Labidura Riparia
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''Labidura riparia'' is a species of
earwig Earwigs make up the insect order (biology), order Dermaptera. With about 2,000 species in 12 families, they are one of the smaller insect orders. Earwigs have characteristic cercus, cerci, a pair of forceps-like pincer (biology), pincers on ...
in the family
Labiduridae Labiduridae, whose members are known commonly as striped earwigs, is a relatively large family of earwigs in the suborder Neodermaptera. Taxonomy The family contains a total of approximately 72 species, spread across seven genera in three subfa ...
characterized by their modified cerci as forceps, and light tan color.Tawfik, M., Abul-Nar, S., and El-hussein, M. 1973. The biology of ''Labidura riparia'' Pallas. Bulletin of the Entomological Society of Egypt 76, 75-92. They are commonly known as the shore earwig, tawny earwig, riparian earwig, or the striped earwig due to two dark longitudinal stripes down the length of the
pronotum The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum (ventral), and the propleuron (lateral) on e ...
. They are sometimes wrongly referred to as ''Labidura japonica'', although said species is actually a
subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...
, ''Labidura riparia japonica'', found only in
Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
.Kimimura, Y. 2014 Pre- and postcopulatory sexual selection and the evolution of sexually dimorphic traits in earwigs. Entomological Science, 17, 139-166. ''L. riparia'' are a
cosmopolitan species In biogeography, a cosmopolitan distribution is the range of a taxon that extends across most or all of the surface of the Earth, in appropriate habitats; most cosmopolitan species are known to be highly adaptable to a range of climatic and en ...
primarily in tropical to subtropical regions. Body size varies greatly, ranging from 16 mm to 30 mm, with 10
abdominal The abdomen (colloquially called the gut, belly, tummy, midriff, tucky, or stomach) is the front part of the torso between the thorax (chest) and pelvis in humans and in other vertebrates. The area occupied by the abdomen is called the abdominal ...
segments. Males and females differ in forcep size, with males having much larger and stronger curve, while females have smaller, straighter forceps with a slight curve at the end. Earwigs use these forceps to assist in
predation Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
, defense,
sexual selection Sexual selection is a mechanism of evolution in which members of one sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex ...
,
courtship Courtship is the period wherein some couples get to know each other prior to a possible marriage or committed romantic, ''de facto'' relationship. Courtship traditionally may begin after a betrothal and may conclude with the celebration of marri ...
and mating, and wing folding.Jarvis, K., Hass, F., and Whiting, M. 2005. Phylogeny of earwigs based on molecular and morphological evidence. Systematic Entomology, 30, 442-453. ''L. riparia'' are a subsocial earwig with complex maternal habits.Radl, R., and Linsenmair, K. 1991. Maternal behavior and nest recognition in the subsocial earwig ''Labidura riparia'' Pallas. Ethology, 89, 287-296. They are voracious predators, and highly regarded as efficient for pest control in many situations. Repugnitory glands in the earwigs cause them to secrete a foul smelling pheromone to deter predators, which is said to smell like decomposition. Males of this species have two penises in which they can use interchangeably.Kamimura, Y. 2006. Right-handed penises of the earwig ''Labidura riparia''. Journal of Morphology, 267, 1381-1389. Individuals have a preference on which they dominantly use though. Just like humans’ limb dexterity, ''L. riparia'' have a 90% prevalence of “right-handed” penises. This unequal proportion is unique to this species compared to all other earwigs, and may have a relationship with the
spermatheca The spermatheca (pronounced : spermathecae ), also called ''receptaculum seminis'' (: ''receptacula seminis''), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, Oligochaeta worms and certain other in ...
location on females.


