Russian Wheat Aphid
FACTS, IDENTIFICATION & CONTROL
The Russian wheat aphid is a small green insect with a football-shaped body about 2 mm in length. It has short, rounded cornicles, which it uses to emit pheromones or defensive secretions. Its legs and antennae are shorter than those of other aphids. Unlike other aphid species, it has a supracaudal structure, meaning it has a twin-tailed appearance. Russian wheat aphids are typically covered with a powdery wax coating.BEHAVIOR, DIET & HABITS
Russian wheat aphids can be found on grasses or the underside of small grain leaves all year long. Their host plants are natural grasses including wheat, barley and rye. They are tolerant of cold weather and able to survive in below-freezing temperatures. The aphids also are able to survive in a variety of other habitats because of their ability to withstand a wide range of temperatures. Russian wheat aphids prefer temperate terrestrial areas including savannas and grasslands.
These insects are native to southern Russia, Central Asia and the Middle East. They spread to other countries beginning in the early 1900s, and now they can be found on every continent except Australia and Antarctica. They most recently have invaded Canada and the United States. All states North and West of Texas now have the Russian wheat aphid established within.REPRODUCTION
The Russian wheat aphid can reproduces both sexually and asexually. Because most of the population in North America consists solely of females, many aphids do not have the opportunity to mate at any time during their lives. Non-North American Russian wheat aphids are known to mate in the fall. During asexual reproduction, females do not lay eggs. Over the course of 60 to 80 days, they give birth to genetically identical daughters. Because there is no male aphid population in North America, female aphids rely on asexual reproduction to produce offspring.
Russian wheat aphids generally take nine to 55 days to reach maturity and start reproducing. Temperature dictates when they decide to reproduce. The reproduction cycle is typically completed in temperatures ranging from 15 to 21 degrees Celsius. Anything below 4 degrees Celsius will completely stop reproduction. During the right temperatures, an aphid can produce one to two daughter nymphs per day in a given month. On occasion, females can produce up to four nymphs in a single day.SIGNS OF A RUSSIAN WHEAT APHID INFESTATION
Russian wheat aphids can be found on the young leaves of wheat crops. They prevent leaves from unrolling when they feed, as they inject toxins into the plant tissue. The toxins cause the leaf to curl up and white, purple or yellow streaks form. Heavily infested plants appear flattened or prostrate. Wheat grain heads may be bleached in appearance. Some of these symptoms can be caused by other diseases and disorders like viral damage, herbicide or nutrient deficiencies. If these symptoms are found, however, it is important to have the plants examined for aphids by a local extension service.ADDITIONAL INFORMATION
Russian wheat aphids are considered one of the most invasive pests of small grains in the world and many efforts have been made to control their populations. Some biological or chemical controls have been known to help manage infestations. Insecticides can reduce the chance of an aphid infestation. The following rules of thumb also can help reduce the likelihood of an infestation: test soil regularly, remove any unused grains, plant spring grains early to prevent aphids from starting colonies, keep grain fields healthy since aphids tend to do well in stressed fields.