Brochosome

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The most common brochosomes Brochosomes1.jpg
The most common brochosomes
A female Homalodisca vitripennis carries on her wings masses of specialized brochosomes (the white spot) to be used during egg-laying. Homalodisca vitripennis - Glassy-winged sharpshooter (16283561424).jpg
A female Homalodisca vitripennis carries on her wings masses of specialized brochosomes (the white spot) to be used during egg-laying.
A model of a typical brochosome from leafhopper integument (on the right dissected to show the interior). 3D model of brochosome.jpg
A model of a typical brochosome from leafhopper integument (on the right dissected to show the interior).

Brochosomes are intricately structured microscopic granules secreted by leafhoppers (the family Cicadellidae of the insect order Hemiptera) and typically found on their body surface and, more rarely, eggs. Brochosomes were first described in 1952 with the aid of an electron microscope. [2] [3] Brochosomes are hydrophobic and help keep the insect cuticle clean. These particles have also been found in samples of air [4] and can easily contaminate foreign objects, which explains erroneous reports of brochosomes on other insects. [5]

Contents

The name, derived from the Greek words βρóχoς ("brochos": mesh of a net) and σωμα ("soma": body), refers to the characteristic reticulated surface of the granules.

Structure and composition

Most species of leafhoppers produce hollow spherical brochosomes, 0.2–0.7 micrometres in diameter, with a honeycombed outer wall. They often consist of 20 hexagonal and 12 pentagonal cells, making the outline of each brochosome approximating a truncated icosahedron – the geometry of a soccer ball and a C60 buckminsterfullerene molecule. The chemical composition of brochosomes includes several kinds of proteins [6] and, according to some studies, lipids. [7] [8] The main protein family, called brochosomins, and other kinds of proteins identified in the composition of brochosomes and their corresponding genes show no relationship to proteins and genes of any organisms outside of Membracoidea and thus are considered to be examples of orphan genes. [6]

Origin

Development of brochosomes (stages I to IV) in a secretory cell. Brochosome secretion En.jpg
Development of brochosomes (stages I to IV) in a secretory cell.

Brochosomes are produced within cells of specialized glandular segments of the Malpighian tubules – the primary excretory organs of insects, which often serve additional functions. Each cell simultaneously manufactures a large number of brochosomes within its Golgi complexes and eventually releases them into the lumen of the tubule. [7] [8] [9] [10]

Functions

A freshly molted female of Igutettix oculatus (Ldb.) uses its hind tibiae to transfer brochosome-containing secretory droplets from the anus (left) onto the forewings (middle), where the sediment of brochosomes dries as a pair of white spots (right), sometimes erroneously referred to as "wax areas". Igutettix anointing.jpg
A freshly molted female of Igutettix oculatus (Ldb.) uses its hind tibiae to transfer brochosome-containing secretory droplets from the anus (left) onto the forewings (middle), where the sediment of brochosomes dries as a pair of white spots (right), sometimes erroneously referred to as "wax areas".

After each molt, most leafhopper species release droplets of the brochosome-containing fluid through the anus and actively spread them over the newly formed integument. [11] [12] [13] This behavior is called anointing. [12] Dry brochosomes are further distributed across the body and appendages in repeated bouts of grooming, in which leafhoppers scrub themselves with their legs. The transport of brochosomes is facilitated by groups and rows of strong setae on the legs. The resulting coat makes the integument highly repellent to water (superhydrophobic) [1] and to the leafhopper’s own liquid excreta, [14] the latter often being sugary and sticky, and thus potentially dangerous for the insect. Additional protective functions of the brochosomal coating have been hypothesized. [13] For example, there is evidence that the anti reflective property of brochosome make surfaces coated by it appear similar to a leaf in the eyes of insects thus it can be used as camouflage for the eggs. [15]

