Pachypappa sacculi

Pemphigus bursarius

Thecabius populiconduplifolius

Asiphum sacculi Gillette 

[A photo of this gall appears on page 2 of the pdf]

This species was described from Colorado by Gillette (1914) and recorded from Utah by Knowlton and Bischoff (1939). Palmer (1952) considered Pemphiglacnus kaibabensis described from Arizona by Knowlton (1928) to be a synonym. 

A. sacculi has been found in the foothills and mountain areas of southern Alberta since 1959. It forms a pseudogall on Populus tremuloides Michaux by causing a leaf to increase greatly in area and its sides and end to fold over (Fig. 1). In the gall are the fundatrix and her offspring with large numbers of ants. A. sacculi has also been found in Ontario on P. tremuloides (G. A. Bradley, personal communication). 

Pemphigus bursarius L. 

[A photo of this gall appears on page 2 of the pdf]

This species, commonly known as the lettuce root aphid, has been found in the United States (Palmer 1952), Europe (Stroyan 1964), New Zealand (Cottier 1953). North Africa, and the Middle East (Bodenheimer and Swirski 1957). In Canada it has been found on Lombardy poplars in Ontario and Quebec. P. bursarius has also been reported as an important pest of lettuce in England and the United States (Dunn 1959; Lange et al. 1957). 

In Alberta P. bursarius was first found in 1963 on a few specimens of Populus nigra L. var. italica Muenchhausen in a garden at Lethbridge, and could become a pest of lettuce in southern Alberta. The galls, which are generally on the petiole but are occasionally found on young shoots, vary in size and shape but are purseor flask-shaped (Fig. 2). In the gall are the fundatrix and her offspring. 

Dunn (1959) considered that synonyms of P. bursarius are Aphis bursarius L., Pemphigus glandifomis Rudow, P. lactucarius Passerini, and Eriosoma populi Mosley.

Thecabius populiconduplifolius Cowen 

This species was first described from Populus monilifera Aiton (= P. deltoides Marsh) in Colorado (Cowen 1895). Palmer (1952) also reported it from Colorado on Populus sargentii Dode. In Canada T. populiconduplifolius has been found in New Brunswick on Populus balsamifera (M. E. MacGillivray, personal communication).

This species has been found on Populus balsamifera L. in a farm shelterbelt and in the St. Mary's River Valley near Lethbridge, Alberta. The fundatrix causes the leaf margin to fold under to form a gall (Fig. 3). Her offspring leave the gall and feed on the underside of newly emerging leaves causing the outer edges to fold inwards toward the centre (Fig. 4). These pseudogalls vary considerably in shape. 

Palmer (1952) reported the summer host as Ranunculus L. in Colorado and California and considered Pemphigus ranunculi Davidson and P. californicus Davidson to be synonyms. 

Palmer indicated that T. populiconduplifolius is similar to T. affinis (Kaltenbach) and that Mordvilko considered them to be inseparable. The species are separated in her key by the number of secondary sensoria on the sixth segment of the antennae of the fundatrigenia but she indicates that affinis is a European species. In a collection of aphids initially considered to be T. populiconduplifolius, from a few trees in one small area of southern Alberta, the author found specimens with characteristics of each species. In this collection some of the specimens were not bilaterally symmetrical and would have been placed in affinis on the basis of one antenna and populiconduplifolius on the basis of the other antenna. 

Bodenheimer and Swirski (1957) reported the secondary host of affinis to be Ranunculus. As the secondary hosts of the two species are the same and some specimens have characteristics of both species, it appears that afinis and populiconduplifolius may be synonymous or perhaps that there is hybridization between the species. 

Three Additional Poplar Gall Aphids From Southern Alberta