Host plants: Dialeurodes citri is polyphagous; among citrus species and varieties it prefers orange and easy peeler cultivars. Morphology: The. Dialeurodes citri (Riley et Howard) (Coutin R. / OPIE) Damage on lemon Leaves are curved and the underside is coated with honeydew and sooty moulds. Dialeurodes citri first appeared in California in , but never became a serious pest (Kennett et al. ). Citrus whitefly was found in France around
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The citrus whitefly, Dialeurodes citri Ashmeadwas once the most important citrus pest in Florida, but today it ranks below the snow scale, citrus rust mite, and several others. Nevertheless, it is still a serious pest in Florida. A native of India, it appears to have been introduced into Florida sometime between and Morrill and Back It is now found throughout Florida and parts of other Gulf States and California and in greenhouses in many parts of the United States.
Central America citrl Caribbean: Some reported records of D. The adults of both sexes have two pairs of wings covered with a white, powdery wax which gives the insects their common name. In the middle of each wing, cloudywinged whitefly adults have a darkened area that is lacking in the wings of the citrus whitefly, and the wings fold to a flatter position than those of the citrus whitefly.
Adults of the citrus whitefly, Dialeurodes citri Ashmead. The nymph is a flat, elliptical, scale-like object, closely fastened to the underside of a leaf. It becomes fixed after daleurodes first molt. The nymphs, after the first instar, are flattened, oval, and are citrri in appearance citro the early instars of dialeruodes unarmored scale insects.
Like the scale insects, whiteflies lose their normal legs and antennae after the first molt they are kept, but are abbreviatedbut unlike the scale insects, the females gain them back in the adult stage.
The nymphs of the citrus whitefly lack a fringe of conspicuous, white, waxy plates or rods extending out from the margin of the body, which characterizes some species of whiteflies.
Nymphs and pupae dialeuroees the citrus and cloudywinged whiteflies are almost indistinguishable.
Nymphs of both species are translucent, oval in outline, and very thin. Because the green color of the leaf shows through the body, nymphs are difficult to see. Pupae are similar but are thickened and are somewhat opaque, and eye spots of the developing adult dialeuroes show through the pupal skin. Eggs and nymphs of the citrus whitefly, Dialeurodes citri Ashmead.
Pupa of the citrus whitefly, Dialeurodes citri Ashmead. The citrus whitefly lays yellow eggs diapeurodes a nearly smooth surface, distinguishing them from eggs of the cloudywinged whitefly, which are yellow when freshly cigri, but soon turn black and have a surface that is netted with a system of ridges.
The identification key provided here is designed to identify the four major species of whiteflies that commonly infest citrus in Florida. Another key that covers 16 species of whiteflies that may infest Florida citrus was developed by the Florida Department of Agriculture and Consumer Services’ Division of Plant Industry, and uses color photographs of nymphs to assist in identification.
It is available at http: The whitefly adult is white or white with dark spots on the wings. Nymphs are difficult to see or identify. The whitefly adult is slate blue in color, eggs are present and dialeuodes in spirals. Nymphs are black with prominent spines. The whitefly adult is all white without any dark spots on wings. The whitefly adult is white with a darkened area at the end of each wing. Occasionally a yellow fungus is present.
The whitefly female adult is all white and is surrounded by waxy filaments. Eggs are laid in a circle with the female at rest in dialeudodes center. The winter is passed in the mature larval or nymphal stage, usually on the undersides of leaves. dia,eurodes
EPPO Global Database
Early in the spring pupae appear, and in March and April adults emerge. Eggs are deposited on foliage and hatch in eight to 24 days, depending on the season. Unfertilized eggs develop into males only. The nymphs soon settle to feed and do not move about until the adult stage is reached.
There are several overlapping broods each year. Nymphal life span averages 23 to 30 days. Pupal development requires 13 to 30 days. The adult lives an average of about 10 days, but has been known to live for as long as 27 days. The adult female lays about eggs under outdoor conditions. The entire life cycle from egg to adult requires from 41 to days, but a great variation has been noted even among eggs laid on the same leaf on the same day. Citrus is the most important host, but the following are also food plants — allamanda, banana shrub, Boston ivy, cape jasmine, chinaberry, crape myrtle, coffee, English ivy, Ficus macrophyllagardenia, green ash, jasmine, laurel cherry, lilac, mock olive, myrtle, pear, privet, osage orange, persimmon, pomegranate, Portugal cherry, prickly ash, smilax, tree of heaven, trumpet vine, umbrella tree, water oak, and devilwood or wild olive.
