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 padswing pads:
  undeveloped or incomplete wing structures that are found on the immature individuals of insects that do not undergo complete metamorphosis, e.g., stink bugs, leaf-footed bugs, grasshoppers
  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 abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  . Adult aphids have two dark tubular structures called siphunculisiphunculi:
  paired, triangular-shaped tubes projecting from the rear of an aphid abdomen; also referred to as cornicles
  . The African citrus psyllid does not have siphunculisiphunculi:
  paired, triangular-shaped tubes projecting from the rear of an aphid abdomen; also referred to as cornicles
  on the rear of its abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  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 headhead:
  one of the three main body segments in insects; the anterior-most segment containing the many sensory structures including the eyes, antennae, and mouthparts
  . The underside (ventral part) of the body is greenish-white.
• Abdomen abdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  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 padswing pads:
  undeveloped or incomplete wing structures that are found on the immature individuals of insects that do not undergo complete metamorphosis, e.g., stink bugs, leaf-footed bugs, grasshoppers
  .

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 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 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 flushflush:
  period of rapid growth in the terminal shoots of citrus trees that may be associated with flowering or may be vegetative
  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 headhead:
one of the three main body segments in insects; the anterior-most segment containing the many sensory structures including the eyes, antennae, and mouthparts
and elevating their body to a 45 degree angle respective to their headhead:
one of the three main body segments in insects; the anterior-most segment containing the many sensory structures including the eyes, antennae, and mouthparts
.

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 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

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, Invasiveinvasive:
term used to describe species that are not native and have the ability to adversely effect habitats they invade either ecologically or economically
Species Specialist Group. 2009. Global Invasiveinvasive:
term used to describe species that are not native and have the ability to adversely effect habitats they invade either ecologically or economically
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