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common name: ash whitefly
scientific name: Siphoninus phillyreae (Haliday) (Insecta: Hemiptera: Aleyrodidae: Aleyrodinae)

Introduction - Synonymy - Distribution - Description and Biology - Host Plants - Natural Enemies - Selected References

Introduction (Back to Top)

The ash whitefly, Siphoninus phillyreae (Haliday), is a pest of numerous ornamental and fruit crops, including citrus. It causes severe damage to pear and apple in Europe. Most ash whiteflies in California were found on pomegranate, ash tree, pear, apple, loquat and citrus. Heavy infestations cause leaf wilt, early leaf drop and smaller fruit (Bellows et al. 1990).

Discovered in Florida in 2010, if it becomes established it could become a pest of ornamental plants and possibly other crops.

Several life stages of the ash whitefly, Siphoninus phillyreae (Haliday), on fallen Bradford pear leaves.

Figure 1. Several life stages of the ash whitefly, Siphoninus phillyreae (Haliday), on fallen Bradford pear leaves. Photograph by Lyle J. Buss, University of Florida.

Synonymy (Back to Top)

The ash whitefly, Siphoninus phillyreae, was described as Aleyrodes phillyreae by Haliday (1835), on Phillyrea latifolia collected in Dublin, Ireland. It has several synonyms listed in Mound and Halsey (1978).

Distribution (Back to Top)

Native to Europe, the Mediterranean and northern Africa, the ash whitefly is found in numerous countries, including:

Africa: Cameroon, Egypt, Ethiopia, Libya, Morocco, Sudan

Asia: India, Iran, Israel, Pakistan, Saudi Arabia, Syria

Europe: Austria, Corsica, Czech Republic, Cyprus, England, France, Germany, Hungary, Ireland, Italy, Poland, Romania, Spain, Switzerland, Yugoslavia

North America: United States (California, Florida)

Oceania: Australia (New South Wales, South Australia, Queensland and Victoria)

(Mound and Halsey 1978, Bellows et al. 1990, Raymond Gill personal communication, Chris Baptista personal communication, Stocks and Hodges 2010).

In the United States, ash whitefly was first collected in Los Angeles County, California in 1988, and then spread to other counties. It was later discovered in Arizona, Nevada and New Mexico. It appeared in Raleigh, North Carolina in 1993. It is also reported from Arizona, Georgia, Nevada, New Mexico, South Carolina and Texas. A successful biological control program using a parasitic wasp reduced infestations to undetectable levels (western states) or possibly eliminated the infestion (North Carolina). In 2010, it was discovered in central (Lake Buena Vista) and northwestern (Panama City) Florida (Stocks and Hodges 2010).

Description and Biology (Back to Top)

Adult: The adult appears much like a typical whitefly with a light dusting of white wax. Depending on temperature, females live from 30 to 60 days, while males live an average of nine days. This rapid development time, without the presence of the parasitiod, initially produced numerous generations per year in California, whereas only two to three generations were reported in Egypt. Plus, the ability of all life stages to overwinter on non-deciduous hosts allows a rapid build-up in population at the start of the season (Stocks and Hodges 2010). Winged females lays eggs on the underside of the leaves. When the nymphs emerge, they rarely move far and feed on the plant sap until pupation (Gillespie 2000).

Adult ash whiteflies, Siphoninus phillyreae (Haliday).

Figure 2. Adult ash whiteflies, Siphoninus phillyreae (Haliday). Photograph by Lyle J. Buss, University of Florida.

Pupa: On first observation, the pupal case appears similar to the white armor of a male snow scale. Closer observation with a hand lens reveals a whitefly pupal case with two longitudinal tufts of white wax. The vasiform orifice is surrounded by dark brown derma (inner, thicker layer of the cuticle), with the anal area appearing as a dark brown spot. Lateral areas of the pupal case are light beige. Depending on the age, lesser or greater amounts of white wax will be present. The dorsal surface has 40 to 50 long glassy tubercles similar to the cornicles found on aphids. These tubercular structures produce a droplet of glassy wax and this gives the pupal case an unusual appearance. The longitudinal white tufts of wax obscure some glassy tubercles (R.J. Gill, personal communication). The pupal case size is 0.8 to 1.0 mm long by 0.55 to 0.7 mm wide and is tan or beige in color(Mound 1966, Stocks and Hodges 2010).

