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

Cotton whitefly, Green house white fly and Red cotton bug

3. Cotton whitefly

• Common name: Cotton whitefly
• Scientific name: Bemisia tabaci
• Family: Aleyrodidae
• Order: Hemiptera
• Distribution: Throughout the northern and western regions of the Indian sub continent.
• Host range: Cotton, okra, cabbage, cauliflower, sarson, toria, melon, potato, egg plant, tobacco and some weeds

Damage:

• Nymphs and adults suck the cell sap
• Lower the vitality of the plant
• They also excrete honey dew on which sooty mould grows which interferes with the photosynthesis of the plants
• Affected plants give a sickly black appearance.
• B. tabaci also transmits a number of viruses including vein clearing disease of okra

Identification

• The eggs are stalked, sub-elliptical and light yellow at first and turns brown later on
• Nymphs on emergence look elliptical
• They are sluggish creatures, clustered together on the underside of the leaves
• Their pale bodies make them stand out against the green background

Life cycle

• Incubation period is 3-5 days in April-September
• Nymphs grow through three stages
• Become pupae in 9-14 days during April to September
• Pupal period is 2-8 days
• Total life cycle is completed in 14-122 days.

Salient features

• The insect breeds throughout the year
• Lay eggs singly on the under side of the leaves
• Life cycle is prolonged during winter
• Nymphs grow through three stages

Management:

• Clean cultivation
• Seed treatment with imidacloprid @ 2.5 g/ Kg
• Protect nursery by using nylon nets (200 mesh)
• Insecticides like phosphamidon @ 0.04% or dimethoate @ 0.003% or oxy-demeton methyl @ 0.025% or imidacloprid @ 0.025%
• Parasitoids like Eretmocerus sp and Encarsia sp. and predator ,Chysoperla zastrowi sillemi

4. Green house white fly

Discussed earlier

5. Red cotton bug

• Common name: Red cotton bug
• Scientific name: Dysdercus koenigii
• Family: Pyrrhocoridae
• Order: Hemiptera
• Distribution: All over the Indian subcontinent.
• Host range: Cotton, okra, holly hock, maize, sorghum, millets , musk melon, hemp, rose and other malvaceous plants .

Damage:

• Both nymphs and adults suck the sap from fruits and leaves
• Devitalize the plants
• Feeding deprives the plants of carbohydrates, free amino acids and proteins

Identification

• The eggs are spherical, bright yellow
• Young nymphs have flabby abdomens
• Older ones are more slender and develop black markings on the body
• Adults are red coloured bugs.

Life cycle

• lay on an average 100-300 eggs
• Eggs hatch in 7-8 days
• Nymphs complete their development in 49-89 days
• Five stages
• Adults’ longevity is variable and may live up to 3 months during winter.

Salient features

• The insect is active throughout the year
• Passes winter in the adult stage
• During spring bugs become active
• Lay eggs in moist soil or in cracks and crevices in the ground in clusters

Management:

• Same as discussed under cotton jassids