Since then it has been described under various names by Aizenberg , Mimeur , Bodenheimer and Swirsky and Anon. Although its integument is slick just after moult, it soon becomes covered with a waxy white exudate. The eyes and distal third of the antennae are dark; the head and thorax of winged adults are also dark. It has six-segmented antennae about half the length of the body. The rostrum reaches to about the middle coxae.
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Since then it has been described under various names by Aizenberg , Mimeur , Bodenheimer and Swirsky and Anon. Although its integument is slick just after moult, it soon becomes covered with a waxy white exudate. The eyes and distal third of the antennae are dark; the head and thorax of winged adults are also dark. It has six-segmented antennae about half the length of the body.
The rostrum reaches to about the middle coxae. The cauda is elongate, and above the cauda is a supracaudal process on the 8th abdominal tergite, which gives it the appearance of having two caudae and distinguishes it from all other cereal aphid species.
The supracaudal process is almost as long as the cauda on apterous adults, but it is smaller and less conspicuous on alates and nymphs. Blackman and Eastop , Stoetzel , Pike et al. Aalbersberg et al.
A record of D. The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Although it has not yet become a pest in Argentina and Chile, its rapid spread suggests that it may soon become one. However, Hughes and Maywald , using a climate-matching model, predicted potentially severe infestation of Australian cereals if D. Although nymphs and adults are very unlikely to be transported alive on harvested grains or fodder, overwintering eggs could be transported in this way. However, D. Although it is possible that the sexual phase was lost after colonization, it appears more likely that the founders were also anholocyclic.
Kindler and Springer found that D. They found that it did not develop on any of 27 legume species or 17 forb species to which it was exposed. Pike and Allison compiled a list of host plants from the literature, comprising grass species with varying degrees of suitability for D.
Zea mays does not appear suitable for D. Thus it appears that D. Furthermore, it reproduces best and does most damage on cool-season grasses. Although D. Even very small colonies of D. The streaks usually extend most of the long axis of the leaf and are irregularly distributed across the short axis of the leaf.
Rolling extends in severity from simple folding of the leaf along the mid-vein, to one side of the leaf rolled in upon itself, to the whole leaf being tightly rolled around the aphid colony. Large colonies can roll the flag leaf to the point where the tip of the inflorescence becomes trapped, giving it a fish-hook shape. Young plants are often stunted and even killed. Plants attacked after flowering show few to no obvious symptoms.
Duration of infestation may have more impact than aphid density on yield loss Burd and Burton, ; Kieckhefer and Gellner, Hughes , and Araya et al. With a daily fecundity of nymphs per day and adult longevity of about 80 days in the laboratory, D.
Plant growth stage, temperature, and their interaction affect D. For D. Winter survival can depend on the details of aspect and snow cover so that within a field, survival can be high on the south-facing sides of furrows receiving greater solar insolation Hammon and Peairs, The geographical range of D.
Furthermore, even in areas with low rainfall, D. Alates are formed when plants are water stressed, not when aphids are crowded Baugh and Phillips, The rapid spread of D. However, quantitative measurements are lacking, and it seems likely that it was present in many areas at low numbers before being detected, so that its rate of spread may have been less than it would appear. Wheat and barley can provide suitable habitat for months of the year, but wild grasses are very important for persistence and growth of D.
In Eurasia, some populations have both sexual and asexual generations i. However, in other European populations e. Besides differences in life-cycle among populations, D. Despite initial indications that D. Coccinellids were found associated with D. Coccinella septempunctata was the species most frequently found in association with D. Although some of the other species, for example Scymnus spp.
Yu and Liang described 17 species of coccinellid attacking D. Both larvae and adults of coccinellids can prey on aphids; however, they attack other prey as well: for example, eggs of Lepidoptera. Furthermore, these predators do not in general show strong prey preferences or great differences in development when exposed to various aphid species Michels and Flanders, ; Formusoh and Wilde, Syrphids were associated with D.
Syrphid adults eat nectar, honeydew and pollen, but their larvae eat aphids. The number of eggs laid by adult female E. Leucopis spp. Most have been identified as L.
