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Home  >> Tree Care  >> Tree Insects  >> Asian Citrus Psyllid

ASIAN CITRUS PSYLLID


Diaphorina citriAsian Citrus Psyllid adult

The Asian Citrus Psyllid was initially discovered in the United States in 1998 in Palm Beach County, Florida. It spread rapidly, showing up in Louisiana and again in the Rio Grande Valley in Hidalgo County, Texas in 2001; and by 2008 it was detected in San Diego County in southern California. Confirmed sightings of Asian Citrus Psyllid have since been reported in Alabama, Arizona, Georgia, Hawaii, Mississippi, and South Carolina.

The aphid-like Asian Citrus Psyllid is known to feed on the leaves and stems of up to 56 different host plants. The feeding damage caused by the Asian Citrus Psyllid is relatively minor, but what is of greater consequence is the potential for the insect to spread a disease that is deadly to citrus trees. Some Asian Citrus Psyllid insects are carriers of a bacterial tree disease called Huanglongbing (HLB) or Citrus Greening Disease.

Citrus Greening Disease has no impact on human health, but is considered to be the most serious citrus tree disease in the world. The disease affects the appearance of citrus fruit and renders the fruit useless by ruining the appearance of the fruit and turning the juice bitter. Currently, there is no cure for Citrus Greening Disease and infected trees will be killed 2 to 5 years after infection.

HOW CAN HOMEOWNERS & CONSUMERS HELP?

Several quarantine areas have been designated where the Asian Citrus Psyllid has been discovered. It is illegal to move citrus trees or cuttings from quarantined areas. Homeowners and consumers can play an important part in limiting the spread of Asian Citrus Psyllid by:

HOW IS ASIAN CITRUS PSYLLID MOVING IN THE U.S.?

Asian Citrus Psyllid nymph
The movement of Asian Citrus Psyllid is not restricted to the transportation of citrus trees. It has been discovered hitchhiking on a number of nursery, ornamental, and floral plants shipped in a variety of ways. Asian Citrus Psyllid has been intercepted in packages of fruits, trees, ornamental plants, herbs, and bouquets of cut flowers. The Asian Citrus Psyllid has been transported on airplanes, cars, ships, trucks, and even in the U. S. mail. This is in addition to the insects’ own ability to fly a limited distance.

Two common host plants on which Asian Citrus Psyllid have been transported are Indian Curry and Orange Jasmine plants. Psyllid-infested Indian Curry plants shipped from Hawaii have been intercepted and destroyed. Officials have also discovered, and destroyed, psyllid-infested floral bouquets containing Orange Jasmine destined for California from Mexico. For three years after its discovery in Florida the primary means of Asian Citrus Psyllid movement was on Orange Jasmine plants sold at retail nurseries.

Asian Citrus Psyllid eggs

Asian Citrus Psyllid eggs.

Photo: Jeffrey W. Lotz, FL Dept. of Ag., Bugwood.org

  • Washing any fruit you are giving as a gift.
  • Removing any leaves or stems from fruit you are giving as a gift.
  • Not moving citrus fruit or plants from quarantined areas.
  • Planting only certified citrus trees which are known to be free of Citrus Greening Disease.
  • Double-bagging clippings before putting them in the trash.
  • Drying out plant clippings for two weeks before putting them out as green waste to be recycled.
  • Inspecting your citrus trees once a month for Asian Citrus Psyllid adults, nymphs, or eggs.

SYMPTOMS CITRUS GREENING DISEASE

Both immature Asian Citrus Psyllid insects, called nymphs, and adult Asian Citrus Psyllid insects feed on the young foliage of a plant by sucking the juices from the leaves. The feeding activity will cause the leaves to curl and heavy feeding may kill the growing tip of a plant. The insects exude a sweet, sticky substance called honeydew, which may be colonized by a gray or black fungus called sooty mold. The presence of Asian Citrus Psyllid insects or sooty mold does not necessarily mean a citrus tree is infected with Citrus Greening Disease.

Detecting, and responding to, Citrus Greening Disease is complicated by the fact that symptoms of Citrus Greening Disease may not be seen until the tree has already been infected for one to two years. One of the earliest symptoms is the development of mottled yellow leaves on an individual branch or in one portion of the canopy of the tree. As the disease moves throughout the tree twig and limb dieback will increase and the remaining small leaves will point upward. The tree may also produce yellow shoots.

The fruit of citrus trees infected with Citrus Greening Disease will gradually take on certain characteristics such as:

  • Lopsided fruit
  • Fruit with dark, aborted seeds
  • Fruit will drop prematurely
  • The juice of the citrus fruit will become bitter


Eventually, the tree will stop bearing fruit and the entire tree will die.

