Insect Pests of Vegetable, Ornamental and Spice Crops (2+1)

Exercise: Cucurbits
1. Fruit flies: Bactrocera cucurbitae

• Damage: The larvae feed inside the fruits, contaminating them with frass and providing entry points for fungi and bacteria to cause fruits to rot. Owing to feeding on pulp, the fruits become unfit for consumption and drop prematurely. The young fruits can be destroyed in a few days, but oldest fruits show less obvious symptoms, but on splitting open, a mass of maggots in pulp is found. In melons the infestation sometimes reaches up to 100 per cent while in other cucurbits, the infestation may be up to 50 per cent.
• Larvae: The maggots are leg less and look as head less, dirty white wriggling creatures, thicker at posterior end and tapering to a point at the anterior. Full grown maggot measures 9-10 mm in length and 2 mm in breadth broad in the middle of the body.
• Adults: Flies are reddish brown with lemon yellow marking on the thorax and have fuscous areas on the outer margins of their wings.

2. Hadda beetles: Discussed under tomato

3. Red pumpkin beetle, Aulacophora foveicollis (Chrysomelidae: Coleoptera)

• Damage: Both grubs and beetles are damaging, grubs feed on under ground plant parts, where as beetles causes severe damage to cotyledons, flowers and tender leaves of many cucurbits. Grubs enter in to the roots under ground stems and sometimes the fruits touching the ground. The under ground parts start rotting due to attack by saprophytic fungi and the fruits become unfit for human consumption. Adults are very destructive particularly during the initial stage of crop growth.
• Identification: Adults of A. foevicollis are orange coloured, 6-8 mm long with black ventral surface clothed with hairs. A. cincta is almost similar except that the colour of elytra is greenish yellow to brownish grey with distinct pale margins. Adults of A. lewisii are dirty white, 10-12 mm long and pupae are pale white.

4. Blister beetles (Mylabris pustulata, M. phalerata, M. mecilenta, M. tiflensis) (Meloidae: Coleoptera)

• Damage: Damage is caused by the adults only. They feed on pollens and petals of the flowers and flower buds as a result, fruit setting is adversely affected.
• Larvae: Full grown grubs are coarctate and form pseudopupae, which become pupae later. Pseudopupae are devoid of functional appendages and hibernation takes place in this stage in the soil.
• Adults: The beetles have three black and three yellowish orange bands running across and alternatively on elytra. Among different species, the beetles of M. pustulata are the biggest in size (22-26 mm in length), the beetles of M. phalerata are slightly smaller in size (20-24 mm in length) than M. pustulata and has its yellowish red bands narrower than black bands. The beetles of a M. Mecilenta and M. tiflensis are relatively smaller than the earlier two species.
• When handled or disturbed these beetles exude an acrid yellow fluid which contains cantharidine which is irritant to touch and cause blisters on human skin hence the common name.

5. Stink bugs (Aspongopus janus, A. brunneus and A. observus)

• Damage: Both nymphs and adults suck the cell sap and there by devitalizing the plant and retarding their growth.

• The adults are flat, medium sized bugs. A. janus is about 30 mm long, pronotum and base of elytra are bright red while head and wings membranes are black. A. brunneus is pale brown in colour and slightly smaller in size. The bugs emit characteristic buggy smell hence the common name stink bug.

6. Serpentine leaf miner: Discussed under tomato

7. Phytophagous mites: Discussed under tomato

8. Green house whitefly: Discussed under tomato

9. Hadda beetles: