Asiphum rosettei Maxson

Collections. On petioles and leaves of Populus tremuloides, causing leaves to be bent backward at base and stunting stems so as to form a rosette; fundatrix feeds on petiole and fundatrigeniae on unexposed side of leaves). Colorado: Canyon of South Saint Vrain (in Boulder County). Fundatrix and fundatrigeniae in July; very rare.

Pachypappa rosettei (Maxson)

Feeding by the fundatrix (BL 2.5-2.8 mm, appearance in life unknown) causes bending of leaves and stunting of stems to form a rosette-like nest, as in the closely-related European species P. tremulae. On Populus tremuloides in Colorado and Utah, USA, and secondary host populations are now recorded from Washington and Alaska (Pike et al. 2012). Alatae (BL 2.2-2.5 mm) are produced in July. Host alternation to roots of Picea spp. has now been confirmed by DNA bar-coding, and the apterous exule (BL 0.8-1.4 mm) redescribed (Pike et al. 2012). Aphids on roots of Pseudotsuga menziesii have also been tentatively assigned to P. rosettei (Danielsson 1990a). Anholocyclic overwintering may occur on spruce roots (Pike et al. 2012). Aphids infesting the roots of potted conifers in Canada and identified as P. tremulae may also be this species.

[records of Pachypappa tremulae, a European species are likely attributable to P rosettei:] The numerous records from North America on roots of Picea spp. and Pseudotsuga menziesii (also as Asiphum tremulae and Rhizomaria piceae; Lavallee 1987) may all be due to confusion with P. rosettei (Footit et al. 2006).

Asiphum rosettei n. sp.

Described from holotype and 9 paratypes taken on Populus tremuloides, 7,000 feet elevation in canyon of South St. Vrain Creek, Boulder Co., Colo., July, 1915.

The fundatrix appears to feed on the petioles of the newly opening leaves, causing them to become curved more or less backward. This forms a rosette of leaves by stunting the growth of the internodes of the young branch.

The fundatrigenia feed on the unexposed surfaces of the leaves forming the rosette. After the migration the young wood elongates somewhat so that the rosette gradually disappears except for a slight deformity of the branch and leaves.

Taxonomy: This species is very near Asiphum tremulae De Geer as described by Tullgren, but differs from it in having wax pores on lobes of metathorax and fewer secondary sensoria on III and IV of the antennae of the fundatrigenia.