit fly B. zonata Saunders and Guava fruit fly B. correcta Bezzi
The flies attack fruits at different stages of maturity but damage is more obvious at harvest maturity stages.
B. Dorsalis B. zonata B. correcta
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5. Identification Adult – Reddish brown with transparent wing
Larva – creamish yellow apodous maggots.
Pupa- ranges in color from dull red or brownish yellow
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6. Symptoms
The female insert eggs in small clusters inside the mesocarp of the fruits
Ovipunctures and oozing of fluid
After hatching larvae feeds on the pulp which appears normal from outside.
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7. Nature of Damage Brownish rotten patches on fruits.
Fruits finally drops down.
The larvae pupate in soil (5-10 cm) and flies start emerging from April onwards with maximum population during May to July which coincides with fruit maturity.
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8. Life Cycle of Fruit Fly Egg laying Starts After 2-3 weeks Eggs Eggs
1-2 day
Larvae
6-9 day
Adults
2-3 months
Pupa
Larvae
Pupate in soil
Pupa
8-10 day
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9. Mango Stone Weevil, Sternochetus mangiferae (Coleoptera: Curculionidae)
The mango stone weevil (Sternochetus mangiferae) is an important monophagous pest of mango, infesting the seed within.
Adult weevils become reproductively active when mango trees come to flower.
The females oviposit on developing mango fruits. Small marble-size fruits are preferred.
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10. Identification
Adult - Adult is dark brown with a short snout. weevils are 5 to 8 mm long.
Grub - A full grown grub is legless, fleshly and yellow with dark head.
Pupa - Pupation takes place inside the seed
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11. Symptoms Grub makes zigzag tunnels in pulp
Eats unripe tissue and bore into cotyledons
Fruit dropping at marble stage
oviposition injuries on marble sized fruits.
Tunnelled cotyledons in mature fruit by grubs.
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12. Nature of Damage
Larval development and pupation occur within the seed. Adults emerge from the fruits boring exit holes, damaging the flesh of ripe fruits.
Life-cycle is completed in 40 to 50 days during June-July. Adults hibernate until the next fruiting season. There is only one generation in a year.
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13. Mango Pulp Weevil Sternochetus frigidus (Coleoptera: Curculionidae)
The pest is known to exist in north-east India
 Mango pulp weevils look similar to the mango seed weevil already found in some parts of India.
But the pulp weevil attacks the flesh rather than the seed.
There are no signs of the weevil on the outside of the fruit.
The weevils burrow into the pulp of the fruit to feed.
The flesh rots and becomes inedible.
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14. Identification
The adult weevil is a dark brown weevil with paler patches. This small stout weevil has a small head and the body covered with papillate scales. It is between 6-9 mm in length
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15. Symptoms
No outward signs of attack are evident until the adult weevil bores out of the fruit.
To check for infestation, the fruit must be sliced open. Internal signs of infestation include brown tunnels in the flesh and the presence of larvae, pupae or adults.
Brown tunnels in
the flesh
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16. Nature of damage No outward signs of attack are evident End Previous
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17. Life Cycle
Eggs are laid on fruit from which larvae develop and tunnel through the flesh forming a chamber adjacent to the seed.
The larva is plump, pale coloured and legless, with a well defined head.
Pupa stays in a chamber hollowed out of the flesh and develops into an adult.
The adult weevil stays in the chamber until mature and emerges from the fruit by boring a hole through the skin.
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18. Summary
Mango fruit fly is world’s most serious pest of horticultural crops and in India. There are eight species of genus Bactrocera which are considered as quarantine pest of mango. The adults are flies with transparent wings while larvae are apodous. Larvae feed upon the pulp of fruit .The emergence of the fruit fly starts from April onwards and maximum population is reached in May-July.
Mango stone weevil is monophagous pest of mango which infests seed (stone) of the fruit. Adults are dark brown, stout and long . Grubs are legless, fleshy, yellow with dark head. Grubs tunnels through the pulp endocarp and seed coat and destroys it by feeding it. Finally it pupates inside the seed.
Mango pulp weevils look similar to the mango seed weevil already found in some parts of India. But the pulp weevil attacks the flesh rather than the seed. There are no signs of the weevil on the outside of the fruit. The weevils burrow into the pulp of the fruit to feed. The flesh rots and becomes inedible.
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