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Ischnocera

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Ischnocera
A chewing louse as seen from the side on an off-white background
Undetermined Strigiphilus species from a Ural owl (Strix uralensis), side view
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Psocodea
Suborder: Troctomorpha
Infraorder: Phthiraptera
Parvorder: Ischnocera
Kellogg, 1896
Families[1]

Ischnocera is a large parvorder of lice from the infraorder Phthiraptera. It is a chewing louse, which feeds on the feathers and skin debris of birds. Many species of Ischnocera have evolved an elongated body shape. This allows them to conceal themselves within plumage to avoid being dislodged during preening or flight. Ischnocera contains the large family Philopteridae, along with a few other minor families.

Classification

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Ischnocera previously included the mammalian parasitic lice Trichodectera. However, phylogenetic studies had found the grouping to be paraphyletic, specifically in regards to the two major families Philopteridae and Trichodectidae. In order to resolve this, de Moya et al. proposed retaining the majority of the species (including Philopteridae) within Ischnocera, and then moving Trichodectidae to its own grouping called Trichodectera.[2] Some scientific authorities have grouped Ischnocera and Amblycera in a single group called Mallophaga.[3]

Below is a cladogram showing the position of Ischnocera within Phthiraptera:[2]

Phthiraptera

Characteristics

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Ischnocera lice are characterized by pulvinus-like mandibles and two tarsal claws on each of their legs.[4][5] Like all chewing lice, they are wingless with dorsoventrally flattened bodies. They are permanent ectoparasites that live all of their life on a host bird.[6] They do not have ocelli, and their antennae is broken into 3 to 5 segments.[7] The length of adults ranges from 0.3 to 12 millimeters depending on the species.[7] Their head is typically broad and triangular shaped, with hook-like structures on the surface. The post-clypeus region is broad, with vertical stripes of thin cuticles.[8] The head also contains repeating ridges, which is used to help strengthen the exoskeleton.[8] Unlike their close taxonomic relative Amblycera, Ischnocera lack maxillary palps used to manipulate food.[9] Their color is typically brown, however some species can be black or white, and the rostrum is elongated significantly.[10] Their abdomens are usually divided into 8 segments, with the males characterized by having a large anterior plate, and the females having a continuous plate across their backs.[11] Younger members of the Ischnocera's evolutionary lineage have paired structures called mycetomes.[12] Species of Ischnocera are very host specific, with some birds receiving their classification based off the individual species of lice they are hosting.[13]

Life cycle

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Ischnocera lice can survive multiple weeks living off of their hosts.[14] The life cycle consists of a simple metamorphosis, with three separate stages. Adult female lice lay eggs (also referred to as "nits") on the bodies of their host, where they will develop and hatch within 7 to 10 days.[15] This is followed by the nymph stage for around 5 to 10 days, before finishing development in adults.[15] After the lice are sufficiently fed, the males use their antennae to touch the heads of females to signal they are ready to mate.[16] When the adult louse lays eggs, they typically do so in batches of 200 to 300 that are glued onto the feathers of their host to repeat the cycle.[17] The glue is a cement-like material that is excreted from the louse's oviducts.[18] Ischnocera lice are unable to move from the feathers to the skin of their hosts due to their specialized anatomy.[19] In order to move across individual birds, Ischnocera "hitchhikes" on hippoboscid flies that land on the current host. This is done to avoid competition from other lice by finding a new host to feed on.[20]

Guimaraesiella tovornikae and Sturnidoecus, found in Ischnocera

Distribution

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Ischnocera lice are distributed globally, with 3,800 different species across multiple continents.[21] The majority of species identified reside in Europe, North America and the Neotropical realm.[21] The lice are found most dense in agricultural regions.[22] They are found in areas where birds suffer from malnutrition and overcrowding as well, due to the ease of moving across individuals.[9]

Feeding

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Ischnocera primarily feeds on the feathers and skin debris of different species of birds. They are highly host specific, and usually do not deviate from their chosen species.[23] Ischnocera do not consume the blood of its host, and are found within it's feathers to avoid being dislodged.[23] The lice have specific areas of the bird that they prefer to feed on, and typically do not move away from that area.[24] Preferred areas of the birds are the head, neck and the croup. [25] Birds in humid regions are more prone to being infested by Ischnocera, with the trend continuing regardless of the species.[26] Species such as the Columbicola columbae feed mostly on the feather's barbules, as well as keratin-rich skin near the wing and tail feathers.[27] The lice also tend to feed on oils secreted by the bird.[28] Ischnocera contains an endosymbiotic bacteria that aids in the digestion of the debris and feathers of their host.[19]