TREES AND SHRUBS ATTACKED BY ASIAN CITRUS PSYLLID

The Asian Citrus Psyllid feeds on all citrus trees and other closely related ornamental plants. Plants attacked by Asian Citrus Psyllid include:
  • Box Orange
  • Calamondin
  • Grapefruit trees
  • Indian Curry
  • Kumquat
  • Lemon
  • Lime
  • Mandarin Orange
  • Orange trees
  • Orange Jasmine
  • Sweet Orange
  • Tangerine trees

Natural predators may also help limit the spread of Asian Citrus Psyllid. Natural enemies to Asian Citrus Psyllid include:
  • Spiders
  • Lacewings
  • Hover flies
  • Some beetle species
  • Parasitic wasps
  • Lady beetle adults
  • Lady beetle larvae
  • Syrphid fly larvae
  • Minute pirate bugs
  • Birds
  • Fungal pathogens

Asian Citrus Psyllid

AdultAsian Citrus Psyllid

Asian Citrus Psyllid nymph2

Asian Citrus Psyllid nymph.

Photo: Jeffrey W. Lotz, FL Dept. of Ag., Bugwood.org

Asian Citrus Psyllid adult2

Asian Citrus Psyllid adult.

Photo: Jeffrey W. Lotz, FL Dept. of Ag., Bugwood.org

Asian Citrus Psyllid adult3

Asian Citrus Psyllid adult. Photo: Jeffrey W. Lotz, FL Dept. of Ag,, Bugwood.org

LIFECYCLE OF ASIAN CITRUS PSYLLID

After egg hatch the Asian Citrus Psyllid progresses through five nymphal stages. Each nymphal stage looks similar, but the insects increase in size after each molt. Inspecting trees for Asian Citrus Psyllid is best accomplished with a magnifying glass due to the small size of the insects.

Asian Citrus Psyllid eggs may be yellow to orange in color and are almond shaped. Look for groups of eggs near the end of twig tips.

The nymphs of Asian Citrus Psyllid are dull orange to yellow-brown in color. The nymphs have red eyes and grow waxy tubules that direct the honeydew away from their bodies. The tubules can be used as an identifying characteristic and are a white curly tube with a bulb at the end.

Asian Citrus Psyllid adults are the size of an aphid, about 1/8 inch in length, and are mottled, grayish-tan in color. Their feeding position is characteristic in that the back of the insect is raised at a 45-degree angle. A female Asian Citrus Psyllid insect may lay several hundred eggs in its lifetime.

HOW TO CONTROL ASIAN CITRUS PSYLLID

Homeowners should inspect the new growth each month for the presence of Asian Citrus Psyllid. Many new detections of the insect have been made by homeowners on residential trees. The discovery of Asian Citrus Psyllid should be reported to Department of Agriculture officials in your state even if you are going to treat your tree or are going to have a tree service provide Asian Citrus Psyllid control treatments for you. Reporting the discovery of Asian Citrus Psyllid can help government agencies limit the spread of this disease-carrying invasive insect.

Pesticide Options

Spraying trees for Asian Citrus Psyllid is more effective at controlling the adult insects than it is for controlling the nymphs. Asian Citrus Psyllid nymphs may be protected from the tree spraying when they are feeding in leaves that have not fully expanded. More than one tree spraying treatment per year may be necessary to fully control Asian Citrus Psyllid.
A second option for controlling Asian Citrus Psyllid is a soil injected insecticide. One treatment per year is injected into the soil around the trunk of the citrus tree.
Contact the Department of Agriculture or a local tree service to find the right time for a soil injection or tree spraying to control Asian Citrus Psyllid in your area.

Biological Options

An imported parasitic wasp, Tamarixia radiate, has been released in Florida to combat the Asian Citrus Psyllid.
The parasitic wasp was successfully introduced in Taiwan to control Asian Citrus Psyllid and was found to produce almost two generations for each pest generation. The female parasitic wasp feeds on all life stages of the Asian Citrus Psyllid and also lays its eggs on the nymphs – which then kill the nymphs. A single female parasitic wasp can kill in excess of 500 Asian Citrus Psyllids in its lifetime.

Government agencies are asking for your help in limiting the spread of Asian Citrus Psyllid. Sightings of Asian Citrus Psyllid should be reported to the Department of Agriculture in your home state.

  • Alabama Department of Agriculture & Industries-Plant Protection: (334)240-7225
  • Arizona Department of Agriculture, Office of Pest Management: (602) 255-3664
  • California Department of Food and Agriculture. CDFA Pest Hotline: (800) 491-1899.
  • Florida Division of Plant Industry: (800) 282-5153
  • Georgia Department of Agriculture, Plant Protection Section: (770) 228-7215
  • Hawaii Department of Agriculture, Plant Pest Control: (808) 973-9530
  • Louisiana Department of Agriculture & Forestry, Horticulture and Quarantine: (225) 952-8100
  • Mississippi Department of Agriculture, Bureau of Plant Industry: (662) 325-3390
  • South Carolina Department of Agriculture: (803) 734-2210
  • Texas Citrus Center: (956) 447-3360

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