Waterlilly aphid

Appearance

Apterae of Rhopalosiphum nymphaeae are more or less shiny reddish-brown to dark olive, and are dusted with a light grey wax, especially on abdominal tergites 1-4. The dorsal cuticle has reticulation formed by regularly shaped roundish bead-like spinules. The siphunculi are more than twice the length of the cauda and are swollen on the distal half. The antennae are about 0.6 times the body length. The terminal process of antennal segment VI is prominently long and about 3-4 times the length of the base of that segment. The cauda is elongate and slender. On the primary host the apical rostral segment is more than 0.14 mm long and is 1-1.1 times as long as the second hind tarsal segment. On the secondary host the apical rostral segment is 0.15-0.2 mm long and is 1.15-1.45 times as long as the second hind tarsal segment. The body length of the aptera is 1.6-2.6 mm.

Behavior

Large colonies may develop on water lilies, the aphids congregating along the leaf veins and invading the flowers. The rate of development, natality and survivorship rates of Rhopalosiphum nymphaeae has been studied in relation to its potential for virus transmission both to crops and aquatic weeds. The optimal temperatures for Rhopalosiphum nymphaeae were 21 to 27 deg C.

Habitat

In spring the water lily aphid feeds on various Prunus species (such as Prunus spinosa) where it feeds on leaf petioles and fruit stalks curling the leaves. In early summer alatae migrate to the secondary hosts comprising a large variety of water plants, including Nymphaea (water lilies), Potamogeton (pondweeds), and Sparganium (arrowheads). The distribution is almost cosmopolitan.