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Tuberolachnus salignus

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Tuberolachnus salignus
Tuberolachnus salignus, showing dorsal tubercle
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Hemiptera
Suborder:
Sternorrhyncha
Superfamily:
Aphidoidea
Family:
Aphididae
Genus:
Tuberolachnus
Species:
T. salignus
Binomial name
Tuberolachnus salignus
Gmelin, 1790

Tuberolachnus salignus, or the giant willow aphid, is a species of aphid, in the genus Tuberolachnus. They are reputed to be the largest aphids, with a body length of up to 5.8mm.[1][2] First described by Johann Friedrich Gmelin in 1790, it feeds on many species of willow (Salix species), and has one known host-specific parasite, Pauesia salignae.[2]

Tuberolachnus salignus does not require a male for reproduction. Only females have ever been recorded, which suggests that reproduction is parthenogenetic and all offspring produced are genetically identical clones.[3]

Description[edit]

Adults exhibit a pear-shaped body with dark brown/grayish coloration[4]. This aphid species has distinct black dots that form rows along its body[4]. Along the dorsal side of their abdomen, about 2/3 of the way down, Tuberolachnus salignus displays a defining single large conical tubercle or bump that resembles a thorn which can grow to 0.2-0.3 mm[5][6]. Closer to the posterior and along the sides of the body are two smaller black cone structures which excrete honeydew[4]. Honeydew is a modified form of honey that looks dark in coloration and crystalizes when exposed to air[7].

Tuberolachnus salignus reproduces solely through parthenogenesis so all aphid adults are female[5][7][8][9]. Adults can be either winged or wingless[4]. The two pairs of wings are clear with a dark brown edge along the forewing[4]. When looking at Tuberolachnus salignus under a microscope the presence of numerous tiny hairs is apparent[4][5]. This gives the abdomen a grayish-gold hue[4][5]. Adult Tuberolachnus salignus has three pairs of legs that are primarily a dark brownish color, but smaller, red/orange sections are also present[4][5]. They also have a pair of antennae that are less than half of the aphid’s body length[4][5].

Range[edit]

Natural Global Range[edit]

Tuberolachnus salignus is a cosmopolitan species[7][10]. They exist anywhere that willow species grow naturally or are cultivated[7][10]. The giant willow aphid originated in parts of Asia but has now spread to all parts of the globe (except Antarctica)[7][10]. There is no known exact place of origin for this aphid species, but it is believed to be somewhere within Japan and Korea[9][11]. The only known parasitoid of this species is endemic to Japan, leading to the belief that this may be the place of their origin[9][11].

Tuberolachnus salignus is now found in all parts of New Zealand where willow species are present[9][11]. It only recently made it to New Zealand, with the first confirmed sighting in December of 2013 in Auckland[9][11].

Habitat[edit]

Tuberolachnus salignus is almost entirely dependent on willow trees[9][11]. They live on the bark of these trees and feed on their sap[9][11]. These giant aphids survive year-round with the most activity being in late summer and early fall[5][9][11]. Their population numbers are known to be largely weather and temperature related[12]. Following instances of large amounts of rain, Tuberolachnus salignus populations have been known to increase rapidly[3].

Ecology[edit]

Life cycle/Phenology[edit]

Tuberolachnus salignus has a generation period of 2–3 weeks, which is largely dependent on temperature[6][3]. Once hatched, the aphid larvae go through four stages of development until they reach their adult forms[5][13]. Ideal temperatures for Tuberolachnus salignus generation range from 17.5–22.5 degrees Celsius[6]. It takes two weeks for nymphs to become adults, with adults living an additional five weeks after that[5]. Mature aphids can produce anywhere from 35–71 offspring[5][14][15]. Generally, Tuberolachnus salignus is most active in the warmer months, with populations peaking in late summer and early autumn[6][3]. In colder moths, the overall fecundity decreases but colonies are still active[6][3]. In the spring, colonies are usually not visible[5][6][3]. During this time, it is thought Tuberolachnus salignus retreats behind the willow tree bark or into the ground to escape the harsh climate[5][6][3].

Tuberolachnus salignus reproduces via parthenogenesis[5][7][8][9]. Resulting in a population consisting of all females[5][7][8][9]. All offspring are identical genetic clones of their mothers[5][7][8][9]. In turn, there are no mating behaviors that occupy these aphids as they do not participate in sexual reproduction[5][7][8][9].

