short note- black bean aphid aphis fabae scopoli (homoptera –aphididae) an important pest of seed beet

black bean aphid is widely distributed in the world. it has several hosts from weeds and cultivated plants. this aphid passes the winter as egg on some permanent weeds, box tree and etc. young wingless hatches from the eggs in the spring and the winged aphids after appearance migrate to seed beet fields. after producing some generations, they fly to the various summer hosts such as bean, sugar beet and weeds. damage to tissue of the lower surface of the leaf, loss of sap and injection of toxic saliva curls the leaves severely and causes wilting and stunting of the plants. as the aphids multiply, leaf curling increases so that the aphids are sheltered, thus adding to the difficulty of killing them with insecticide. colonies in the hearts of sugar beet  injure the young leaves. damage to young inner leaves is always more severe than to the older and outer leaves. a sticky fluid known as honeydew, which is excreted from gut of the aphid, coats the leaves and encourages growth of sooty moulds preventing photosynthesis. on seed crops, a. fabae feeds also on the flower heads and prevents them from normal development. the flowering shoots of sugarbeet and terminal buds of beans are especially susceptible to infestation and are covered with aphids in a short time. this aphid can limit the seed production. high infestation reduces the seed yield and quality of the seed. during a mild winter and a dry spring, the population of this aphid increases, therefore the percentage of infested plants is to rise and fall in different years. control is achieved by spraying with oxydimethon metyl (1 liter per hectar) and thiomethon (1 liter per hectar ).