Currant-lettuce aphid

The currant-lettuce aphid (Hyperomyzus lactucae) belongs to the family Aphididae within the order Hemiptera. It is a migratory aphid species known for its distinct host alternation behavior, which is a critical factor in understanding its economic impact on horticultural crops.

The primary hosts of this pest include species of the genus Ribes (currants), which serve as winter hosts, and a wide range of Asteraceae species, particularly lettuce (Lactuca sativa) and sow thistles, which act as summer hosts. This ability to switch hosts allows the population to sustain itself throughout the growing season.

Regarding its biology, the species overwinters as eggs on currant shoots. In spring, fundatrices emerge and establish colonies on the undersides of young leaves. By early summer, winged forms (alatae) migrate to the secondary herbaceous hosts. After several generations on the summer hosts, winged migrants return to the currant bushes in autumn to mate and deposit overwintering eggs.

The damage caused by Hyperomyzus lactucae is significant. On currants, aphid feeding leads to leaf curling, distortion, and the development of reddish blisters. On lettuce, the aphids cluster on leaves, causing stunted growth and yellowing. Beyond direct physical damage, these aphids are vectors for several persistent plant viruses, which can lead to severe crop yield losses.

Effective management requires an integrated approach. Cultural practices such as maintaining weed-free borders, especially by removing sow thistles near lettuce fields, can reduce population pressure. When chemical control is necessary, systemic insecticides should be applied early in the season before the leaves curl, as curled leaves provide physical protection to the aphids, making contact sprays less effective.