Pests of Cucurbits
MAJOR PESTS
1. Fruit Flies
2. Pumpkin Beetles
3. Leaf Eating Caterpillar
4. Leaf Miner
5. Snake Gourd Semi Looper
MINOR PESTS
1. Stem Gall Fly
2. Stem Borer /Clear Winged Moth
3. Stem Boring Grey Beetle
4. Plume Moth
5. Stink Bug
6. Spotted Beetle
7. Flower Feeder
1. Fruit flies: Bactrocera cucurbitae (Coquillet) (Tephritidae: Diptera)
Distribution and status
Commonest and most destructive pest throughout India. Also found in Pakistan, Myanmar, Malaysia, China, Formosa, Japan, East Africa, Australia and the Hawaiian Islands Two other allied species common in India are Dacus ciliatis and Bactrocera dorsalis.
Host range: Melons, tomato, chillies, guava, citrus, pear, fig, cauliflower, etc.
Damage symptoms
Only the maggots cause damage by feeding on near-ripe fruits, riddling them and polluting the pulp. Damage by the maggots of this pest causes oozing of brown, resinous fluid from fruits and the fruits become distorted and malformed. The maggots feed on the pulp of fruits and cause premature dropping. The attacked fruits decay because of secondary bacterial infection. After the first shower of the monsoon, the infestation often reaches 100 per cent.
Bionomics
Maggots legless and appear as headless, dirty-white wriggling creatures, thicker at one end and tapering to a point at the other. The adult flies are reddish brown with lemon-yellow markings on the thorax. Adult flies emerge from pupae in the morning hours and mate at dusk. The female, on an average, lays 58-95 eggs in 14-54 days. Egg period 1-9 days, larval period 3 - 21 days. It pupates deep in the soil. The pupae are barrel-shaped, light brown, pupal period 6-30 days. There are several generations in a year.
Distribution and status
Commonest and most destructive pest throughout India. Also found in Pakistan, Myanmar, Malaysia, China, Formosa, Japan, East Africa, Australia and the Hawaiian Islands Two other allied species common in India are Dacus ciliatis and Bactrocera dorsalis.
Host range: Melons, tomato, chillies, guava, citrus, pear, fig, cauliflower, etc.
Damage symptoms
Only the maggots cause damage by feeding on near-ripe fruits, riddling them and polluting the pulp. Damage by the maggots of this pest causes oozing of brown, resinous fluid from fruits and the fruits become distorted and malformed. The maggots feed on the pulp of fruits and cause premature dropping. The attacked fruits decay because of secondary bacterial infection. After the first shower of the monsoon, the infestation often reaches 100 per cent.
Bionomics
Maggots legless and appear as headless, dirty-white wriggling creatures, thicker at one end and tapering to a point at the other. The adult flies are reddish brown with lemon-yellow markings on the thorax. Adult flies emerge from pupae in the morning hours and mate at dusk. The female, on an average, lays 58-95 eggs in 14-54 days. Egg period 1-9 days, larval period 3 - 21 days. It pupates deep in the soil. The pupae are barrel-shaped, light brown, pupal period 6-30 days. There are several generations in a year.
B. cucurbitae |
B. ciliatus
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B. zonata
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Hyaline wings with costal band broad and prominent, anal stripes well developed and hind cross veins thickly margined with brown and grey spots at the apex
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Smaller than B. cucurbitae,ferruginous brownbody, prominent dark brown oval spot on either side of 3rd tergite.
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Body yellowish with pale yellow band on 3rdtergite and wing expanding10-12mm costal band incomplete and anal band wanting.
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Management
- Collect infested fruits and dried leaves and dump in deep pits.
- In endemic areas, change the sowing dates as the fly population is low in hot dry conditions and at its peak during rainy season.
- Frequent rake the soil under the vine or plough the infested field after the crop to kill pupae.
- Use ribbed gourd as trap crop and apply carbaryl 1.0 kg or malathion 1.0 L/ha in 500 L water on congregating adult flies on the undersurface of leaves.
- Use attractants like citronella oil, eucalyptus oil, vinegar (acetic acid), dextrose and lactic acid to trap flies.
