Cotton Whitefly

A minor pest in many parts, cosmopolitan occurring as far north as Europe and Japan. Occasional pest which is widely distributed in our country (Bihar, Delhi, Haryana, Punjab, Rajasthan and Maharashtra). It is a polyphagous pest which feed on several crops like tobacco, cassava, cabbage, cauliflower, melon, mustard, brinjal, cotton and is important as a vector of leaf curl virus.

Appearance:

Adult is a white tiny soft bodied insects with milky white wings and yellow body highly dusted with waxy powder.  Nymphs are oval, scale like and remain attached to the leaf surface.

          Adults                                                       Nymphs

Life cycle:

Eggs are laid on the under surface of tender leaves in group and hatch in 3-5 days. The hatched young ones are called crawlers which are flat move for a day or two and fix a place for feeding where it spends all its nymphal period. The further molting leads to reduced legs and stick on to a single place for 9-14 days (summer); it is extended in winter up to 70-73 days. Normally pupal period last for 2-8 days with a total life cycle of 14-20 days depending on the weather & even life span extended up to 107 days in winter.
                                 

           Eggs on Under surface of tender leaves                                 Pupa 

Nature of damage:

• Nymphs and adults suck the sap from foliage.
• They secrete honeydew on which sooty mould develops and interfere in the photosynthesis.

Damage symptoms:

• Chlorotic spots on leaves.
• Yellowing of leaf leading to dropping of matured leaves.
• Vegetative growth is retarded, boll formation hampered.
• Shedding of squares and bolls.
• Bad boll opening in matured bolls and reduces the quality of cotton.
• Severe infestation after boll bursting makes the lint sticky due to deposition of honey dew.
• It also transmits the leaf curl virus.

Factors responsible for the incidence:

Generally infests the crop from November to February. Temperature around 30 ºC and high humid situations helps multiplication of the pest. Dry season favour the incidence, but they disappear rapidly with the onset of rain.