InfluentialPoints.com
Biology, images, analysis, design...
Aphids Find them How to ID AphidBlog
"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

Search this site

Aphidinae : Macrosiphini : Brachycolus
 

 

Genus Brachycolus

Brachycolus aphids

On this page: Genus Brachycolus cerastii cucubali stellariae

Brachycolus [Macrosiphini]

Brachycolus are narrowly oval, wax covered aphids. The antennae are 6-segmented, considerably shorter than the body, with a terminal process much longer than the base of antennal segment VI. Antennal segment III of the aptera has only short hairs, and no secondary rhinaria. The rostrum reaches to the middle coxae or between fore and middle coxae, and the apical rostral segment is shorter than the second hind tarsal segment. The abdominal dorsum of the aptera is membranous. Alatae have marginal sclerites on the abdomen in from of the siphunculi and cross bars on tergites VII & VIII. Marginal tubercles are occasionally present on segments II-VI. An unpaired supracaudal process is occasionally present on abdominal tergite VIII. The siphunculi are very short, asymmetrical with a small aperture, and sited on the posterior part of tergite V. There is no flange. The cauda is triangular or tongue-shaped, about 1.5 times as long as its width at base, and with 5-6 hairs.

There are 5 Brachycolus species in the world, 3 in Europe, and single species in Canada and (possibly) China. Brachycolus mostly feed on members of the pink family Caryophyllaceae, galling the leaves of their hosts; the possible Chinese species feeds on a member of the Apiaceae, Bupleurum. All species are thought to be monoecious holocyclic. They are not attended by ants.

 

Brachycolus cerastii (Mouse-ear gall aphid) Europe

The aphid Brachycolus cerastii induces pseudogalls on the shoots of mouse ear (Cerastium), especially Cerastium arvense. Leaf margins are thickened and curved inwards to form small, rose-like, yellowish green, oviform or oblong pseudogalls (see picture below) in the shoot tips. The aphids live and feed within these galls.

Adult apterae of Brachycolus cerastii (see picture above - a few apterae are just visible around the periphery of the gall) are dirty green in colour, and are dusted with white wax powder. The head, antennae, and legs are brown, and the siphunculi are light brown. The antennae are 0.3-0.4 times as long as the body, with a terminal process 2.2-2.7 times as long as the base of antennal segment VI. The apical rostral segment (RIV+V) is about the same length as the second hind tarsal segment (HTII) (cf. Brachycolus stellariae which has RIV+V only 0.55-0.72 times HTII). Abdominal tergite VIII has a small supracaudal process (cf. Brachycolus stellariae. which does not have a supracaudal process). The siphunculi are very short, only 0.01 times body length, and 0.15-0.19 times the cauda (cf. Brachycolus cucubali, which has siphunculi about 0.5 times cauda). The cauda is oblong, triangular, with 5 hairs. The body length of adult Brachycolus cerastii apterae is 1.3-1.7 mm.

First image above copyright Mark Wilson under a public domain licence.
Second image Krzysztof Ziarnek via Wikimedia Commons, under a CC4.0 license.

The alate Brachycolus cerastii (not pictured) is pale green, with faint marginal sclerites and crossbands on tergites VII & VIII. The antennae are 0.7 times body length, with a terminal process about 3.3 times the base of antennal segment VI. Antennal segment III has about 3-6 secondary rhinaria along one side. The longest hair on segment III is about 0.7 times the basal diameter of that segment.

Brachycolus cerastii is monoecious holocyclic on Cerastium species. Feeding by the aphids causes shoots to be stunted and deformed into gall-like structures. The species is found over most of Europe.

Read more...

 

Brachycolus cucubali (Campion leafroll aphid) Europe, West Asia, Africa

Brachycolus cucubali produce a leafroll pseudogall (see first picture below) on their host, campions (Silene species), by rolling the leaves inwards and compacting the inflorescence. The aphids live and feed in the pseudogall. They also cause stem-shortening and malformations of the plant.

