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 | |
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| Tuberolachnus salignus, showing dorsal tubercle | |
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| Species: | T. salignus
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| Tuberolachnus salignus Gmelin, 1790
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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
editAdults 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, T. 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 (siphunculi).[4]
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 T. 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 T. 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
editNatural Global Range
editTuberolachnus 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
editThis species 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, T. salignus populations have been known to increase rapidly.[3]
Ecology
editLife Cycle/Phenology
editTuberolachnus 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 T. 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, T. salignus is most active in the warmer months, with populations peaking in late summer and early autumn.[6][3] In colder months, 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 T. 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
editTuberolachnus 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 many herbivorous Hemiptera, T. salignus uses modified mouthparts 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] They prefer 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] These are excreted as a sugary liquid known as honeydew, which 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 T. salignus.[4][5][7][9]
Predators, Prey, and Parasites
editDue to the almost exclusive feeding of willow sap by T. 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 honeydew of this species.[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 T. salignus in 2020.[19] Elsewhere, like North America and parts of Europe, parasitic wasps, lady beetles, hover fly maggots, lace wings are frequent predators.[5]
Interactions with Humans
editTuberolachnus 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 T. salignus populations begin to rapidly grow on the willow tree, many negative impacts start to become apparent.[9][11]
Willow trees are an 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 T. salignus colonies on willow trees, many of the contributions listed above are severely hindered.[7][3][20] Additionally, honeybees that forage on T. salignus honeydew have poorer health and produce a lower quantity and quality of honey.[7]
References
edit- ^ "Tuberolachnus salignus". Retrieved 26 November 2016.
- ^ a b "Giant Willow Aphid (Tuberolachnus salignus) Have we solved one of its mysteries?". Retrieved 26 November 2016.
- ^ a b c d e f g h i j k l Jones, Trevor G.; Min Tun, Kyaw; Minor, Maria; Clavijo McCormick, Andrea (November 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. doi:10.1111/afe.12443.
- ^ a b c d e f g h i j k l m n o p q r s t u v Martin, NA (1 August 2017). "Giant willow aphid - Tuberolachnus salignus. Interesting Insects and other Invertebrates". Landcare Research. Retrieved March 29, 2023.
- ^ 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 Bochniarz, Alina (2020). "Giant willow aphid (Tuberolachnus salignus Gmelin, 1790) – a literature review". Polish Journal of Agronomy. 43: 113–124. doi:10.26114/pja.iung.449.2020.43.11.
- ^ a b c d e f g Sopow, Stephanie L.; Jones, Trevor; McIvor, Ian; McLean, John A.; Pawson, Stephen M. (August 2017). "Potential impacts of Tuberolachnus salignus (giant willow aphid) in New Zealand and options for control: Impacts of giant willow aphid in NZ". Agricultural and Forest Entomology. 19 (3): 225–234. doi:10.1111/afe.12211.
- ^ a b c d e f g h i j k l m n o p q r s t u Tun, Kyaw Min; Minor, Maria; Jones, Trevor; Clavijo McCormick, Andrea (August 2021). "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. doi:10.1111/afe.12428.
- ^ a b c d e Aradottir, Gudbjorg I.; Hanley, Steven J.; Collins, C. Matilda; Dawson, Kevin J.; Karp, Angela; Leather, Simon R.; Shield, Ian; Harrington, Richard (May 2012). "Population genetics of Tuberolachnus salignus, an obligate parthenogenetic aphid". Agricultural and Forest Entomology. 14 (2): 197–205. doi:10.1111/j.1461-9563.2011.00559.x.
- ^ a b c d e f g h i j k l m n o p q r s t u v Sopow, Stephanie; Wardhaugh, Carl; Turner, Rebecca; Gresham, Belinda; Sutherland, Roanne; Woodall, Georgia; Withers, Toni (December 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 (6): 739–751. doi:10.1007/s10526-021-10107-5.
- ^ a b c Collins, C. Matilda; Fellowes, Mark D. E.; Sage, Rufus B.; Leather, Simon R. (August 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. doi:10.1046/j.1461-9555.2001.00105.x.
- ^ a b c d e f g h i j k Swears, Rosemary M.; Manley-Harris, Merilyn (May 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: 128662. doi:10.1016/j.foodchem.2020.128662. PMID 33310258.
- ^ Matilda Collins, C.; Leather, Simon R. (19 June 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. doi:10.14411/eje.2001.033.
- ^ Llewellyn, M.; Rashid, R.; Leckstein, P. (1974). "The Ecological Energetics of the Willow Aphid Tuberolachnus salignus (Gmelin); Honeydew Production". Journal of Animal Ecology. 43 (1): 19–29. doi:10.2307/3155. JSTOR 3155.
- ^ Özder, N.; Sağlam, ö.; Güven, A.; Aydın, V. (August 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. doi:10.1007/BF02980702.
- ^ Ozder, Nihal; Saglam, Ozgur (May 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. hdl:20.500.11776/9601. Gale A187963575.
- ^ "Tuberolachnus salignus Giant willow aphid". Influential Points. 2023-02-12. Retrieved 2023-02-12.
- ^ Hussain, Barkat; War, Abdul Rasheed; Singh, Satnam; Ahmad, Shanawaz (25 May 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 (5). doi:10.3157/021.129.0508.
- ^ 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.
- ^ "Spread of GWA biocontrol agent, Pauesia nigrovaria". iNaturalist NZ. Retrieved 20 June 2023.
- ^ a b c d Tun, Kyaw Min; Clavijo McCormick, Andrea; Jones, Trevor; Minor, Maria (June 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 (3): 313–321. doi:10.1007/s10526-020-10010-5.
Further reading
edit- Collins, C. Matilda; Leather, Simon 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. doi:10.14411/eje.2001.033.
- Collins, C Matilda; Rosado, Rui G; Leather, Simon R (April 2001). "The impact of the aphids Tuberolachnus salignus and Pterocomma salicis on willow trees". Annals of Applied Biology. 138 (2): 133–140. doi:10.1111/j.1744-7348.2001.tb00095.x.
- Mittler, T. E. (September 1957). "Studies on the Feeding and Nutrition of Tuberolachnus Salignus (Gmelin) (Homoptera, Aphididae)". Journal of Experimental Biology. 34 (3): 334–341. doi:10.1242/jeb.34.3.334.