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Whitefly

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Various development stages of the cotton whitefly Bemisia tabaci.
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Cotton whitefly nymphs Bemisia tabaci.
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Bemisia tabaci eggs and young larvae.
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Adult cotton whiteflies Bemisia tabaci.

Scientific Name

Bemisia tabaci (GENNADIUS)

Products

  • Admire® 200 OD

Biology

Description

The adults are about 1 mm (0.039 inch) long; their body is sulphur-yellow in color, the wings are white, and the animal is entirely coated with a white, wax-like powder

Damage

Infestation is easily recognized by examining the undersides of leaves, where all stages of the insect can usually be found. The adults rise when the plant is shaken, and flutter around for a moment. In extreme cases, huge numbers of adults can rise thus in a cloud when disturbed, e.g. by a person walking through the field.  At first, the damage consists of chlorotic spots. The leaves will start to show a yellow mosaic, with the green areas becoming ever smaller. Twisting of stems and curling of leaves may occur, and the plants may become stunted. Heavily-infested leaves often wilt and fall off.
In addition to direct feeding, all stages damage the plants through abundant production of honeydew, which encourages the growth of sooty molds, and, most importantly, by the transmission of viruses. The nymphs excrete large quantities of honeydew, which is rich in carbohydrates and supports the growth of sooty mold, causing parts of the plant to turn black

Lifecycle

The first instar nymph (called the “crawler”) is about 0.3 mm (0.012 inch) in length. It moves about in search of a place to insert its mouthparts into the phloem. Having found one, it molts to the second instar, which is sessile - as are the following 3 instars, each larger than the previous one. All stages feed on intracellular liquids. There is no pupa, as the Hemiptera have incomplete metamorphosis.
Each female can produce up to 200 eggs in her lifetime. The larvae hatch 1-2 weeks after oviposition. The duration of the larval stage varies widely, depending upon the temperature, so the time needed for one generation cycle can be from two weeks to 100 days.

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