Ecology

The striped earwig prefers dark, moist environments with shelter that it can hide in during the daytime. They can be found in a variety of niches though, from
cultured Culture ( ) is a concept that encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, attitudes, and habits of the individuals in these groups ...
and uncultured farmlands,
woodland A woodland () is, in the broad sense, land covered with woody plants (trees and shrubs), or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunli ...
s, and the margins of ponds and lakes.Earl, H., and Tryon, J. 1986. The striped earwig, and ant predators of sugarcane rootstock borer, in Florida citrus. The Florida Entomologist, 69, 336-343. To save energy, the earwigs will occupy abandoned
mole cricket Mole (or Molé) may refer to: Animals * Mole (animal) or "true mole" * Golden mole, southern African mammals * Marsupial mole, Australian mammals Other common meanings * Nevus, a growth on human skin ** Melanocytic nevus, a specific type of ...
burrows for
brooding Broodiness is the action or behavioral tendency to sit on a clutch of eggs to Egg incubation, incubate them, often requiring the non-expression of many other behaviors including feeding and drinking.Homedes Ranquini, J. y Haro-García, F. Zoogen ...
nests. Individuals are known to fly after a disturbance in search of a new nest as theirs may have become waterlogged or destroyed. Flight towards light has been observed due to their methods of orientation via the moon.Ugolini, A., and Chiussi. R. 1995. Astronomical orientation and learning in the earwig ''Labidura riparia''. Behavioural Processes, 36, 151-161. ''L. riparia'' are generalist predators whose diet consists entirely of insects or scavenged meat.Ktsuyuki, K., Takeda, M., and Hamamura. T. 2007. Insecticide susceptibility of a generalist predator ''Labidura riparia''. Applied Entomology and Zoology, 42, 501-505. They have a preference to Lepidoptera larvae and insect eggs, but will eat any available insect.Afify, A. Farghaly, H. 1971. Comparative laboratory studies on the effectiveness of ''Labidura riparia'' Pall. and ''Coccinella undecimpunctata'' Reiche, as predators of eggs and newly hatched larvae of ''Spodoptera littoralis''. Bulletin of the Entomological Society of Egypt, 54, 277-282. The earwig may use its long and powerful cerci to kill and immobilise larger insects. Because of their flexible eating habits, they easily adapt to any habit as long as there are insect around. In absence of a ready food supply, they have been known to eat
nymph A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...
s and eggs of their own species. As
nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...
insects, earwigs only hunt after sunset, but feed primarily just after sunset occurs. Feeding habits of females depend more on their ovulatory cycle, and will go long periods of time without eating in preparation of egg laying.Bassal, T., El-Naggar, M., Fahmy, N., Dorrah, M., Sallam, M., and Saama, M. 2001. Carnivory, rate of digestion, and prey consumption by ''Labidura riparia''. Efflatounia, 1, 13-19. The primary predator to ''L. riparia'' is ants, as they prey on unattended eggs. Overlap of predation does occur between organisms though as the earwigs prey on the ant eggs as well, the effect of ants on earwigs seems to be greater than the reverse relationship, as populations of earwigs increase if the ants decrease.Gross, H. 1967. Ecology and control of the striped earwig ''Labidura riparia'', in Louisiana. Unpublished Ph. D dissertation, Louisiana state university and agricultural and mechanical college.


Nesting and life cycle

Nests are essential for protection from the environment, and
predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
s, and needed for the success of their offspring's survival. Special nests are dug for
molting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...
, feeding, and egg laying. A suitable nest is chosen and dug out by the female under a rock or tree bark. Female earwigs are the primary caregivers as they become hostile to males while in their brooding chambers. While the female is laying her eggs she grabs them and cleans them of any
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
or dirt one by one as they are laid. They do this to 60-100 eggs, and once finished they lay over top of the eggs much like a hen. The female continues to groom the eggs and stay guarding them for 10 days until they begin to hatch. At this time the mother goes in search of food for her young, and continues feeding and grooming them until they leave the nest themselves 2–5 days later. Each female will do this up to three times in her life, sometimes more than one at a time. Some females get lost returning to their brood and start caring for another individual clutch as they are not able to distinguish between their own young and another's. The young will go on to dig their own nest for molting taking anywhere from 4 to 50 days to reach the next instar, repeating to a total of 6
instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...
s before adulthood. Once adults, the individuals will live for only 2–3 months, and begin courting immediately. This is done by a feeling of antennae, and mutual grabbing of each other's abdomens with their forceps until
copulation Sexual intercourse (also coitus or copulation) is a sexual activity typically involving the insertion of the erect male penis inside the female vagina and followed by thrusting motions for sexual pleasure, reproduction, or both.Sexual inte ...
occurs. 2-3 generations will occur in a year, with the last generation hibernating underground through winter.


See also

* List of Dermapterans of Australia * List of Dermapterans of Sri Lanka


References

{{Taxonbar, from=Q728526 Forficulina Insects described in 1773 Insects of the United States Cosmopolitan insects Taxa named by Peter Simon Pallas