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Acyrthosiphon lactucae

Lettuce seed-stem aphid

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

Identification & Distribution

Adult apterae of Acyrthosiphon lactucae (see first picture below) are pale yellowish green or pink. The dorsal surface has a pale grey wax bloom, often appearing as pale transverse stripes. The head is smooth, and the antennal tubercles are well developed with smooth broadly-divergent inner faces. The terminal process is less than 7.5 times as long as the base of antennal segment VI. Antennal segment III has secondary rhinaria and bears hairs that are less than 0.7 times the diameter of that segment. The fused apical rostral segment (R IV+V) is 0.6-0.7 times the length of the second hind tarsal segment (HTII), and has 16-25 accessory hairs (cf. Acyrthosiphon ilka, which has RIV+V 0.8-0.9 times the length of HTII, with 6-8 accessory hairs). There are no dark markings on the dorsum (cf. Nasonovia ribisnigri, which on the secondary host - lettuce - has dark intersegmental sclerites between each abdominal segment). Abdominal tergites I and VII usually have no marginal tubercles. The siphunculi are long and tapering with no polygonal reticulation (cf. Hyperomyzus lactucae, which has distinctly swollen siphunculi). The cauda is finger-shaped, clearly longer than its basal length. The body length of adult apterae is 1.7-2.9 mm. Immature apterous Acyrthosiphon lactucae (see second picture below) resemble the adult apterae, but have shorter siphunculi and cauda.

Both images above by permission, copyright Claude Pilon, all rights reserved.

Acyrthosiphon lactucae alatae (see picture below of immature and adult alate) show the same two colour forms as the apterae, but have somewhat dusky siphunculi.

Image above by permission, copyright Claude Pilon, all rights reserved.

Images above by permission, copyright Claude Pilon, all rights reserved.

Images of Acyrthosiphon lactucae copyright CBG Photography Group under a Creative Commons - Attribution Non-Commercial Share-Alike License.

Acyrthosiphon lactucae feeds on stems and undersides of leaves of lettuce (Lactuca species). It does not host alternate, remaining on lettuce year round. Sexuales develop in autumn, with alate males. Acyrthosiphon lactucae is a native Eurasian species and is found throughout Europe, the Middle East, Kazakhstan and Pakistan. In Britain the lettuce seed-stem aphid has only been found in southern counties. It was introduced to North America many years ago and is now widely distributed there. More recently Acyrthosiphon lactucae has been recorded from Argentina (Mier Durante et al. 2011) and Chile (Nieto Nafría et al. 2018).

 

Other aphids on the same host

  • Acyrthosiphon lactucae is recorded from 5 species of lettuce (Lactuca) (Lactuca perennis, Lactuca saligna, Lactuca sativa, Lactuca serriola, Lactuca viminea ssp. chandrilliflora).

    Blackman & Eastop list 28 species of aphid as feeding on lettuce (Lactuca sativa) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 21 as occurring in Britain (Show British list).

  • Acyrthosiphon lactucae has also been recorded from Mulgedium tataricum, Mycelis muralis and Sonchus oleraceus.

    Blackman & Eastop list 36 species of aphid as feeding on common sowthistle (Sonchus oleraceus) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 24 as occurring in Britain (Show British list).

 

Damage and control

Lettuce is attacked by several different aphid species, the most important of which are Acyrthosiphon lactucae, Aulacorthum solani, Macrosiphum euphorbiae, Myzus persicae and Nasonovia ribis-nigri. There are also several root aphids, for example Pemphigus bursarius, Trama caudata and Trama troglodytes. Which species is the most important varies within and between countries.

Palumbo (2004) describes insecticide alternatives for aphid management in head lettuce in Arizona, USA. Two insecticides have both contact and systemic activity - pymetrozine (pyridine azomethine) and acetamiprid (a neonicitinoid). A newer insecticide, flonicamid is a nicotinamide with systemic activity. All these products have been shown to provide good efficacy against lettuce aphids if applied at low aphid densities before head formation begins. Palumbo (2018) gives a more up-to-date account of aphid control on lettuce including cultural management, encouragement of natural enemies, scouting for aphids, aphid identification and early application of foliar insecticides.

Mifsud et al. (2011) notes that Acyrthosiphon lactucae is frequently damaging to cultivated lettuce in Italy, preferentially infesting the inflorescence. It is also a vector of Lettuce Mosaic Virus.

Acknowledgements

We are especially grateful to Claude Pilon for pictures of Acyrthosiphon lactucae (for more of her excellent pictures see)

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

  • Mier Durante, M.P. et al. (2004). Three aphid species (Hemiptera: Aphididae) recorded for the first time from South America. Florida Entomologist 94(4), 839-842. Full text

  • Mifsud, D. et al. (2011). Aphids associated with shrubs, herbaceous plants and crops in the Maltese Archipelago (Hemiptera, Aphidoidea). Bulletin of the Entomological Society of Malta 4(1), 5-53. Full text

  • Nieto Nafría, J.M. et al. (2018). Novedades para la fauna chilena de pulgones (Hemiptera, Aphididae) con primera cita de dos especies para América del Sur. Boln.Assoc esp. Ent. 42 (3-4), 275-294. Full text

  • Palumbo, J.C. (2004). Insecticide alternatives for aphid management in head lettuce. Full text

  • Palumbo, J.C. (2018). 4 keys to effective aphid management in leafy vegetables. Full text