Diet and Foraging[edit]

Tuberolachnus salignus is known to feed primarily on willow and Salix tree species such as the white willow (Salix alba), the common sallow (Salix cinerea')[16] and the Indian willow (Salix tetrasperma).[17] It has also been recorded on Quince (Cydonia oblonga)[18], Apple (Malus spp.)[18] and Poplar (Populus spp.)[18]

Like all Hemiptera, Tuberolachnus salignus uses modified mouth parts to pierce the phloem of plants and feed on its sap[4][5]. As the name suggests, giant willow aphids prefer willows of the Salix species but have been known to feed on poplar, apple, and pear species in New Zealand[4][5]. Tuberolachnus salignus prefers to feed during the day and during the warmer hours[5]. When feeding, the aphid will climb to the tip of the willow where the shoot begins[4][5]. The flesh of the plant is softer here, allowing the aphid to inject its stylets into the plant’s phloem[4][5].

Tuberolachnus salignus uses two stylets to extract the sap flowing within the phloem[4][5]. One is used to inject saliva into the phloem, while the other is used to ingest the sap and saliva mixture[4][5]. Willow sap is an extremely nutritious food source, as it provides critical sugars and water to various parts of the willow tree[4][5]. As the aphid feeds, it is ingesting an incredible amount of these sugars and water, so much so that it needs to excrete them to avoid overfeeding[4][5][7][9]. Towards the posterior of the aphid are two cones called siphunculi, which are used to excrete the excess sap[4][5]. The sap that is released is known as honeydew and attracts various other insect species such as honeybees, wasps, and ants[4][5][7][9]. These other species will feed on the honeydew that is excreted from Tuberolachnus salignus[4][5][7][9].

Predators, Prey, and Parasties[edit]

Due to the almost exclusive feeding of willow sap by Tuberolachnus salignus, the honeydew that is produced as a result attracts numerous types of insects[4][5][7][9]. Wasps, bees, ants, flies and coccinellids have all been observed to feed on Tuberolachnus salignus honeydew[4][5][7][9]. These insects feed only on the honeydew, not the actual aphid[4][5][7][9]. In New Zealand, Pauesia nigrovaria was introduced as a biocontrol parasitoid of Tuberolachnus salignus in 2020[19]. Elsewhere, like North America and parts of Europe, parasitic wasps, lady beetles, hover fly maggots, lace wings are frequent predators of Tuberolachnus salignus[5].

Cultural Uses[edit]

Tuberolachnus salignus has only recently come into the limelight in New Zealand[9][11]. Upon arriving here in 2013, cause for alarm was immediately raised[9][11]. As previously noted, these giant aphids feed almost exclusively on willow species[9][11]. As Tuberolachnus salignus populations begin to rapidly grow on the willow tree, many negative impacts start to become apparat[9][11].

Willow trees are an extremely important group of plants in New Zealand[7][3]. While they are not native, they are used in many facets of society in order to increase land stabilization and reduce soil erosion[7][3]. Historically, willows have been planted along riverbanks and on particularly sloping land to help keep the soil beneath from eroding away[7][3]. Furthermore, willows play an important roll in honey production throughout New Zealand[7][3][20]. The flowers of willows are rich with pollen and nectar and attract honeybees[7][20]. In other parts of the world, such as the U.K., large amounts of willows are cultivated for biomass production[20]. With the presence of large Tuberolachnus salignus colonies on willow trees, many of the contributions listed above are severely hindered[7][3][20].

References[edit]

