| Therea petiveriana | |
|---|---|
 | |
 | |
| Male above, female below (with shorter antennae) | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Blattodea |
| Family: | Corydiidae |
| Genus: | Therea |
| Species: | T. petiveriana |
| Binomial name | |
| Therea petiveriana | |
| Synonyms[2] | |
Corydia petiveriana | |
Therea petiveriana, variously called thedesert cockroach,seven-spotted cockroach,domino cockroach, orIndian domino cockroach, is a species ofcrepuscular cockroach found in southernIndia. They are members of abasal group within the cockroaches.[3][4] This somewhat roundish and contrastingly marked cockroach is mainly found on the ground inscrub forest habitats where they may burrow under leaf litter or loose soil during the heat of the day.[5]
The black and white pattern of adults is believed to have evolved tomimic the pattern of the aggressiveground beetleAnthia sexguttata that has strong defenses, including the ability to spray chemical irritants.[6] The upperside of the abdomen is orange-yellow, but is hidden by thetegmina. The spots on the asymmetrical tegmina are placed so that when closed, the spots appear symmetrical. The right tegmen lobe is bright orange-yellow. The species has been said to be one of the few cockroaches with "grace and beauty".[7] The head is bent back underneath the pronotal shield (hypognathous) and theocelli (simple eyes) face forward, helping sense light and thereby time, and they forage actively during early morning and late evening.[5]
Once a female has copulated with a male, she does not allow other males to approach, kicking them away with her hind legs.[8] The eggs are laid inleaf litter.[9] Up to 13oothecae are produced by a female over 3 to 40 days[5] (blocking the ocelli of the females has been found to inhibit the laying of eggs[5]). The oothecae are produced as in other cockroaches by the secretions from the asymmetrical colleterial glands of the females.[10] Once the ootheca is extruded it is deposited in suitably moist leaf litter.[11] Nymphs lead a life hidden below the ground and may go as deep as 30 cm during thedry season.[12]
This is thetype species for the genusTherea. The species epithet is afterJames Petiver (1663–1718), who obtained specimens fromMadras and its vicinity (probably from the surgeon atFort St. George, eitherSamuel Browne or more likelyEdward Bulkley[13]).Carl Linnaeus placed the species underCassida and describedC. petiveriana and another that he calledC. septemguttata, now considered asynonym.[1]
Like other cockroaches,T. petiveriana uses chemicalpheromones to communicate with each other. When disturbed, they are said to raise their wings and evert lateral glands on the second and thirdabdominal segments. Their glandular secretions were found to contain volatile compounds N-3-methylbutylacetamide (MBA) and N-3-methylbutylpropanamide (MBP), making up nearly 60% of the volatile fraction. These chemicals appeared to induce alarm behaviour.[14]
Liketermites, these cockroaches havesymbiotic bacteria andflagellates in their gut that aid in digestion.[15][16]
The conspicuously markedTherea cockroaches are popular as pets and easy to keep. The most commonly kept species has often been identified asT. petiveriana, but in 2009 it was instead suggested that the captive population actually belongs to a separate species,T. bernhardti, that differs primarily in the hindwings (which usually are hidden behind the tegmina), but also in small details of the tegmina pattern.[17]
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