Effects

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Ischnocera can cause significant irritation and damage to the feathers of their hosts. Infestations can also cause damage to egg production and fattening in poultry.[29] The lice can cause preening and scratching in hosts, along with the loss of feathers, potentially resulting in bald spots.[30] Birds with poor hygiene and weak immune systems are vulnerable to infestations due to a reduced ability to fight them.[30] Bald patches in birds can result in decreased insulation and disease susceptibility.[31] Self-grooming by the bird can help dislodge some of the infestation, although it is usually not enough to remove them entirely. The ability to remove the lice largely depends on the size of the bird's beak.[32] If a bird has a damaged beak, it can become significantly more susceptible to infestations. Some birds use an oil they secrete from their uropygial gland and spread it across their bodies to make it more difficult for the lice to attach themselves.[31] Flight performance, lifespan and sexual selection are also negatively affected in infested birds. The host's metabolic rate and overall body mass are also lowered during an infestation.[33] The lice can serve as vectors carrying bacterial diseases to the birds.[33] Infested birds show nervousness and discomfort, especially while they are nesting.[34] Spraying the infested with pesticides allows the lice to be killed by drying out their bodies.[22]

Families

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Ischnocera currently consists of the following families:[1][35]

References

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  1. ^ a b Hopkins, H.; Johnson, K. P.; Smith, V. S. "Ischnocera Kellogg, 1896". Psocodea Species File. Retrieved May 16, 2025.
  2. ^ a b de Moya, Robert S; Yoshizawa, Kazunori; Walden, Kimberly K O; Sweet, Andrew D; Dietrich, Christopher H; Kevin P, Johnson (2021-06-16). Buckley, Thomas (ed.). "Phylogenomics of Parasitic and Nonparasitic Lice (Insecta: Psocodea): Combining Sequence Data and Exploring Compositional Bias Solutions in Next Generation Data Sets". Systematic Biology. 70 (4): 719–738. doi:10.1093/sysbio/syaa075. ISSN 1063-5157. PMID 32979270.
  3. ^ "Chewing louse | Parasite, Poultry, Livestock | Britannica". www.britannica.com. Retrieved 2025-06-10.
  4. ^ Allaby 2020, p. 322
  5. ^ Allaby 2020, p. 476
  6. ^ SMITH, VINCENT S. (2001-05-01). "Avian louse phylogeny (Phthiraptera: Ischnocera): a cladistic study based on morphology". Zoological Journal of the Linnean Society. 132 (1): 81–144. doi:10.1111/j.1096-3642.2001.tb02272.x. ISSN 0024-4082.
  7. ^ a b H. Resh 2009, p. 777
  8. ^ a b Manglik, Rohit (July 9, 2024). Insect Morphology and Phylogeny. EduGorilla Publication. p. 307. ISBN 9789368176152.
  9. ^ a b "Lice (Phthiraptera) - Factsheet for health professionals". www.ecdc.europa.eu. 2022-02-15. Retrieved 2025-06-09.
  10. ^ Beutal, Rolf; Friedrich, Frank; qin-Ge, Si; Yang, Xingke (2014). Insect morphology and phylogeny : a textbook for students of entomology. Berlin: De Gruyter. p. 307. doi:10.1515/9783110264043. ISBN 9783110264043.
  11. ^ Kumar & Tandan 1971, p. 119
  12. ^ Bourtzis, Kostas; A. Miller, Thomas (October 28, 2008). Insect Symbiosis, Volume 3. CRC Press. p. 168. ISBN 9781040209806.
  13. ^ "Characteristics of Louse Prove Interesting to Scribe". The Houston Post. November 17, 1946. p. 24.
  14. ^ "Lice Dogs and Cats: chewing (Mallophaga), and sucking (Anoplura) - Learn About Parasites - Western College of Veterinary Medicine". wcvm-learnaboutparasites. Retrieved 2025-06-09.
