Stigmaeidae is a family of prostigmatan mites in the order Trombidiformes. At over 600 species, it is the largest family in superfamily

Raphignathoidea Raphignathoidea is a superfamily of the Acari (mite) order Trombidiformes, comprising 1087 species in 62 genera and 12 families. Morphology Adult Raphignathoidea are generally oval or round in shape, with 2 pairs of vertical setae on the prod ...

. It has a worldwide distribution.

Description

As mites, Stigmaeidae have unsegmented bodies with eight legs (six in larvae). They can be recognised by: prodorsum without transversal groove, sacs or tubes; suranal and aggenital shields separate; cheliceral bases usually separate (rarely fused or conjunct); palps stout with tibial claws at least 1/3 length of tarsus; peritreme absent. Males differ from females in being somewhat tapered posteriorly.

Life cycle

The stigmaeid life cycle has the five stages of egg, larva, protonymph, deutonymph and adult. The larva and two nymph stages are also each followed by a quiescent period. The whole life cycle takes no more than four weeks. Males usually reach adulthood slightly faster than females, allowing them to mate with females as soon as the latter have reached adulthood. Offspring exhibit a female-biased sex ratio (often in the 60-70% range), except for offspring of unmated females which are all male. Most Stigmaeidae are active year-round, but some species are known to go into diapause for the winter. Overwintering locations include litter at the base of trees and under bark scales on apple.

Habitat

Over a third of Stigmaeidae species are free-living

predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

that occur on the leaves and branches of plants (e.g. many ''Agistemus'' and ''Zetzellia''). There are also stigmaeids (e.g. many ''Eustigmaeus, Ledermulleriopsis'' and ''Stigmaeus'') that live in soil and leaf litter and are believed to feed on

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.sandflies Sandfly (or sand fly) is a colloquial name for any species or genus of flying, biting, blood-sucking dipteran (fly) encountered in sandy areas. In the United States, ''sandfly'' may refer to certain horse flies that are also known as "greenhea ...

. Some species can survive, feed and even develop while immersed in water, but cannot reproduce.

Diet

Predatory Stigmaeidae have generalist diets, consuming other mites (e.g.

spider mite Spider mites are members of the Tetranychidae family, 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 ...

s, false spider mites, gall and rust mites and broad mites) as well as small insects (

Hemiptera Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, Reduviidae, assassin bugs, Cimex, bed bugs, and shield bugs. ...

Lepidoptera Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...

) and plant

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

. They usually prefer to feed on immature stages such as eggs. They feed by piercing prey with their chelicerae and sucking out the fluids. Moss-feeders, such as those in genus ''Eustigmaeus'' (formerly ''Ledermuelleria''), feed on moss leaves. They suck out cell contents while leaving the

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...

s intact. They can feed and survive on many moss species, though only a few species allow mite reproduction. Stigmaeidae that attach to sandflies are presumed to be parasitic, leaving behind scars on the abdomens of their hosts.

Biological control

Due to their predatory activity, some stigmaeids (e.g ''Agistemus exsertus'' and ''Zetzellia mali'') have been studied for use as biological control agents of pest mites. Modelling indicates that stigmaeids are more effective control agents than phytoseiids at low prey densities (but less effective at high prey densities), and a combination of stigmaeids and phytoseiids is more effective than either predator alone.

Genera

* '' Agistemus'' * '' Cheylostigmaeus'' * '' Eryngiopus'' * '' Eustigmaeus'' * '' Ledermuelleria'' * '' Ledermuelleriopsis'' * '' Mediolata'' * '' Mullederia'' * '' Primagistemus'' * '' Pseudostigmaeus'' * '' Stigmaeus'' * '' Storchia'' * '' Summersiella'' * '' Zetzellia''