In several New World genera of the leafhopper subfamily Cicadellinae (including the glassy-winged sharpshooter and related species) brochosomes are also used as a coating on egg masses. [16] [17] In gravid females from these genera, the Malpighian tubules switch over [10] from production of regular brochosomes, described above, to production of larger, typically elongate particles, up to 20 micrometres in length. Prior to laying eggs, the female places masses of such brochosomes onto its forewings, and later scrapes them off onto the freshly laid eggs with its hindlegs. [17] The resulting powdery coat may serve various protective functions, including protection against egg-parasitoids from the order Hymenoptera (Chalcidoidea). [18] The shape and sculpture of such "egg" brochosomes can vary significantly among species, providing additional characteristics for species identification. [17]

Related Research Articles

<span class="mw-page-title-main">Hemiptera</span> Order of insects often called true bugs

Hemiptera is an order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, assassin bugs, bed bugs, and shield bugs. They range in size from 1 mm (0.04 in) to around 15 cm (6 in), and share a common arrangement of piercing-sucking mouthparts. The name "true bugs" is often limited to the suborder Heteroptera.

<span class="mw-page-title-main">Malpighian tubule system</span> Excretory and osmoregulatory system

The Malpighian tubule system is a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids and tardigrades.

<span class="mw-page-title-main">Glassy-winged sharpshooter</span> Species of leafhopper

The glassy-winged sharpshooter is a large leafhopper, similar to other species of sharpshooter.

<span class="mw-page-title-main">Leafhopper</span> Family of insects

Leafhopper is the common name for any species from the family Cicadellidae. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or trees. Their hind legs are modified for jumping, and are covered with hairs that facilitate the spreading of a secretion over their bodies that acts as a water repellent and carrier of pheromones. They undergo a partial metamorphosis, and have various host associations, varying from very generalized to very specific. Some species have a cosmopolitan distribution, or occur throughout the temperate and tropical regions. Some are pests or vectors of plant viruses and phytoplasmas. The family is distributed all over the world, and constitutes the second-largest hemipteran family, with at least 20,000 described species.

<span class="mw-page-title-main">Auchenorrhyncha</span> Suborder of insects

The Auchenorrhyncha suborder of the Hemiptera contains most of the familiar members of what was called the "Homoptera" – groups such as cicadas, leafhoppers, treehoppers, planthoppers, and spittlebugs. The aphids and scale insects are the other well-known "Homoptera", and they are in the suborder Sternorrhyncha.

<span class="mw-page-title-main">Cicadomorpha</span> Infraorder of insects

Cicadomorpha is an infraorder of the insect order Hemiptera which contains the cicadas, leafhoppers, treehoppers, and spittlebugs. There are approximately 35,000 described species worldwide. Distributed worldwide, all members of this group are plant-feeders, and many produce either audible sounds or substrate vibrations as a form of communication. The earliest fossils of cicadomorphs first appear during the Late Permian.

<span class="mw-page-title-main">Membracoidea</span> Superfamily of true bugs

The superfamily Membracoidea of sap-sucking true-bugs includes two of the largest families within what used to be called the "Homoptera": the leafhoppers (Cicadellidae) and the treehoppers (Membracidae). The other families in this group are quite small, and have, at various points, generally been included as members within other families, though they are all presently considered to be valid, monophyletic groups. The relict family Myerslopiidae is restricted to New Zealand and South America while the Melizoderidae consist of two genera restricted to South America. The great diversity of Neotropical taxa suggests that the group originated in that region.

David Allan Young Jr. was an American entomologist who specialized in the taxonomy of the Cicadellidae and authored a comprehensive treatment of the family with numerous genera and species described and named by him. This work in three parts, Taxonomic Study of the Cicadellinae , covered 292 genera.

<span class="mw-page-title-main">Machaerotidae</span> Family of true bugs

Machaerotidae are a family of bugs in the superfamily Cercopoidea which were formerly placed within Cercopidae. They are sometimes called tube-forming spittle-bugs as the nymphs form a calcareous tube within which they live. These bugs are mainly found in the Old World tropics. The adults of many genera have a long, free and spine-like process originating from the scutellum and thus superficially similar to the tree-hoppers, Membracidae. The tegmen or forewing, like typical bugs of the suborder Heteroptera, always has a distinct, membranous apical area.

