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Aphids on plum and cherry

There are about 72 species of aphids which feed on plants in the genus Prunus worldwide. Prunus is here taken to include plum and cherry, as well as almond, apricot, cherry laurel, peach and blackthorn. Many of these aphids are in the genera Brachycaudus, Hyalopterus, Thopalosiphum, Myzus and Phorodon, and have Prunus as the primary host genus. Please refer to Blackman & Eastop  for formal identification keys and further information on aphids found worldwide on Prunus.

Any of the species listed below may be equally common - depending upon the season, growing environment, and plant species.

Assistance on identifying different species of Prunus is given below. 

 

Brachycaudus cardui (Plum - thistle aphid)

Identification:The apterae (see first picture below) are brownish-yellow, pale green or brown, with a large black spot situated dorsally on the abdomen and 2 or 3 black stripes at the tip. The siphunculi are black, thick and cylindrical and 1.7-3.4 the length of the cauda. The rostrum is long and reaches the hind coxae. The body length of apterae is 1.8-2.4 mm. Immatures (see second picture below) often have reddish patches on a greenish background.

 

The primary hosts are various Prunus species, mainly cherry, plum and apricot. Aphids migrate to various wild and cultivated daisies (Asteraceae) especially thistle (Carduus and Cirsium spp.) and borage (Boraginaceae). Infested leaves undergo severe curling. Dense colonies occur at the base of flower heads and on the leaves. A return migration to primary hosts occurs in autumn. The plum-thistle aphid is found throughout Britain and Europe as well as in Asia, north Africa and North America.

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Brachycaudus helichrysi (Leaf-curling plum aphid)

The adult aptera (see first picture below) on the primary host is variable in colour ranging from yellow to green to brown, often shiny with a slight wax dusting. On the secondary hosts they can be yellow, green, or almost white or pinkish. The antennae are shorter than the body with dusky tips. The dorsum of the abdomen is without a black shield. The siphunculi are pale, tapered and short - 0.8-2.0 times the length of the cauda. The cauda is pale, short and blunt. The body length of apterae is 0.9 - 2.0mm.

 

The leaf-curling plum aphid host alternates between various plum (Prunus) species (especially domestic plum and blackthorn) and a wide range of Asteraceae such as asters, chrysanthemums, yarrow and groundsel. The populations on red clover (Trifolium pratense) have been called var warei, but are not thought sufficiently distinct to warrant subspecific status. This aphid is a serious pest on fruit trees causing the leaves to roll up tightly perpendicular to thr mid-rib (see second picture above).

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Hyalopterus pruni (Mealy plum aphid)

The aptera is a small to medium sized aphid with an elongate shape. It is usually pale green with a fine darker green mottling, covered with wax meal. The antennae are quite short, between 0.5 - 0.75 times the body length. The siphunculi are very short, and are thicker and darker towards the apex; they are also flangeless and rounded at apex. The cauda is 1.5 - 3.0 times longer than the siphunculi. The body length of apterae is 1.5-2.6 mm. The winged form is green with white wax patches on the dorsum of each abdominal segment.

 

The mealy plum aphid host-alternates between its winter host - Prunus species, mainly plum but also peach, apricot and almond, and its summer host - reeds (Phragmites), Giant Cane (Arundo donax) and some other wetland grasses. Some aphids remain on plum all the year round.

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Myzus cerasi (Black cherry aphid)

A small to medium sized aphid. Adult apterae on the primary host are shiny, very dark brown to black with a sclerotized dorsum. The siphunculi are cylindrical and black with the distal part slightly curved outward. The legs and antennae are yellowish and black and the cauda is brown. The body length of apterae is 1.8-2.6 mm.

 

Most populations of the black cherry aphid host alternate and have a sexual stage in the life cycle. Host alternation is between cherry (Prunus cerasus, Prunus avium) as the primary host and bedstraws (Galium), eyebrights (Euphrasia) and speedwell (Veronica spp) as the secondary hosts. However, colonies can be found on cherry throughout the summer. Forms on Prunus cerasus and Prunus avium are sometimes considered as different subspecies or even species. Aphids on the primary host cause the leaves to curl and produce leaf nests (see second picture above). Distributed throughout the palearctic zone and now almost cosmopolitan.

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Myzus ornatus (Ornate aphid, Violet aphid)

The apterae are somewhat dorso-ventrally flattened. The dorsum is sclerotic, pale yellow or green, marked with conspicuous dark green or brownish pigmented paired intersegmental sclerites. This is a very small sphid with a body length of only 1.0-1.7 mm.

 

The ornate aphid does not host alternate and is extremely polyphagous. It often occurs in mixed species colonies where it can be difficult to spot amongst other aphids. It is an important pest on crucifers, cucurbits and onions and also attacks peas, soybean, strawberry and many garden ornamentals. It also feeds on some trees such as Catalpa and Prunus, often feeding away from the main veins. It occurs throughout the world.

