Temporal range: 228–0 Ma Late Triassic – Recent
Blattodea is an order of insects that contains the cockroaches and the termites. Formerly, the termites were considered a separate order, Isoptera, but genetic and molecular evidence suggests an intimate relationship with the cockroaches, both cockroaches and termites having evolved from a common ancestor. The Blattodea and the mantises (order Mantodea) are now all considered part of the superorder Dictyoptera. There are approximately 4,400 species of cockroach in almost 500 genera, and about 3,000 species of termite in around 300 genera.
Cladistic analysis of five DNA sequences in 107 species representing all the termite subfamilies, all 6 cockroach families, including 22 of the 29 subfamilies, and 5 of the 15 mantis families (as out-groups) showed that the termites are nested within the cockroaches, and that the Cryptocercidae is a sister group to the termites. The mantids were shown to be the sister group to Blattodea. Cryptocercus also shares characteristics such as species of gut bacteria with the termites.
The evolutionary relationships of the Blattodea (cockroaches and termites), based on Eggleton, Beccaloni & Inward (2007), are shown in the cladogram: The cockroach families Lamproblattidae and Tryonicidae are not shown but are placed within the superfamily Blattoidea. The cockroach families Corydiidae and Ectobiidae were previously known as the Polyphagidae and Blattellidae.
Arthropods similar to living cockroaches dominated the insect communities of the Carboniferous era. Modern cockroaches radiated from them by the middle of the Mesozoic. The cockroach is flattened dorso-laterally and is roughly oval with a shield-like prothorax that covers the head. The antennae are many-segmented, long and slender, and the mouthparts are adapted for chewing. The fore-wings are normally leathery and the hind wings membranous. The coxae of the legs are flattened to enable the femurs to fit neatly against them when folded. Cockroaches are hemimetabolous; there is no pupal stage and the nymphs resemble the adults apart from their size and the absence of wings.
All species of termite are to some degree eusocial and exhibit cooperative behaviour involving a male and female pair of reproductives, and the workers and soldiers that form the other members of the colony. Some species have small, simple colonies where the workers and soldiers are capable of becoming reproductives themselves. Others have large complex societies where each member has a role that does not change throughout its lifetime. One can think of termites as "eusocial, juvenilized cockroaches".
- Integrated Taxonomic Information System entry
- "Order Blattodea: Cockroaches and Termites". BugGuide. Retrieved 2015-08-27.
- Inward, Daegan; Beccaloni, George; Eggleton, Paul (2007). "Death of an order: a comprehensive molecular phylogenetic study confirms that termites are eusocial cockroaches". Biology Letters 3 (3): 331–5. doi:10.1098/rsbl.2007.0102. PMC 2464702. PMID 17412673.
- Djernæs, M. (2012). "Phylogeny of cockroaches (Insecta, Dictyoptera, Blattodea), with placement of aberrant taxa and exploration of out-group sampling". Systematic Entomology 37 (1): 65–83. doi:10.1111/j.1365-3113.2011.00598.x.
- Eggleton P., Beccaloni G., Inward D.; et al. (2007). "Invited reply: Response to Lo et al". Biology Letters 3 (5): 564–565. doi:10.1098/rsbl.2007.0367.
- Beccaloni G. W., Eggleton P. (2011). "Order Blattodea Brunner von Wattenwyl, 1882. In: Zhang, Z.-Q. (Ed.). Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness". Zootaxa 3148: 199–200.
- Bell, William J.; Roth, Louis M.; Nalepa, Christine A. (2007). Cockroaches: Ecology, Behavior, and Natural History. JHU Press. pp. xii, 1. ISBN 978-0-8018-8616-4.
- Choe, Jae C.; Crespi, Bernard J. (1997). The Evolution of Social Behaviour in Insects and Arachnids. Cambridge University Press. p. 52. ISBN 978-0-521-58977-2.