Blister beetle

Blister beetles are beetles of the family Meloidae, so called for their defensive secretion of a blistering agent, cantharidin. About 7,500 species are known worldwide. Many are conspicuous and some are aposematically colored, announcing their toxicity to would-be predators.

Blister beetles
Hycleus lugens, Meloidae
Hycleus lugens
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Meloidae
Gyllenhaal, 1810
Subfamilies

Eleticinae
Meloinae
Nemognathinae
Tetraonycinae

Description

Cantharidin, a poisonous chemical that causes blistering of the skin, is used medically to remove warts[1] and is collected for this purpose from species of the genera Mylabris and Lytta, especially Lytta vesicatoria, better known as "Spanish fly".

Colletes hederae parasitized-pjt
Ivy bee (Colletes hederae), carrying parasitic triungulins of Stenoria analis

Blister beetles are hypermetamorphic, going through several larval stages, the first of which is typically a mobile triungulin. The larvae are insectivorous, mainly attacking bees, though a few feed on grasshopper eggs. While sometimes considered parasitoids, in general, the meloid larva apparently consumes the immature host along with its provisions, and can often survive on the provisions alone; thus it is not an obligatory parasitoid, but rather a facultative parasitoid, or simply a predator. The adults sometimes feed on flowers and leaves of plants of such diverse families as the Amaranthaceae, Asteraceae, Fabaceae, and Solanaceae.

Toxicity

Cantharidin is the principal irritant in "Spanish fly", a folk medicine prepared from dried beetles in the family Meloidae.

The largest genus, Epicauta, contains many species toxic to horses. A few beetles consumed in a single feeding of alfalfa hay may be lethal.[2] In semiarid areas of the western United States, modern harvesting techniques may contribute to cantharidin content in harvested forage. The practice of hay conditioning, crushing the stalks to promote drying, also crushes any beetles present and causes the release of cantharidin into the fodder. Blister beetles are attracted to alfalfa and weeds during bloom. Reducing weeds and timing harvests before and after bloom are sound management practices. Using equipment without hay conditioners may reduce beetle mortality and allow them to escape before baling.[3]

Systematics

Subfamily Eleticinae

Tribe Derideini

  • Anthicoxenus
  • Deridea
  • Iselma
  • Iselmeletica

Tribe Morphozonitini

  • Ceriselma
  • Morphozonitis
  • Steniselma

Tribe Eleticini

  • Eletica

Tribe Spasticini

  • Eospasta
  • Protomeloe
  • Spastica
  • Xenospasta

Subfamily Meloinae

Black blister beetle
Black blister beetle, Epicauta pennsylvanica (Meloinae: Epicautini)
Cysteodemus armatus - Inflated Beetle Mojave desert 2016-04-05 (4)
Cysteodemus armatus near Ridgecrest, California in the Mojave Desert: The white coating is cuticular wax, which can vary from white to yellow in this species [1].

Tribe Cerocomini

Tribe Epicautini

Tribe Eupomphini

Green insect on hand
Blister beetles like this Lytta vesicatoria (Meloinae: Lyttini) can be safely handled, provided the animal is not startled, and allowed to move around freely. Otherwise, painful poisonings may occur.
Ölkäfer Meloë violaceus 2
Meloe violaceus (Meloinae: Meloini): Note the drop of dark orange defensive fluid on its thorax.
Mylabris quadripunctata01
Mylabris quadripunctata (Meloinae: Mylabrini)

Tribe Lyttini

  • Acrolytta
  • Afrolytta
  • Alosimus
  • Berberomeloe
  • Cabalia
  • Dictyolytta
  • Eolydus
  • Epispasta
  • Lagorina
  • Lydomorphus
  • Lydulus
  • Lydus
  • Lytta
  • Lyttolydulus
  • Lyttonyx
  • Megalytta
  • Muzimes
  • Oenas
  • Parameloe
  • Paroenas
  • Physomeloe
  • Prionotolytta
  • Prolytta
  • Pseudosybaris
  • Sybaris
  • Teratolytta
  • Tetraolytta
  • Trichomeloe

Tribe Meloini

Tribe Mylabrini

Meloidae Actenodia CMR beetle 3491
A yellow-and-black species of Actenodia, one of many known in South Africa as "CMR beetle"
  • Ceroctis
  • Croscherichia
  • Hycleus
  • Lydoceras
  • Mimesthes
  • Mylabris
  • Paractenodia
  • Pseudabris
  • Semenovilia
  • Xanthabris

