Russian wheat aphids are able to survive in a variety of habitats as a result of their ability to withstand a wide range of temperatures. Unlike other aphids which move to woody areas throughout the course of the year, the Russian wheat aphids live inside the rolled leaves of cereal crops and grasses year round. Of these cereal crops, wheat and barley are the plants most commonly infested by (Dolatti, et al., 2005; Hodgson and Karren, 2008; Michaud J. P and Sloderbeck, 2005). Other cool season grasses such as crested wheat grasses, intermediate wheat grasses, and wild ryes serve as host plants when the preferred cereal crops are not available. These cool season grasses are essential for the survival of the Russian wheat aphid during the warm seasons between wheat harvest and wheat emergence.
Russian wheat aphids are green and relatively small, ranging from 1.6 to 2.1 mm long. The body of the aphids is spindle-shaped, appearing wider in the middle and tapering on each end. Russian wheat aphids have short antennae and a piercing-sucking stylet on their head. When the aphid is observed from the posterior end, the sides create what looks like a double tail. Russian wheat aphids have reduced cone-shaped cornicles with their wings which appear like shoulder pads. (Hodgson and Karren, 2008; Michaud J. P and Sloderbeck, 2005; Hein, et al., 1989; Hodgson and Karren, 2008; Michaud J. P and Sloderbeck, 2005)
The Russian wheat aphid life cycle begins inside a parthenogenetic female, where development takes place without fertilization. These females give birth to live, genetically identical daughters. Young nymphs appear similar to the adult aphid but covered with a white waxy filament. The maturation of (Merchant, 2014; Michaud J. P and Sloderbeck, 2005; Sutherland, 2006)depends on the temperature of their environment. If the temperature in their environment is below 25 degree Celsius, they mature at a slow rate. Whereas an aphid living in an environment with a temperature at or above 25 degrees Celsius will grow at a much faster rate. On average, Russian wheat aphids take nine to 55 days to become a mature adult aphid. In some populations, sexual reproduction takes place between males and females just before winter. The female lays eggs that overwinter, and emerge again in the spring.
The Russian wheat aphid can reproduce both sexually and asexually. North American populations consist solely of females, so they do not mate at any point in their lives. Other non-North American populations mate in the fall, though there is little additional information available. (Hodgson and Karren, 2008; Merchant, 2014)
The Russian wheat aphid can reproduce sexually and asexually. During asexual reproduction, female aphids do not lay eggs, and instead give birth to live genetically identical daughters over the course of 60 to 80 days. Asexual reproduction causes massive growth within the population. In North American populations, there have been no traces of male aphids. As a result, the female aphids are unable to reproduce sexually and rely solely on asexual reproduction to produce their offspring.
reproduces in high numbers forming colonies that benefits its survival. On average, Russian wheat aphids take 9 to 55 days to reach maturity and start reproducing. Temperature that best suits the reproduction cycle of the aphids ranges from 15 to 21 degrees Celsius. Although Russian wheat aphids can survive in a variety of temperatures, a temperature below 4 degrees Celsius will stop aphid reproduction. On average during temperatures between 15 and 21 degrees Celsius, a mature Russian wheat aphid can produce up to 1.5 daughter nymphs per day over the span of a month. In some cases, females can reproduce up to four nymphs in a single day.
In non-North American populations, sexual reproduction may occur in the fall, where females mate and then lay eggs that overwinter. (Hein, et al., 1989; Hodgson and Karren, 2008; Merchant, 2014; Michaud J. P and Sloderbeck, 2005)
, like most aphids, lives in large colonies. There are several generations of winged aphids produced each year. Aphids in general are poor fliers and strongly rely on wind to move them from area to area as they search for new host plants. The rest of the aphids are wingless.
The every day behavior of Russian wheat aphids can be sorted into phases, based on their feeding activity. During the first phase, the aphids find a potential plant to feed on. This is a random process that is referred as the pre-alighting behavior. During the second phase, the aphids will begin to examine and explore the plant's leaves searching for a spot to feed upon. This phase is known as the exploration of the plant surface and the immediate subepidermal tissues. The third and fourth phase are joined phases. In these phases the aphids look for the parts of the plant that are nutritional tissues and begin eating. The aphids feed from the phloem in the leaves. When an aphid is done taking the nutrients it needs, it moves on to a new potential plant. (Caillaud, et al., 1995; Hodgson and Karren, 2008; Merchant, 2014)
Alate Russian wheat aphids fly to plants in new areas to establish new colonies. Since aphids are poor fliers, it is unlikely that they travel long distances unless on a particularly strong wind current. Wingless aphids and nymphs are sedentary and remain in the same general area. (Hodgson and Karren, 2008; Merchant, 2014)
Russian wheat aphids communicate with each other by producing an alarm pheromone. The alarm pheromone is secreted by the cornicles located at the end of the abdomen. The alarm pheromone helps detect another aphid or a predator near them. If a predator is near they respond by dropping off the host plant. (Becker, 2000)
Russian wheat aphids feed on phloem from plants, using their stylet mouth parts to pierce the plant material. They tend to be found in small grain fields or grasses year round. They favor mostly wheat and barley and in cold seasons they switch their diet to wheatgrass, intermediate wheatgrass, and Canada wild rye. They start feeding on the top or edge of the plant depleting the plants nutrients. Once the plant loses its nutrients and a colony of large numbers begins to form, the leaf begins to rapidly roll inward, protecting the aphids from dangers including natural enemies and insecticidal sprays.
