Giant Whitefly Home Page
Giant Whitefly, Aleurodicus dugesii Cockerell, is native to Mexico. It was first discovered in San Diego County, California in October 1992. From then until now this pest has found its way into much Southern California, parts of Arizona, Louisiana, Texas, and Florida
The first through last stages of a Giant Whitefly infestation
Introduction To Giant Whitefly.
Since the introduction of Giant Whitefly into Southern California in 1992, it has spread rapidly northward along the coast from San Diego through the Santa Barbara and Goleta communities. The types of plants it lives and feeds on has grown from a few tropical plants to include many of our most beautiful flowering shrubs, trees and even vegetables.
While one Whitefly may seem like any other Whitefly in Southern California gardens there are many different types; Citrus Whitefly, Greenhouse whitefly, Nesting Whitefly, Silverleaf Whitefly, Sweet potato whitefly, and Wooley Whitefly. Giant Whitefly is the largest of them all, Greenhouse whitefly is the smallest.
Biology Of Giant Whitefly
Giant Whitefly gets its name from it's large size (adults up to 3/16 in. {4mm}) relative to many other whitefly species in Southern California, and slowest to move around. The other Whiteflies you are used to seeing in your garden are about 1/4 of this size or smaller. This species can also be identified by spirals of wax which are deposited by adults as they walk on leaves. These deposits occur on both upper and lower leaf surfaces. Eggs are often laid amongst these waxy deposits. The nymphs produce long, hair like filaments of wax up to 2 in. (50 mm) long. This imparts a bearded appearance to affected leaves. These plants often look like they came from the stage set of a spooky movie, as if they had been draped heavily in spider webs.
The eggs are generally laid in a spiral pattern with a lot of wax on the undersides of the leaves of the host plant. The first instar larvae, the crawlers, appear to settle close to the spiral, and the second and third instar larvae develop there. The second and third instar larvae are green to yellow-green ovals that blend well with the leaves they are feeding on. The fourth instar larvae are covered with a white wax and numerous very long waxy filaments. Leaves supporting colonies of fourth instar larva appear to be growing long flowing white beards.
It takes Giant Whitefly months to establish itself in our gardens. People working in landscapes and gardens get the impression that the pest has quickly taken hold, but in fact may have taken 3 to 6 months to get to stage.
Damage To Plants From Giant Whitefly
Giant Whitefly, as with all other types of Whitefly damages plants in three ways. The first is direct damage that is caused by the loss of plant sap. Both nymphs and adult whiteflies feed by inserting their needle-like mouth parts into the vascular tissues or phloem of the leaves and suck out the plant sap. If the numbers of whiteflies per leaf are great enough, the plant will suffer from lack of water and nutrients, resulting in a weakened plant, loss of leaves, and possible plant death.
The second kind of damage caused by Whiteflies is indirect damage. During the feeding process, whiteflies excrete a sticky, sugary solution called honeydew. This sticky honeydew accumulates on the leaves and fosters the growth of a black sooty mold fungus. This sooty mold is not only unsightly but reduces the photosynthetic abilities of the leaves.
The third is by attracting ants. Ants feed on the honey dew and return provide protection of the Whiteflies from their natural enemies. In addition ants may move other pests onto the plants or protect pests that begin to build up their populations. I have seen many plants the were infested with Aphids, Scales and Whitefly. The ants do not mind having these many guests to care for since these pests all provide honeydew for them the ants to eat.
Good ant control is almost always necessity for getting complete and long lasting control of Whitefly and other pests.
Whiteflies, like many insects, have immature and adult stages. The immature are called nymphs. Whitefly nymphs have small, oval bodies with no wings and no apparent legs or antennae. The adults that emerge from mature nymphs are winged and look like a very tiny moth. Both immature and adult stages occur on the undersides of leaves where they spend their entire life cycle.
Chemical Controls For Giant Whitefly
Many landscapers, gardeners and pest control people have sought to fight Giant Whitefly with chemical controls. This for the most part can provide control for one week to a few months depending on the product. Popular products like crop oils (Ultra Fine), insecticidal soaps, Safer Soap & Impede or hard insecticides like Malathion, Merit and Orthen. Giant Whitefly is usually not complete controlled by these chemicals and in fact grows stronger against the hard pesticides by breeding resistance in the next generations. High pressure water will provide just as much control as the chemicals will for most plants.
Short Term Biological Control Solutions For Giant Whitefly
Some cousins of our common ladybug or “lady beetle”, Delphastus catalinae , and Cryptolaemus montazorri have proven effecting in slowing down or controlling Giant Whitefly in many settings. Since 1996 Applied Bio Pest has provided several hundred thousand of these beetles to gardeners, nurseries and plant managers in Southern California. But until recently nothing has proven itself effective at getting rid of it.
In a recent trip to the Walt Disney World facility in Orlando, Florida I observed another parasite called Entedononecremnus krauteri, "EK" In their tropical setting of Hibiscus and Plumeria this parasite with the short name of "EK" proved to be very effective. They went from cotton candy like plants to almost no more Giant Whitefly within a few months. Since being introduced into San Diego in 1997 "EK" has not been very effective in our area and only stings the Giant Whitefly nymphs through the backside of the leaf that they are feeding on. This limits their ability to control Giant Whitefly on many of the thick leafed plants in our area
Long Term Biological Control Solutions For Giant Whitefly
About 3 years ago researchers from from California went to on exploration trip to locate existing local controls for this pest. After extensive searches and careful examination they brought back some beneficial insects, very tiny wasps that attack the Giant Whitefly, not people. natural enemies. The exploration was initiated in Guadalajara because of its extensive ornamental plantings and good ecological match to southern California. The whitefly was rare and apparently under excellent natural control. Examinations of the collected plant parts showed that 80% of the Whitefly nymphs were "stung" or parasitized by two one of the two different species of natural enemies.
The tiny little Giant Whitefly killers have the names of the parastiods Idioporus affinis and Encarsiella noyesii, we will call them the Giant Whitefly Destroyers. The size of adults of these parasites are 1/16 in. (1.5 mm) long. These parasitoids lay eggs directly into whitefly nymphs. These natural enemies were brought to the quarantine facilities to make sure that they would not pose a danger to existing predators and parasites here in our State. Separate colonies were established for each parasitoid. The first field releases of these wasps were made in August 1997. The El Nino and La Nina weather patterns are said to hampered early control efforts. According to the most recent information available to us at this time the State of California has released about 40,000 of these parasites in selected areas of Southern California.
Applied Bio Pest's Biological Control Solutions
For Giant Whitefly
The State's Giant Whitefly control effort is a multi year program designed to monitor the movement of the parasites or Giant Whitefly Destroyers and see how they establish themselves. Having observed this program for the last year or so and seen that it is effective Applied Bio Pest is launching a different program. Our program is designed to provide property owners and plant health management specialists the option for starting immediate control of the pest Giant Whitefly before any further damage to the plant occurs. Our climate is not a moderate as that of Guadalajara, Mexico so it is taking a longtime to get the Giant Whitefly Destroyers established here in our State. We are currently raising Canna plants ( a flowering subtropical shrub) with Giant Whitefly on them and harvesting the parasites for sale.