Tuberolachnus salignus

Adults exhibit a pear-shaped body with dark brown/grayish coloration.{{Cite web |last=Martin |first=NA |date=1 August 2017 |title=Giant willow aphid - Tuberolachnus salignus. Interesting Insects and other Invertebrates |url=https://nzacfactsheets.landcareresearch.co.nz/factsheet/InterestingInsects/Giant-willow-aphid---Tuberolachnus-salignus.html |access-date=March 29, 2023 |website=Landcare Research}} This aphid species has distinct black dots that form rows along its body. 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.{{cite journal |last1=Bochniarz |first1=Alina |title=Giant willow aphid (Tuberolachnus salignus Gmelin, 1790) – a literature review |journal=Polish Journal of Agronomy |date=2020 |volume=43 |pages=113–124 |doi=10.26114/pja.iung.449.2020.43.11 }}{{cite journal |last1=Sopow |first1=Stephanie L. |last2=Jones |first2=Trevor |last3=McIvor |first3=Ian |last4=McLean |first4=John A. |last5=Pawson |first5=Stephen M. |title=Potential impacts of Tuberolachnus salignus (giant willow aphid) in New Zealand and options for control: Impacts of giant willow aphid in NZ |journal=Agricultural and Forest Entomology |date=August 2017 |volume=19 |issue=3 |pages=225–234 |doi=10.1111/afe.12211 }} Closer to the posterior and along the sides of the body are two smaller black cone structures (siphunculi).

Tuberolachnus salignus reproduces solely through parthenogenesis so all aphid adults are female.{{cite journal |last1=Tun |first1=Kyaw Min |last2=Minor |first2=Maria |last3=Jones |first3=Trevor |last4=Clavijo McCormick |first4=Andrea |date=August 2021 |title=Effect of willow cultivar and plant age on the melezitose content of giant willow aphid (Tuberolachnus salignus) honeydew |journal=Agricultural and Forest Entomology |volume=23 |issue=3 |pages=261–268 |doi=10.1111/afe.12428}}{{cite journal |last1=Aradottir |first1=Gudbjorg I. |last2=Hanley |first2=Steven J. |last3=Collins |first3=C. Matilda |last4=Dawson |first4=Kevin J. |last5=Karp |first5=Angela |last6=Leather |first6=Simon R. |last7=Shield |first7=Ian |last8=Harrington |first8=Richard |title=Population genetics of Tuberolachnus salignus, an obligate parthenogenetic aphid |journal=Agricultural and Forest Entomology |date=May 2012 |volume=14 |issue=2 |pages=197–205 |doi=10.1111/j.1461-9563.2011.00559.x }}{{cite journal |last1=Sopow |first1=Stephanie |last2=Wardhaugh |first2=Carl |last3=Turner |first3=Rebecca |last4=Gresham |first4=Belinda |last5=Sutherland |first5=Roanne |last6=Woodall |first6=Georgia |last7=Withers |first7=Toni |title=Host specificity testing of Pauesia nigrovaria (Hymenoptera: Braconidae: Aphidiinae) for classical biological control of Tuberolachnus salignus (Hemiptera: Aphididae: Lachninae) in New Zealand |journal=BioControl |date=December 2021 |volume=66 |issue=6 |pages=739–751 |doi=10.1007/s10526-021-10107-5 |bibcode=2021BioCo..66..739S }} Adults can be either winged or wingless. The two pairs of wings are clear with a dark brown edge along the forewing. When looking at T. salignus under a microscope the presence of numerous tiny hairs is apparent. This gives the abdomen a grayish-gold hue. Adult T. salignus has three pairs of legs that are primarily a dark brownish color, but smaller, red/orange sections are also present. They also have a pair of antennae that are less than half of the aphid's body length.

Tuberolachnus salignus is a cosmopolitan species.{{cite journal |last1=Collins |first1=C. Matilda |last2=Fellowes |first2=Mark D. E. |last3=Sage |first3=Rufus B. |last4=Leather |first4=Simon R. |title=Host selection and performance of the giant willow aphid, Tuberolachnus salignus Gmelin – implications for pest management |journal=Agricultural and Forest Entomology |date=August 2001 |volume=3 |issue=3 |pages=183–189 |doi=10.1046/j.1461-9555.2001.00105.x }} They exist anywhere that willow species grow naturally or are cultivated. The giant willow aphid originated in parts of Asia but has now spread to all parts of the globe (except Antarctica). There is no known exact place of origin for this aphid species, but it is believed to be somewhere within Japan and Korea.{{cite journal |last1=Swears |first1=Rosemary M. |last2=Manley-Harris |first2=Merilyn |title=Composition and potential as a prebiotic functional food of a Giant Willow Aphid (Tuberolachnus salignus) honeydew honey produced in New Zealand |journal=Food Chemistry |date=May 2021 |volume=345 |pages=128662 |doi=10.1016/j.foodchem.2020.128662 |pmid=33310258 }} The only known parasitoid of this species is endemic to Japan, leading to the belief that this may be the place of their origin.

