Aphis gossypii
Encyclopedia
Aphis gossypii is a tiny insect or greenfly in the superfamily Aphidoidea in the order Hemiptera
. It is a true bug and sucks sap from plants. It is a widely distributed pest of a variety of agricultural crops in the families Cucurbitaceae
, Rutaceae
and Malvaceae
. Common names include cotton aphid, melon aphid and melon and cotton aphid.
which are three quarters of the length of the body. The apices of the femora, tibia
and tarsi
are black. The cylindrical black siphunculi are wide at the base and one fifth of the body length. The winged female has a fusiform body. Its head and thorax are black, the abdomen yellowish-green with black lateral spots and the antennae are longer than those of the apterous female. The nymphs vary in colour, being shades of green, tan and gray. They often have a dark head, thorax and wing pads and the distal portion of the abdomen is usually dark green. The body appears dull because it is dusted with wax secretions. The oval eggs are yellow when first laid but soon turn glossy black.
and involve two host species, with a broadleaved tree such as Catalpa
, Rhamnus or Hibiscus
acting as the primary host. In Europe it reproduces exclusively by asexual reproduction
and can produce nearly fifty generations a year under favourable conditions. In Russia various wild plants are hosts to the overwintering eggs. Winged forms then migrate to secondary host species in the families Rosaceae
, Chenopodiaceae
, Malvaceae
, Cruciferae, Cucurbitaceae
, Solanaceae
, Compositae and others. Parthogenesis on these hosts allows large populations of aphids to build up quickly. The life span of a parthogenetic female is about twenty days in which time it can produce up to 85 nymphs. These mature in about twenty days at 10°C and in about four days at 30°C. As autumn approaches, the winged forms migrate back to the primary hosts. Here, both males and sexual females are produced, mating takes place and the females lay eggs which overwinter, ready to repeat the life cycle the following year.
Predators include midges, lacewings, syrphid fly larvae, anthocorid bugs
and ladybirds (ladybeetles). Several members of the Aphidiinae
and Aphelinidae
wasp families are parasitoids of aphids. One which shows promise as a biocontrol agent is Aphelinus asychis
.
. Other vegetable crops attacked include pepper
, eggplant, okra
and asparagus
. It also affects citrus
, cotton
and hibiscus
.
, CTV
and other virus diseases. The aphids' impact is especially important on vegetable crops such as courgette, melon, cucumber, aubergine and strawberry and on cotton, citrus and mallow.
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...
. It is a true bug and sucks sap from plants. It is a widely distributed pest of a variety of agricultural crops in the families Cucurbitaceae
Cucurbitaceae
The plant family Cucurbitaceae consists of various squashes, melons, and gourds, including crops such as cucumber, pumpkins, luffas, and watermelons...
, Rutaceae
Rutaceae
Rutaceae, commonly known as the rue or citrus family, is a family of flowering plants, usually placed in the order Sapindales.Species of the family generally have flowers that divide into four or five parts, usually with strong scents...
and Malvaceae
Malvaceae
Malvaceae, or the mallow family, is a family of flowering plants containing over 200 genera with close to 2,300 species. Judd & al. Well known members of this family include okra, jute and cacao...
. Common names include cotton aphid, melon aphid and melon and cotton aphid.
Distribution
It is not known where this species originated but it is now found in tropical and temperate regions throughout the world except extreme northern areas. It is common in North and South America, Central Asia, Africa, Australia, Brazil, East Indies, Mexico and Hawaii and in most of Europe. It thrives outdoors in southern Europe but survives only under glass in northern Europe. In the former Soviet Union it is found up to 54°N.Morphology
The wingless female cotton aphid has an ovoid body about two milimetres long in varying shades of green. The legs are yellow, as are the antennaeAntenna (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....
which are three quarters of the length of the body. The apices of the femora, tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
and tarsi
Arthropod leg
The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments are of Latin origin, and may be confused with terms for bones: coxa , trochanter , femur, tibia, tarsus, ischium, metatarsus, carpus, dactylus ,...
are black. The cylindrical black siphunculi are wide at the base and one fifth of the body length. The winged female has a fusiform body. Its head and thorax are black, the abdomen yellowish-green with black lateral spots and the antennae are longer than those of the apterous female. The nymphs vary in colour, being shades of green, tan and gray. They often have a dark head, thorax and wing pads and the distal portion of the abdomen is usually dark green. The body appears dull because it is dusted with wax secretions. The oval eggs are yellow when first laid but soon turn glossy black.
Biology
In the souther half of the USA, as far north as Arkansas, sexual reprodution of the cotton aphid is not important. Females continue to produce offspring without mating so long as the weather is favourable for feeding and growth. Further north, the cotton aphid can be holocyclicHolocyclic
In entomology, holocyclic means that an insect undergoes sexual reproduction during at least part of its life cycle....
and involve two host species, with a broadleaved tree such as Catalpa
Catalpa
Catalpa, commonly called catalpa or catawba, is a genus of flowering plants in the trumpet vine family, Bignoniaceae, native to warm temperate regions of North America, the Caribbean, and East Asia....
