''Macrosiphum euphorbiae'', the potato
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 ...
, is a sap-sucking
pest insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...
in the family
Aphididae
The Aphididae are a very large insect family in the aphid superfamily ( Aphidoidea), of the order Hemiptera. These insects suck the sap from plant leaves. Several thousand species are placed in this family, many of which are considered plant/crop ...
. It infests
potato
The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae.
Wild potato species can be found from the southern Unit ...
es and a number of other commercially important crops.
Distribution
''Macrosiphum euphorbiae'' originated in North America but it has spread to the temperate parts of Europe and Asia and is found in all areas in which potatoes are grown.
Description
The wingless female potato aphid is green or occasionally pink, often with a darker dorsal stripe. It has a pear-shaped body reaching about four millimetres long. The
antennae are dark at the joints between the segments and are longer than the body. They are set on outward facing tubercles. The legs are longer than in other aphids, pale green but darker at the apices. The
siphunculi
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.
...
are pale coloured, cylindrical with dark tips and
operculi, and are about one third the length of the body. The tail is sword-shaped and bears 6 to 12 hairs and is much shorter than the siphunculi. The winged female has a uniform darker coloured body and appendages and has a green abdomen. The nymphs are like miniature versions of the adults and go through several moults in the course of about ten days.
The green biotype is most often found on the lower, older leaves of potato plants whereas the pink biotype had no such preference. The numerical predominance of the green biotype was greater on older plants.
Biology
Female potato aphids overwinter as eggs on weeds, the sprouts of potatoes in storage and on lettuce under glass.
[ They usually emerge in April and begin feeding on ]perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...
weed
A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
s, preferring plants in the family Chenopodiaceae
Amaranthaceae is a family of flowering plants commonly known as the amaranth family, in reference to its type genus '' Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, making i ...
. In May or early June, they migrate to potato
The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae.
Wild potato species can be found from the southern Unit ...
, cabbage, tomato
The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...
and others crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydropon ...
s where they feed on shoots, the lower side of leaves, buds and flowers, often on the lower parts of the plant. They are highly polyphagous, feeding on over two hundred species in more than twenty plant families, but their preference is for plants in the family Solanaceae.[ The female produces up to seventy young 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 ...
over the course of three to six weeks and there may be ten generations over the summer.[ The optimum temperature for population increase is 68 °F. When populations build up, winged individuals are produced and fly off to infest new host plants. The production of winged individuals is also dependent on the day length, the temperature, the parent type (winged or wingless) and the generation.
The aphids migrate back to primary hosts in August and overwinter as eggs on weeds. In North America they are heavily parasitized by the braconid wasp '']Aphidius nigripes
''Aphidius nigripes'' is a species of parasitoid wasp in the subfamily Aphidiinae of the family Braconidae. It is the most common parasitoid of the potato aphid '' Macrosiphum euphorbiae'' in eastern North America. Many other species of aphids ma ...
'', which lays its eggs in the aphid nymphs, and these are eventually killed by the wasp larvae developing inside them.
Management
Various factors influence aphid populations. High temperatures or heavy rainfall may reduce infestations and the numbers are naturally controlled by predators
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
, parasites
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
and pathogen
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
s. Some plant varieties are more resistant to attack than others. In a study on tomatoes, it was shown that the aphids preferred smooth to hairy leaves and that susceptible tomato plants had higher sucrose, lower quinic acid
Quinic acid is a cyclitol, a cyclic polyol, and a cyclohexanecarboxylic acid. It is a colorless solid that can be extracted from plant sources. Quinic acid is implicated in the perceived acidity of coffee.
Occurrence and preparation
The compound ...
and higher alanine
Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side ...
and tyrosine
-Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...
levels. In lettuce, butterhead varieties are mostly moderately to highly resistant to the aphid whereas crisphead varieties are susceptible. If numbers of aphids are sufficiently high, chemical control can be attempted using insecticidal soaps. This is not always effective because the aphids usually congregate on the underside of lower leaves where they are difficult to reach with sprays.
Disease spread
A number of virus diseases are spread by ''Macrosiphum euphorbiae''. These include lettuce mosaic virus, bearded iris mosaic virus, narcissus yellow stripe virus, tulip breaking virus
''Tulip breaking virus'' is one of five plant viruses of the family ''Potyviridae'' that cause color-breaking of tulip flowers. These viruses infect plants in only two genera of the family Liliaceae: tulips (''Tulipa'') and lilies (''Lilium''). ...
,Encyclopedia of Life
/ref> potato leaf roll virus, potato virus Y
Potato virus Y (PVY) is a plant pathogenic virus of the family ''Potyviridae'', and one of the most important plant viruses affecting potato production.
PVY infection of potato plants results in a variety of symptoms depending on the viral str ...
, beet mild yellowing virus and beet yellows virus.[
]
References
{{Taxonbar, from=Q3274988
Macrosiphini
Agricultural pest insects
Hemiptera of North America
Insects described in 1878
Taxa named by Oldfield Thomas