Calliphoridae


The Calliphoridae are a family of insects in the order Diptera, with almost 1,900 known species. The maggot larvae, often used as fishing bait, are known as gentles. The family is known to be polyphyletic, but much remains disputed regarding proper treatment of the constituent taxa, some of which are occasionally accorded family status.

Description

Characteristics

Calliphoridae adults are commonly shiny with metallic colouring, often with blue, green, or black thoraces and abdomens. Antennae are three-segmented and aristate. The aristae are plumose their entire length, and the second antennal segment is distinctly grooved. Members of Calliphoridae have branched Rs 2 veins, frontal sutures are present, and calypters are well developed.
The characteristics and arrangements of hairlike bristles are used to differentiate among members of this family. All blowflies have bristles located on the meron. Having two notopleural bristles and a hindmost posthumeral bristle located lateral to presutural bristle are characteristics to look for when identifying this family.
The thorax has the continuous dorsal suture across the middle, along with well-defined posterior calli. The postscutellum is absent or weakly developed. The costa is unbroken and the subcosta is apparent on the insect.

Development

Most species of blowflies studied thus far are anautogenous; a female requires a substantial amount of protein to develop mature eggs within her ovaries. The current theory is that females visit carrion both for protein and egg laying, but this remains to be proven. Blowfly eggs, usually yellowish or white in color, are about 1.5 mm × 0.4 mm, and when laid, look like rice grains. While the female blowfly typically lays 150–200 eggs per batch, she is usually iteroparous, laying around 2,000 eggs during the course of her life. The sex ratio of blowfly eggs is usually 50:50, but one exception is females from two species of the genus Chrysomya, which are either arrhenogenic or thelygenic.
Hatching from an egg to the first larval stage takes about 8 hours to a day. Larvae have three stages of development ; each stage is separated by a molting event. The instars are separable by examining the posterior spiracles, or openings to the breathing system. The larvae use proteolytic enzymes in their excreta to break down proteins on the livestock or corpse on which they are feeding. Blowflies are poikilothermic – the rate at which they grow and develop is highly dependent on temperature and species. Under room temperature, the black blowfly Phormia regina can change from egg to pupa in 150–266 hours. When the third larval stage is complete, it leaves the corpse and burrows into the ground to pupate, emerging as an adult 7–14 days later.

Food sources

Adult blowflies are occasional pollinators, being attracted to flowers with strong odors resembling rotting meat, such as the American pawpaw or dead horse arum. Little doubt remains that these flies use nectar as a source of carbohydrates to fuel flight, but just how and when this happens is unknown. One study showed the visual stimulus a blowfly receives from its compound eyes is responsible for causing its legs to extend from its flight position and allow it to land on any surface.
Larvae of most species are scavengers of carrion and dung, and most likely constitute the majority of the maggots found in such material, although they are not uncommonly found in close association with other dipterous larvae from the families Sarcophagidae and Muscidae, and many other acalyptrate muscoid flies.

Predators

Predators of blowflies include spiders, beetles, frogs, and birds, including chickens.
In the Chihuahuan desert of Mexico, a fungus, Furia vomitoriae affects bluebottle flies. It forms masses of conidiophores erupting through the intersegmental areas on the abdominal dorsum of the flies and eventually kills them.

Host-microbe interactions

Blowflies feed and develop in microbially dense and chemically dynamic substrates such as carrion and necrotic wounds. Because blowflies, their larvae and necrobiome-associated microbiota engage in resource partitioning, blowflies often act as both pathogen vectors and engage in facultative bacterivory. Bacterial digestion by Lucilia sericata larvae is well-established for some microorganisms like Escherichia coli but it has been hypothesized that other microbial taxa are spared or excluded from significant rates of digestion. While it is known that Providencia spp. bacteria are detrimental to Cochliomyia macellaria larvae under gnotobiotic conditions and several blowfly species benefit from feeding under gnotobiotic, "mixed microbial environments", in general, the taxonomic specificities and causal mechanisms behind this phenomenon — which would help delineate passive microbial persistence in the animal's tissues from parasitism or mutualism — remains unknown. For example, a study showed that Lactobacillus, Proteus, Diaphorobacter, and Morganella were the main taxa associated with third larval instar Lucilia sericata salivary glands ; which suggests an apparent balance between lactic acid-producing Gram-positive and urease-producing Gram-negative microbial taxa. Despite this aforementioned insight, dedicated studies on the effect of altered substrate pH levels on blowfly larvae development have yet to connect their findings to either blowfly host-specific pH preferences, fermentation, or microbial activity in general; the last of which is the main contributor towards pH modulation in necrotic biomass substrates. Despite these unknowns, a causal mechanism of blowfly-larval microbiome selection and mechanisms governing larval microbiome community assembly was investigated using axenic Lucilia sericata larvae-microbe exposure assays. It was found that larvae mount distinct immune transcriptional programs when challenged with Pseudomonas aeruginosa versus Acinetobacter baumannii, suggesting that blowflies do not deploy a generic “one-size-fits-all” immune response but instead engage pathogen-specific signaling through the IMD and Toll pathways.
Consistent with this immunological specificity, comparative surveys of wild Lucilia sericata and Phormia regina show that microbiome composition is strongly associated with host species identity, regardless of shared environments or sampling conditions. Taxonomic profiles differ significantly between species, with genera such as Ignatzschineria and Dysgonomonas enriched in P. regina, while Vagococcus and Escherichia–Shigella are more prevalent in L. sericata. These patterns support a role for host filtering in blowfly-microbiome assembly, and indicate that species-level differences in microbial associations may translate into differing risks of pathogen carriage.

