Brachycaudus prunicola

Identification & Distribution

Adult apterae of Brachycaudus prunicola are olive-green to chestnut reddish brown with shiny black broad cross bands on each abdominal segment. The dorsal crossbands are often not completely fused intersegmentally and/or have a spinal gap, and are not connected to the marginal sclerites, at least on abdominal tergites II-III (see two pictures below showing, first, a lightly marked aptera and, second, a heavily marked aptera) (cf. Brachycaudus prunifex, which has the dorsal cross bands usually fused into a solid patch on abdominal tergites II-V that connects on each side with the marginal sclerites). The longest hair on the inner side of antennal segment II is 0.4-1.0 times longer than the basal diameter of antennal segment III (cf. Brachycaudus prunifex where that hair is 0.8-1.6 times longer than the basal diameter of antennal segment III). The apical rostral segment (RIV+V) is 0.88-1.05 times the length of the second hind tarsal segment (HTII). There is often a chestnut-reddish suffusion around the siphuncular bases and on the dorsum of the prothorax. The black siphunculi are rather short, less than twice as long as the cauda. The body length of adult apterae is 1.4-2.4 mm. Immature Brachycaudus prunicola are grey green with chestnut-reddish areas of suffusion.

Brachycaudus prunicola feeds on the young growth of blackthorn (Prunus spinosa), domestic plum (Prunus domestica) and damson (Prunus insititia) causing severe leaf curl and discoloration. Some populations remain all year on Prunus but some may host alternate to salsify (Tragopogon). Brachycaudus prunicola is found throughout continental Europe (but apparently not in Britain) into Russia, Kazakhstan and Pakistan.

Biology & Ecology

Vasilev & Andreev (2015) studied the population dynamics of Brachycaudus prunicola (see picture below of colony) in plum orchards and of Brachycaudus schwartzi in peach orchards in the region of Plovdiv, Bulgaria during 2014.

First image above copyright Marko Šćiban, all rights reserved.

Both species of Brachycaudus were widespread, and found in most of the areas examined - with the exception of Haskovo, Yambol, Kardzhali and the southern part of the region of Bourgas. Brachycaudus prunicola occurred in the orchards till September, but the aphid only colonized shoots at the base of plum trees.

Other aphids on the same host

Primary hosts

Brachycaudus prunicola has been recorded from 6 Prunus species: Prunus amygdalus (almond), Prunus armeniaca (apricot), Prunus avium (Sweet Cherry, Mazzard), Prunus cerasifera (cherry plum), Prunus divaricata, and Prunuus domestica (common plum, European plum).

• Blackman & Eastop list 13 species of aphid as feeding on blackthorn (Prunus spinosa) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 9 as occurring in Britain (Show British list).

• Blackman & Eastop list 26 species of aphid as feeding on common plum (Prunus domestica) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 19 as occurring in Britain (Show British list).

Secondary hosts

Brachycaudus prunicola has been recorded as unusual/doubtful on Galium intermedium, Lepidolopsis turkestanica, Senecio vulgaris, and on 4 Tragopogon species (Tragopogon dubius, Tragopogon graminifolius, Tragopogon porrifolius, Tragopogon pratensis).

• Blackman & Eastop list 24 species of aphid (25 if we accept the Brachycaudus prunicola records) as feeding on Tragopogon spp. worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 15 as occurring in Britain (Show British list).

Damage and control

In Bulgaria Vasilev & Andreev (2015) concluded that Brachycaudus prunicola should not be considered as a primary pest on plums because it did not colonise the fruit-bearing stems of plums. This was contrary to the situation with Brachycaudus schwartzi on peach which causes heavy deformations of the leaves and shoots. Cambra et al. (2004) looked at the possible role of Brachycaudus prunicola and other aphid species in the epidemiology of plum pox virus (PPV) in Spain. Brachycaudus prunicola was found to comprise just 6% of the visiting alate aphid species, and none was found to be carrying the virus. In contrast Aphis spiraecola comprised 43% of the visiting alate aphid species, and 12.3% were carrying the virus.

Acknowledgements We are extremely grateful to Marko Šćiban (HabitProt) and Mihajlo Tomić for the images of live Brachycaudus prunicola in Serbia. 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 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 Cambra, M. et al. (2004). Epidemiology of plum pox virus in Japanese Plums in Spain. Acta Horticulturae no. 657, 195-200. 90, 33-49. Full text Cocuzza, G. et al. (2007). Morphological and molecular analysis of Brachycaudus, subgenus Appelia-complex (Rhynchota Aphididae). Redia 90, 33-49. Full text Vasilev, P. & Andreev, R. (2015). Distribution and population dynamics of Brachycaudus schwartzi Borner and Brachycaudus prunicola Kaltenbach (Hemiptera: Aphididae) on prune fruit trees in the region of South Bulgaria. Agricultural Sciences 7(17), 119-124. Full text