Pemphigus bursarius (Linnaeus, 1758)

Morphological characters

1.5-2.7 mm.
Apterous: yellowish white, with tufts of wax on posterior part of abdomen.
Alate: grey-green, antennae short, abdomen light-coloured, cornicles absent, cauda rounded, very short.

See identification file

Life cycles

Dioecious holocyclic . and probably anholocyclic on secondary hosts

Host plants

Primary host: Populus spp (poplars),
Secondary hosts: cultivated Asteraceae: Lactuca (lettuce), Cichorium (chicory and endive) and wild: Lampsana, Sonchus.

Particular characteristics

P. bursarius spends winter as eggs sheltering in crevices of poplar bark. In spring, the egg gives rise to a fundatrix which settles on a leaf petiole. Her injections induce the formation of a characteristic purse-shaped gall (see photo).
Some weeks afterwards, the gall opens and hundreds of fundatrigenia fly off to colonize Asteraceae roots which become covered with a whitish waxy secretion. This eventually envelops the whole insect. At the end of summer, the winged sexual forms appear and return to lay eggs on poplar. However, asexual reproductive cycles can be observed on the secondary host.

Agronomic impact

The contaminated lettuce struggle to develop, leaves go yellow and wilt owing to the large quantities of sap the aphid draws from the roots.
Control using aphicide is not easy to achieve.

Natural enemies

Parasitoids :

• Aphelinus nikolskajae
• Monoctonia vesicarii