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Citrus Pests

 

Asian citrus psyllid

 

Scientific name

 

Diaphorina citri (Hemiptera:Psyllidae)

Other common names

 

citrus psylla, oriental citrus psyllid

Similar species

 

African citrus psyllid, Trioza erytreae

  • Wing characteristics separate the African citrus psyllid from the Asian citrus psyllid.
  • Adult Asian citrus psyllids have front wings that are widest near the tip and can have either transparent wings with white spots or light brown wings with a central beige band.
  • Adult African citrus psyllids have front wings pointed at the tip. All four wings are clear and unspotted.
  • In juveniles, wing pads of the African citrus psyllid are smaller than the Asian citrus psyllid.

Immature psyllids are sometimes confused with aphids.

  • Psyllids and aphids can be easily distinguished by examining the rear of the abdomen. Adult aphids have two dark tubular structures called siphunculi. The African citrus psyllid does not have siphunculi on the rear of its abdomen during any developmental stage.
  • Adult psyllids are also differentiated from aphids by behavior. Psyllids are very active and able to jump, whereas aphids move slowly when disturbed.

Distribution

 

United States: Alabama, Arizona, California, Florida, Georgia, Guam, Hawaii, Louisiana, Mississippi, Puerto Rico, South Carolina, and Texas.

Worldwide: Central and South America, the Middle East, tropical and sub-tropical Asia, the Virgin Islands.

Native to southern Asia.

Diagnostic characteristics

 
Adults
  • 3 - 4 mm (0.12 - 0.16 in.) in length.
  • Mottled, yellowish-brown body with brown legs and a light brown head. The underside (ventral part) of the body is greenish-white.
  • Abdomen of females turns bright yellow-orange when ready to lay eggs (gravid).
  • Transparent wings with white spots, or light-brown with a central beige band. Forewings widest near tip.
  • Very short antennae (0.48 mm [0.019 in.]), eight yellow segments, two terminal black segments, and two short hairs at the tip.
  • Appears dusty due to a whitish, waxy secretion.
Immatures
  • Five nymphal instars.
  • 0.25 mm- 1.7 mm (0.01- 0.07 in.) in length.
  • Light yellow to dark brown.
  • Red eyes.
  • Well-developed, large wing pads.
Eggs
  • Approximately 0.01 - 0.15 mm (less than 0.005 in.).
  • Bright yellow-orange.
  • Almond-shaped, thicker at the base, and taper towards the opposite end.

Hosts

 
Citrus hosts

All species in the plant family Rutaceae, which includes all citrus and non-citrus varieties, are hosts of the Asian citrus psyllid.

Non-citrus hosts
  • orange jasmine or orange jessamine, Murraya paniculata

Host damage

 
Flowers
  • Young flowers may drop.
Fruits
  • Young fruit often drop.
  • Asian citrus psyllids are a vector of citrus greening disease, a disease that causes misshapen, bitter fruit and ultimately kills the tree (see Comments section).
  • Honeydew excreted by psyllids coats the outside of fruits and leaves, and promotes the growth of sooty mold fungus that inhibits photosynthesis, weakens the plant, and makes fruit unattractive.
Leaves
  • Asian citrus psyllids inject a toxin which stops shoot elongation and deforms leaves and shoots.
  • Severely curled leaves, premature defoliation is common.
  • Twenty-four hours of feeding by a psyllid can cause permanent deformation of the leaf.
  • Terminal death of young flush shoots can dramatically slow growth of young trees.
Twigs
  • Dieback occurs during heavy infestation.

Biology

 

Asian citrus psyllids may complete 30 generations per year under favorable conditions. Eggs are laid on the tips of growing shoots, in the crevices of the leaves, or at the base of newly-formed leaf buds. Nymphs flourish on newly emerged or flushing vegetation. Therefore, population densities are lower when active growth is not occurring. In southern Florida, peak psyllid densities usually occur in May, August, and October through December. The psyllids feed on the underside of leaves and exhibit a distinctive feeding stance by lowering their head and elevating their body to a 45 degree angle respective to their head.

Comments

 

The Asian citrus psyllid is an extremely efficient vector of citrus greening (Candidatus Liberibacter asiaticus), a highly virulent and fatal bacterial disease that inhabits the food transport tissue (phloem-limited) of citrus trees. Common symptoms of citrus greening are mottling and yellowing (chlorosis) of the leaves that can resemble some nutrient deficiencies, especially zinc deficiency. Trees are frequently stunted and have partial defoliation. Twig dieback, leaf and fruit drop, and off-season blooming are other common symptoms. The fruit is affected as well, appearing misshapen, improperly colored, and with a bitter taste.

All phloem-feeding, honeydew-producing insect pests have the potential to be tended by ants. The ants feed on the honeydew excreted by the pest and protect the pest from natural enemies. This protection can disrupt biological control programs.

References

 

Grafton-Cardwell, E.E., K.E. Godfrey, M.E. Rogers, C.C. Childers, and P.A. Stansley. 2006. Asian citrus psyllid. Pub. 8205. University of California, Division of Agriculture and Natural Resources (http://anrcatalog.ucdavis.edu/pdf/8205.pdf).

Halbert, S., and D.J. Voegtlin. 2006. Pest alert: Asian citrus psyllid - A serious exotic pest of Florida citrus. Fla. Dept. Agric. Consumer Services - Div. Plant Industry. (http://www.doacs.state.fl.us/pi/enpp/ento/dcitri.htm).

(IUCN) International Union for the Conservation of Nature, Species Survival Commission, Invasive Species Specialist Group. 2009. Global Invasive Species Database: Diaphorina citri.(http://www.issg.org/database/species/ecology.asp?si=1497&fr=1&sts=sss&lang=EN).

Mead, F.W. 2009. Featured creatures fact sheet: Asian citrus psyllid, Diaphorina citri Kuwayama (Insecta: Hemiptera: Psyllidae). Publication EENY-033. University of Florida. (http://edis.ifas.ufl.edu/pdffiles/IN/IN16000.pdf).

(NAPIS) National Agricultural Pest Information System. Purdue University. 2012. Survey Status of Asiatic Citrus Psyllid - Diaphorina citri (2008 to present). (http://pest.ceris.purdue.edu/map.php?code=IRAXAWA&year=3year).

Rogers, M.E., and P.A. Stansly. 2006. Biology and management of the Asian citrus psyllid, Diaphorina citri Kuwayama, in Florida citrus. (http://edis.ifas.ufl.edu/pdffiles/IN/IN66800.pdf).

Stigter, H. 2005. Diagnostic protocol Asian citrus psyllid: Diaphorina citri. OEPPO/ EPPO Bulletin 35: 331-333. (http://www.eppo.org/QUARANTINE/insects/Diaphorina_citri/pm7-52%281%29%20DIAACI%20web.pdf).

(USDA) United States Department of Agriculture. Species profiles: Asian citrus psyllid.(http://www.invasivespeciesinfo.gov/animals/acp.shtml).

(USDA APHIS PPQ) U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine. 2010. National quarantine map: citrus greening and Asian citrus psyllid map.(http://www.aphis.usda.gov/plant_health/plant_pest_info/citrus_greening/downloads/pdf_files/nationalquarantinemap.pdf).

Walker, K. 2007. Asiatic citrus psyllid (Diaphorina citri). Pest and diseases image library. (http://www.padil.gov.au).

Authors

 

Martin, K.W., A.C. Hodges, and N.C. Leppla

 

Citrus Pests
Content last updated June, 2012
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