Rhopalosiphum insertum (apple-grass aphid)

On apple, R. insertum feeds on the undersides of young leaves, causing the leaves to curl from base to tip, rather than from edge to edge. No colour changes occur in leaves, unlike foliage damage due to other apple aphids.

R. insertum is an economic pest of apples in Europe and North America. Damage is due to direct feeding on the young leaves, shoots and buds. Most damage is caused in spring, when the flower buds are opening. Considerable crop yield losses can occur due to the constant sucking of sap, which decreases fruit set and can cause the premature fall of fruitlets. R. insertum is one of several aphid species responsible for considerable loss of crops annually, particularly in orchards that are not regularly sprayed ( Rogerson, 1947 ; Evenhuis, 1968 ).R. insertum is also a pest of cereals, due to its ability to transmit the persistent barley yellow dwarf luteovirus (BYDV). All the major cereal aphids are vectors of BYDV, including Rhopalosiphum padi, Sitobion avenae and Metopolophium dirhodium, in addition to R. insertum. Yield losses due to early season inoculation with BYDV can be as high as 35-44% in wheat, 35-51% in barley and 67-81% in oats ( Vickerman and Wratten, 1979 ). R. insertum can also transmit potato Y potyvirus N (PVYN) (Van Hoof, 1980).