Saturday, March 3, 2012

Invasive Species: Cotton Whitefly

The cotton whitefly (Bemisia tabaci) is also known as the sweet potato whitefly
These little insects are rather cute, but that doesn't change the fact that they are invasive. Found on every continent besides Antarctica, the native range of this species can't actually be confirmed, but is believed to be in India.  Global transport of goods has been the main cause of the now wide-spread distribution. The source of original importation to the United Kingdom is believed to be the ornamental poinsettia, which is known to be a host of these animals. However, the insects have also been found on numerous other plants. It's likely that many different goods were involved in causing the current distribution.Adults are also able to fly from crop to crop in local areas.

These creatures are parasites that feed on the fluids found inside of plants. They will feed from a wide variety of plants, of which at least six hundred are known. Though the act of the insects feeding on the plant is damaging, it is not the only point of concern. This species is known to carry over one hundred different plant viruses. Thanks to this fact, an infestation of these small insects can lead to the loss of an entire crop! In addition, the watery droppings of the larval whiteflies, known as honeydew, causes the growth of mold, further damaging the plant.

These small flies disperse and reproduce quickly, making an infestation difficult to control. Of major concern is the potential danger to staple crops of poor farming communities, such as cassava in Africa and elsewhere. If cassava crops become infected with viruses that the whiteflies carry, it will be devastating to a poor area. Management is possible, but success requires many steps. This includes removing infected plants, spraying pesticides, use of nets and traps, and biological controls.

This species is currently listed as one of the 100 World's Worst Invasives at #14.

Image is from Wikimedia Commons and is copyright free.


  1. The 100 worst invasive species, huh? Can't be a terribly accurate list: homo sapiens isn't even on it, let alone in the #1 spot...

    1. That is true, but it appears to be only non-human species. It's difficult to determine how problematic humans are since a reference point would be problematic. Humans have been causing issues far longer than we have been studying these sorts of things.

  2. How does this species affect the food web in the areas it has invaded?