Cereal Aphids

Cereal aphids represent the most damaging arthropod pests of wheat in most of the Great Plains. Russian wheat aphid and greenbug are by far the most common and most devastating aphids, but other species, such as bird cherry-oat aphid, corn leaf aphid, and English grain aphid are occasional pests in wheat. The most detailed integrated management techniques and control methods have been developed for Russian wheat aphid and greenbug because of their persistent damage in parts of the Great Plains each year. Problems stemming from infestations of the other species can be ascertained using sampling methods similar to those for Russian wheat aphid and greenbug.

When approaching cereal aphid management, it should be kept in mind that the wheat ecosystem is complex. Aphids feeding on wheat are often attacked by naturally occurring predators and parasitoids (biological control). These natural enemies suppress aphid abundance and in many years can be relied upon as effective control agents. Coupling naturally occurring biological control with host plant resistance is often a completely effective control combination that does not require additional intervention.

Economically important cereal aphid infestations usually occur when the natural balance is disrupted. These disruptions can be the result of harsh climatic conditions that negatively impact natural enemies, the selection and proliferation of aphid genotypes virulent to genetic resistance bred into wheat, or the inappropriate use of insecticides.

Scouting wheat for pest presence is paramount for management of cereal aphids in those years when nonchemical controls fail. Sampling techniques have been developed to help producers properly sample fields to determine if cereal aphids will develop into a problem that might require chemical control. Relying on chemical control as a prophylactic or insurance treatment is a poor management option. It is environmentally unsound and economically inefficient to “program in” chemical control. Efficient and easy-to-use sampling methods, in most years, result in a decision not to use chemical control. Releasing commercially available aphid predators or parasitoids can prove to be a wasteful and unsound practice, as well.

Barley yellow dwarf virus (BYDV) is a common disease problem associated with most cereal aphids (see Chapter 9- “Disease Management of Wheat”). Although a serious problem in wheat, there are no specific management strategies to control BYDV transmission by these aphids. Bird cherry-oat aphid and English grain aphid likely are the most important carriers of BYDV, but greenbug and corn leaf aphid can transmit it as well. Control methods mentioned throughout this chapter are directed at controlling damage caused by aphid feeding habits and will not reduce the incidence of BYDV.