Psocodea

Psocodea Temporal range: 163–0  Ma PreꞒ Ꞓ O S D C P T J K Pg N Late Jurassic – Recent
An unidentified bark louse in the family Stenopsocidae
Human body louse
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
(unranked):	Paraneoptera
Order:	Psocodea Hennig, 1966
Suborders [1]
Psocomorpha Troctomorpha Phthiraptera (lice) Trogiomorpha

Psocodea is a taxonomic group of insects comprising the bark lice, book lice and parasitic lice. ^[2] It was formerly considered a superorder, but is now generally considered by entomologists as an order. ^{[1] [3] [4]} Despite the greatly differing appearance of parasitic lice (Phthiraptera), they are believed to have evolved from within the former order Psocoptera , which contained the bark lice and book lice, now found to be paraphyletic. ^{[5] [6]} They are often regarded as the most primitive of the hemipteroids. ^[7] Psocodea contains around 11,000 species, divided among four suborders and more than 70 families. ^{[1] [2] [8]} They range in size from 1–10 millimetres (0.04–0.4 in) in length.

The species known as booklice received their common name because they are commonly found amongst old books—they feed upon the paste used in binding. The barklice are found on trees, feeding on algae and lichen.

Anatomy and biology

Psocids are small, scavenging insects with a relatively generalized body plan. They feed primarily on fungi, algae, lichen, and organic detritus in nature but are also known to feed on starch-based household items like grains, wallpaper glue and book bindings. ^[9] They have chewing mandibles, and the central lobe of the maxilla is modified into a slender rod. This rod is used to brace the insect while it scrapes up detritus with its mandibles. They also have a swollen forehead, large compound eyes, and three ocelli. Their bodies are soft with a segmented abdomen. ^[10] Some species can spin silk from glands in their mouth. ^[11] They may festoon large sections of trunk and branches in dense swathes of silk. ^[12]

Some psocids have small ovipositors that are up to 1.5 times as long as the hindwings, and all four wings have a relatively simple venation pattern, with few cross-veins. The wings, if present, are held tent-like over the body. ^[10] The legs are slender and adapted for jumping, rather than gripping, as in the true lice. The abdomen has nine segments, and no cerci. ^[11]

There is often considerable variation in the appearance of individuals within the same species. Many have no wings or ovipositors, and may have a different shape to the thorax. Other, more subtle, variations are also known, such as changes to the development of the setae. The significance of such changes is uncertain, but their function appears to be different from similar variations in, for example, aphids. Like aphids, however, many psocids are parthenogenic, and the presence of males may even vary between different races of the same species. ^[11]

Psocids lay their eggs in minute crevices or on foliage, although a few species are known to be viviparous. The young are born as miniature, wingless versions of the adult. These nymphs typically molt six times before reaching full adulthood. The total lifespan of a psocid is rarely more than a few months. ^[11]

Booklice range from approximately 1 mm to 2 mm in length (1/25″ to 1/13″). Some species are wingless and they are easily mistaken for bedbug nymphs and vice versa. Booklouse eggs take two to four weeks to hatch and can reach adulthood approximately two months later. Adult booklice can live for six months. Besides damaging books, they also sometimes infest food storage areas, where they feed on dry, starchy materials. Although some psocids feed on starchy household products, the majority of psocids are woodland insects with little to no contact with humans, therefore they are of little economic importance. They are scavengers and do not bite humans. ^[13]

Psocids can affect the ecosystems in which they reside. Many psocids can affect decomposition by feeding on detritus, especially in environments with lower densities of predacious micro arthropods that may eat psocids. ^[14] The nymph of a psocid species, Psilopsocus mimulus, is the first known wood-boring psocopteran. These nymphs make their own burrows in woody material, rather than inhabiting vacated, existing burrows. This boring activity can create habitats that other organisms may use. ^[15]

Interaction with humans

Some species of psocids, such as Liposcelis bostrychophila , are common pests of stored products. ^[16] Psocids, among other arthropods, have been studied to develop new pest control techniques in food manufacturing. One study found that modified atmospheres during packing (MAP) helped to control the reoccurrence of pests during the manufacturing process and prevented further infestation in the final products that go to consumers. ^[17]

External phylogeny

Psocodea has been recovered as a monophyletic group in recent studies. Their next closest relatives are traditionally recognized as the monophyletic grouping Condylognatha that contains Hemiptera (true bugs) and Thysanoptera (thrips), which all combined form the group Paraneoptera. However, this is somewhat unclear, as analysis has shown that Psocodea could instead be the sister taxon to Holometabola, which would render Paraneoptera as paraphyletic. ^[6]