The whitefly injures the plant by consuming large quantities of sap, which it obtains with its sucking mouth parts.
Further injury is caused by sooty mold fungus which grows over fruit and foliage in the copious amount of honeydew excreted by the whitefly. This black fungus may cover the leaves and fruit so completely that it interferes with the proper physiological activities of the trees.
Heavily-infested trees become weak and produce small crops of insipid fruit. Also, fruit covered with sooty mold will be retarded in ripening and late in coloring, especially the upper part, which may remain green after the lower portion has assumed the color of ripe fruit. The fruit often must be washed before it is put on the market.
A secondary injury to the trees may result from an excessive increase of the common scales of citrus which find protection under the sooty mold that covers leaves and branches.
Citrus leaves with sooty mold growing on honeydew excreted by the citrus whitefly, Dialeurodes citri Ashmead. Whiteflies become a problem when they continually sap the plant of energy dialeurodez for growth. This occurs when there is constant flushing and availability of new growth, such as after severe hedging and topping.
EENY/IN Citrus Whitefly, Dialeurodes citri (Ashmead) (Insecta: Hemiptera: Aleyrodidae)
Several parasites and predators attack the citrus whitefly. An introduced parasitoid wasp Encarsia lahorensis Howard is established in Florida’s citrus regions and is reducing citrus whitefly populations. Delphastus catalinae Horna California species, was introduced into Florida by University of Florida entomologists, and it also feeds on whitefly eggs.
Morrill and Back recorded two other ladybird beetles, Cycloneda sanguinea L. Citrus whitefly parasite, Encarsia lahorensis Howard, ovipositing in an immature citrus whitefly. Adult coccinellid predator of whitefly nymphs, Delphastus catalinae. Lacewing larva Chrysoperla sp. In large commercial plantings of citrus, citrus whitefly and cloudywinged whitefly are largely controlled in rainy weather by whitefly fungi.
Some important species are the red fungus Aschersonia aleyrodis Webber and the brown fungus Aegerita webberi Fawcett.
A yellow fungus, Aschersonia goldianadoes not attack the citrus whitefly, but is very effective against the cloudywinged whitefly. The presence of the yellow fungus guarantees that cloudywinged whitefly is present.
These fungi are generally present dilaeurodes all citrus groves in Florida and increase in numbers when the proper environmental conditions prevail. These fungi are commonly referred to as “friendly fungi,” and the two major species are often referred to as red Aschersonia and yellow Aschersonia.
Red, Aschersonia aleyrodisand yellow, A. Whiteflies also are controlled by sprays applied primarily for control of scale insects. Spraying of commercial citrus exclusively for whitefly control is seldom practiced in Florida. Recommended control measures for commercial or dooryard citrus are significantly different. Please consult the specific management guide for your situation.
It is important to note that spraying with copper for control of harmful fungal diseases will also inhibit growth of “friendly fungi”, resulting in an increase in whitefly populations. Dialeuroees, more than one application of sulfur per year can have an adverse effect on parasites.
Spray oil has some insecticidal properties, but is primarily used to remove sooty mold that grows on the fruit and leaves.
Distribution maps of insect pests. Series A, Map No. Commonwealth Institute of Entomology, London, England. White-fly studies in Florida Agricultural Experiment Station Bulletin White fly, Aleyrodes citri and citr allies. Insect Pests of Farm, Garden, and Orchard. John Wiley and Sons, Inc. Whitefly taxonomic and ecological Website: An on-line interactive catalog of the whiteflies Hemiptera: Aleyrodidae of the world and their parasites and predators. Whitefly pests of citrus. No longer available online.
Fasulo TR, et al. A hypertext knowledgebase on the silverleaf, sweetpotato, greenhouse and bandedwinged whiteflies. United States Department of Agriculture.
Approaches to the biological control of whiteflies. Whitefly of citrus in Florida. Resistance in aphids and whiteflies: Distribution Maps of Plant Pests. Contributions toward a monograph of the Aleurodidae, a family of Hemiptera-Homoptera. Transactions and Proceedings of the New Zealand Institute 28 n. The orange and other citrus fruits, from seed to market, with insects beneficial and injurious, with remedies for the latter.