The greenbug, or wheat aphid (''Schizaphis graminum''), is an

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

in the superfamily Aphidoidea in the order Hemiptera. It is a true bug and feeds on the leaves of

Gramineae Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns and ...

(grass) family members. Its original distribution is the

Palaearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

, but it has been introduced to other parts of the world. It is one of about 40 recognized ''Schizaphis'' species worldwide.

Description

Adult greenbugs are long. The head and thorax are straw-colored to pale green and the abdomen is mid-green, with a dark green dorsal stripe in late-stage nymphs and adults. The antennae are dark and the

cornicle The cornicle (or siphuncule) is one of a pair of small upright backward-pointing tubes found on the dorsal side of the 5th or 6th abdominal segments of aphids. They are sometimes mistaken for cerci. They are no more than pores in some species. ...

s are pale with dark tips. Early in the season the adults are wingless, but under conditions of over-crowding, winged forms appear and migrate to neighbouring plants.

Host plants

This aphid feeds almost exclusively on a range of grasses in the family Poaceae; genera attacked include ''

Agropyron ''Agropyron'' is a genus of Eurasian plants in the Poaceae, grass family), native to Europe and Asia but widely naturalized in North America. Species in the genus are common name, commonly referred to as wheatgrass. ; Species * ''Agropyron bada ...

'', ''

Avena ''Avena'' is a genus of Eurasian and African plants in the grass family. Collectively known as the oats, they include some species which have been cultivated for thousands of years as a food source for humans and livestock. They are widespre ...

'', ''

Bromus ''Bromus'' is a large genus of grasses, classified in its own tribe Bromeae. They are commonly known as bromes, brome grasses, cheat grasses or chess grasses. Estimates in the scientific literature of the number of species have ranged from 100 ...

'', ''

Dactylis ''Dactylis'' is a genus of Eurasian and North African plants in the bluegrass subfamily within the grass family. ''Dactylis'' is native to North Africa, they are found throughout the world, and are an invasive species. They are known in Englis ...

'', ''

Eleusine ''Eleusine'' is a genus of Asian, African, and South American plants in the grass family,Festuca ''Festuca'' (fescue) is a genus of flowering plants belonging to the grass family Poaceae (subfamily Pooideae). They are evergreen or herbaceous perennial tufted grasses with a height range of and a cosmopolitan distribution, occurring on ever ...

'', '' Hordeum'', '' Lolium'', ''

Oryza ''Oryza'' is a genus of plants in the grass family. It includes the major food crop rice (species ''Oryza sativa'' and ''Oryza glaberrima''). Members of the genus grow as tall, wetland grasses, growing to tall; the genus includes both annual an ...

'', ''

Panicum ''Panicum'' (panicgrass) is a large genus of about 450 species of grasses native throughout the tropical regions of the world, with a few species extending into the northern temperate zone. They are often large, annual or perennial grasses, growi ...

'', '' Poa'', '' Sorghum'', ''

Triticum Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologica ...

'' and '' Zea''. It has been reported as a pest of the pearl millet in Pakistan.

Ecology

Schizaphis graminum adults on sorghum bicolor

In warm or moderate climates, the greenbug reproduces by

parthenogenesis Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...

, female insects producing

nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ...

at the rate of up to five per day on

paspalum ''Paspalum'' is a genus of plants in the grass family. The group is widespread across much of Asia, Africa, Australia, and the Americas. Commonly known as paspalum, bahiagrasses, crowngrasses or dallis grasses, many of the species are tall pere ...

near the Florida coast. There are three

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...

stages and a generation length of seven to nine days at . In cooler climates, females mate in the autumn with winged males, and the eggs overwinter on such grasses as ''

Poa pratensis ''Poa pratensis'', commonly known as Kentucky bluegrass (or blue grass), smooth meadow-grass, or common meadow-grass, is a perennial species of grass native to practically all of Europe, North Asia and the mountains of Algeria and Morocco. Altho ...

''. Within the

Post-Soviet states The post-Soviet states, also known as the former Soviet Union (FSU), the former Soviet Republics and in Russia as the near abroad (russian: links=no, ближнее зарубежье, blizhneye zarubezhye), are the 15 sovereign states that wer ...

there can be up to fifteen generations in the year and the most favourable temperature is around for wingless forms, and for winged ones. When feeding on grasses, the aphids suck the sap and at first cause yellow or red spots on the leaves. As the greenbugs become more numerous, the plant progressively develop yellow and red hues, leaves die, roots die and in extreme cases, the whole plant succumbs. On susceptible cultivars of small grain crops, the plant size and yield are affected. In turf grass, the tips and blades of the leaves turn yellow with brown tips, which contrasts strongly with healthy leaves. As the leaves die back, the aphids move on to fresh foliage. The greenbug is the

vector Vector most often refers to: *Euclidean vector, a quantity with a magnitude and a direction *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...

of several plant viruses including barley yellow dwarf virus,

sugarcane mosaic virus ''Sugarcane mosaic virus'' (SCMV) is a plant pathogenic virus of the family ''Potyviridae''. The virus was first noticed in Puerto Rico in 1916 and spread rapidly throughout the southern United States in the early 1920s. SCMV is of great concern ...

maize dwarf mosaic virus ''Maize dwarf mosaic virus'' (MDMV) is a pathogenic plant virus of the family ''Potyviridae''. Depending on the corn plant’s growth stage, the virus can have severe implications to the corn plant’s development which can also result in economi ...

and millet red leaf virus.

References

External links

* {{Taxonbar, from=Q4330567 Palearctic insects Aphidini Agricultural pest insects Insects described in 1852 Insect pests of millets