Here is a simple cladogram showing the traditional relationships with a monophyletic Paraneoptera: ^[6]

Neoptera	Polyneoptera Eumetabola Holometabola Paraneoptera Psocodea Condylognatha Thysanoptera (thrips) Hemiptera (true bugs)

Here is an alternative cladogram showing Paraneoptera as paraphyletic, with Psocodea as sister taxon to Holometabola: ^[6]

Neoptera	Polyneoptera Eumetabola Holometabola Psocodea Condylognatha Thysanoptera (thrips)   Hemiptera (true bugs)	Paraneoptera

Internal phylogeny

Here is a cladogram showing the relationships within Psocodea: ^[3]

Psocodea	Troctomorpha Phthiraptera Philopteridae Anoplura Rhynchophthirina Trichodectidae Amblycera Liposcelididae Pachytroctidae Sphaeropsocidae Amphientometae Psocomorpha Homilopsocidea Caeciliusetae Psocetae Epipsocetae Philotarsetae Archipsocetae Trogiomorpha Atropetae Psyllipsocetae Prionoglaridetae (paraphyletic)

Classification

The order Psocodea (formerly 'Psocoptera') is divided into three extant suborders.

Suborder Trogiomorpha

Trogiomorpha have antennae with many segments (22–50 antennomeres) and always three-segmented tarsi. ^[18]

Trogiomorpha is the smallest suborder of the Psocoptera sensu stricto (i.e., excluding Phthiraptera), with about 340 species in 7 families, ranging from the fossil family Archaeatropidae with only a handful of species to the speciose Lepidopsocidae (over 200 species). Trogiomorpha comprises infraorder Atropetae (extant families Lepidopsocidae, Psoquillidae and Trogiidae, and fossil families Archaeatropidae and Empheriidae) and infraorder Psocathropetae (families Psyllipsocidae and Prionoglarididae).

Suborder Troctomorpha

Troctomorpha have antennae with 15–17 segments and two-segmented tarsi.

Troctomorpha comprises the Infraorder Amphientometae (families Amphientomidae, Compsocidae, Electrentomidae, Musapsocidae, Protroctopsocidae and Troctopsocidae) and Infraorder Nanopsocetae (families Liposcelididae, Pachytroctidae and Sphaeropsocidae). Troctomorpha are now known to also contain the order Phthiraptera (lice), and are therefore paraphyletic, as are Psocoptera as a whole.

Some Troctomorpha, such as Liposcelis (which are similar to lice in morphology), are often found in birds' nests, and it is possible that a similar behavior in the ancestors of lice is at the origin of the parasitism seen today. ^[18]

Suborder Psocomorpha

Psocomorpha are notable for having antennae with 13 segments. They have two- or three-segmented tarsi, this condition being constant (e.g., Psocidae) or variable (e.g., Pseudocaeciliidae) within families. Their wing venation is variable, the most common type being that found in the genus Caecilius (rounded, free areola postica, thickened, free pterostigma, r+s two-branched, m three-branched). Additional veins are found in some families and genera (Dicropsocus and Goja in Epipsocidae, many Calopsocidae, etc.)

Psocomorpha is the largest suborder of the Psocoptera sensu stricto (i.e., excluding Phthiraptera), with about 3,600 species in 24 families, ranging from the species-poor Bryopsocidae (2 spp.) to the speciose Psocidae (about 900 spp). ^[18] Psocomorpha comprises Infraorder Epipsocetae (families Cladiopsocidae, Dolabellopsocidae, Epipsocidae, Neurostigmatidae and Ptiloneuridae), Infraorder Caeciliusetae (families Amphipsocidae, Asiopsocidae, Caeciliusidae, Dasydemellidae and Stenopsocidae), Infraorder Homilopsocidea (families Archipsocidae, Bryopsocidae, Calopsocidae, Ectopsocidae, Elipsocidae, Lachesillidae, Mesopsocidae, Peripsocidae, Philotarsidae, Pseudocaeciliidae and Trichopsocidae) and Infraorder Psocetae (families Hemipsocidae, Myopsocidae, Psilopsocidae and Psocidae).

