Erythraeidae
Taxonomy
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Subclass: Acari
Order: Trombidformes
Family: Erythraeidae
Erythraeidae is a family of mites that fall under the Trombidiformes order, specifically the Prostigmata suborder. Erythraeidae falls into the Arachnida class under the arthropod phyla, and is part of the broader animal kingdom.
The Prostigmata is a suborder of mites within the Trombidiformes order that contains the “sucking” members of the mite family. Many species of Prostigmata are known as notorious plant pests, but many others live as parasites on different vertebrate species.
Certain other members of this family can even prey on small invertebrates, and many alter their food source as they mature from larva to deutonymph to adult. There are over 460 species of Erythraeidae mites.
Body Composition
Erythraeidae have oval shaped bodies, and are typically bright red in color, sometimes with white on the idiosoma dorsum. They are relatively large (1000-2500 μm as adults) and have many small hairs covering their bodies. Their first and fourth pair of legs are especially long & adapted for running. These mites can be distinguished from similar families by the presence of a single claw on the tibia of the palp.
The Trombidiformes order is characterized by several traits that unite the Prostigmata. These characteristics include anamorphic segments, hysterosomal segment C with fewer than four pairs of setae, and hysterosomal segments D and E with fewer than two pairs of setae. Many trombidiform mites have a pad-like or rayed median empodium rather than the claw-like empodium of sarcoptifoms. Within the Trombidiformes order, the Prostigmata group is united by stigmatal openings to their tracheal system located near the base of the mouthpart.
Urnulae Structures
There may be one or two pairs of urnulae (the mite’s eye-like structures). Until recently, the function of this structure was unknown, and not found in other actinotrichid mites. Recent studies on these structures have suggested two main functions, which are that they provide a defensive secretion and that they provide a secretion enhancing resistance against the loss of water and eventual desecration. These studies exposed mites to predators such as ants, and observed increased secretions, which had a repellant effect on the ants as well as other arthropods, They were also able to demonstrate that the larvae which do not yet contain the urnulae structures are the most susceptible to water loss and avoid exposure to sunlight.
Life Cycle
These mites have three active life stages, beginning as a larva, moving to a deutonymph and eventually becoming an adult mite.
Larvae
Many larval forms of Erythraeidae mites are parasitic on various other arthropods, but adults are non-parasitic predators. Larvae bite a hole into the cuticula of a host and use a stylostome, a body part that acts as a sort of straw, to drink the host’s body fluids and dissolved body tissues.
Deutonymph & Adult Mites
Certain members of the Erythraeidae family exist as free-living predators not only in the nymph and adult stage, but in the larval stage as well. They prey on small, soft-bodied arthropods on the trees. It has been observed attacking all stages of the European red mite, the San Jose scale, as well as the apple aphid. Several Erythraeidae species feed on bees in their larval forms.
Reproduction & Season
Mites in this family have two generations per year, and are active from March until December; they are likely to be in diapause over the summer.
References
1. Proctor, Heather. 1998. Trombidiformes. Trombidiform mites. Version 09 August 1998. http://tolweb.org/Trombidiformes/2568/1998.08.09 in The Tree of Life Web Project, http://tolweb.org/
2. Proctor, Heather. 1998. Acariformes. The "mite-like" mites. Version 09 August 1998. http://tolweb.org/Acariformes/2563/1998.08.09 in The Tree of Life Web Project, http://tolweb.org/
3. Zoological Journal of the Linnean Society, Volume 127, Issue 2, 1 October 1999, Pages 113–276, https://doi.org/10.1111/j.1096-3642.1999.tb00677.x
4. Gerd Alberti, Joanna Mąkol, Fine structure of the urnulae of Balaustium mites (Actinotrichida: Erythraeidae) representing peculiar defense organs, Arthropod Structure & Development, Volume 42, Issue 6, 2013, Pages 483-494, ISSN 1467-8039, https://doi.org/10.1016/j.asd.2013.09.003.
5. WSW. (2016). Balaustium [Photograph]. Retrieved from http://www.nhm.ac.uk/natureplus/message/83908?fromGateway=true
6. Arthur, A. L., Weeks, A. R., Hill, M. P., & Hoffmann, A. A. (2010). The distribution, abundance and life cycle of the pest mites Balaustium medicagoense (Prostigmata: Erythraeidae) and Bryobia spp. (Prostigmata: Tetranychidae) in Australia. Austral Entomology. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1440-6055.2010.00778.x
7. William L. Putman; Life History and Behavior of Balaustium putmani (Acarina: Erythraeidae), Annals of the Entomological Society of America, Volume 63, Issue 1, 15 January 1970, Pages 76–81, https://doi.org/10.1093/aesa/63.1.76