POTENTIAL OF MYZUS-LYTHRI (HOMOPTERA, APHIDIDAE) TO INFLUENCE GROWTH AND DEVELOPMENT OF LYTHRUM-SALICARIA (MYRTIFLORAE, LYTHRACEAE)

The host-alternating life cycle of Myzus lythri, an aphid of European origin that feeds on purple loosestrife (Lythrum salicaria), is detail ed. The complex life cycle and low availability of primary host plants are hypothesized as limiting early-season development of aphid popula tions on purple loosestrife. Experiments were undertaken in 1993 to de termine if large populations of this aphid could influence the growth and development of purple loosestrife. Two-year plants each inoculated with five aphids showed significantly lower root and shoot weight aft er a 7-wk period as compared with matched controls. Over half of 20 se edlings (3 mo old) inoculated with two or five M. lythri were dead or clearly dying 11 wk after inoculation. Mass rearing for early-spring r elease and planting primary hosts are possible methods to augment the potential of this aphid to function as a biological control agent for purple loosestrife.