genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
mite
Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...
s in the
spider mite
Spider mites are members of the family Tetranychidae, which includes about 1,200 species. They are part of the subclass Acari (mites). Spider mites generally live on the undersides of leaves of plants, where they may spin protective silk webs, a ...
family, Tetranychidae. The
taxonomy
image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy
Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...
of the genus is difficult. The genus has been revised several times. It is difficult to distinguish these tiny species from each other on the basis of morphological characters, and there is little agreement on which characteristics are of importance. Also, species can be variable in morphology. Over 130 species have been described, but many of the names are likely
synonyms
A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...
''Bryobia'' mites are among the largest spider mites. The adult is visible to the naked eye. Mites of this genus are mainly distinguished by the arrangement of the
seta
In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms.
Animal setae
Protostomes
Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...
e on their bodies.Khanjani, M., et al. (2008) A species of the genus ''Bryobia'' Koch (Acari: Tetranychidae) from Iran. ''International Journal of Acarology'' 34(3) 243-49. In general, these mites are red in color with whitish setae and long legs with hooked claws.Walter, D. E Invasive Mite Identification: Tools for Quarantine and Plant Protection. Lucid v. 3.3. 2006.
Biology
''Bryobia'' mites feed on plants. They puncture the plant tissues with their sucking mouthparts. They are often found on leaves, but they also live on branches and twigs.
The life history is variable across species. Typically, it takes about a month for a mite to develop from egg and
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
to adult.
This depends on environmental conditions such as temperature and humidity. Some species overwinter in the egg stage. Some species have a single generation per year, while others have several. The eggs are laid singly or in clutches, and some mites may cover the eggs with dust or other matter. Unlike some other spider mites, bryobia mites do not spin webs.
The great majority of ''Bryobia'' mites are
asexual
Asexual or Asexuals may refer to:
*Asexual reproduction
**Asexual reproduction in starfish
*Asexuality, the lack of sexual attraction to anyone or lack of interest in or desire for sexual activity.
**Gray asexuality, the spectrum between asexualit ...
(although certain species do
reproduce sexually
Sexual reproduction is a type of reproduction that involves a complex Biological life cycle, life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to p ...
). Their populations are all female, and individuals reproduce by
thelytoky
Thelytoky (from the Ancient Greek, Greek θῆλυς ''thēlys'' "female" and τόκος ''tókos'' "birth") is a type of parthenogenesis and is the absence of mating and subsequent production of all female diploid offspring as for example in aph ...
, a form of
parthenogenesis
Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...
. They emerge from unfertilized eggs.
Phylogenetic
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analysis shows that the asexual species in the genus are not a
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
group; indicating that asexual reproduction evolved several times or that sexuality re-evolved. The asexual species have a high level of
genetic diversity
Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...
considering that they are clones; this may have arisen through hybridization and
mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, ...
. In at least two species, namely ''Bryobia kissophila'' and ''B. praetiosa'', asexuality is caused by the
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...
bacterium ''
Wolbachia
''Wolbachia'' is a genus of gram-negative bacteria infecting many species of arthropods and filarial nematodes. The symbiotic relationship ranges from parasitism to obligate mutualism. It is one of the most common parasitic microbes of arthrop ...
apomixis
In botany, apomixis is asexual development of seed or embryo without fertilization. However, other definitions include replacement of the seed by a plantlet or replacement of the flower by bulbils.
Apomictically produced offspring are geneti ...
in the mites, so that a female produces only offspring that are identical to her.Weeks, A. R. and J. A. J. Breeuwer. (2001) ''Wolbachia''–induced parthenogenesis in a genus of phytophagous mites. ''Proc. R. Soc. Lond. B'' 268(1482) 2245-51. It is possible that ''Wolbachia'' could influence the reproductive processes of most bryobia mite species.
Familiar species
Perhaps the best known species is '' Bryobia praetiosa'', the clover mite or brown clover mite, an economically important pest of over 250 species of plants. It occurs nearly worldwide.Gomez, C. and R. F. Mizell Clover Mite, ''Bryobia praetiosa''. Document EENY437. University of Florida IFAS Extension. 2008. Like other bryobia mites, this species is herbivorous, but there have been occasional reports of it occurring as an
ectoparasite
Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
on humans, particularly children. It causes an itchy skin irritation.Ebeling, W Chapter 12 - Miscellaneous Pests: Mites. Urban Entomology. UC Riverside. 2002. There has also been an isolated case report of an infestation in a
domestic cat
The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small Domestication, domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have sh ...
olive
The olive, botanical name ''Olea europaea'' ("European olive"), is a species of Subtropics, subtropical evergreen tree in the Family (biology), family Oleaceae. Originating in Anatolia, Asia Minor, it is abundant throughout the Mediterranean ...
alfalfa
Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial plant, perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, ...
.