References

1. Johnson, Kevin P.; Smith, Vincent S. (2021). "Psocodea species file online, Version 5.0" . Retrieved 2021-11-01.
2. P. J. Gullan & P. S. Cranston (2010). "Taxobox 17 – Psocodea: "Psocoptera" (bark lice and book lice)". The Insects: an Outline of Entomology (4th ed.). John Wiley & Sons. p. 479. ISBN   9781444317671.
3. De Moya, Robert S.; Yoshizawa, Kazunori; Walden, Kimberly K. O.; Sweet, Andrew D.; et al. (2021). "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 . PMID   32979270.
4. "Psocodea". GBIF. Retrieved 2021-11-01.
5. C. H. C. Lyal (1985). "Phylogeny and classification of the Psocodea, with particular reference to the lice (Psocodea: Phthiraptera)". Systematic Entomology . 10 (2): 145–165. doi:10.1111/j.1365-3113.1985.tb00525.x. S2CID   86331606.
6. Kevin P. Johnson; Christopher H. Dietrich; Frank Friedrich; Rolf G. Beutel; Benjamin Wipfler; Ralph S. Peters; Julie M. Allen; Malte Petersen; Alexander Donath; Kimberly K. O. Walden; Alexey M. Kozlov; Lars Podsiadlowski; Christoph Mayer; Karen Meusemann; Alexandros Vasilikopoulos; Robert M. Waterhouse; Stephen L. Cameron; Christiane Weirauch; Daniel R. Swanson; Diana M. Percy; Nate B. Hardy; Irene Terry; Shanlin Liu; Xin Zhou; Bernhard Misof; Hugh M. Robertson; Kazunori Yoshizawa (Dec 2018). "Phylogenomics and the evolution of hemipteroid insects". Proceedings of the National Academy of Sciences . 115 (50): 12775–12780. Bibcode:2018PNAS..11512775J. doi: 10.1073/pnas.1815820115 . PMC   6294958 . PMID   30478043.
7. Christopher O'Toole (2002). Firefly Encyclopedia of Insects and Spiders . Toronto: Firefly Books. ISBN   978-1-55297-612-8.
8. David Grimaldi & Michael S. Engel (2005). "The paraneopteran orders". Evolution of the Insects. Cambridge Evolution Series. Cambridge University Press. pp. 216–330. ISBN   9780521821490.
9. Green, P.W.C.; Turner, B.D. (January 15, 2004). "Food-selection by the booklouse, Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)". Journal of Stored Products Research. 41 (1): 103–113. doi:10.1016/j.jspr.2004.01.002.
10. Gullan & Granston (2005). The Insects: An Outline of Entomology 3rd Edition. pp. 499–505.
11. Hoell, H.V., Doyen, J.T. & Purcell, A.H. (1998). Introduction to Insect Biology and Diversity, 2nd ed. Oxford University Press. pp. 404–406. ISBN   978-0-19-510033-4.
12. "Psocoptera - Barklice, Booklice, Psocids -- Discover Life". www.discoverlife.org.
13. "Stored Product Pests: Booklice (Psocids) FAC". US Army Public Health Command fact sheet.
14. Whitford, W.G. (2000). Invertebrates as webmasters in ecosystems: Keystone arthropods as webmasters in desert ecosystems. UK: CAB International. pp. 25–43. ISBN   0-85199-394-X.
15. Smithers, C.N. (1995). "Psilopsocus mimulus Smithers (Psocoptera: Psilopsocidae), The first known wood boring psocopteran". Australian Journal of Entomology. 34 (2): 117–120. doi: 10.1111/j.1440-6055.1995.tb01299.x .
16. Stejskal, V.; Hubert, J.; Aulicky, R.; Kucerova, Z. (October 2015). "Overview of present and past and pest-associated risks in stored food and feed products: European perspective". Journal of Stored Products Research. 64: 122–132. doi:10.1016/j.jspr.2014.12.006.
17. Riudavets, Jordi; Castañé, Cristina; Alomar, Oscar; Pons, María José; Gabarra, Rosa (April 2009). "Modified atmosphere packaging (MAP) as an alternative measure for controlling ten pests that attack processed food products". Journal of Stored Products Research. 45 (2): 91–96. doi:10.1016/j.jspr.2008.10.001.
18. C. Lienhard & C. N. Smithers (2002). "Psocoptera (Insecta): World Catalogue and Bibliography". Instrumenta Biodiversitatis . 5.

External links

• National Barkfly Recording Scheme
• Psoco Net
• Tree of Life: Psocodea
• Archipsocus nomas, a webbing barklouse on the UF / IFAS Featured Creatures Web site