Tribe Pyrotini

  • Bokermannia
  • Brasiliota
  • Denierota
  • Glaphyrolytta
  • Lyttamorpha
  • Picnoseus
  • Pseudopyrota
  • Pyrota
  • Wagneronota

Genera incertae sedis

  • Australytta
  • Calydus
  • Gynapteryx
  • Oreomeloe
  • Pseudomeloe

Subfamily Nemognathinae

Horia sal
Horia sp. from Bannerghatta (Bangalore)
Sitaris muralis
Sitaris muralis (Nemognathinae: Sitarini)

Tribe Horiini

Tribe Nemognathini

Tribe Sitarini

  • Allendeselazaria
  • Apalus
  • Ctenopus
  • Glasunovia
  • Nyadatus
  • Sitaris
  • Sitarobrachys
  • Stenoria

Genera incertae sedis

Subfamily Tetraonycinae

Tribe Tetraonycini

See also

References

  1. ^ Bhattacharjee, Pradip; Brodell, Robert T. (2003). "Cantharidin". In Robert T. Brodell; Sandra Marchese Johnson (eds.). Warts: Diagnosis and Management—an Evidence-Based Approach. London: Martin Dunitz. pp. 151–160. ISBN 1-84184-240-0.
  2. ^ University of Arizona VDL Blister Beetle Poisoning in Horses Archived July 24, 2008, at the Wayback Machine
  3. ^ University of Colorado Extension Blister Beetles in Forage Crops Archived 2015-01-10 at the Wayback Machine

External links

Blister beetle dermatitis

Blister beetle dermatitis is a cutaneous condition that occurs after contact with any of several types of beetles, including those from the Meloidae and Oedemeridae families. Blister beetles secrete an irritant called cantharidin, a vesicant that can get onto humans if they touch the beetles.

The term "blister beetle dermatitis" is also occasionally and inappropriately used as a synonym for Paederus dermatitis, a somewhat different dermatitis caused by contact with pederin, an irritant in the hemolymph of a different group of beetles, the rove beetles.

Cantharidin

Cantharidin is an odorless, colorless fatty substance of the terpenoid class, which is secreted by many species of blister beetles. It is a burn agent or a poison in large doses, but preparations containing it were historically used as aphrodisiacs. In its natural form, cantharidin is secreted by the male blister beetle and given to the female as a copulatory gift during mating. Afterwards, the female beetle covers her eggs with it as a defense against predators.

Poisoning from cantharidin is a significant veterinary concern, especially in horses, but it can also be poisonous to humans if taken internally (where the source is usually experimental self-exposure). Externally, cantharidin is a potent vesicant (blistering agent), exposure to which can cause severe chemical burns. Properly dosed and applied, the same properties have also been used therapeutically, for instance for treatment of skin conditions such as molluscum contagiosum infection of the skin.

Cantharidin is classified as an extremely hazardous substance in the United States and is subject to strict reporting requirements by facilities that produce, store, or use it in significant quantities.

Epicauta

Epicauta is a genus of beetles in the blister beetle family, Meloidae. The genus was first scientifically described in 1834 by Pierre François Marie Auguste Dejean. Epicauta is distributed nearly worldwide, with species native to all continents except Australia. Surveys have found the genus to be particularly diverse in northern Arizona in the United States. Few species occur in the Arctic, with none farther north than the southern Northwest Territory of Canada.Adult beetles feed on plants. The larvae are predators on the eggs of grasshoppers. The beetles can significantly damage plants, and many Epicauta are known as agricultural pests around the world, even known to cause crop failures at times. As do other blister beetles, these produce cantharidin, a toxic terpenoid which can kill animals such as horses if they ingest enough of the beetles.This is one of the largest blister beetle genera, with about 360 described species as of 2011.

Epicauta funebris

Epicauta funebris, known generally as the margined blister beetle or ebony blister beetle, is a species of blister beetle in the family Meloidae. It is found in North America.

Epicauta maculata

Epicauta maculata, the spotted blister beetle, is a species of blister beetle in the family Meloidae. It is found in Central America and North America.

Epicauta vittata

Epicauta vittata is a species of beetle in the family Meloidae, the blister beetles. It is native to eastern North America, including eastern Canada and the eastern United States. It is known commonly as the striped blister beetle and the old-fashioned potato beetle. It is known as an agricultural pest.

Lytta

Lytta is a genus of blister beetles in the family Meloidae. There are at least 70 described species in Lytta.