- Apply the bait spray containing 50 ml of malathion 50 EC + 0.5 kg of gur/sugar in 50 L of water per ha. Repeated at weekly intervals. Keep the bait in earthen lids placed at various corners of the field.
- Spray the bait on the maize plants grown as trap crop
- Use fly trap: Keep 5 g of wet fishmeal in plastic container with six holes (3 mm dia), two cm from the bottom of the bag. Add a drop (0.1 ml) of dichlorvos in cotton plug and keep it inside the bag. Dichlorvos should be added every week and fishmeal renewed once in 20 days (20 traps/acre).
- Use fly traps having methyl eugenol soaked plywood piecies (2” x 2”). Collect and destroy the flies.
- Conserve pupal parasitoids viz.,Opius fletcheri, O. compensatus and O. insisus (Braconidae), Spalangia philippinensis and Pachycepoideus debrius. (Pteromalidae), Dirhinus giffardi and D. lzonensis . (Chalcididae).
Caution:
In cucurbits, DDT, lindane 1.3 D, copper oxychloride, Bordeaux mixture and sulphur dust should not be used as these are highly phytotoxic.
In cucurbits, DDT, lindane 1.3 D, copper oxychloride, Bordeaux mixture and sulphur dust should not be used as these are highly phytotoxic.
2. Pumpkin beetles: Aulacophora foveicollis, A. cincta, A.intermedia (Galerucidae: Coleoptera)
Distribution and status: Widely distributed in Asia, Australia, southern Europe and Africa
Serious pest
Host range: Ash gourd ,pumpkin, tinda, ghia tori, cucumber and melon.
Damage symptoms
Both grubs and beetles damage. Grubs remain below the soil surface feeding on roots, underground stems of creepers and on fruits lying in contact with the soil The adults feed on those parts of the plant which are above the ground. The early sown cucurbits are so severely damaged that they have to be resown.
Bionomics
Freshly hatched grubs are dirty white; full grown are creamy yellow, 22 mm long. Adult: A. foveicollis: red, 6.8 mm long. A. cincta: grey with black having glistening yellow-red border and A. intermedia: blue in color.
The creamy, oblong, white grubs with a slightly darker oval shield at the back lead a subterranean life and when full-grown, they measure about 12 mm in length. Adults are oblong , 5-8 mm long, beetles are found concealed in groups. In their life span of 60-85 days, they lay about 300 oval, yellow eggs singly or in batches of 8-9 in moist soil, near the base of the plants. The eggs hatch in 6-15 days. Grub period 13- 25 days and pupate in thick-walled earthen chambers in the soil, at a depth of about 20-25 cm. The pupal stage lasts 7-17 days The life-cycle is completed in 26-37 days and the pest breeds five times in a year.
Management
- Early planting of pumpkin during October – November to avoid damage by this pest
- Frequent raking of soil beneath the crop to expose and kill the eggs and grubs.
- Hand collection and destruction of infested leaves and fruits.
- Spray malathion 50 EC 750 ml, dimethoate 30 EC 500 ml, methyl demeton 25 EC 500 ml, 500 g of carbaryl 50WP in 500-750 L of water per ha or apply 7.0 kg of carbofuran. 3G per ha 3-4 cm deep in the soil near the base of the plants just after germination and irrigate.
3. Leaf eating caterpillar : Plusia peponis, P. signata and P. orichalcea (Noctuidae: Lepidoptera)
Distribution and status: Regular and serious pest all over the country.
Damage symptoms
The caterpillar cuts the edges of leaf lamina, folds it over the leaf and feeds from within leaf roll.
Bionomics
Stout adult moth lays spherical sculptured greenish white eggs singly on the tender leaves. Larva is a greenish semi looper with black warts. It is humped on a anal segment. They are active in winter. They pupate in the debris on the ground. Moths are very active at dusk.
Management
Collect and destroy caterpillars.
Encourage activity of Apanteles plusia and A. taragamae
Spray malathion 50 EC 750 ml, dimethoate 30 EC 500 ml, methyl demeton 25 EC 500 ml in 500-750 L of water per ha
