Crithidia
Encyclopedia
Crithidia are members of the trypanosome protozoa
. They are parasites
that exclusively parasitise arthropod
s, mainly insects. They pass from host to host as cysts in infective faeces and typically, the parasites develop in the digestive tracts of insects and interact with the intestinal epithelium
using their flagellum
. They display very low host-specificity and a single parasite can infect a large range of invertebrate hosts. At different points in its life-cycle, it passes through amastigote
, promastigote, and epimastigote phases; the last is particularly characteristic, and similar stages in other trypanosomes are often called crithidial.
Crithidia bombi is perhaps the most well documented species and is a parasite of bumblebees. Other species include C. fasciculata
, C. deanei, C. desouzai, C. oncopelti, C. guilhermei and C. luciliae. C. deanei is atypical of the Crithidia genus, and it has been argued not a member of the Crithidia at all. It is also not typical of trypanosomatids because of its unusual shape and it harbours endosymbiotic bacteria. Crithidia luciliae is the substrate for the antinuclear antibody test used to diagnose lupus and other autoimmune disorders
These parasites may be at least partially responsible for colony collapse in wild bee populations. (no citation provided. colony collapse refers to honey bees, not bumblebees) They cause the bees to lose their ability to distinguish between flowers that contain nectar and those that don't. They make many mistakes by visiting nectar scarce flowers and in so doing, slowly starve to death. Commercially bred bees are used in greenhouses, to pollinate, for example, tomatoes and these bees typically harbor this parasite, while wild bees do not. It is believed that the commercial bees transmitted the parasite to wild populations in some cases. They escape from the greenhouses through vents and a simple mesh could help prevent their escape.
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
. They are parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
that exclusively parasitise arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s, mainly insects. They pass from host to host as cysts in infective faeces and typically, the parasites develop in the digestive tracts of insects and interact with the intestinal epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
using their flagellum
Flagellum
A flagellum is a tail-like projection that protrudes from the cell body of certain prokaryotic and eukaryotic cells, and plays the dual role of locomotion and sense organ, being sensitive to chemicals and temperatures outside the cell. There are some notable differences between prokaryotic and...
. They display very low host-specificity and a single parasite can infect a large range of invertebrate hosts. At different points in its life-cycle, it passes through amastigote
Amastigote
An amastigote is a cell that does not have a visible external flagella or cilia. The term is used mainly to describe a certain phase in the life-cycle of trypanosome protozoans. It is also called the leishmanial stage, since in Leishmania it is the form the parasite takes in the vertebrate host,...
, promastigote, and epimastigote phases; the last is particularly characteristic, and similar stages in other trypanosomes are often called crithidial.
Crithidia bombi is perhaps the most well documented species and is a parasite of bumblebees. Other species include C. fasciculata
Crithidia fasciculata
Crithidia fasciculata is a species of parasitic protist. C. fasciculata, like other species of Crithidia have a single host life cycle with insect host, in the case of C. fasciculata this is the mosquito. C. fasciculata have low host species specificity and can infect many species of mosquito.-Life...
, C. deanei, C. desouzai, C. oncopelti, C. guilhermei and C. luciliae. C. deanei is atypical of the Crithidia genus, and it has been argued not a member of the Crithidia at all. It is also not typical of trypanosomatids because of its unusual shape and it harbours endosymbiotic bacteria. Crithidia luciliae is the substrate for the antinuclear antibody test used to diagnose lupus and other autoimmune disorders
These parasites may be at least partially responsible for colony collapse in wild bee populations. (no citation provided. colony collapse refers to honey bees, not bumblebees) They cause the bees to lose their ability to distinguish between flowers that contain nectar and those that don't. They make many mistakes by visiting nectar scarce flowers and in so doing, slowly starve to death. Commercially bred bees are used in greenhouses, to pollinate, for example, tomatoes and these bees typically harbor this parasite, while wild bees do not. It is believed that the commercial bees transmitted the parasite to wild populations in some cases. They escape from the greenhouses through vents and a simple mesh could help prevent their escape.