Worldwide pest of corn and related grass crops; present nearly everywhere corn is grown
Can cause yield loss by feeding and causing stress on the plant but also is an important vector of corn viral diseases such as maize dwarf mosaic in corn and barley yellow virus in wheat
Usually female; males are very rare
Life Cycle of Corn Leaf Aphid
Develop through gradual metamorphosis
nymph, adult
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 produced when colony becomes stressed or overcrowded
Dense colonies formed on plants; shed skins are white and shriveled
40-50 generations per year
Overwinters on winter cereals
Impact on Crop
Favorable conditions for crop injury:
Warm temperatures (77 F +)
Drought stressed plants
Low populations of natural enemies
Host range is corn, barley, sorghum, wild grasses, cultivated grasses, winter wheat, other grasses
The winter host of corn leaf aphid is winter barley but winter rye and winter wheat are alternates
Pollination is NOT affected unless nearly all tassels are covered with aphids
Aphids interfere with photosynthesis and cause water and nutrient stress, reducing ear size and yield
Management of Corn Leaf Aphid
IPM Practices
When the crop is under moisture stress populations may increase rapidly
Aphid populations are highly susceptible to control from natural enemies,especially scout fields which have had early season insecticide applications as it may be conducive to aphid outbreaks
Scout three and two weeks prior to tasseling. Consider treating if colonies of 30-100 CLA can be found in the whorl, especially if corn is under moisture stress and evidence of natural enemies is low
Treating high numbers of aphids at tasseling is usually too late to recover costs or damages
Hybrid Selection – There are no truly resistant hybrids to CLA, nor is there any transgenic approach to their control at present. However, hybrids that exert their tassel better under stress may allow natural enemies access to the aphid and thus result in fewer highly infested plants