The Asian citrus psyllid, Diaphorina citri, is a sap-sucking, hemiptera

Hemiptera

Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...

n bug in the family, Psyllidae. It is an important pest of citrus

Citrus

Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...

 being one of only two known vectors of the serious citrus disease, Huanglongbing or greening disease. It is widely distributed in southern Asia and has spread to other citrus growing regions. The other vector is the African citrus psyllid, Trioza erytreae

Trioza erytreae

The African citrus psyllid, Trioza erytreae, is a sap-sucking insect, a hemipteran bug in the family, Triozidae. It is an important pest of citrus being one of only two known vectors of the serious citrus disease, Huanglongbing or greening disease. It is widely distributed in Africa...

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Distribution

The Asian citrus psyllid originated in Asia but it is now also found in parts of the Middle East, South and Central America, Mexico and the Caribbean. In the United States, this psyllid was first detected in Florida in 1998 and is now also found in Louisiana, Georgia and South Carolina. In Southern California, where it first appeared in backyard citrus in 2008, an eradication programme has been instituted to try to prevent it becoming established. In the whole of the United States and its territories, areas where this psyllid are found are under quarantine restrictions.

Description

The adult psyllid

Jumping plant louse

Psyllids or jumping plant lice are small plant-feeding insects that tend to be very host specific, i.e. they only feed on one plant species or feed on a few related plants...

 is about four millimetres long with a fawn and brown mottled body and a light brown head. It is covered with a whitish, waxy secretion which makes it look dusty. The forewings are broadest at the back and have a dark edging around the periphery with a pale gap near the apex. The antennae

Antenna (biology)

Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

 are pale brown with black tips. These features distinguish it from the superficially similar African citrus psyllid. It typically adopts a head down, tail up posture as it sucks sap. Aphid

Aphid

Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

s are often also present on citrus and psyllids can be distinguished from them by being more active, jumping insects, whereas aphids are sedentery. In addition, the antennae of a psyllid has ten segments whereas those of aphids usually have four or six segments. Most aphids have cornicles on the abdomen and psyllids lack these.

The psyllid nymph

Nymph (biology)

In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, a nymph's overall form already resembles that of the adult. In addition, while a nymph moults it never enters a...

 moults five times. It is a yellowish-orange colour and has no abdominal spots. The wing pads are prominent, especially in the later instar

Instar

An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...

s.

The eggs

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 are approximately 0.3 millimetres long, almond-shaped, thicker at the base and tapering toward the top. They are at first a pale colour but turn yellow and later orange before they hatch. The long axis is placed vertical to the surface of the leaf.

Life cycle

Eggs are laid on the tips of growing shoots, between and near the unfolding leaves. A female may lay up to 800 eggs during her lifetime which may be several months. The whole development cycle takes from two to seven weeks depending on the temperature and the time of year.

Damage

Psyllids nymphs are found on new shoots of citrus trees. As they feed they produce a toxin that causes the plant tips to die back or become contorted and prevents the leaves expanding normally. Of more importance is the fact that they are vectors for the bacteria that causes one of the most devastating of citrus diseases, huanglongbing. Affected trees bear small, asymmetrical fruit which are partially green and which are unsaleable because of their poor size and quality.

Control

The Asian citrus psyllid has a number of natural enemies including hoverflies

Hoverfly

Hoverflies, sometimes called flower flies or syrphid flies, make up the insect family Syrphidae. As their common name suggests, they are often seen hovering or nectaring at flowers; the adults of many species feed mainly on nectar and pollen, while the larvae eat a wide range of foods...

, lacewings

Chrysopidae

Green lacewings are insects in the large family Chrysopidae of the order Neuroptera. There are about 85 genera and 1,300–2,000 species in this widespread group...

, several species of ladybird

Coccinellidae

Coccinellidae is a family of beetles, known variously as ladybirds , or ladybugs . Scientists increasingly prefer the names ladybird beetles or lady beetles as these insects are not true bugs...

 and a number of species of parasitic wasp

Wasp

The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...

. One of these wasps, Tamarixia radiata, has proved very effective at controlling the pest and has been successfully released and become established in a number of citrus growing areas including Florida. Both adults and nymphs of the psyllid can be controlled by the use of a wide range of insecticide

Insecticide

An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...

s. Citrus greening disease is best controlled through an integrated strategy involving the use of healthy planting material, the prompt removal of infected trees and branches and the control of vectors.

External links

• Species Profile-Asian Citrus Psyllid (Diaphorina citri), National Invasive Species Information Center, United States National Agricultural Library
  United States National Agricultural Library
  The United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
  
  . Lists general information and resources for Asian Citrus Psyllid.