Agelastica alni

Agelastica alni
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Family:	Chrysomelidae
Subfamily:	Galerucinae
Tribe:	Hylaspini
Genus:	Agelastica
Species:	A. alni
Binomial name
Agelastica alni (Linnaeus, 1758)
Synonyms[1][2]
sensu stricto Adimonia violacea Laicharting, 1781 Cryptocephalus violacea Geoffroy, 1762 Chrysomela alni Linnaeus, 1758 glabra Adimonia glabra Fischer von Waldheim, 1842 Agelastica sillemi Laboissière, 1935 Agelastica orientalis Baly, 1878

Agelastica alni, the alder leaf beetle, is a species of leaf beetle (Chrysomelidae) in the genus Agelastica.^[3] Agelastica alni is distributed in Europe, the Caucasus, Siberia, north-eastern Kazakhstan, and in the 19th century was introduced to the United States.^[4]

The beetle and the beetle's larval host is the grey or speckled alder (Alnus incana) and to a lesser extent black alder (Alnus glutinosa), but it will also be found on hazel, birch or hornbeam^[5] if there is a shortage of food. It causes large holes and gaps in leaves from the end of April onwards, which are produced by the larvae in the first two stages, but the main damage is produced by larvae in the third stage.

Previously rare, and considered extinct in the UK,^[6] since being found in Manchester in 2004 it appears to be on the increase in the North West of England. Its range has been extending and it was found in Nottinghamshire and Hampshire in 2014 and in North Wales in 2018.^[5][7] This beetle has now been seen in North Yorkshire as of 29-09-24.

Description

The alder leaf beetle is a relatively small beetle, around 6–7 mm, black or metallic blue in colour. The winged adults overwinter and emerge in the spring. There is one generation each year. The larvae are normally black. Although the damage to alder trees can be unsightly, the trees will usually tolerate the damage.^[5][8]

• 
  Alder leaf beetle laying eggs.
• 
  Larva of the alder leaf beetle
• 
  The skeletonized remains of a black alder
• Video of a pregnant female on alder
• Video of a Agelastica alni in Germany

Subspecies

There are two subspecies of Agelastica alni:^[1][2]

• A. a. alni (Linnaeus, 1758)
• A. a. glabra (Fischer von Waldheim, 1842) (formerly known as A. a. orientalis Baly, 1878 until 2015)

References

1. Beenen, R. (2010). "Galerucinae Latreille, 1802". In Löbl, I.; Smetana, A. (eds.). Catalogue of Palaearctic Coleoptera. Volume 6. Chrysomeloidea. Stenstrup, Denmark: Apollo Books. pp. 443–491. ISBN 978-87-88757-84-2.
2. Bezděk, J. (2015). "A review of palaearctic Scelolyperus (Coleoptera: Chrysomelidae: Galerucinae), with description of S. perreus sp. nov. from Turkey". Annales Zoologici. 65 (1): 21–39. doi:10.3161/00034541ANZ2015.65.1.003.
3. "Agelastica alni". BioLib.cz. Retrieved 2017-03-31.
4. Kolk, A; Starzyk, J.R. (1996). Atlas szkodliwych owadów leśnych (The atlas of harmful forest insects). Warszawa: The Polish Forest Research Institute. Multico Ofic. Wyd. p. 705.
5. RHS (2019). "Alder leaf beetle". Royal Horticultural Society. Retrieved 11 June 2019.
6. "Alder Leaf Beetle". Archived from the original on 2009-12-19. Retrieved 2017-03-31.
7. "A beetle thought to have been extinct in Britain has been found in ..... Northop Deeside.com". www.deeside.com. Retrieved 2018-08-16.
8. "Primary and secondary host plants differ in leaf-level photosynthetic response to herbivory: evidence from Alnus and Betula grazed by the alder beetle, Agelastica alni" (PDF). New Phytol. 140: 239–249. 1998. Archived from the original (PDF) on 2010-06-29.