<i>Japananus hyalinus</i> Species of true bug

Japananus hyalinus, the Japanese maple leafhopper, is a species of leafhopper of the subfamily Deltocephalinae and tribe Opsiini. Believed to be native to eastern Asia, it has been carried with the trade in cultivated maples and is now widely found in Europe, North America and Australia.

<span class="mw-page-title-main">Potato leafhopper</span> Species of true bug

Potato leafhopper belongs to family Cicadellidae and genus Empoasca within order Hemiptera. In North America they are a serious agricultural pest. Every year millions of dollars are lost from reduced crop yields and on pest management. Crops that are impacted the most are potatoes, clover, beans, apples and alfalfa.

<span class="mw-page-title-main">Corn stunt disease</span> Bacterial plant disease

Corn stunt disease is a bacterial disease of corn and other grasses. Symptoms include stunted growth and leaves turning red. It is caused by the bacterium Spiroplasma kunkelii.

<span class="mw-page-title-main">Aetalionidae</span> Family of true bugs

Aetalionidae are a family of treehoppers in the superfamily Membracoidea. Aetalionidae are somewhat like Membracidae in that they have one to three rows of short spines on the hind tibia but differ in having the front femur fused to the trochanter and the scutellum is completely exposed. The females have finger-like protrusions on the genital capsule. The family is mostly Neotropical. The subfamily Biturritiinae is Neotropical while the subfamily Aetalioninae has a Neotropical genus Aetalion and the sole Old World representative genus Darthula with a single species Darthula hardwickii.

<i>Agallia</i> Genus of true bugs

Agallia is a genus of leafhoppers in the family Cicadellidae. There are about eight described species in Agallia. During courtship displays and mating, both males and females of the species A. constricta alternate in making ticking sounds.

<span class="mw-page-title-main">Coelidiinae</span> Subfamily of leafhoppers

Coelidiinae is a subfamily of leafhoppers in the family Cicadellidae. There are at least 8 tribes, 108 genera, and over 900 species in Coelidiinae.

<span class="mw-page-title-main">Scaphoideini</span> Tribe of leafhoppers

Scaphoideini is a tribe of leafhoppers. There are 64 genera and over 600 described species in Scaphoideini.

<i>Paraulacizes irrorata</i> Species of leafhopper

Paraulacizes irrorata, the speckled sharpshooter, is a species of sharpshooter in the family Cicadellidae.

<span class="mw-page-title-main">C.A. Viraktamath</span> Indian entomologist (born 1944)

Chandrashekaraswami Adiveyya Viraktamath is an Indian entomologist who specializes in the systematics of leaf-hoppers, Cicadellidae. He served as a professor of entomology at the University of Agricultural Sciences, Bangalore.

<i>Jikradia olitoria</i> Species of leafhopper

Jikradia olitoria is a species of leafhopper found mainly in eastern North America. The insect acts as a vector for the North American grapevine yellows.

<i>Erasmoneura vulnerata</i> Species of leafhopper

Erasmoneura vulnerata is a species of leafhopper native to North America. The species was found to be in Europe in 2004 where it causes significant economic damage to grapevine yards. E. vulnerata is commonly found on wild and cultivated grapes from both continents. Its Latin name translates to "wounded Erasmoneura" from its original description.