Adult apterae of Brachycolus cucubali (see second picture below) are pale green to whitish yellow, with the head, legs, siphunculi and cauda dark, and dark cross-bars on tergites VII and VIII. The live aphids are covered with white wax-powder. The antennae are 0.40-0.52 times as long as the body, with the terminal process 1.29-2.30 times the base of antennal segment VI. The longest hair on antennal segment III is about 0.6 times the basal diameter of the segment. The rostrum reaches to the middle coxae, with the apical rostral segment 0.68-0.79 times the second hind tarsal segment, with 2-4 accessory hairs. The siphunculi are barrel-shaped, wrinkled, very short, only 0.39-0.53 times the caudal length, without a well developed flange. The cauda is oblong, triangular, obtuse, 1.1-1.6 times as long as broad, and with 6-8 hairs. The body length of adult Brachycolus cucubali apterae is 1.4-2.2 mm.

Images above by permission Sébastian Carbonnelle, all rights reserved.

The alate viviparae of Brachycolus cucubali (see clarified mount in second picture above) are similar to the apterae, but have marginal and dorsal sclerites, and crossbars on the posterior abdominal tergites. The antennae are 0.68-1.01 times the body length, and the terminal process is 1.86-2.61 times the base of antennal segment VI. Secondary rhinaria are distributed 9-16 on antennal segment III and 0-2 on segment IV.

Brachycolus cucubali are monoecious on campion (Silene spp.), rolling the leaves into pseudogalls. There are also unconfirmed reports from Kazakhstan of them feeding on other Caryophyllaceae, namely Cerastium davuricum, Cerastium tianschanicum & Saponaria officinalis. It has long been assumed they are holocyclic, given their similarity to other Brachycolus species, but until recently the sexuales had not been observed. However, Casiraghi et al. (2020) have now described the ovipara and the small apterous male. Some apterous viviparae also live through the winter within the galls. Brachycolus cucubali is found over much of Europe, extending to eastern Siberia, Kazakhstan and north Africa.

Read more...

 

Brachycolus stellariae (Stitchwort leafroll aphid) Europe

Brachycolus stellariae lives on the upper side of the leaves of stitchworts (Stellaria spp.), especially Stellaria holostea (see uninfested plant in first picture below). The leaves are rolled into oblong pseudogalls (see first two pictures below).

Adult apterae of Brachycolus stellariae (see third picture below) are pale green, and covered with white wax powder. The head, antennae, and legs are brown, the siphunculi are pale and the cauda is dusky. Antennae are quite short, about 0.48-0.65 the body length, with the terminal process 2.4-3.6 times the base of antennal segment VI. The hairs on antennal segment III are about 0.6-0.8 times the basal diameter of that segment. The apical rostral segment is 0.55-0.72 times the second hind tarsal segment. The siphunculi are very small, flangeless, conical or barrel-shaped, with no polygonal reticulation, and less than 0.20-0.25 times the cauda (cf. Macrosiphum euphorbiae and Macrosiphum stellariae, which have long tubular siphunculi with subapical polygonal reticulation). The cauda is oblong, triangular, much shorter than the terminal process, and with 5-6 hairs (cf. Brachycolus brachysiphon in Canada, which has the cauda elongate, longer than the terminal process). Abdominal tergite VII has no supracaudal process. Body length of the adult Brachycolus stellariae aptera is 1.1-2.0 mm.

First image above copyright John Lyden, under a Creative Commons License.
Second & third image, by permission, copyright AC Grosscurt, all rights reserved.

Alate Brachycolus stellariae (see picture below) have paired small faint sclerites on tergites I-III, and small crossbars on VII & VIII. Antennae are about 0.75 times body length, and bear 4-9 secondary rhinaria on antennal segment III, and 0-1 on segment IV. The cauda is rather slender and pointed.

Brachycolus stellariae is monoecious on stitchwort (Stellaria species), rolling the leaves into pseudogalls. It has also been recorded on a species of another genus in the Caryophyllaceae, namely Moehringia trinervia. Brachycolus stellariae is holocyclic, producing oviparae and very small apterous males in September. Brachycolus stellariae is found through most of Europe, excluding Norway.

Read more...

Acknowledgements

We have made provisional 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 sp 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

  • Blackman, R.L. & Eastop, V.F. (2006). Aphids on the world's herbaceous plants and shrubs. Vols 1 and 2. John Wiley & Sons.