Like syrphids, adult Leucopis spp. Although they occur in a variety of habitats, their small size has led some to argue that they should excel at attacking D. Adult female L. Females oviposit preferentially in aphid colonies and lay more eggs where aphid density is higher Dabire, Although females tend to lay more eggs in leaf sheaths, neither they nor their larvae prefer D.
The number of aphids consumed has a great impact on larval development and survival and on adult size and fecundity Dabire, Aphelinus spp. They are solitary endoparasitoids of nymphs and adults of many aphid species: A. Females are only weakly attracted by volatiles from the plant-host complex Farias, Adult females of Aphelinus spp.
However, in the Montpellier region of France , levels of parasitism of D. The taxonomy of the genus Aphelinus needs revision. Although parasitism of D. Parasitoid species in the braconid subfamily Aphidiinae were collected from D. Diaeretiella rapae was the most frequently collected from D.
Aphidiines are solitary endoparasitoids of nymphs and adults of a wide variety of aphid species: D. Unlike aphelinids, they do not host feed. Aphidius matricariae develops on D.
They are attracted to volatiles from the plant-host complex in general and from D. Parasitism of D. Fungal pathogens were collected from D. This may be in part because some collectors lacked the training to collect and culture entomopathogenic fungi. Nonetheless, epizootics of fungal pathogens in D. Prevalence of fungal pathogen infections has also been low in the US Feng et al. At least two viruses, aphid lethal paralysis virus and Rhopalosiphum padi virus, are known to attack D.
It is a phloem feeder like other aphids and the symptoms evident on plants are a result of this feeding mechanism. By feeding on the phloem, the aphid damages the plants through nutrient drainage Dixon, which results in chlorosis, necrosis, wilting, stunting, and curling of the leaves, misshapen or nonappearance of new growth, and localised cell death at the site of aphid feeding.
Barley and wheat are the most important cultivated hosts of D. It is particularly injurious to late-sown barley in continental climates. Spring wheat suffers greatest yield loss when attacked during tillering to boot stage; winter wheat suffers greatest loss after vernalization Gray et al.
Early, heavy infestations on barley can cause total crop loss Adisu et al. Aphid feeding on susceptible genotypes causes chlorosis and longitudinal streaking of leaves, and emerging leaves remain tightly rolled, which traps spikes and prevents their normal development Mornhinweg, Infestation of wheat seedlings by D. In general, damage is greatest when crop ripening coincides with peak aphid numbers. In the Crimea, D. Since its appearance in Texas in Stoetzel, , D. Since its introduction in , it has also become the major pest of wheat in South Africa Walters et al.
Macedo et al. Wheat plants tolerant to D. In addition to direct feeding damage, major indirect losses in wheat and barley can be caused as a result of D. There have been conflicting reports on the effect of D.
List of symptoms / signs
Manya B. By the end of , D. Damage to wheat and barley during was extensive in some fields in Texas, New Mexico, and Colorado; crop losses were heavy in these areas. In addition to D. A brief summary of taxonomic characteristics, usual hosts, and known distribution within the United States is given here for each species along with a couplet key and pictorial plates. This information should prove very useful to county, state, and federal personnel involved with surveys of grain aphids, particularly those surveys for D.
Russian wheat aphid
The Russian wheat aphid, Diuraphis Noxia , is one of the most invasive agricultural pests found across the globe. As a result, these aphids are now found on every continent except Australia and Antarctica. Most recently, the Russian wheat aphid has invaded Canada and the United States. Dolatti, et al. P and Sloderbeck, ; Zhang, et al. 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.
The Russian wheat aphid Diuraphis noxia is an aphid that can cause significant losses in cereal crops. The species was introduced to the United States in and is considered an invasive species there. Cornicles are very short, rounded, and appear to be lacking. There is an appendage above the cauda giving the aphid the appearance of having two tails.
Diuraphis noxia (Kurdjumov, 1913)
Metrics details. The Russian wheat aphid, Diuraphis noxia Kurdjumov, is one of the most important pests of small grains throughout the temperate regions of the world. This phytotoxic aphid causes severe systemic damage symptoms in wheat, barley, and other small grains as a direct result of the salivary proteins it injects into the plant while feeding. We sequenced and de novo assembled the genome of D. The D.