During the Russian wheat aphid feeding process they release toxins that cause discoloration on the plants they feed on. The toxin released inside the plants causes the plants to become discolored and can appear white, purple, and yellow to the naked eye. When feeding on developing plants they can prevent the head of the plant to open up stunting the plants development. In some cases, the Russian wheat aphid causes the edges of wheat grains to become bleached, halting the grains development.
Natural predators of the Russian wheat aphids include the convergent lady beetle (Hippodamia convergens), the seven-spotted lady beetle (Coccinella sepempuncata), the lady beetle Hippodamia variegata, Aphidiid wasps (Aphidiidae), hover flies (Diptera: Syrphidae), Scymnus beetles, lacewings (Chrysopidae), rove beetles (Staphylinidae), and spiders (Araneae). The Russian wheat aphid hides in the curled leaves of a wheat plant, making it hard for larger predators to reach them. Convergent lady beetles, seven-spotted lady beetles and Scymnus beetles are small enough to crawl inside the curled part of the leaves and feed on the aphids. They also drop off their host plants when a predator is near, and alert the colony of a predators' presence with an alarm pheromone. (Adisu, et al., 2003; Knutson, et al., 1997; Michaud J. P and Sloderbeck, 2005)
As one of the most invasive agricultural species in the world, Russian wheat aphids have an extensive impact on the ecosystems they invade. As their habitat range continues to expand into new regions, Russian wheat aphids are continually destroying the plants they feed on, which include a variety of cereal grains, such as wheat and barley. While feeding, the Russian wheat aphid transfers a toxin that causes extreme discoloration. Plants that become heavily infested with the toxin have leaves with identifiable purple, white, or yellow streaks. Heavy feedings fromcan also prevent normal formation and distortion of grain heads and leaves. In some cases their feeding averts the proper unrolling of leaves and causes the formation of bleached heads with poorly shaped grains. As a result, grain production and quality is drastically reduced.
Like all aphid species, Buchnera spp. This is an obligate relationship for both organisms, as Buchnera can survive outside of bodies of aphids. In return, Buchnera produces essential amino acids that Russian wheat aphids need to survive and do not get from their plant phloem diet.has an endosymbiotic bacterium,
Russian wheat aphids are also parasitized by many parasitoid wasp species. The wasps lay an egg inside of the aphid's body, which cause the eventually mummification and death of the aphid. These wasps are often used as natural biocontrol methods to prevent infestations of Aphidius species such as Aphidius colemani, braconid wasps, Aphelinus albipodus, and Lysiphlebus testaceipes. (Adisu, et al., 2003; Hodgson and Karren, 2008; Lai, et al., 1996; Michaud J. P and Sloderbeck, 2005; Turanli, et al., 2012). Parasitoid wasps species for Russian wheat aphids include
There are no known positive effects ofon humans.
In the United States, the Russian wheat aphid has caused many significant economic losses. Since their discovery in Texas in March 1986, the United States has lost millions of dollars in wheat and barley production. In addition to the depletion of cereal crops, millions of dollars have been spent on pesticide treatments in attempts to quarantine the species. In 1988, the annual yield losses peaked at $274 million dollars but in later years dropped to $10 million. While in recent years the appearance of the Russian wheat aphid has decreased, the species still appears occasionally across the High Plains in Nebraska, Wyoming, Colorado, Kansas, and New Mexico. (Hein, et al., 1989; Michaud J. P and Sloderbeck, 2005)
As an invasive species, (Turanli, et al., 2012)has no special conservation status. Instead, Russian wheat aphids are considered to be one of the most invasive pests of small grains in the world, and there are many efforts to control their populations.
Najma Salah (author), Grand View University, Kassie Sopher (author), Grand View University, Ashley Sowder (author), Grand View University, Felicitas Avendano (editor), Grand View University, Dan Chibnall (editor), Grand View University, Angela Miner (editor), Animal Diversity Web Staff.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the southern part of the New World. In other words, Central and South America.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
living in landscapes dominated by human agriculture.
reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
An animal that eats mainly plants or parts of plants.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
fertilization takes place within the female's body
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
found in the oriental region of the world. In other words, India and southeast Asia.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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