Life cycle and risk factors for rose–grain aphid in cereals

Direct feeding damage from rose–grain aphid can cause yield losses in cereals in summer if populations exceed thresholds. Although this species can transmit Barley yellow dwarf virus (BYDV), it is generally unimportant as a vector as it is not normally found in cereals in the autumn. 

• The earlier senescence of winter barley puts it at lower risk 
• Plants that are stressed (for example, by drought, or pests and diseases) suffer more because they have lower reserves of soluble stem carbohydrates 
• Dry, settled weather during early grain filling increases risk 
• Rose–grain aphids tend to be more problematic after hard winters when natural enemies are scarcer 

Scientific name: Metopolophium dirhodum 

Wingless adults are medium–sized, 1.6–3 mm long and light green or, rarely, pink. Green varieties have a bright green stripe down the centre of their back.  

Winged adults have a pale yellow-green abdomen with darker green markings. 

Dec–Feb: Eggs overwinter on wild and garden roses. 

Mar–Apr: Winged forms migrate to crops and reproduce. 

May–Sep: Aphids feed on the leaves of crops and grasses. Only very severe infestations produce visible symptoms in crops. Infested leaves turn yellow and senesce prematurely. 

Oct–Nov: Eggs are laid on wild and garden roses. 

Dec–Apr: Adults can overwinter on grasses but are not normally found in cereals in autumn. 

Non-chemical control 

Natural enemies include lacewings, ground beetles, soldier beetles, rove beetles, ladybirds, spiders, and fungal diseases. Grass banks and field margins provide overwintering habitats, alternative foraging sites and refuges for natural enemies in summer. While grasses can harbour infective aphids, they also help maintain populations of parasitic wasps, facilitating faster colonisation in spring.

Monitoring 

Check lower leaves at about the time the cereals come into ear and monitor top leaves during later growth stages. Aphids do not move to the ear.  

Thresholds 

Before the start of flowering (growth stage 61): 50% of tillers infested.  

After the start of flowering (growth stage 61) to 2 weeks before end of grain filling: 66% of tillers are infested and aphid numbers are increasing.  

Insecticide resistance 

None known.