References

  1. 1 2 Rakitov R. & Gorb S.N. (2013) Brochosomal coats turn leafhopper (Insecta, Hemiptera, Cicadellidae) integument to superhydrophobic state. Proceedings of the Royal Society B 280 (1752). doi : 10.1098/rspb.2012.2391.
  2. ↑ Tulloch G.S., Shapiro J.E. & Cochran G.W. (1952) The occurrence of ultramicroscopic bodies with leafhoppers and mosquitoes. Bulletin of the Brooklyn Entomological Society 47: 41-42.
  3. ↑ Day M.F. & M. Briggs (1958) The origin and structure of brochosomes. Journal of Ultrastructure Research 2: 239-244. PMID   13631751
  4. ↑ Wittmaack K. (2005) Brochosomes produced by leafhoppers - a widely unknown, yet highly abundant species of bioaerosols in ambient air. Atmospheric Environment 39: 1173-1180.
  5. ↑ Rakitov R.A. (2011) Contamination as the cause of erroneous records of brochosomes. Psyche: A Journal of Entomology 2011, Article ID 767963, doi : 10.1155/2011/767963.
  6. 1 2 Rakitov R., Moysa A. A., Kopylov A. T., Moshkovskii S. A., Peters R. S., Meusemann K., Misof B., Dietrich C. H., Johnson K. P., Podsiadlowski L., Walden K. K. O. (2018) Brochosomins and other novel proteins from brochosomes of leafhoppers (Insecta, Hemiptera, Cicadellidae). Insect Biochemistry and Molecular Biology, 94, 10-17. doi : 10.1016/j.ibmb.2018.01.001
  7. 1 2 Smith D.S. & Littau V.G. (1960) Cellular specialization in the excretory epithelia of an insect, Macrosteles fascifrons Stål (Homoptera). Journal of Cell Biology 8: 103-133.
  8. 1 2 Gouranton J. & Maillet P.L. (1967) Origine et structure des brochosomes. Journal de Microscopie 6: 53-64.
  9. ↑ Rakitov R.A. (1999) Secretory products of the Malpighian tubules of Cicadellidae (Hemiptera, Membracoidea): an ultrastructural study. International Journal of Insect Morphology and Embryology 28: 179-192. doi : 10.1078/0044-5231-00025
  10. 1 2 Rakitov R.A. (2000) Secretion of brochosomes during the ontogenesis of a leafhopper, Oncometopia orbona (F.) (Insecta, Homoptera, Cicadellidae). Tissue & Cell 32: 28-39. PMID   10798315
  11. ↑ Navone P. (1987) Origine, struttura e funzioni di escreti e secreti entomatici di aspetto ceroso distribuiti sul corpo mediante zampe. Annali della Facolta‘ di Scienze Agrarie della Universita‘ degli Studi di Torino 14: 237-294.
  12. 1 2 Rakitov R.A. (1996) Post-moulting behaviour associated with Malpighian tubule secretions in leafhoppers and treehoppers (Auchenorrhyncha: Membracoidea). European Journal of Entomology 93: 167-184.
  13. 1 2 Rakitov R.A. (2009) Brochosomal coatings of the integument of leafhoppers (Hemiptera, Cicadellidae). In: S.N. Gorb (ed.), Functional Surfaces in Biology, Vol. 1, 113-137. ISBN   978-1-4020-6696-2.
  14. ↑ Rakitov R. & Gorb S.N. (2013) Brochosomes protect leafhoppers (Insecta, Hemiptera, Cicadellidae) from sticky exudates. Journal of the Royal Society Interface 10 (87). doi : 10.1098/rsif.2013.0445.
  15. ↑ "Leafhoppers use tiny light-absorbing balls to conceal their eggs". Science News. 2017-11-03. Retrieved 2020-01-31.
  16. ↑ Hix R.L. (2001) Egg-laying and brochosome production observed in glassy-winged sharpshooter. Archived 2016-03-03 at the Wayback Machine California Agriculture 50 (4): 19-22.
  17. 1 2 3 Rakitov R.A. (2004) Powdering of egg nests with brochosomes and related sexual dimorphism in leafhoppers (Insecta, Hemiptera, Cicadellidae). Zoological Journal of the Linnean Society 140: 353-381. doi : 10.1111/j.1096-3642.2003.00103.x
  18. ↑ Velema H.P., Hemerik L., Hoddle M.S. & Luck R.F. (2005) Brochosome influence on parasitisation efficiency of Homalodisca coagulata (Say) (Hemiptera: Cicadellidae) egg masses by Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae). Ecological Entomology 30: 485-496. doi : 10.1111/j.0307-6946.2005.00731.x
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