  15. ^ a b "Lice: What They Are and How to Control Them | NC State Extension Publications". content.ces.ncsu.edu. Retrieved 2025-06-09.
  16. ^ Marshall, Adrian G (1981). The ecology of ectoparasitic insects. London: Academic Press. p. 68. OCLC 8166601.
  17. ^ Taylor, Coop & Wall 2013, p. 71
  18. ^ Ahmad, Aftab (June 25, 2018). "Egg laying pattern and the egg morphology of an ischnoceran louse, Goniocotes jirufti (Ansari, 1947) parasitizing black partridges, Francolinus francolinus (Phthiraptera: Ischnocera)". Journal of Applied and Natural Science. 10 (3): 838–840. doi:10.31018/JANS.V10I3.1714. S2CID 92446624.
  19. ^ a b T. Atkinson, Carter; J. Thomas, Nancy; Hunter, D. Bruce (2008). "Parasitic Diseases of Wild Birds" (PDF). darwin.biology.utah.edu. Retrieved June 9, 2025.
  20. ^ Pistone, John P.; Light, Jessica E.; Campbell, Tyler A.; Catanach, Therese A.; Voelker, Gary (2021). "Restricted Geographic Sampling Yields Low Parasitism Rates but Surprisingly Diverse Host Associations in Avian Lice (Insecta: Phthiraptera) from South Texas". Diversity (14242818). 13 (9): 430. Bibcode:2021Diver..13..430P. doi:10.3390/d13090430.
  21. ^ a b Takano, Oona M.; Voelker, Gary; Gustafsson, Daniel R.; Light, Jessica E. (2019). "Molecular phylogeny and novel host associations of avian chewing lice (Insecta: Phthiraptera) from South Africa". Systematic Entomology. 44 (2): 289–304. Bibcode:2019SysEn..44..289T. doi:10.1111/syen.12319.
  22. ^ a b Rezai, Nima (2022). Encyclopedia of Infection and Immunity. Amsterdam: Elsevier. p. 994. ISBN 9780323903035. OCLC 1397392951.
  23. ^ a b Ricardo Panizzi, Antônio; R. P. Parra, José (March 8, 2012). Insect Bioecology and Nutrition for Integrated Pest Management. Taylor & Francis. p. 647. ISBN 9781439837085.
  24. ^ Lucius 2017, p. 418
  25. ^ "Parasites of Poultry". The Australian Town and Country Journal. May 16, 1896. p. 23.
  26. ^ Marcondes, Carlos (2017). Arthropod Borne Diseases. Springer, Cham. p. 505. ISBN 9783319138848. OCLC 962834440.
  27. ^ Singh, Suneel Kumar; Arya, Surman; Singh, Sanjay Kumar; Khan, Vikram (2010-06-01). "Feeding and reproductive behaviour of pigeon slender louse, Columbicola columbae (Phthiraptera, Insecta, Ischnocera)". Journal of Applied and Natural Science. 2 (1): 126–133. doi:10.31018/jans.v2i1.111. ISSN 2231-5209.
  28. ^ Carro & Andrés 2015, p. 106
  29. ^ "Bird louse | Parasitic, Feather-Feeding, Poultry | Britannica". www.britannica.com. Retrieved 2025-06-09.
  30. ^ a b Begazo, Alfredo (2023-12-21). "Feather Lice in Backyard Birds". Avian Report. Retrieved 2025-06-09.
  31. ^ a b "Feather Picking in Pet Parrots". www.cliniciansbrief.com. Retrieved 2025-06-09.
  32. ^ Galloway, Terry; Lamb, Robert (2021). "Population Dynamics of Chewing Lice (Phthiraptera) Infesting Birds (Aves)" (PDF). Annual Review of Entomology. 66: 209–224. doi:10.1146/annurev-ento-041420-075608. Retrieved June 9, 2025.
  33. ^ a b Zerek, Aykut (2024). "Chewing Lice (Psocodea: Phthiraptera) Detected in Wild Birds in Hatay, Türkiye, a New Record of the Colpocephalum ecaudati Price and Beer from Black Kite (Milvus migrans)" (PDF). Kafkas Universitesi Veteriner Fakultesi Dergisi. doi:10.9775/kvfd.2023.30713. Retrieved June 9, 2025.
  34. ^ "No Competition". The Grand Rapids Press. July 16, 1960. p. 16.
  35. ^ "Ischnocera Kellogg, 1896 | COL". www.catalogueoflife.org. Retrieved 2025-06-10.

Sources

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