''Calliphora vicina'' is a member of the family

Calliphoridae The Calliphoridae (commonly known as blow flies, blow-flies, carrion flies, bluebottles, greenbottles, or cluster flies) are a family of insects in the order Diptera, with almost 1,900 known species. The maggot larvae, often used as fishing ba ...

, which includes blow flies and bottle flies. These flies are important in the field of

forensic entomology Forensic entomology is the scientific study of the colonization of a dead body by arthropods. This includes the study of insect types commonly associated with cadavers, their respective life cycles, their ecological presences in a given environme ...

, being used to estimate the time of a person's death when a

corpse A cadaver or corpse is a dead human body that is used by medical students, physicians and other scientists to study anatomy, identify disease sites, determine causes of death, and provide tissue to repair a defect in a living human being. Stud ...

is found and then examined. ''C. vicina'' is currently one of the most entomologically important fly species for this purpose because it arrives at and colonizes a body following death in consistent timeframes.

Taxonomy

''Calliphora vicina'' was described by the French entomologist

Jean-Baptiste Robineau-Desvoidy André Jean Baptiste Robineau-Desvoidy (1 January 1799 in Saint-Sauveur-en-Puisaye – 25 June 1857 in Paris) was a French physician and entomologist specialising in the study of Diptera (flies) and to some extent of the Coleoptera (beetles). Ac ...

in 1830. Its specific epithet is derived from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''vicinus'' 'neighbouring'. ''Calliphora vicina'' is closely related to '' Calliphora vomitoria'', another species important in forensics.

Description

''Calliphora vicina'' is known as a blue bottle fly because of the metallic blue-gray coloration of its

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

and

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

. It is distinguished from the commonly known '' C. vomitoria'' by its bright orange cheeks. The blue bottle fly is approximately 10–11 mm in length. The

sclerite A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...

s at the base of the coxa are yellow or orange. By

chaetotaxy Chaetotaxy is the arrangement of bristles (macrochaetae) on an arthropod or annelid, or taxonomy based on their position and size. For example, it is important in Diptera, in which group it was formalised by Ernst August Girschner. The term chaeto ...

, the study of bristle arrangement, Calliphorids are characterized by having black bristles on the meron and two to three bristles on the

notopleuron The notopleuron (plural notopleura) is a region on an insect thorax. Notopleura are useful in characterizing species, particularly, though not uniquely, in the Order Diptera (the "true flies"). The notopleuron is a thoracic pleurite (a sclerite ...

. The similarities between the different species of ''Calliphora'' can make identification of immature stages nearly impossible. From the first

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ...

to the pupa stage ''C. vicina'' is identical to that of ''C. vomitoria''.

Lifecycle

''Calliphora vicina'' goes through five generations in a year at a threshold temperature of 27˚ C (81˚ F). A female ''C. vicina'' can lay up to 300 eggs, on fresh carrion or on open wounds. The

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e go through three

stages. The first instar hatches in approximately 24 hours after the eggs are laid. It goes through its second instar in 20 hours and its third instar in 48 hours. Under favorable conditions, the larvae feed for about three to four days. When the larvae complete their development, they disperse to find an adequate place to pupate. The ''C. vicina''

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...

stage last about 11 days. At 27˚ C, ''C. vicina''’s life cycle lasts approximately 18 days. Climatic factors, such as temperature, are known to influence egg-laying and development of instar-larvae. In warmer weather the life cycle can last a little less, and in cooler temperatures the life cycle takes a little longer. Knowing the duration between the three instars and pupa stage and post-feeding larval dispersal can be useful to determine the

post mortem interval The post-mortem interval (PMI) is the time that has elapsed since an individual's death. When the time of death is not known, the interval may be estimated, and so an approximate time of death established. Postmortem interval estimations can ra ...

in a criminal case.

Distribution

''Calliphora vicina'' are found throughout the U.S. in urban areas and are most abundant in early spring and fall where the temperatures are around 55-75˚F (13-24˚C). The species predominates in Europe and the New World, but has found its way into other countries via harbors and airports. It was first recorded in South Africa in 1965 when a specimen was collected near Johannesburg, but specimen collections have been few and sporadic since then. It also occurs as an exotic in Australia and New Zealand.

Post mortem interval estimation

One of the key characteristics of using blow flies in developing a

estimate is the succession of insects that colonize the body. Based on the insects present at the time, a reasonable time frame for death may be established. ''C. vicina'' has its own part in the succession of the corpse. ''Calliphora vicina'' plays a major role in corpse colonization during the winter months, with less of a presence during the warmer months when temperature is less of a constraint. This fly has a lower threshold temperature for flight activity than other blow-flies, allowing for greater

prevalence In epidemiology, prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number o ...

during colder periods. This period of activity must be considered when evaluating the presence or absence of this fly. When using the age of

maggots A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera flies, such as houseflies, cheese flies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and crane flies. Entom ...

to determine the PMI, the time before arrival is an important factor. The succession of ''C. vicina'' involves the arrival of adults two days after death. Therefore, two days must be added to the maximum age determined for flies found on the body.

Behavior

''Calliphora vicina'' play an integral part in post mortem interval determination. Factors such as region, weather temperatures, time of day and conditions under which the body was found all contribute to determining a post mortem interval (PMI). To complete the calculation the entomologist must consider what is commonly known about ''C. vicina'' and integrate it with experimental data gathered from a crime scene. The entomologist must know how the blow-fly behaves specifically in the area where the body was discovered. This involves recording environment temperatures at the crime scene as well as retrieving a history of the climate in the region. ''C. vicina'' in particular is adapted to cooler temperatures, appearing most commonly in winter and less often in the summer months. This puts their flight activity threshold at above 55-60 °F (13-16 °C), a lower temperature than most other blow-flies.Catts P, Haskell N, ''Entomology & Death: A Procedural Guide'', Joyce's Print Shop, Inc., 1990. Knowing the threshold temperature allows the entomologist to calculate accumulated

degree day A degree day is a measure of heating or cooling. Total degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing. Weekly or monthly degree-day figures may also be used wi ...

s, which in turn helps determine PMI. Some knowledge regarding ''C. vicina'' behavior is well known. Case studies have shown that it is not the first species in arrival, although it does appear one to two days before ''

Phaenicia sericata The common green bottle fly (''Lucilia sericata'') is a blowfly found in most areas of the world and is the most well-known of the numerous green bottle fly species. Its body is in length – slightly larger than a house fly – and has brilli ...

''.Arnaldos MI, García MD, Romera E, Presa JJ, Luna A. ''Estimation of postmortem interval in real cases based on experimentally obtained entomological evidence.'' Forensic Sci Int. 2005 Apr 20;149(1):57-65. Determining PMI is an intricate process because there is still much that we do not know about ''C. vicina'' behavior. For instance, it is a long held belief that the species is not nocturnally active. However, it has recently been shown that ''C. vicina'' is indeed active at night under certain experimental conditions.Gennard D, ''Forensic Entomology: An Introduction'', Wiley, John & Sons, Incorporated, 2007.

Future research

As ''Calliphora vicina'' continues to be researched, more information about the behavior will be gained to allow for a more complete picture of the lifecycle, thereby leading to better estimates of time of colonization. New knowledge, such as the activity of ''C. vicina'' at night, will provide forensic

entomologists Entomology () is the scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as arach ...

with a better tool for their PMI estimation development.

References

External links

* * {{Taxonbar, from=Q1060187 Calliphoridae Diptera of New Zealand Insects described in 1830 Taxa named by Jean-Baptiste Robineau-Desvoidy