Therioaphis trifolii (Monell, 1882)

Morphological characters

1.4-2.0 mm.
Apterous: whitish to yellowish with small abdominal patches more or less dark topped with a hair and a knobbed cauda, weakly pigmented on a bilobed anal plate.
Alate: abdomen light-coloured with a network of small patches, ends of wing veins smudged, cornicles very short, slightly pigmented, cauda knobbed, slightly pigmented on a bilobed anal plate.

Life cycles

Monoecious holocyclic in regions with climate cold.
Anholocyclic in the other regions.

Host plants

Fabaceae: Medicago (lucerne), Trifolium (clover), Melilotus (melilot), Onobrychis (sainfoin), Lotus (birdsfoot trefoil).

Particular characteristics

T. trifolii is not frequent in France.

Agronomic impact

Injections by T. trifolii lead to drying and shriveling of leaves.
The secretion of honeydew leads to formation of sooty mould which diminishes chlorophyll uptake.
It transmits lucerne mosaic virus (AMV) according to the non-persistent mode.

Natural enemies

Parasitoids :

• Aphelinus asychis
• Praon exoletum
• Trioxys complanatus