Aphis frangulae species group

Identification & Distribution:

Aphis frangulae alatae have 3-16 secondary rhinaria on the third antennal segment, 0-8 on the fourth segment and 0-3 on the fifth. The images below show adult apterous Aphis frangulae, dorsally and ventrally, in alcohol.

Subspecies

Until recently Aphis frangulae / gossypii was regarded as a cryptic group with uncertain separation between Aphis frangulae and Aphis gossypii. The two taxa were usually differentiated on the basis of life cycle and host plant. The work of Cocuzza et al. (2009a,b) and Carletto et al. (2009) has clarified the genetic separation between the two species in Europe.

In Europe, several subspecies are recognised:

• Aphis frangulae frangulae is the nominate subspecies which, in Europe, host alternates between alder buckthorn (Rhamnus frangula = Frangula alnus) as the primary host and rosebay willowherb (Epilobium angustifolium) as the secondary host. Additional secondary hosts are shepherd's purse (Capsella bursa-pastoris) and yellow loosestrife (Lysimachia vulgaris).
• Aphis frangulae beccabungae host alternates from alder buckthorn (Rhamnus frangula = Frangula alnus) to speedwell (Veronica beccabunga), as well as potato (Solanum tuberosum) and various Lamiaceae.
• Aphis frangulae testacea (only found in Germany) is monoecious on alder buckthorn.

There are several other postulate species of the Aphis frangulae group living on Lamiaceae, namely Aphis lamiorum on Lamium species, Aphis stachydis on Stachys species, and Aphis symphyti on comfrey (Symphytum officinale). Cocuzza & Cavalieri (2014) have suggested that these should be synonomized with Aphis frangulae, although this may be premature given their different life cycles.

Outside Europe, and for some populations within Europe, populations can usually only be identified as "Aphis frangulae group". Sexual forms occur in autumn. The closely related Aphis gossypii (cotton or cucumber aphid) is a cosmopolitan polyphagous pest of warm climates, and is a greenhouse pest in cooler climates.

Biology & Ecology:

Life cycle

Aphis frangulae is fairly easy to find in spring on its primary host, alder buckthorn, when the overwintering eggs have hatched, and young shoots are often crumpled or distorted by the feeding aphids (see picture below).

It commonly feeds on young leaves alongside the main vein or on young shoots (see picture below).

In late spring, Aphis frangulae migrates to one of its many secondary hosts. We have not yet found Aphis frangulae frangulae on either potato or its main secondary host, rosebay willowherb, but we have found the other subspecies, Aphis frangulae beccabungae, on germander speedwell (Veronica chamaedrys) (see pictures below).

The pictures below show some very interesting aphids. They were found on Eupatorium in Cambridgeshire in October 2022, in the same garden as Aphis frangulae sexuales were found a month thereafter (see below). Immatures varied from green to yellowish, as did the alatae produced. The only adult aptera was greenish brown with black siphunculi, and a paler but dusky cauda. Using the usual identification characteristics, the aptera was identified as a member of the Aphis gossypii / frangulae group. Borner (1952) identified Eupatorium cannabinum as one of the main secondary hosts of Aphis frangulae.

Both images above copyright Ian Barton, all rights reserved.

Stroyan (1984), reported that experiments carried out by K.H. Thomas provided no evidence that any member of the complex alternated between Frangula and Eupatorium. We, however, suspect that Eupatorium is a secondary host for Aphis frangulae, and note that Blackman, in Aphids on Worlds Plants, lists both Aphis frangulae and Aphis gossypii as occurring on Eupatorium.

In autumn Aphis frangulae return to the primary host, alder buckthorn, where they produce sexuales. An ovipara is shown in the picture below.

The oviparae are apterous, and have strongly swollen hind tibiae which bear numerous pseudosensoria (scent plaques).

Both images above copyright Ian Barton, all rights reserved.

The males of all subspecies are winged, and are usually yellow-brown with dark cross bands on the abdomen. After mating (see above), the oviparae deposit the overwintering eggs on the primary host.

Colour

Aphis frangulae colour varies greatly, it is mainly different shades of green, but also orange-brown and greenish-black. The oviparae (see above) especially vary considerably from pale yellowish brown to dark green.

Ant attendance

Although there is little mention of it in the literature, we have usually found Aphis frangulae on the primary host to be ant attended. The picture below shows Aphis frangulae feeding on alder buckthorn attended by Lasius niger.

The picture below shows Aphis frangulae feeding on alder buckthorn attended by a Myrmica species.

Other aphids on same host:

Primary host

Blackman & Eastop list at least 5 species of aphid as feeding on alder buckthorn (Rhamnus frangula) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 3 as occurring in Britain (Show British list).

Secondary hosts

• Blackman & Eastop list 22 species of aphid as feeding on rosebay willowherb (Epilobium angustifolium) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 15 as occurring in Britain (Show British list).

• Blackman & Eastop list 42 species of aphid as feeding on shepherd's purse (Capsella bursa-pastoris) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists perhaps 31 as occurring in Britain (Show British list).

• Blackman & Eastop list 9 species of aphid as feeding on yellow loosestrife (Lysimachia vulgaris) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 6 as occurring in Britain (Show British list).

• Blackman & Eastop list 11 species of aphid as feeding on speedwell (Veronica beccabunga) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists all 11 as occurring in Britain (Show British list).

• Blackman & Eastop list 23 species of aphid as feeding on potato (Solanum tuberosum) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists perhaps 21 as occurring in Britain (Show British list).

Damage and control

Aphis frangulae beccabungae may cause feeding damage to potatoes, and is also an important potato virus vector, transmitting potato virus Y and potato virus M. Kostiw (2009) reports on the abundance and species composition of aphids on potatoes in Poland from 1970-2005. The number of alates trapped in yellow dishes over this period declined markedly in all sampling sites. The authors attributed this decline to a decrease in the land area cropped for potatoes which by 2005 was only one fifth of the area cropped in 1970.

Acknowledgements Our particular thanks to Ian Barton for allowing us to reproduce some of his images, shown above. Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974), Stroyan (1977), Stroyan (1984), Blackman & Eastop (1984), Heie (1980-1995), Dixon & Thieme (2007) and Blackman (2010). We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks

References  Borner, C. (1952). Europae centralis Aphides (Die Blattlause Mittaleuropas). Mitteillungen der Thuringischen Botanischen Gesellschaft Beiheft 3, 1-488.  Carletto, J. et al. (2009). DNA-based discrimination between the sibling species Aphis gossypii Glover and Aphis frangulae Kaltenbach. Systematic Entomology 34(2), 307-314. Abstract  Cocuzza, C.E.M. et al. (2009a). Preliminary results in the taxonomy of the cryptic group Aphis frangulae/gossypii obtained from mitochondrial DNA sequence. Bulletin of Insectology. 61(1) 125-126.. Abstract  Cocuzza, C.E.M. et al. (2009b). Genetic relationships inside of Aphis frangulae/gossypii group based on mitochondrial DNA sequences. Proceedings of the 8th International Symposium on Aphids Catania, Italy, 8-12 June 2009. Redia 92 65-68. 14(3), 447-457. Abstract  Cocuzza, C.E.M. & Cavalieri, V. (2014). Identification of aphids of Aphis frangulae-group living on Lamiaceae species through DNA barcode. Molecular Ecology Resources 14(3), 447-457. Abstract  Kostiw, M. (2009). Aphis frangulae Kaltenbach, 1845 on potato crop in 1970-2005 and the ongoing changes. Aphids and other Hemipterous Insects 13, 91-98. Abstract