Poplar-cudweed aphid

Taxonomic position: The poplar-cudweed aphid (Pemphigus populinigrae) belongs to the order Hemiptera and the family Aphididae. It is a heteroecious aphid species, meaning it alternates between a primary woody host and a secondary herbaceous host throughout its life cycle.

Host plants: The primary host is the poplar tree, specifically the black poplar (Populus nigra). The secondary hosts consist of various plants from the Asteraceae family, particularly those within the genus Gnaphalium (cudweed), where the aphid colonizes the root system.

Biology and life cycle: The species overwinters as eggs in the crevices of poplar bark. Upon spring bud burst, nymphs hatch and feed on the foliage, inducing the formation of characteristic galls. Within these structures, the aphid develops until winged morphs are produced in mid-summer, which subsequently migrate to the roots of the secondary herbaceous hosts to continue the reproductive cycle.

Damage and economic impact: The presence of this aphid is primarily detected by the formation of unsightly galls on the petioles and leaves of poplar trees. While the damage to poplars is mostly aesthetic, the infestation on secondary hosts can lead to reduced plant vigor, stunted development, and increased susceptibility to other pathogens due to the extraction of phloem sap from the roots.

• Monitor poplar foliage during early spring for initial gall formation.
• Manually remove and destroy infested leaves before winged aphids emerge.
• Apply systemic insecticides during the bud burst phase to target emerging fundatrices.
• Maintain tree health through adequate irrigation and nutrient management to increase tolerance.
• Avoid high-density planting of susceptible poplar varieties in susceptible regions.