Bureau of Methods Development &
Biological Control

DISTRIBUTION: The giant whitefly, Aleurodicus dugesii, is a tropical species native to Mexico. It occurs in Costa Rica, Guatemala, and Mexico. In the United States it is found in Arizona, California, Florida, Louisiana and Texas. In Florida it was first discovered in Red Hill, Volusia County, in December 1996. The population has increased dramatically and spread to at least 14 other counties including Brevard, Broward, Flagler, Highlands, Hillsborough, Indian River, Lake, Manatee, Martin, Osceola, Orange, Polk, Seminole, and St. Lucie Counties (Fig. 1).

BIOLOGY: Giant whitefly has six life stages: egg, four immature stages, and adult. Female giant whiteflies lay eggs in a spiral pattern (Fig. 2) on the underside of host leaves, and at the same time deposit white wax with each egg. The egg stage lasts about three days then hatches into a small crawler. The fourth nymphal stage is often called a pupa. The third and fourth nymphal stages (Fig. 3a & 3b) secrete long glassy filaments of wax.

Wax filaments are only 1-2 inches long in the field due to wind breakage, but up to 10-18 inches long in the rearing laboratory (Fig. 4). The wax filaments become matted and cover the entire underside of the host leaf (Fig. 5).

Adult giant whiteflies emerge through the T-shaped sutures [see Fig 3b.] on the dorsum of the pupal case (fourth stage). Males and females are similar. They congregate in large numbers on the underside of the natal leaf where they feed and oviposit until these leaves fall onto the ground.

A complete life cycle from egg to adult lasts about 25-30 days in Florida's warm and humid summers.

HOST PLANTS AND DAMAGE: Immature and adult stages of giant whitefly remove large amounts of sap from the plant. The third and fourth nymphal stages secrete wax filaments that are contaminated by excreted honeydew during the feeding process. This leads to the development of sooty mold fungus. During heavy infestation the plant becomes weak, its leaves turn yellow, dry-up and fall, and the plant may die (Fig. 6).

At least 70 plant species are infested by giant whitefly. Among these, hibiscus is the most preferred host.

BIOLOGICAL CONTROL: In 1997, a parasitic wasp, Entedononecremnus krauteri Zolnerowich and Rose (Fig. 7 & 8), was obtained from California with the assistance of M. Rose, C. Pickett and D. Kellum. During May to June 1997, about 500 E. krauteri were released in Seminole, Indian River, St. Lucie and Volusia Counties. During a survey in late June, 1997, E. krauteri pupae were detected at most of the release sites.

Another parasitic wasp, Encarsiella noyesi Hayat (Fig. 9 & 10), was received in Florida from Tom Bellows (California) in June 1998. About 100 E. noyesi were released in Volusia and Indian River Counties on June 12, 1998.

On July 30, 1998, at the Volusia County location where E. noyesi was released, E. krauteri, E. noyesi, and Encarsia sp. (a native parasite in Florida) were detected. The parasite complex population consisted of E. krauteri at 66%, E. noyesi at 30% and Encarsia sp. at 4%.

During June 2001, a survey was conducted at two newly detected infections of giant whitefly in Winter Haven (Polk County). At one location, of 233 parasites collected, E. noyesi was dominant (86%) and the remaining 14% were E. krauteri, but at another location about 10 miles away, E. krauteri (88.7%) was dominant of the 177 parasites collected. E. noyesi made up the remaining. A light infestation of giant whitefly parasitized only by E. krauteri was detected in Broward county in November 2001. Thus E. krauteri and E. noyesi have been established and are providing adequate biological control of giant whitefly in Florida.

ACKNOWLEDGEMENT: The authors express their gratitude to K. Hibbard, A.N. Capitano and all FDACS and DPI personnel for assisting in this study.

REFERENCES: Hayat, M. 1983. The genera of Aphelinidae (Hymenoptera) of the world. Systematic Entomology. 8:63-102.
Headrick, D., T. Bellows, and C. Meisenbacher. 1997. The giant whitefly: Pest status, biology and control options. Fact Sheet for "County Entomologists, Cooperative Extension Personnel, and Farm Advisors, Univ. California, Riverside", pp. 1-4.
Zolnerowich, G., and M. Rose. 1996. A new species of Entedononecremnus (Hymepnotera: Chalcidoidae: Eulophidae) parasitic on the giant whitefly, Aleurodicus dugesii Cockerell (Homoptera: Aleyrodidae). Proc. Entomol. Soc. Wash. 98(2):369-373.

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Fig. 1. Distribution of Aleurodicus dugesii in Florida.

Fig 2. Egg spirals of giant whitefly.

Fig 3a. 3th instar of giant whitefly.

Fig 3b. Empty 4th instar skin and glassy wax filaments.

Fig 4. Long wax filaments of giant whitefly in the laboratory.

Fig 5. Matted wax filaments of giant whitefly in the field.

Fig 6. Heavily infested hibiscus plants.

Fig 7. Entedononecremnus krauteri Zolnerowich and Rose adult.

Fig 8. Fourth instar parasitized by
Entedononecremnus krauteri.

Fig 9. Encarsiella noyesi adult.

Fig 10. Exit hole of Encarsiella noyesi.