Toxoptera citricida
Encyclopedia
Toxoptera citricida is a species of aphid
known by the common names brown citrus aphid, black citrus aphid, and oriental citrus aphid. It is a pest of citrus
and vector for the pathogenic plant virus citrus tristeza virus
. The aphid spread the virus through citrus groves in Brazil
and Venezuela
in the 1970s, leading to the near destruction of the citrus industry there. This aphid was first discovered in Florida
in 1995.
The adult aphid is shiny black and wingless (aptera) or winged (alate or alatoid), and the nymph
is dark reddish brown. The aphid feeds on new buds and leaves. The virus is transmitted when the aphid introduces it into the phloem
of the plant.
In most parts of the world, there is no sexual reproductive stage in the autumn as there is in other aphid species and there are no males and no eggs. All the individuals are viviparous parthenogenetic females all year round. Populations increase very rapidly when the conditions are favourable. The nymphs mature in about a week at temperatures of 20º C or higher. It has been calculated that a single aphid could produce over 4,400 offspring in three weeks in the absence of predation by natural enemies.
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...
known by the common names brown citrus aphid, black citrus aphid, and oriental citrus aphid. It is a 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...
and vector for the pathogenic plant virus citrus tristeza virus
Citrus tristeza virus
Citrus tristeza virus is a viral species of the Closterovirus genus that causes the most economically damaging disease to its namesake plant genus, Citrus. The disease has led to the death of millions of Citrus trees all over the world and has rendered other millions useless for production...
. The aphid spread the virus through citrus groves in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
and Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
in the 1970s, leading to the near destruction of the citrus industry there. This aphid was first discovered in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
in 1995.
The adult aphid is shiny black and wingless (aptera) or winged (alate or alatoid), and the 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...
is dark reddish brown. The aphid feeds on new buds and leaves. The virus is transmitted when the aphid introduces it into the phloem
Phloem
In vascular plants, phloem is the living tissue that carries organic nutrients , in particular, glucose, a sugar, to all parts of the plant where needed. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word "bark"...
of the plant.
In most parts of the world, there is no sexual reproductive stage in the autumn as there is in other aphid species and there are no males and no eggs. All the individuals are viviparous parthenogenetic females all year round. Populations increase very rapidly when the conditions are favourable. The nymphs mature in about a week at temperatures of 20º C or higher. It has been calculated that a single aphid could produce over 4,400 offspring in three weeks in the absence of predation by natural enemies.