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

This species is almost entirely dependent on willow trees. They live on the bark of these trees and feed on their sap. These giant aphids survive year-round with the most activity being in late summer and early fall. Their population numbers are known to be largely weather and temperature related.{{cite journal |last1=Matilda Collins |first1=C. |last2=Leather |first2=Simon R. |title=Effect of temperature on fecundity and development of the Giant Willow Aphid, Tuberolachnus salignus (Sternorrhyncha: Aphididae) |journal=European Journal of Entomology |date=19 June 2001 |volume=98 |issue=2 |pages=177–182 |doi=10.14411/eje.2001.033 }} Following instances of large amounts of rain, T. salignus populations have been known to increase rapidly.{{cite journal |last1=Jones |first1=Trevor G. |last2=Min Tun |first2=Kyaw |last3=Minor |first3=Maria |last4=Clavijo McCormick |first4=Andrea |title=The giant willow aphid (Tuberolachnus salignus) and its effects on the survival and growth of willows |journal=Agricultural and Forest Entomology |date=November 2021 |volume=23 |issue=4 |pages=420–428 |doi=10.1111/afe.12443 }}

Tuberolachnus salignus has a generation period of 2–3 weeks, which is largely dependent on temperature. Once hatched, the aphid larvae go through four stages of development until they reach their adult forms.{{cite journal |last1=Llewellyn |first1=M. |last2=Rashid |first2=R. |last3=Leckstein |first3=P. |title=The Ecological Energetics of the Willow Aphid Tuberolachnus salignus (Gmelin); Honeydew Production |journal=Journal of Animal Ecology |date=1974 |volume=43 |issue=1 |pages=19–29 |doi=10.2307/3155 |jstor=3155 |bibcode=1974JAnEc..43...19L }} Ideal temperatures for T. salignus generation range from 17.5 to 22.5 degrees Celsius. It takes two weeks for nymphs to become adults, with adults living an additional five weeks after that. Mature aphids can produce anywhere from 35 to 71 offspring.{{cite journal |last1=Özder |first1=N. |last2=Sağlam |first2=ö. |last3=Güven |first3=A. |last4=Aydın |first4=V. |title=Effect of temperature on development, mortality, fecundity and reproduction ofTuberolachnus salignus on weeping willow (Salix babylonica) and corkscrew willow (Salix matsudana) |journal=Phytoparasitica |date=August 2007 |volume=35 |issue=4 |pages=386–391 |doi=10.1007/BF02980702 |bibcode=2007Phyto..35..386O }}{{cite journal |last1=Ozder |first1=Nihal |last2=Saglam |first2=Ozgur |title=Effect of temperature on the biology of Tuberolachnus salignus (Gmelin) (sternorrhyncha: Aphididae) on (Salix alba) |journal=Journal of Central European Agriculture |date=May 2008 |volume=9 |issue=1 |pages=155–160 |id={{Gale|A187963575}} |hdl=20.500.11776/9601 |url=https://hrcak.srce.hr/24911 }} Generally, T. salignus is most active in the warmer months, with populations peaking in late summer and early autumn. In colder months, the overall fecundity decreases but colonies are still active. In the spring, colonies are usually not visible. During this time, it is thought T. salignus retreats behind the willow tree bark or into the ground to escape the harsh climate.

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

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'){{Cite web |date=2023-02-12 |title=Tuberolachnus salignus Giant willow aphid |url=https://influentialpoints.com/Gallery/Tuberolachnus_salignus.htm#:~:text=The%20giant%20willow%20aphid%20lives,cosmopolitan%20wherever%20willows%20are%20grown. |access-date=2023-02-12 |website=Influential Points}} and the Indian willow (Salix tetrasperma).{{cite journal |last1=Hussain |first1=Barkat |last2=War |first2=Abdul Rasheed |last3=Singh |first3=Satnam |last4=Ahmad |first4=Shanawaz |title=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 |journal=Entomological News |date=25 May 2021 |volume=129 |issue=5 |doi=10.3157/021.129.0508 }} It has also been recorded on Quince (Cydonia oblonga),{{Cite news |last=Horton |first=Helena |date=2023-02-12 |title=Have you seen this bug? Scientists call on Britain's gardeners to track elusive aphid |work=The Guardian |url=https://www.theguardian.com/environment/2023/feb/12/track-willow-aphid-gardeners-royal-horticultural-society-scientists?CMP=Share_iOSApp_Other&fbclid=IwAR1bOLZf6ps1ttRAmY6Pk_E7yMHxNlasF5IJH1aYe7SxcHDGdM8c878BS-A |access-date=2023-02-12}} Apple (Malus spp.) and Poplar (Populus spp.)