* '' Bryobia cristata'' is reported from nearly every continent. It occurs on many grasses, including
wheat
Wheat is a group of wild and crop domestication, domesticated Poaceae, grasses of the genus ''Triticum'' (). They are Agriculture, cultivated for their cereal grains, which are staple foods around the world. Well-known Taxonomy of wheat, whe ...
and
barley
Barley (), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains; it was domesticated in the Fertile Crescent around 9000 BC, giving it nonshattering spikele ...
. It is also found on
azalea
Azaleas ( ) are flowering shrubs in the genus ''Rhododendron'', particularly the former sections ''Rhododendron sect. Tsutsusi, Tsutsusi'' (evergreen) and ''Pentanthera'' (deciduous). Azaleas bloom in the spring (April and May in the temperate ...
clover
Clovers, also called trefoils, are plants of the genus ''Trifolium'' (), consisting of about 300 species of flowering plants in the legume family Fabaceae originating in Europe. The genus has a cosmopolitan distribution with the highest diversit ...
, and alfalfa. In
Iceland
Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
it infests
hay
Hay is grass, legumes, or other herbaceous plants that have been cut and dried to be stored for use as animal fodder, either for large grazing animals raised as livestock, such as cattle, horses, goats, and sheep, or for smaller domesticate ...
fields and it can also be found living inside houses.Hallas, T. E. and B. E. Gudleifsson. (2004) Phenology of ''Bryobia cristata'' (Acari, Prostigmata) in hayfields in northern Iceland. ''Experimental and Applied Acarology'' 33 103-07.
* '' Bryobia graminum'' is a pest of fruit trees, clover, and grasses across Europe, Africa, Asia, and elsewhere, and of daisies, and in Australia and New Zealand.
* '' Bryobia kissophila'' is a familiar pest of common ivy (''Hedera helix''). It causes yellowing of the leaves. It sometimes lives in
greenhouse
A greenhouse is a structure that is designed to regulate the temperature and humidity of the environment inside. There are different types of greenhouses, but they all have large areas covered with transparent materials that let sunlight pass an ...
s. It is also known from
potato
The potato () is a starchy tuberous vegetable native to the Americas that is consumed as a staple food in many parts of the world. Potatoes are underground stem tubers of the plant ''Solanum tuberosum'', a perennial in the nightshade famil ...
crops. It is found in Europe,
New Zealand
New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
,
Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, and elsewhere.
* '' Bryobia lagodechiana'' may invade greenhouses and it infests
bean
A bean is the seed of some plants in the legume family (Fabaceae) used as a vegetable for human consumption or animal feed. The seeds are often preserved through drying (a ''pulse''), but fresh beans are also sold. Dried beans are traditi ...
s,
cucumber
The cucumber (''Cucumis sativus'') is a widely-cultivated creeping vine plant in the family Cucurbitaceae that bears cylindrical to spherical fruits, which are used as culinary vegetables.currants, and several other cultivated plants. It is known from Europe to
Canada
Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
to
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
almond
The almond (''Prunus amygdalus'', Synonym (taxonomy)#Botany, syn. ''Prunus dulcis'') is a species of tree from the genus ''Prunus''. Along with the peach, it is classified in the subgenus ''Amygdalus'', distinguished from the other subgenera ...
. It causes discoloration of the bark and leaves.The Bryobia Mite and the Pear-leaf Blister Mite. Victoria State Government Department of Environment and Primary Industries: Agriculture. Note No. AG0094, 2000, updated 2010. On
apricot
An apricot (, ) is a fruit, or the tree that bears the fruit, of several species in the genus ''Prunus''.
Usually an apricot is from the species '' P. armeniaca'', but the fruits of the other species in ''Prunus'' sect. ''Armeniaca'' are also ...
it causes spotting of the fruit. It is a pest of
vineyard
A vineyard ( , ) is a plantation of grape-bearing vines. Many vineyards exist for winemaking; others for the production of raisins, table grapes, and non-alcoholic grape juice. The science, practice and study of vineyard production is kno ...
s in the
Pacific Northwest
The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...
of the United States.Grape: Bryobia mite. Pacific Northwest Insect Management Handbook. Oregon State University. 2013.
* '' Bryobia vasiljevi'' occurs on a variety of crops, including
apple
An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...
s,
asparagus
Asparagus (''Asparagus officinalis'') is a perennial flowering plant species in the genus ''Asparagus (genus), Asparagus'' native to Eurasia. Widely cultivated as a vegetable crop, its young shoots are used as a spring vegetable.
Description ...
, and wheat, in Australia, New Zealand, and elsewhere.
* '' Bryobia watersi'' has been found on mallow, cucumber,
peanut
The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), goober pea, pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible seeds. It is widely grown in the tropics and subtropics by small and large ...
, and
Bermuda grass
''Cynodon dactylon'', commonly known as Bermuda grass, also known as couch grass in Australia and New Zealand, is a grass found worldwide. It is native to Europe, Africa, Australia and much of Asia. It has been introduced to the Americas. Contra ...