Seychelles scale

Scientific name

Icerya seychellarum (Hemiptera: Margarodidae)

Other common names

iceplant scale

Similar species

Because of the waxy coating, the Seychelles scale may be confused with some species of mealybugs in the family Pseudococcidae.

Distribution

United States: not known to occur.

Worldwide: Africa, Australia, Columbia, French Guiana, India, Madagascar, the Pacific Islands, and Southeast Asia.

Native to the Indo-Pacific region.

Diagnostic characteristics

Adults

• Females are covered in white to yellow powdery wax.
• Body is orange to dark red with areas of bright yellow.
• Long, fine silky hairs projecting from body.
• Eyes apparent.
• Legs and antennae are apparent and black.
• Double row of rounded plates on either side of an anterioranterior:
  situated near the front of the body; nearer to the head
  to posteriorposterior:
  orientation pertaining to the rear of the body
  central ridge occuring on the dorsum.
• Ovisac ovisac:
  structure attached to the body that contains eggs; produced by many scale insects
  present.
• Mobile.
• Males are rarely seen when present, but are red-bodied and winged.

Immatures

• Yellow.
• Three nymphal instars.

Eggs

• Orange.
• Laid in ovisacovisac:
  structure attached to the body that contains eggs; produced by many scale insects
  .

Hosts

Citrus hosts

• All Citrus species and their hybrids.

Non-citrus hosts

Very wide host rangehost range:
the range of species that a particular organism can feed on to achieve successful growth and reproduction
. In addition to forest and ornamental species, agricultural crops and weeds are widely used as host plants. A partial list includes:

• African oil palm, Elaeis guineensis
• avocado, Persea americana
• banana, Musa spp.
• bean, Phaseolus vulgaris
• carambola, Averrhoa carambola
• coconut, Cocos nucifera
• coffee, Coffea spp.
• Crotalaria spp.
• fig, Ficus spp.
• guava, Psidium guajava
• Hibiscus spp.
• jackfruit, Artocarpus heterophylla and A. incisa
• jasmine, Jasminum spp.
• lettuce, Lactuca sativa
• loquat, Eriobotrya japonica
• lychee, Litchi chinensis
• mango, Mangifera indica
• morning glory, Convolvulus spp.
• peach, Prunus spp.
• pear, Pyrus spp.
• pepper, Capsicum spp.
• Plumeria spp.
• pomegranate, Punica granatum
• tea, Camellia sinensis
• strawberry, Fragaria spp.
• sweet potato, Ipomoea batatas
• tomato, Solanum lycopersicum
• trifoliate orange, Poncirus trifoliata

Host damage

Fruits

• Occasionally infested.
• Honeydew honeydew:
  the sugar-rich waste product excreted by aphids, mealybugs, and scales insects as a result of feeding on the phloem of plants
  excreted by scales coats the outside of fruit and promotes the growth of sooty mold fungus that inhibits photosynthesis, weakens the plant, and makes fruit unattractive.

Leaves

• Can be found on stems and near the midribs and on the undersides of older leaves.
• Can cause yellowing and premature loss.

Stems

• Primarily infests stems.

Twigs

• Young shoots can be killed when heavily infested by scales.

Biology

Adults can be found on the branches or trunks of trees. Females have both male and female sexual organs (hermaphrodites) and can produce female offspring asexually through parthenogenesisparthenogenesis:
a form of asexual reproduction in which a female produces eggs without fertilization by a male
. Eggs are contained within an ovisacovisac:
structure attached to the body that contains eggs; produced by many scale insects
attached to the body of the female. Mobilemobile:
able to move
crawlers hatch from the eggs, disperse to a suitable leaf vein, and begin to feed. Seychelles scales retain their legs, eyes, and antennae for their entire life and remain mobilemobile:
able to move
. Older instars move to the twigs, branches, or the trunk to feed. Males are rare and exist in the species to allow the scale to reproduce sexually producing both females and males. Seychelles scales can have multiple generations per year.

Comments

All phloem-feeding, honeydew-producing pests have the potential to be tended by ants. The ants feed on the honeydewhoneydew:
the sugar-rich waste product excreted by aphids, mealybugs, and scales insects as a result of feeding on the phloem of plants
excreted by the pest and protect the pest from natural enemies. This protection can disrupt biological control programs.

References

Butcher, C.F. 1983. Cottony cushion scale, Seychelles scale, and Egyptian fluted scale. Department of Scientific and Industrial Research, Auckland, New Zealand. (http://www.spc.int/pps/PDF%20PALs/PAL%2016%20Scales%201983.pdf).

(CABI) Centre for Agricultural Bioscience International. 2012. Plantwise: pest map for Icerya seychellarum. (http://www.plantwise.org/default.aspxsite=234&page=4393&speciesID=21918&dsID=28434).

Hill, D.S. 2009. Pests of crops in warmer climates and their control. Springer-Verlag, New York.

Authors

Weeks, J.A., A.C. Hodges, and N.C. Leppla