Wednesday, January 13, 2010

Whiteflies on Houseplants

The silverleaf whitefly is the most economically important whitefly species in Texas, with a host range of more than 500 plant species, including poinsettias. Adults are 1/16 inches in length with white wings and pale yellow bodies. They will flutter around when disturbed and tend to be more active during the late morning and afternoon, compared to early morning and evening.
The female whitefly will lay oblong, smooth, yellow to amber-brown colored eggs randomly on the underside of leaves. The eggs hatch into flat, greenish-yellow, oval nymphs that begin to suck the sap of plants. Both the nymphs and adults remove phloem from leaves, which causes the leaves to turn pale and die or drop off. Since whiteflies remove phloem, they also excrete honeydew. This honeydew is a perfect media for sooty mold to grow. In addition, plant disorders and virus transmission can result from whitefly feeding.

Some Suggestions for Control Options:

Some Non-Chemical Control Options:

1) Inspect new plants before purchase and treat any infested material.
2) Remove and destroy heavily infested plants from the landscape or interiorscape.
3) Introduce and preserve natural enemies, such as ladybeetles, green lacewings, minute pirate bugs, big eyed bugs and damsel bugs that are predators of whiteflies and minute wasps, such as Encarsia formosa and Eretmocerus eremicus are parasitoids of whiteflies.
4) Beauveria bassiana, a fungus sold commercially can be used to control whiteflies.

Some Chemical Control Options:

Insecticide misuse can result in whitefly populations that cannot be controlled, since chemical overspray can lead to whitefly resistance. Several classes of insecticides are labeled for use against whiteflies and these classes should be rotated in order to avoid resistance. Systemic insecticides can be used such as those containing imidacloprid, dinotefuran or thiamethoxam. Also insecticidal soaps and horticultural oil can be used.

Picture of whitefly. Photo by Dr. Scott Ludwig, Program Specialist-IPM, Texas AgriLife Extension, Texas A&M University System.

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