Corn Leaf Aphid

Pest Facts Crop Impact • Latin name: Rhopalosiphum maidis • Favorable conditions for crop injury: • Warm temperatures (77 F +) • Worldwide pest of corn and related grass crops; • Drought stressed plants present nearly everywhere corn is grown • Low populations of natural enemies • Can cause yield loss by feeding and causing stress • Host range is corn, barley, sorghum, wild grasses, on the plant but also is an important vector of corn cultivated grasses, winter wheat, other grasses viral diseases such as maize dwarf mosaic in corn and barley yellow virus in wheat • The winter host of corn leaf aphid is winter barley but winter rye and winter wheat are alternates • Usually female; • Pollination is NOT affected unless nearly all tassels males are very rare are covered with aphids

Corn Leaf • Aphids interfere with photosynthesis and cause water Aphids and nutrient stress, reducing ear size and yield

Corn ears from uninfested (left), and heavily Pest Symptoms / Injury ID infested (right) • Feeds primarily in corn whorls plants • Removes moisture and nutrients • Excess sap ingested is secreted as sticky honeydew Natural Enemies which may attract ants • Heavy infestation turns leaves red or yellow from nutrient loss and stress, which may shrivel and die • Colony may expand to tassel at emergence; tassel may be killed from extensive feeding • Late season colonies move to the lower stalk and ear husk or other protected areas of the plant Lady beetle Lacewing Syrphid Fly • Adult • Green or Brown • Larvae Predatory Bugs (Aphis Lion) • Damsel Bug • Minute Pirate Bug Entomoptera Fungus Parasitic Wasps • Big Eyed Bug

Upper leaves Heavily killed by aphids infested tassel

Pioneer Agronomy Sciences ®, TM, SM Trademarks and service marks of Pioneer Hi-Bred. © 2010, PHII Pest ID Management Considerations Key Characteristics • Blue-green color, trimmed IPM Practices in black • When the crop is under moisture stress populations • Black head with medium may increase rapidly length black cornicles or “tailpipes” • Aphid populations are highly susceptible to control • Short black antennae and from natural enemies, especially scout fields which black legs have had early season insecticide applications as it may be conducive to aphid outbreaks Related/Confused Species • Scout three and two weeks prior to tasseling. • Green bug: Light green with Consider treating if colonies of 30-100 CLA can be brighter stripe down the back, found in the whorl, especially if corn is under cornicles long with black tip, green moisture stress and evidence of natural enemies is legs and antennae low • Oat-bird cherry aphid: Dark green, medium length black tipped • Treating high numbers of aphids at tasseling is cornicles, reddish brown saddle at usually too late to recover costs or damages the base of the cornicles. Green or gray legs. More round than • Hybrid Selection – There are no truly resistant corn leaf aphids (CLA). Found in hybrids to CLA, nor is there any transgenic approach small colonies or mixed with CLA. to their control at present. However, hybrids that • English grain aphid: Bright green, exert their tassel better under stress may allow very long dusty cornicles, long natural enemies access to the aphid and thus result dusty gray antennae and green in fewer highly infested plants legs with black joints. Usually found in very small colonies of just • Select pesticides that do not harm beneficials a few individuals.

Life Cycle • Develop through gradual metamorphosis Pregnant • nymph, adult Adult Female • Four nymphal stages, resemble adults • Reproduce without mating; give birth to live nymphs, males extremely rare • Wingless forms most common • Winged forms with black head and thorax are Nymphs A. Adult male; B. Adult female- winged; C. Adult female- wingless produced when colony becomes stressed or overcrowded • Dense colonies formed on plants; shed skins are Molted Skin white and shriveled • 40-50 generations per year • Overwinters on winter cereals Overwintering