, Rhamnus or Hibiscus
Hibiscus
Hibiscus is a genus of flowering plants in the mallow family, Malvaceae. It is quite large, containing several hundred species that are native to warm-temperate, subtropical and tropical regions throughout the world...
acting as the primary host. In Europe it reproduces exclusively by asexual reproduction
Apomixis
In botany, apomixis was defined by Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization. This definition notably does not mention meiosis...
and can produce nearly fifty generations a year under favourable conditions. In Russia various wild plants are hosts to the overwintering eggs. Winged forms then migrate to secondary host species in the families Rosaceae
Rosaceae
Rosaceae are a medium-sized family of flowering plants, including about 2830 species in 95 genera. The name is derived from the type genus Rosa. Among the largest genera are Alchemilla , Sorbus , Crataegus , Cotoneaster , and Rubus...
, Chenopodiaceae
Chenopodiaceae
Chenopodiaceae were a family of flowering plants, also called the Goosefoot Family. They are now included within family Amaranthaceae. The vast majority of Chenopods are weeds, and many are salt and drought tolerant. A few food crops also belong to the family: spinach, beets, chard, quinoa, and...
, Malvaceae
Malvaceae
Malvaceae, or the mallow family, is a family of flowering plants containing over 200 genera with close to 2,300 species. Judd & al. Well known members of this family include okra, jute and cacao...
, Cruciferae, Cucurbitaceae
Cucurbitaceae
The plant family Cucurbitaceae consists of various squashes, melons, and gourds, including crops such as cucumber, pumpkins, luffas, and watermelons...
, Solanaceae
Solanaceae
Solanaceae are a family of flowering plants that include a number of important agricultural crops as well as many toxic plants. The name of the family comes from the Latin Solanum "the nightshade plant", but the further etymology of that word is unclear...
, Compositae and others. Parthogenesis on these hosts allows large populations of aphids to build up quickly. The life span of a parthogenetic female is about twenty days in which time it can produce up to 85 nymphs. These mature in about twenty days at 10°C and in about four days at 30°C. As autumn approaches, the winged forms migrate back to the primary hosts. Here, both males and sexual females are produced, mating takes place and the females lay eggs which overwinter, ready to repeat the life cycle the following year.
Predators include midges, lacewings, syrphid fly larvae, anthocorid bugs
Anthocoridae
The Anthocoridae are a family of bugs, commonly called minute pirate bugs or flower bugs.-Name:The vernacular name probably stems from the notion that these very small animals can do much pain to humans, just like small pirate vessels can do so to big ships.The scientific name is a combination of...
and ladybirds (ladybeetles). Several members of the Aphidiinae
Aphidiinae
The Aphidiinae are a subfamily of parasitoid wasps that use aphids as their host. While the larva of the 2–3 mm long Praon leaves the hollowed shell of the aphid from below to pupate in a volcano-like cocoon, most other Aphidiinae pupate inside the dead aphid.Several species have been used in...
and Aphelinidae
Aphelinidae
Aphelinidae is a moderate-sized family of tiny parasitic wasps, with some 1160 described species in some 35 genera. These minute insects are challenging to study as they deteriorate rapidly after death unless extreme care is taken , making identification of most museum specimens difficult...
wasp families are parasitoids of aphids. One which shows promise as a biocontrol agent is Aphelinus asychis
Aphelinus asychis
Aphelinus asychis is a parasitoid wasp native to Eurasia that was introduced to North America to control the Russian wheat aphid.Recent work shows that the species as currently described does not form a monophyletic group and its taxonomy and phylogenetic relationship should be re-examined....
.
Host Plants
The cotton aphid has a very wide host range with at least 60 host plants being known in Florida and perhaps 700 world-wide. Among cucurbit vegetables, it can seriously affect watermelons, cucumbers, cantaloupes, squash and pumpkinPumpkin
A pumpkin is a gourd-like squash of the genus Cucurbita and the family Cucurbitaceae . It commonly refers to cultivars of any one of the species Cucurbita pepo, Cucurbita mixta, Cucurbita maxima, and Cucurbita moschata, and is native to North America...
. Other vegetable crops attacked include pepper
Pepper
- Plants and plant products :The genus Piper of the pepper family , including for example:* Black pepper, white and green pepper, Piper nigrum* Cubeb, Piper cubeba, also known as Java pepper* Long pepper, Piper longum...
, eggplant, okra
Okra
Okra is a flowering plant in the mallow family. It is valued for its edible green seed pods. The geographical origin of okra is disputed, with supporters of South Asian, Ethiopian and West African origins...
and asparagus
Asparagus
Asparagus officinalis is a spring vegetable, a flowering perennialplant species in the genus Asparagus. It was once classified in the lily family, like its Allium cousins, onions and garlic, but the Liliaceae have been split and the onion-like plants are now in the family Amaryllidaceae and...
. It also affects 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...
, cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
and hibiscus
Hibiscus
Hibiscus is a genus of flowering plants in the mallow family, Malvaceae. It is quite large, containing several hundred species that are native to warm-temperate, subtropical and tropical regions throughout the world...
.
Economic significance
The adults and nymphs of the cotton aphid feed on the underside of leaves or on the growing tips of shoots, sucking juices from the plant. The foliage may become chlorotic and die prematurely. There is often a great deal of leaf curling and distortion which hinders efficient photosynthesis. Honeydew is excreted by the aphids and this allows sooty moulds to grow, resulting in a decrease in the quantity and quality of the produce. The aphids are a vector of crinkle, mosaic, rosetteGroundnut rosette virus
Groundnut rosette virus is a peanut pathogenic virus.-External links:**...
, CTV
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...
and other virus diseases. The aphids' impact is especially important on vegetable crops such as courgette, melon, cucumber, aubergine and strawberry and on cotton, citrus and mallow.