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Aphidinae : Macrosiphini : Brachycolus cerastii
 

 

Brachycolus cerastii

Mouse-ear gall aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

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.

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

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.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

The alate Brachycolus cerastii (see second picture above) 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.

 

Other aphids on the same host

Brachycolus cerastii has been recorded on 6 species in the Cerastium genus (Cerastium arvense, Cerastium davuricum, Cerastium fontanum, Cerastium glomeratum, Cerastium tianschanicum, Cerastium tomentosum).

Acknowledgements

We are grateful to Mark Wilson for bringing our attention to his pictures of Brachycolus cerastii and their galls, and making them available for use under a public domain licence. We are also grateful to Krzysztof Ziarnek for making a picture of Cerastium arvense available under a creative commons licence.

Our particular thanks to Roger Blackman for images of his clarified slide mounts.

We have used the species account given by Heie (1992) together with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in 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

  • Heie, Ole E. (1992). The Aphidoidea (Hemiptera) of Fennoscandia and Denmark. IV. Family Aphididae: Part I of tribe Macrosiphini and subfamily Aphidinae. Fauna Entomologica Scandinavica 25, 1-189. (p. 173).