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Aphididae : Aphidinae : Macrosiphini : Aulacorthum
 

 

Genus Aulacorthum

Aulacorthum aphids

On this page: Aulacorthum ibotum linderae muradachi palustre solani

Genus Aulacorthum [Macrosiphini]

Aulacorthum apterae are medium sized and may be whitish, yellowish, green, pinkish-red or brown, often with a patch of different colour at the base of each siphunculus. The dorsum is sclerotic and shiny. In the genus Neomyzus (formerly considered a sub-genus) the dorsum has a pigmented pattern. The antennae are usually longer than the body and the head is distinctly spinulose (=has small spines). The antennal tubercles are well developed with near parallel steep-sided inner face (cf. Neomyzus where they are converging). Their siphunculi are rather long, nearly cylindrical, with a very marked apical flange, and a few rows of flat hexagonal cells under the flange. The cauda is rather short and tongue-shaped.

There are 48 species of Aulacorthum aphids, on a great variety of hosts. Most do not host alternate and are monophagous with a sexual stage in their life cycle. A few are highly polyphagous, often with no sexual stage in their life cycles. Some of these polyphagous species are important crop pests. Aulacorthum aphids are not ant attended.

 

Aulacorthum ibotum (Brown-blotched privet aphid) East Asia

Adult apterae of Aulacorthum ibotum are yellow to pale green with brown marginal markings, and no wax (cf. Aphis crinosa on Ligustrum in the Far East, which has thick white wax secretions). See picture below for yellow form (for green form see Mushinavi). Antennal segments I-IV are pale or dusky with dark bases and apices, segments V is dark with a dusky base and VI is dark, with 0-3 secondary rhinaria on segment III. The rostrum reaches nearly to the third coxae. The thoracic dorsum and abdominal dorsum are mottled with brown patches laterally and around the siphunculi (not visible in clarified mounts). The legs are yellowish except for dark brown apices to the femora and tibiae, and black tarsi. The siphunculi are uniformly black (cf. Myzus ligustri, which have the basal half of the siphunculi pale and distal half dark); they are less than twice the caudal length, and 0.22-0.26 times as long as the body. The cauda is pale (cf. Aphis spiraecola, which has a dark cauda). The body length of adult Aulacorthum ibotum apterae is 1.8-2.3 mm. Immatures are paler in color than the adults, with the wingpads dusky.

Image above by permission, copyright Akihide Koguchi, all rights reserved.

Alate Aulacorthum ibotum are pale green with mainly dark antennae. The terminal process is 8-9 times the length of the base of antennal segment VI. Antennal segment III bears 13-16 secondary rhinaria, which are circular, about the same size, and almost in a row. Sensoria on other segments are normal. The rostrum reaches nearly to the third coxae. The prothorax is yellowish, with the remainder of the thorax dark. The legs are yellow, with the distal ends of the femora and tibiae, and all of the tarsi black. The siphunculi are dark and imbricated throughout, about twice as long as the dark cauda.

Aulacorthum ibotum feeds on the undersides of leaves of privet (Ligustrum species). Their life cycle has not been fully investigated, but Takahashi (1960) reported that wingless oviparae and winged males were collected, presumably on privet, on November 29, 1919, near Tokyo. This strongly suggests that the species is monoecious holocyclic. It is found in Japan and Korea.

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Aulacorthum linderae (Blood orange-blotched lindera aphid) East Asia

Adult apterae of Aulacorthum linderae are pale green to white or creamy, with red-brown to orange-yellow diffuse blotches around and between the bases of the siphunculi and a pair of faint pleural blotches on abdominal tergite II (cf. Aulacorthum muradachi, which has paired submarginal rows of red to reddish-brown patches from the mesonotum to abdominal tergite VI). The antennal tubercles are high and diverging at the inner sides. Their antennae are generally pale, except for segments III-V which are black at the apex and segment VI which is dusky. The antennae are 1.4-1.5 times as long as the body, with 2-6 secondary rhinaria in a line on segment III and a terminal process nearly 5 times as long as the base of VI. The longest hairs on segment III are 0.33-0.5 times the width of the segment at its mid-length. The rostrum reaches the hind coxae, with the apical rostral segment (RIV+V) 1.2-1.4 times as long as the second hind tarsal segment (HTII) (cf. Aulacorthum muradachi, which has RIV+V 0.9-1.0 times the length of HTII). The hairs on the tibiae are about as long as the middle width of the hind tibia. The abdominal tergum is rather weakly sclerotized, with no dark pigmentation and without marginal tubercles. The siphunculi are pale, and usually have dark tips (cf. Aulacorthum muradachi, which has completely dark sclerotic siphunculi). The siphunculi are tapering, imbricated, 11-13 times as long as wide at middle, about 3 times as long as the cauda, with a developed flange. The cauda is bluntly conical, less than twice as long as wide, with 6-8 hairs. The body length of the adult aptera is 2.0-2.2 mm.

Note: There may be more than one aphid species included under the name Aulacorthum linderae.

Images above by permission, copyright Akihide Koguchi, all rights reserved.

The alate Aulacorthum linderae (see third picture above) is similar to the aptera, with dark-tipped pale siphunculi. It has faint dorsal bands on the abdomen, especially on the posterior part. Immature Aulacorthum linderae (see pictures above have similar dorsal pattern of blotches to the apterae, but their blotches are pale orange.