Like many herbivorous Hemiptera, T. salignus uses modified mouthparts to pierce the phloem of plants and feed on its sap. 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. They prefer to feed during the day and during the warmer hours. When feeding, the aphid will climb to the tip of the willow where the shoot begins. The flesh of the plant is softer here, allowing the aphid to inject its stylets into the plant's phloem.

Tuberolachnus salignus uses two stylets to extract the sap flowing within the phloem. One is used to inject saliva into the phloem, while the other is used to ingest the sap and saliva mixture. Willow sap is an extremely nutritious food source, as it provides critical sugars and water to various parts of the willow tree. 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. These are excreted as a sugary liquid known as honeydew, which attracts various other insect species such as honeybees, wasps, and ants. These other species will feed on the honeydew that is excreted from T. salignus.

Due to the almost exclusive feeding of willow sap by T. salignus, the honeydew that is produced as a result attracts numerous types of insects. Wasps, bees, ants, flies and coccinellids have all been observed to feed on honeydew of this species. These insects feed only on the honeydew, not the actual aphid. In New Zealand, Pauesia nigrovaria was introduced as a biocontrol parasitoid of T. salignus in 2020.{{cite web |title=Spread of GWA biocontrol agent, Pauesia nigrovaria |url=https://inaturalist.nz/projects/spread-of-gwa-biocontrol-agent-pauesia-nigrovaria |website=iNaturalist NZ |access-date=20 June 2023}} Elsewhere, like North America and parts of Europe, parasitic wasps, lady beetles, hover fly maggots, lace wings are frequent predators.

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

Willow trees are an important group of plants in New Zealand. While they are not native, they are used in many facets of society in order to increase land stabilization and reduce soil erosion. Historically, willows have been planted along riverbanks and on particularly sloping land to help keep the soil beneath from eroding away. Furthermore, willows play an important roll in honey production throughout New Zealand.{{cite journal |last1=Tun |first1=Kyaw Min |last2=Clavijo McCormick |first2=Andrea |last3=Jones |first3=Trevor |last4=Minor |first4=Maria |title=The potential of harlequin ladybird beetle Harmonia axyridis as a predator of the giant willow aphid Tuberolachnus salignus: voracity, life history and prey preference |journal=BioControl |date=June 2020 |volume=65 |issue=3 |pages=313–321 |doi=10.1007/s10526-020-10010-5 |bibcode=2020BioCo..65..313T }} The flowers of willows are rich with pollen and nectar and attract honeybees. In other parts of the world, such as the U.K., large amounts of willows are cultivated for biomass production. With the presence of large T. salignus colonies on willow trees, many of the contributions listed above are severely hindered. Additionally, honeybees that forage on T. salignus honeydew have poorer health and produce a lower quantity and quality of honey.

{{Reflist}}

• {{cite journal|last1=Collins|first1=C. Matilda|first2=Simon R. |last2=Leather |year=2001 |title=Effect of temperature on fecundity and development of the Giant Willow Aphid, Tuberolachnus salignus (Sternorrhyncha: Aphididae)|journal=European Journal of Entomology|volume=98|issue=2|pages=177–182 |doi=10.14411/eje.2001.033|doi-access=free}}
• {{cite journal |last1=Collins |first1=C Matilda |last2=Rosado |first2=Rui G |last3=Leather |first3=Simon R |title=The impact of the aphids Tuberolachnus salignus and Pterocomma salicis on willow trees |journal=Annals of Applied Biology |date=April 2001 |volume=138 |issue=2 |pages=133–140 |doi=10.1111/j.1744-7348.2001.tb00095.x }}
• {{cite journal |last1=Mittler |first1=T. E. |title=Studies on the Feeding and Nutrition of Tuberolachnus Salignus (Gmelin) (Homoptera, Aphididae) |journal=Journal of Experimental Biology |date=September 1957 |volume=34 |issue=3 |pages=334–341 |doi=10.1242/jeb.34.3.334 |bibcode=1957JExpB..34..334M }}

{{Taxonbar|from=Q14086166}}

Category:Lachninae

Category:Hemiptera of Europe

Category:Insects described in 1790

Category:Taxa named by Johann Friedrich Gmelin