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Primrose aphidIdentification & Distribution Biology & Ecology Damage & Control
Identification & Distribution:Adult apterae of Acyrthosiphon primulae (see first picture below) are shiny pale yellow to greenish yellow. They have dark tips to the antennae and legs, but not to the siphunculi which are entirely pale. The median frontal tubercle is slightly developed. The siphunculi are 2.2-3.1 times longer than the cauda. The cauda of Acyrthosiphon primulae is 1.3-1.6 times longer than the base of antennal segment 6.
The two images below show an apterous adult (first) and an alate (second) Acyrthosiphon primulae in alcohol.
The clarified slide mounts below are of adult viviparous female Acyrthosiphon primulae : wingless, and winged.
Acyrthosiphon primulae lives on the underside of leaves of Primula species, especially cowslip (Primula veris) and Kew primrose (Primula X kewensis). It reproduces solely by parthenogenesis and no sexual forms are known. Acyrthosiphon primulae is found in Britain and some European countries, and has been introduced to Tasmania, New Zealand and California.
Biology & Ecology:
The pictures below show two of the host plants of Acyrthosiphon primulae: cowslip (Primula veris) (first) and common primrose (Primula vulgaris) (second).
There is very little about the primrose aphid in the literature apart from new records of its occurrence in various countries (e.g. Lopes et al. (2016) in Belgium). We have encountered this species only once - on a cultivated cowslip variety in East Sussex. The picture below shows an adult aptera of Acyrthosiphon primulae on cowslip.
Most Acyrthosiphon primulae that we have found were parasitized - the picture below shows a parasitized mummy.
Other aphids on cowslip (Primula veris) and primrose (Primula vulgaris):Blackman & Eastop list 8 species of aphid as feeding on Primula veris and/or Primula vulgaris worldwide, and provide formal identification keys. Baker (2015) lists all 8 species as occurring in Britain: Acyrthosiphon primulae, Aulacorthum solani, Macrosiphum euphorbiae, Myzus ascalonicus, Myzus cymbalariae, Myzus ornatus, Myzus persicae and Neomuzus circumflexus.
Note: Bell et al. (2015) (Appendix S2) have also published an "annotated checklist of aphids present in the UK". We discuss some of the reasons for the differences between Baker's and Bell's lists in our rare aphids page.
We have found several polyphagous aphids on Primula spp. including Myzus ornatus (see first picture below), Aulacorthum solani (see second picture below) and Myzus ascalonicus.
Damage and control
Aphids are commonly cited as pests of primroses and cowslips (Primula spp.) and several polyphagous pest species occur. Fortunately, aphid populations are usually restricted to the undersides of the leaves, and so have less effect on the 'look' of the plant. However, the aphids can induce leaf curl (see below), and the leaves are contaminated with honeydew and exuvia.
We have found the primrose specialist Acyrthosiphon primulae less commonly than the polyphagous species, especially Myzus ornatus and Aulacorthum solani. The only populations of Acyrthosiphon primulae that we have found have been eliminated fairly rapidly by natural enemies, especially parasitoids.