Aulacorthum linderae feeds on undersides of kuromoji leaves (Lindera sericea. Feeding by Aulacorthum linderae causes loose leaf-curl and reddish-brown blotches (Miyazaki, 1971). There is not thought to be any host alternation. The species has only been recorded in Japan.

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Aulacorthum muradachi (Crimson-stained lindera aphid) East Asia

Adult apterae of Aulacorthum muradachi have a brown head and prothorax. The abdomen is milky white, pale yellow or pale green, with conspicuous dorsal pigmentation consisting of paired submarginal rows of red to reddish-brown patches from the mesonotum to abdominal tergites VI, which converge and broaden-out at the bases of the siphunculi (cf. Aulacorthum linderae, which has brown or red patches around the bases of the siphunculi and sometimes on tergites I/II). The antennae are 1.8-1.9 times as long as the body. Antennal segments I & II are dark, III-V are pale with dark apices. Segment VI has a pale base and a dark terminal process, which is about five or six times as long as the base. The antennal tubercles are high, diverging at the inner sides. The apical rostral segment (RIV+V) is 0.9-1.0 times as long as the second hind tarsal segment (HTII) (cf. Aulacorthum linderae, which has RIV+V 1.2-1.4 times the length of HTII). The legs are very long, pale yellowish brown, with the apical half of the femora, both ends of the tibiae and the tarsi black. The siphunculi are 2.5-3 times as long as the short pale cauda, and are completely black (cf. Aulacorthum linderae, which has the siphunculi pale or dark only at the apices). The body length of adult Aulacorthum muradachi apterae is 1.6-2.6 mm.

Images above by permission, copyright Akihide Koguchi, all rights reserved.

The alate Aulacorthum muradachi (see third picture above) is similar to the aptera with completely black siphunculi, but in addition has rather faint dorsal bands on the abdomen, especially on the posterior part. The antennae have 8-11 secondary rhinaria on segment III. Immatures (see pictures above and below) have similar dorsal pigmentation to the apterae, but the paired submarginal rows of patches are pale orange.

Aulacorthum muradachi is found on the leaves of spicewood, Lindera species (Lauraceae), especially Lindera erythrocarpa, abrachan (Lindera praecox), Lindera triloba, and kuro moji (Lindera umbellata). As far as is known, the species is monoecious holocyclic. It is distributed through Japan and Korea.

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Aulacorthum palustre (Wax-banded daisy aphid) Europe

Adult apterae of Aulacorthum palustre (see first picture below) are pinkish-yellow, whitish green, or pale green, with black tips to the antennae and legs. The dorsum and antennae have short capitate hairs. They often have rust-coloured or darker green spots around the bases of the siphunculi. The siphunculi are straight and pale, 1.8-2.5 times the length of the cauda; only the flanges may sometimes be darkened. Immature Aulacorthum palustre (see first picture below) have serial cross bands of whitish wax powder around the body, but these are apparently lost by the adult stage.

The alate Aulacorthum palustre (see second picture above) is reddish or greenish with a brown or black abdominal dorsal pattern. The siphunculi are brown or with brown apices.

Aulacorthum palustre feed on the underside of leaves of plants in the daisy family (Asteraceae) such as cats ear (Hypochaeris), oxtongues (Picris), and possibly dandelions (Taraxacum) and hawkbits (Leontodon). They do not host alternate but live all year round on the same host. They may produce sexuales in autumn and overwinter as eggs, or they may overwinter parthenogenetically as viviparae. Aulacorthum palustre is found throughout Britain and much of Europe.

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Aulacorthum solani (Glasshouse - potato aphid, Foxglove aphid) Cosmopolitan

Aulacorthum solani apterae are pear shaped and shiny greenish yellow, usually with a bright green or rust coloured patch at the base of each siphunculus. Their antennae have darkened joints and are slightly longer than the body. Their siphunculi are pale with dark tips, long, slender, tapered and distinctly flanged. The body length of Aulacorthum solani apterae is 1.5-3.0 mm.

The winged forms have darker antennae, legs and siphunculi and have a variably developed pattern of tranverse dark bars on the dorsal abdomen.

Unusually for an aphid, Aulacorthum solani can go through the sexual phase on many different plant species - but, in temperate climates, most of their population overwinters as nymphs or apterae, especially on potato sprouts and on many glasshouse plants and wild species such as foxglove (Digitalis). As a result, Aulacorthum solani is often one of the first aphid species to find on young plants in the spring.

Aulacorthum solani is extremely polyphagous, it will colonise plants in may different dicotyledonous and monocotyledonous families. The high toxicity of the saliva of the glasshouse - potato aphid may produce deformation and discoloration of leaves being fed upon. This results in direct feeding damage to potatoes and peppers. Aulacorthum solani can also be a vector of about 40 plant viruses, but its relatively poor virus transmission efficiency makes it unimportant as a virus vector in the field. Its importance is much greater in glasshouses. Its distribution is virtually cosmopolitan.

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Acknowledgements

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

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

  • Heie, O.E. (1980-1995). The Aphidoidea, Hemiptera, of Fennoscandia and Denmark. (Fauna Entomologica Scandinavica) E.J. Brill, London.