Pupal stage of the ash whitefly, Siphoninus phillyreae (Haliday), showing glassy, wax droplets.

Figure 3. Pupal stage of the ash whitefly, Siphoninus phillyreae (Haliday), showing glassy, wax droplets. Photograph by Lyle J. Buss, University of Florida.

Puparia (3 tan-colored individuals) and juveniles (translucent nymphs) of the ash whitefly, Siphonius phillyreae (Haliday), on pomegranate.

Figure 4. Puparia (3 tan-colored individuals) and juveniles (translucent nymphs) of the ash whitefly, Siphonius phillyreae (Haliday), on pomegranate. Photograph by Lyle J. Buss, University of Florida.

Host Plants (Back to Top)

The ash whitefly is a polyphagous species found on several plant families, (modified from Bellows et al. 1990) including:

Bignoniaceae:

Catalpa X chilopsis, catalpa hybrid

Leguminosae:

Afzelia sp., pod mahogany

Cercis occidentalis, western redbud; C. siliquastrum, Judas tree

Lythraceae:

Lagerstroemia indica, crape myrtle

Magnoliaceae:

Liriodendron tulipifera, tulip tree

Magnolia stellata, star magnolia

Oleaceae:

Fraxinus excelsior, European ash; F. latifolia, Oregon ash; F. ornus, flowering ash; F. syriaca, Syrian ash; F. uhdei, Shamel ash; F. uhdei 'Tomlinson', Tomlinson ash; F. velutina 'Modesto', Modesto ash; F. velutina var. glabra, Arizona ash; F. velutina var. coriacea, western ash

Ligustrum spp., privets

Olea africana (=O. chrysophylla), wild olive; O. europaea, common olive

Phillyrea latifolia (=P. media), a phillyrea

Syringa X hyacinthiflora, a common lilac; S. laciniata, cut-leaf lilac; S. vulgaris, common lilac

Punicaceae:

Punica granatum, pomegranate

Rhamnaceae:

Rhamnus alaternus, buckthorn

Ziziphus spina-christi, crown of thorns

Rosaceae:

Amelanchier denticulata, serviceberry

Chaenomeles X speciosa, flowering quince

Crataegus mollis, hawthorn; C. monogyna, English hawthorn; C. laevigata (=C. oxyacantha), hawthorn

Cydonia oblonga, quince

Eriobotrya deflexa, golden loquat

Heteromeles arbutifolia, California Christmas berry

Malus domestica, apple; M. floribunda, Japanese flowering crab; M. fusca, Oregon crabapple; M. 'Hopa', a crabapple; M. 'Red Jade', a crabapple; M. X scheideckeri, Scheidecker crabapple

Mespilus sp., mespilus

Prunus armeniaca, apricot; P. X blireiana, blue plum hybrid; P. persica, peach; P. salicina, Santa Rosa plum; P. virginiana var. melanocarpa, choke cherry

Pyracantha sp., pyracantha

Pyrus calleryana, ornamental pear; P. communis (=P. sativa), pear; P. kawakamii, flowering pear; P. pyrifolia, Japanese sand pear

Rubiaceae:

Cephalanthus occidentalis var. californicus, buttonbush

Rutaceae:

Citrus sp., tangerine; C. limon, lemon; C. sinensis, navel orange; C. sinensis, Valencia orange

Fortunella sp., kumquat.

Natural Enemies (Back to Top)

Ash whitefly has the potential to become a serious pest in new environments. However, it has several natural enemies that can control its populations to under economic thresholds. These natural enemies include (Stocks and Hodges 2010):

Predators:

Clitostethus arcuatus (Rossi)

Menochilus sexmaculatus (Fabricius)

Scymnus pallidivestis Mulsant

Parasites:

Coccophagus eleaphilus Silvestri

Encarsia inaron (Walker), E. partenopea Masi, E. formosa Gahan, E. galilea Rivnay, E. punicae Hayat, E. pseudopartenopea Viggiani and Mazzone, E. siphonini Silvestri

Eretmocerus corni Haldeman, E. siphonini Viggiani and Battaglia

The California Department of Food and Agriculture imported Encarsia sp. from Israel and Italy, and the coccinellid beetle Clitostethus arcuatus for the control of ash whitefly in California (Bellows et al. 1990). Encarsia inaron was discovered in the ash whitefly infestation in central Florida, while an unidentified parasitoid was associated with the infestation in northwestern Florida.

Selected References (Back to Top)