Darkling beetle is the common name of the large family of beetles, Tenebrionidae. The number of species in the Tenebrionidae is estimated at more than 20,000 and the family is cosmopolitan. Human transport has spread several individual species inadvertently so that each of them has become cosmopolitan. Examples include Tribolium castaneum and other now-cosmopolitan pests of stored products.
Taxonomy and naming
The name Tenebrionidae means roughly: "those that are like Tenebrio"; Tenebrio was the Latin generic name that Linnaeus had assigned to some flour beetles in his 10th edition of Systema Naturae 1758-59. Tenebrio in turn literally means "seeker of dark places" or figuratively a trickster. In English "darkling" is a more or less literal translation of tenebrio, meaning "dweller in dark".
Many species do inhabit dark places, but there are exceptions; for example many species of Tenebrionidae in genera such as Stenocara and Onymacris are active by day and inactive at night. The name Tenebrionidae accordingly reflects the knowledge available to the taxonomists who first assigned the name; it is not a general reflection of Tenebrionid biology.
The family Tenebrionidae not only includes a large number of species, but an immensely varied range of forms, so much so that it presents great difficulties in classification. Taxonomic work still is in progress, but the following list of subfamilies was largely accepted in 2005.
- Alleculinae Laporte, 1840
- Cossyphodinae Wasmann, 1899
- Diaperinae Latreille, 1802
- Lagriinae Latreille, 1825 (1820)
- Nilioninae Lacordaire, 1859
- Phrenapatinae Solier, 1834
- Pimeliinae Latreille, 1802
- Stenochiinae Kirby, 1837
- Tenebrioninae Latreille, 1802
- Zolodininae Watt, 1974
The misspelling "T e r e b r i o n i d a e", though unusual, occurs frequently enough to be a nuisance and, because it is easily overlooked, it is a possible source of confusion in scans of the literature. The error appears to have no particular significance, but to be the product of misreadings, mis-scans, and mis-typings.
Characteristics
The Tenebrionidae may be identified by a combination of features, including :
- 11-segmented antennae that may be filiform, moniliform, or weakly clubbed
- First abdominal sternite entire and not divided by the hind coxae
- Eyes notched by a frontal ridge
- Tarsi have four segments in the hind pair and five in the fore and mid legs (5-5-4), tarsal claws are simple
Biology and ecology
Darkling beetles vary in their biology. Many feed on plant matter, some on fresh and some on decaying vegetation; some are generalist feeders on detritus, whether of animal or plant material. Many major pests of stored food are species in genera within the Tenebrionidae. Examples include species in the genera Alphitobius, Blaps, Gnatocerus, Latheticus, Palembus, Palorus, Tenebrio, and Tribolium.
Species within the Tenebrionidae occupy various ecological niches and accordingly are important resources for ranges of predators and parasitoids in the food chain, including birds, rodents, reptiles, and arthropods such as sun spiders, Hymenoptera and Acari.
Some species live in intensely dry deserts such as the Namib, and have evolved adaptions by which they collect droplets of fog that deposit on their elytra. As the droplets accumulate the water drains down the beetles' backs to their mouthparts, where they swallow it.
Notable species
The larval stages of several species are cultured as feeder insects for captive insectivores or as laboratory subjects:
- Tenebrio molitor is commonly used to feed terrestrial amniotes kept in terraria.
- Tribolium castaneum is a laboratory animal useful as a model organism, especially in studies of intragenomic conflict and population ecology.
- Zophobas morio, or superworm, is valued as a feed for captive reptiles; it contains less chitin than Tenebrio molitor.
- Many Tenebrionids are pests of cereal and flour silos and other storage facilities, including T. castaneum, other Tribolium species such as Tribolium confusum and Tribolium destructor, and Gnathocerus cornutus.
- In southwestern North America, species of the genus Eleodes (particularly E. obscurus) are well known as "pinacate beetles" or "desert stink beetles".
- Several genera, such as Stenocara and Onymacris, are of interest in ecological studies of arid conditions and their associated adaptations.
Image gallery
References
External links
- Tenebrionidae.net- information and pictures about darkling beetles
- Alphitobius diaperinus, lesser mealworm. University of Florida IFAS
- Leichenum canaliculatum variegatum, Madagascar beetle University of Florida IFAS