Diversity

About 1,900 species of blowflies are known, with 120 species in the Neotropics, and a large number of species in Africa and Southern Europe.
Their typical habitats are temperate to tropical areas that provide a layer of loose, damp soil and litter where larvae may thrive and pupate.

Genera

Sources: MYIA, FE, Nomina, A/O DC
This is a selected list of genera from the Palearctic, Nearctic, Malaysia, and Australasia:
  • Abago Grunin, 1966
  • Amenia Robineau-Desvoidy, 1830
  • Angioneura Brauer & Bergenstamm, 1893
  • Apaulina Hall, 1948
  • Cynomya Robineau-Desvoidy, 1830
  • Aphyssura Hardy, 1940
  • Auchmeromyia Brauer & Bergenstamm, 1891
  • Bellardia Robineau-Desvoidy, 1863
  • Bengalia Robineau-Desvoidy, 1830
  • Booponus Aldrich, 1923
  • Boreellus Aldrich & Shannon, 1923
  • Caiusa Surcouf, 1920
  • Calliphora Robineau-Desvoidy, 1830
  • Callitroga Hall, 1948
  • Catapicephala Macquart, 1851
  • Chloroprocta Wulp, 1896
  • Chrysomya Robineau-Desvoidy, 1830
  • Cochliomyia Townsend, 1915
  • Compsomyiops Townsend, 1918
  • Cordylobia Gruenberg, 1903
  • Cyanus Hall, 1948
  • Dyscritomyia Grimshaw, 1901
  • Eggisops Rondani, 1862
  • Eucalliphora Townsend, 1908
  • Eumesembrinella Townsend, 1931
  • Eurychaeta Brauer & Bergenstamm, 1891
  • Euphumosia Malloch, 1926
  • Hemilucilia Brauer, 1895
  • Hemipyrellia Townsend, 1918
  • Lucilia Robineau-Desvoidy, 1830
  • Melanomya Rondani, 1856
  • Melinda Robineau-Desvoidy, 1830
  • Mufetiella Villeneuve, 1933
  • Nesodexia Villeneuve, 1911
  • Neta Shannon, 1926
  • Onesia Robineau-Desvoidy, 1830
  • Opsodexia Townsend, 1915
  • Pachychoeromyia Villeneuve, 1920
  • Paralucilia Brauer & Bergenstamm, 1891
  • Paramenia Brauer & Bergenstamm, 1889
  • Paraplatytropesa Crosskey, 1965
  • Phormia Robineau-Desvoidy, 1830
  • Phumosia Robineau-Desvoidy, 1830
  • Platytropesa Macquart, 1851
  • Polleniopsis Townsend, 1917
  • Prosthetosoma Silvestri, 1920
  • Protocalliphora Hough, 1899
  • Protophormia Townsend, 1908
  • Ptilonesia Bezzi, 1927
  • Rhynchoestrus Séguy, 1926
  • Sarconesia Bigot, 1857
  • Silbomyia Macquart, 1843
  • Stilbomyella Malloch, 1935
  • Toxotarsus Macquart, 1851
  • Triceratopyga Rohdendorf, 1931
  • Tricyclea Wulp, 1885
  • TricycleopsisVilleneuve, 1927
  • Trypocalliphora Peus, 1960
  • Xenocalliphora Malloch, 1924

    Economic importance

Myiasis

Blowflies have caught the interest of researchers in a variety of fields, although the large body of literature on calliphorids has been concentrated on solving the problem of myiasis in livestock. The sheep blowfly Lucilia cuprina causes the Australian sheep industry an estimated AU$170 million a year in losses.
The most common causes of myiasis in humans and animals are the three dipteran families Oestridae, Calliphoridae, and Sarcophagidae. Myiasis in humans is clinically categorized in six ways: dermal and subdermal, facial cavity, wound or trauma, gastrointestinal, vaginal, and generalized. If found in humans, the dipteran larvae are usually in their first instar. The only treatment necessary is just to remove the maggots, and the patient heals naturally. Whilst not strictly a myiasis species, the Congo floor maggot feeds on mammal blood, occasionally human.