Russian wheat aphid facts for kids

Quick facts for kids Russian wheat aphid
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hemiptera
Suborder:	Sternorrhyncha
Family:	Aphididae
Genus:	Diuraphis
Species:	D. noxia
Binomial name
Diuraphis noxia Kurdjumov, 1913
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The Russian wheat aphid (Diuraphis noxia) is a tiny insect, a type of aphid, that can cause big problems for important crops like wheat and barley. It's originally from southwestern Asia. This aphid was brought to the United States in 1986 and is now considered an invasive species there.

This small insect is pale green and can grow up to 2 millimeters long. It has very short, rounded tubes on its back called cornicles, which almost look like they're missing. A special part above its tail (called the cauda) makes it look like it has two tails! The liquid (called saliva) that this aphid injects into plants is harmful. It causes white stripes on leaves and makes the top leaf (flag leaf) turn white and curl up. This curling can stop the plant's grain head from coming out properly. Russian wheat aphids mostly feed on cereal grains like wheat and barley. They also feed on wild grasses such as wheatgrasses, brome-grasses, and ryegrasses.

What is the Russian Wheat Aphid?

The Russian wheat aphid is one of the most damaging pests for wheat crops around the world. It was first identified as a pest in Crimea in 1901. This aphid likely became a pest on cereal crops in Eurasia a long time ago. Besides directly harming crops, these aphids can also spread plant diseases. They can carry viruses like barley yellow dwarf, barley mosaic, and sugarcane mosaic viruses.

After it was found in the US in 1986, the Russian wheat aphid quickly became a major problem for wheat and barley farms. Scientists found types of wheat that could resist D. noxia in 1996. However, new types (called genotypes) of aphids appeared by 2003 that could overcome these resistant wheat plants.

How Aphids Harm Plants

D. noxia feeds on plants by sucking out nutrients from a part of the plant called the phloem. The phloem is like the plant's food delivery system. When aphids feed, they drain nutrients, which hurts the plant. This can lead to symptoms like leaves turning yellow (chlorosis), parts of the plant dying (necrosis), the plant drooping (wilting), or the plant not growing as tall as it should (stunting). The aphid also makes the plant send more essential amino acids into the phloem sap. This happens because the aphid triggers the plant to break down its own proteins, providing more food for the aphid.

Effects of Aphid Damage

Aphid infestations have many effects on the host plant and the products made from it. When aphids feed, plants lose water pressure (called turgor) and grow less. This is because the aphids cause water imbalances. The aphids also reduce the total plant material (called biomass). However, if the aphids are removed, the plant can recover quickly. Recovering plants become better at using carbon, which helps them grow faster and make up for the leaf damage.

Aphid damage on wheat also affects the flour made from it. When aphids feed on wheat, it reduces both the amount and quality of the flour. Flour from aphid-infested wheat is not as good for making bread. Even though the quality is lower, the flour can still be used.

Surviving Cold Weather

When D. noxia became an invasive species in North America, it showed it could survive cold winters. Aphid groups can live through temperatures between 0 and 5 degrees Celsius. However, temperatures below 10 degrees Celsius can cause a huge drop in their numbers. Besides surviving cold, these aphids can also quickly become resistant to sudden freezing temperatures. This is called rapid cold hardiness (RCH). What's more, they can do this without affecting their ability to have babies.

Managing Russian Wheat Aphids

Plant Resistance

One way to control D. noxia is by growing crops that are naturally resistant to them. Scientists have been studying specific genes in wheat and barley that help plants resist aphids. This information helps farmers breed new types of wheat or barley that are stronger against these pests. Genes like Dn1-Dn9 and Dnx have been found. By choosing plants with these genes, farmers can help manage aphid populations.

Getting Rid of Aphids

Using Natural Enemies

Scientists have looked at how to control D. noxia using natural methods. In Eurasia, where the aphid comes from, it's not as big of a pest. This might be because natural enemies there keep their numbers low. Researchers studied different types of tiny wasps from the Aphelinus genus. They found that one species, Aphelinus hordei, mostly attacks D. noxia. Female A. hordei wasps rarely go near other types of aphids. Because this wasp is so specific to D. noxia, scientists think introducing A. hordei to places like the US could help control the aphid population naturally.

Chemical Control

Scientists have also studied using potassium phosphate to help wheat plants resist D. noxia. This could be a way to deal with aphids that have become resistant to the wheat's natural defenses. Studies showed that wheat plants treated with potassium phosphate had fewer aphids feeding on them. This was true for both resistant and non-resistant types of wheat. This suggests that treating wheat with potassium phosphate could help plants tolerate D. noxia better.

See also

In Spanish: Pulgón ruso del trigo para niños