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Myzus persicae (Peach-potato aphid)

The apterae (first picture below) are generally yellowish-green but vary from whitish or pale yellowish green to mid-green, rose-pink or red. They are often darker in cold conditions. The siphunculi are of medium length and slightly swollen towards the darkened tips. The body length of apterae is 1.2-2.3 mm. The alate (second picture below) has a solid pigmented area occupying the mid-abdominal dorsum from segments 3 to 6, as well as further bars on adjoining segments.

 

The peach-potato aphid does host alternate where the primary host - peach (Prunus persica) occurs. Eggs are laid on the primary host and spring colonies curl the young leaves. However, most of the population overwinters as mobile stages on herbaceous plants and brassicas. The aphid is a major pest on its summer hosts including potatoes, sugar beet, lettuce, brassicas and legumes, mainly because it transmits a number of important plant viruses. Whilst Myzus persicae is a generalist, the subspecies Myzus persicae nicotianae is a tobacco specialist.

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Phorodon humuli (Damson - hop aphid)

Identification:The apterae are small to medium sized, whitish to pale yellowish green and relatively shiny. The abdomen is marked with three dark green longitudinal stripes. The head has the characteristic pair of elongate projections on the inside of the antennal tubercles. The siphunculi are pale with slightly dusky tips and over twice as long as the pale cauda. Body length is 2.0-2.6 mm on plum and 1.1-1.8 mm on hop.

 

The damson-hop aphid host alternates from Blackthorn or Plum (Prunaceae) to Hops (Cannabinaceae). It does not cause leaf curling itself but often lives on plum leaves distorted by Brachycaudus helichrysi. Migration of winged forms to hops takes place from late spring. There is a return migration to the winter hosts in September where sexual forms are produced and eggs laid. It is indigenous to Europe and neighbouring areas, but has been introduced to North America and New Zealand.

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Rhopalosiphum padi (Bird Cherry - Oat Aphid)

Apterae on bird cherry have a coating of mealy wax (first picture below). Under the wax, the apterae are pale green to dark green, brown or nearly black, with a rust-red patch around the base of each siphunculus. These markings are clearly visible in apterae on grasses which have no wax coating (second picture below). The apical end of the siphunculi is slightly swollen and ends with a strong flange preceded by a distinct constriction. The cauda is rather pale and shorter than the siphunculi. The body length of apterae is 1.2-2.4 mm.

 

The bird cherry - oat aphid host alternates between Bird Cherry (Prunus padus) as the primary host and various Grasses (Poaceae) as the secondary host. Some populations reproduce parthenogenetically all year on grasses. It is the principal vector of barley yellow dwarf virus and has a cosmopolitan distribution.

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Species of Prunus

The plum (Prunus domestica) has toothed leaves which are dull green on the upper side and downy on the underside. The flowers appear with the leaves and are in clusters of 2-3, 7-12 mm in diameter and with 5 greenish white petals. The fruit is fleshy with a smooth skin; as it ripens it turns reddish purple and acquires a waxy bloom.

 

The blackthorn or sloe (Prunus spinosa) is a small tree or bush with very thorny twigs. The leaves (see picture above second) have many small teeth and have a dull upper surface with the lower surface hairy on the veins. The 5-petaled white flowers appear before the leaves and are produced in great quantity. The ripe fruit (sloe) are bluish-black largely hidden by a waxy greyish bloom on the skin.

The bird cherry (Prunus padus) is a small tree native to northern Europe and northern Asia. The leaves (see first picture below) are toothed, hairless or with white hairs along the midrib, sometimes only where veins join. There are two small glands on the stem near the base of the leaf. The flowers (see second picture below) are white and are arranged in roughly cylinder-shaped spikes, 11 or more per spike. The flowers are usually less than 10 mm across.

 

Sweet or wild cherry (Prunus avium) is a deciduous tree native to Europe and surrounding areas. It grows to 15-32 m. with a straight trunk and symmetrical conical crown. The leaves are dull on the upper side, sparsely hairy on the underside (see first picture below). Leaf margins have blunt or rounded teeth, often tipped with a red gland. There are also two red glands on the stem near the base of the leaf. Flowers are produced in early spring borne in groups of 2-6. Each flower (see second picture below) is cup shaped with 5 pure white petals and yellowish stamens. Flowers are more than 20 mm across and they hang on stalks more than 15 mm long arising from a central point.

 

Sour or morello cherry (Prunus cerasus) (not pictured) is closely related to sweet cherry. It has more acidic fruit, is smaller (4-10 m) and berries are borne on shorter stalks. Unlike sweet cherry, the leaves are glossy on the upper side and hairless on the underside. Each flower is saucer shaped with 5 pure white petals and yellowish stamens. The sour cherry suffers fewer pests and diseases than the sweet cherry.

The name 'Japanese flowering cherry' encompasses several different species (Prunus serrulata, Prunus sargentii, Prunus speciosa). It is native to east Asia but is widely planted worldwide. The leaves (see pictures below) are hairless or downy beneath depending on species and variety. The leaf margins have pointed teeth, often with bristle-like tips. The flowers are white or pink and may be single or double and range from 25-40 mm across. They are borne on hairless stalks in groups of 2-6. The bark is mostly grey or brown, sometimes peeling to reveal shiny red-brown on the trunk.

 

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 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. Aphids on the world's plants An online identification and information guide. Full text