Lytta magister

Lytta magister (also known as the desert blister beetle or master blister beetle) is a species of blister beetle found in southwestern North America.

Typically 16 to 33 mm (0.6 to 1.3 in) in length, L. magister has a striking red head, legs and prothorax, with black elytra. They can be found in great numbers in the Mojave and Colorado Deserts in spring, and are often seen in swarms.

Females lay eggs in holes in the desert soil. The larvae are insectivorous, mainly attacking bee nests. They consume the immature host along with its provisions, and can often survive on the provisions alone, thus they are not obligatory parasitoids but rather food parasites that are facultatively parasitoid, or simply predatory. Adults feed on flowers and leaves of brittlebush.

Lytta nuttalli

Lytta nuttalli, or Nuttall's blister beetle, is a species of beetle.

Nutall's blister beetles make it easy to spot in native prairie. They will release a skin irritant if squeezed. They eat rapseed plants, causing great irritation to Canadian farmers.

Lytta sayi

Lytta sayi, the Say blister beetle, is a species of blister beetle in the family Meloidae. It is found in North America.

Meloe

The blister beetle genus Meloe is a large, widespread group commonly referred to as oil beetles. They are known as "oil beetles" because they release oily droplets of hemolymph from their joints when disturbed; this contains cantharidin, a poisonous chemical causing blistering of the skin and painful swelling. Members of this genus are typically flightless, without functional wings, and shortened elytra.

As in other members of the family, they are hypermetamorphic, going through several larval stages, the first of which is typically a mobile triungulin that finds and attaches to a host in order to gain access to the host's offspring. In this genus, the host is a bee, and each species of Meloe may attack only a single species or genus of bees; while sometimes considered parasitoids, it appears that in general, the Meloe larva consumes the bee larva along with its provisions, and can often survive on the provisions alone, thus they do not truly qualified (see Parasitoid for definition).

Meloe angusticollis

The short-winged blister beetle, or oil beetle (Meloe angusticollis) is a species of blister beetle, native to North America. They average 8–10 millimetres (0.3–0.4 in) in length.

Mylabris phalerata

Mylabris phalerata is a species of blister beetle belonging to the Meloidae family. Known as the Chinese blister beetle, it is used in traditional Chinese medicine. A fatality from cantharidin poisoning has been reported, where dried beetles had been used as an abortifacient.

Oedemeridae

The family Oedemeridae is a cosmopolitan group of beetles commonly known as false blister beetles, though some recent authors have coined the name pollen-feeding beetles. There are some 100 genera and 1,500 species in the family, mostly associated with rotting wood as larvae, though adults are quite common on flowers.

Paederus dermatitis

Paederus dermatitis is a skin irritation resulting from contact with the hemolymph of certain rove beetles, a group that belongs to the insect order Coleoptera and the genus Paederus. Other local names given to Paederus dermatitis include spider-lick, whiplash dermatitis, and Nairobi fly dermatitis.Rove beetles do not bite or sting but cause skin irritations and blisters when accidentally brushed or crushed against the skin provoking them to release their coelemic fluid which contains a strong blistering chemical. The active agent in the coelemic fluid is commonly referred to as pederin, although depending on the beetle species it may be one of several similar molecules including pederone and pseudopederin."Blister beetle dermatitis," a term more properly used for the different dermatitis caused by cantharidin from blister beetles, is also sometimes used to describe paederus dermatitis caused by rove beetles.

Pyrota insulata

Pyrota insulata, sometimes known by the common name yellow-crescent blister beetle, is a blister beetle, so called because if squeezed, it can produce an irritant called cantharidin that causes a blister on exposed human skin.

Spanish fly

Spanish fly (Lytta vesicatoria) is an emerald-green beetle in the blister beetle family (Meloidae). It and other such species were used in preparations offered by traditional apothecaries, often referred to as Cantharides or Spanish fly. The insect is the source of the terpenoid cantharidin, a toxic blistering agent once used as an aphrodisiac.

L. vesicatoria is sometimes called Cantharis vesicatoria, although the genus Cantharis is in an unrelated family, Cantharidae, the soldier beetles.

Tegrodera aloga

Tegrodera aloga, the iron cross blister beetle, is a species of blister beetle in the family Meloidae. It is found in Central America and North America.The species name T. aloga was coined by Skinner in 1903.

Zonitis

Zonitis is a genus of blister beetles in the family Meloidae. The genus was named and described by Johan Christian Fabricius in 1775.

Extant Coleoptera families

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