  1. ^ "Tuberolachnus salignus". Retrieved 26 November 2016.
  2. ^ a b "Giant Willow Aphid (Tuberolachnus salignus) Have we solved one of its mysteries?". Retrieved 26 November 2016.
  3. ^ a b c d e f g h i j k l Jones, T. G., Min Tun, K., Minor, M., & Clavijo McCormick, A. (4 May 2021). "The giant willow aphid (Tuberolachnus salignus) and its effects on the survival and growth of willows". Agricultural and Forest Entomology. 23 (4): 420–428 – via Royal Entomological Society.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ^ a b c d e f g h i j k l m n o p q r s t u v w Martin, NA (1 August 2017). "Giant willow aphid - Tuberolachnus salignus. Interesting Insects and other Invertebrates". Landcare Research. Retrieved March 29, 2023.{{cite web}}: CS1 maint: url-status (link)
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af Bochniarz, Alina (2020). "Giant willow aphid (Tuberolachnus salignus Gmelin, 1790) – a literature review". Polish Journal of Agronomy (43): 113–124.
  6. ^ a b c d e f g Sopow, S. L., Jones, T., McIvor, I., McLean, J. A., & Pawson, S. M. (24 January 2017). "Potential impacts of Tuberolachnus salignus (giant willow aphid) in New Zealand and options for control". Agricultural and Forest Entomology. 19 (3): 225–234 – via Royal Entomological Society.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ a b c d e f g h i j k l m n o p q r s t u Tun, K. M., Minor, M., Jones, T., & Clavijo McCormick, A. (12 December 2020). "Effect of willow cultivar and plant age on the melezitose content of giant willow aphid (Tuberolachnus salignus) honeydew". Agricultural and Forest Entomology. 23 (3): 261–268 – via Royal Entomological Society.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ a b c d e Aradottir, G. I., Hanley, S. J., Collins, C. M., Dawson, K. J., Karp, A., Leather, S. R., ... & Harrington, R. (30 October 2011). "Population genetics of Tuberolachnus salignus, an obligate parthenogenetic aphid". Agricultural and Forest Entomology. 14 (2): 197–205 – via Rothamsted Research.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ a b c d e f g h i j k l m n o p q r s t u v Sopow, S., Wardhaugh, C., Turner, R., Gresham, B., Sutherland, R., Woodall, G., & Withers, T. (12 August 2021). "Host specificity testing of Pauesia nigrovaria (Hymenoptera: Braconidae: Aphidiinae) for classical biological control of Tuberolachnus salignus (Hemiptera: Aphididae: Lachninae) in New Zealand". BioControl. 66: 739–751 – via Springer Link.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ a b c Collins, C. M., Fellowes, M. D., Sage, R. B., & Leather, S. R. (20 December 2001). "Host selection and performance of the giant willow aphid, Tuberolachnus salignus Gmelin – implications for pest management". Agricultural and Forest Entomology. 3 (3): 183–189 – via Royal Entomological Society.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ a b c d e f g h i j k Swears, R. M., & Manley-Harris, M. (2021). "Composition and potential as a prebiotic functional food of a Giant Willow Aphid (Tuberolachnus salignus) honeydew honey produced in New Zealand". Food Chemistry. 345 – via ScienceDirect.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Collins, C. M., & Leather, S. R. (2001). "Effect of temperature on fecundity and development of the Giant Willow Aphid, Tuberolachnus salignus (Sternorrhyncha: Aphididae)". European Journal of Entomology. 98 (2): 177–182.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ^ Llewellyn, M., Rashid, R., & Leckstein, P. (February 1974). "The Ecological Energetics of the Willow Aphid Tuberolachnus salignus (Gmelin); Honeydew Production". Journal of Animal Ecology. 43 (1): 19–29 – via JSTOR.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  14. ^ Özder, N., Sağlam, Ö., Güven, A., & Aydın, V. (25 February 2007). "Effect of temperature on development, mortality, fecundity and reproduction ofTuberolachnus salignus on weeping willow (Salix babylonica) and corkscrew willow (Salix matsudana)". Phytoparasitica. 35 (4): 386–391 – via SpringerLink.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  15. ^ Özder, N., & Sağlam, Ö. (2008). "Effect of temperature on the biology of Tuberolachnus salignus (Gmelin)(Sternorrhyncha: Aphididae) on (Salix alba)". Journal of Central European Agriculture. 9 (1): 155–160.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  16. ^ "Tuberolachnus salignus Giant willow aphid". Influential Points. 2023-02-12. Retrieved 2023-02-12.
  17. ^ Hussain, Barkat & War, Abdul Rasheed & Singh, Satnam & Ahmad, Shanawaz. (2021). First Record of an Invasive Pest, Giant Willow Aphid, Tuberolachnus salignus (Gmelin) (Hemiptera: Aphididae) on Salix alba in the Cold Arid Region of Ladakh, India. Entomological News. 129. 10.3157/021.129.0508.
  18. ^ a b c Horton, Helena (2023-02-12). "Have you seen this bug? Scientists call on Britain's gardeners to track elusive aphid". The Guardian. Retrieved 2023-02-12.
  19. ^ "Spread of GWA biocontrol agent, Pauesia nigrovaria". iNaturalist NZ. Retrieved 20 June 2023.
  20. ^ a b c d Tun, K. M., Clavijo McCormick, A., Jones, T., & Minor, M. (20 March 2020). "The potential of harlequin ladybird beetle Harmonia axyridis as a predator of the giant willow aphid Tuberolachnus salignus: voracity, life history and prey preference". BioControl. 65: 313–321 – via SpringerLink.{{cite journal}}: CS1 maint: multiple names: authors list (link)

Further reading[edit]

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