Tettigoniid
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Insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s in the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Tettigoniidae are commonly called katydids (especially in North America) or bush crickets. They have previously been known as "long-horned
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grassh ...
s". More than 8,000
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
are known. Part of the suborder
Ensifera Ensifera is a Order (biology), suborder of insects that includes the various types of crickets and their allies, including cricket (insect), true crickets, Rhaphidophoridae, camel crickets, Tettigoniidae, bush crickets or katydids, Prophalangops ...
, the Tettigoniidae are the only extant (living) family in the superfamily Tettigonioidea. Many species are
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 ...
in habit, having strident mating calls and may exhibit
mimicry In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. In the simples ...
or
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
, commonly with shapes and colours similar to leaves.[]


Etymology

The family name Tettigoniidae is derived from the genus ''Tettigonia'', of which the Tettigonia viridissima, great green bush cricket is the type species; it was first described by
Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
in 1758. In Latin ''tettigonia'' means a kind of small cicada,
leafhopper Leafhopper is the common name for any species from the family (biology), family Cicadellidae: based on the type genus ''Cicadella''. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or ...
; it is from the Greek τεττιγόνιον ''tettigonion'', the diminutive of the imitative (
onomatopoeic Onomatopoeia (or rarely echoism) is a type of word, or the process of creating a word, that phonetically imitates, resembles, or suggests the sound that it describes. Common onomatopoeias in English include animal noises such as ''oink'', '' ...
) τέττιξ, ''tettix'',
cicada The cicadas () are a superfamily, the Cicadoidea, of insects in the order Hemiptera (true bugs). They are in the suborder Auchenorrhyncha, along with smaller jumping bugs such as leafhoppers and froghoppers. The superfamily is divided into two ...
. All of these names such as ''tettix'' with repeated sounds are
onomatopoeic Onomatopoeia (or rarely echoism) is a type of word, or the process of creating a word, that phonetically imitates, resembles, or suggests the sound that it describes. Common onomatopoeias in English include animal noises such as ''oink'', '' ...
, imitating the
stridulation Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...
of these insects. The common name ''katydid'' is also onomatopoeic and comes from the particularly loud, three-pulsed song, often rendered "''ka-ty-did''", of the
nominate subspecies In 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), but that can successfully interbreed. ...
of the North American ''
Pterophylla camellifolia ''Pterophylla camellifolia'', the common true katydid, is a common North American insect in the family Tettigoniidae (katydids). Within the Tettigoniidae, it belongs to the subfamily Pseudophyllinae (true katydids). Other common names include n ...
'', belonging to the subfamily
Pseudophyllinae The subfamily Pseudophyllinae contains numerous species in the family Tettigoniidae, the katydids or bush crickets. Sometimes called "true katydids", together with the cricket (insect), crickets of suborder Ensifera, they form part of the insect ...
, which are known as "true katydids".


Description and life cycle


Description

Tettigoniids range in size from as small as to as large as . The smaller species typically live in drier or more stressful habitats which may lead to their small size. The small size is associated with greater agility, faster development, and lower nutritional needs. Tettigoniids are tree-living insects that are most commonly heard at night during summer and early fall. Tettigoniids may be distinguished from the
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grassh ...
by the length of their filamentous antennae, which may exceed their own body length, while grasshoppers' antennae are always relatively short and thickened.


Life cycle

Eggs are typically oval and may be attached in rows to plants. Where the eggs are deposited relates to the way the
ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...
is formed. It consists of up to three pairs of appendages formed to transmit the egg, to make a place for it, and place it properly. Tettigoniids have either sickle-shaped ovipositors which typically lay eggs in dead or living plant matter, or uniform long ovipositors which lay eggs in grass stems. When tettigoniids hatch, the nymphs often look like small, wingless versions of the adults, but in some species, the nymphs look nothing at all like the adult and rather mimic other species such as
ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...
s,
spiders Spiders (order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species di ...
and
assassin bug The Reduviidae is a large cosmopolitan family of the suborder Heteroptera of the order Hemiptera (true bugs). Among the Hemiptera and together with the Nabidae almost all species are terrestrial ambush predators; most other predatory Hemiptera ...
s, or flowers, to prevent predation. The nymphs remain in a mimic state only until they are large enough to escape predation. Once they complete their last molt (after about 5 successful molts), they are then prepared to mate.


Distribution

Tettigoniids are found on every continent except Antarctica. The vast majority of katydid species live in the
tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...
regions of the world. For example, the Amazon basin
tropical forest Tropical forests are forested ecoregions with tropical climates – that is, land areas approximately bounded by the Tropic of Cancer, tropics of Cancer and Tropic of Capricorn, Capricorn, but possibly affected by other factors such as prevailing ...
s are home to over 2,000 species. However, katydids are found in the cool, dry temperate regions, as well, with about 255 species in North America.


Classification

The Tettigoniidae are a large family and have been divided into a number of subfamilies: The Copiphorinae were previously considered a subfamily, but are now placed as tribe
Copiphorini The Copiphorini are a tribe of bush crickets or katydids in the family Tettigoniidae. Previously considered a subfamily (the Copiphorinae), they are now placed in the subfamily Conocephalinae. Like some other members of Conocephalinae, they are k ...
in the subfamily Conocephalinae. The genus ''
Acridoxena ''Acridoxena'' is a monotypic genus of bush crickets (also known as katydids). It is now placed in the tribe Acridoxenini of the subfamily Mecopodinae Mecopodinae are a subfamily of Tettigoniidae, bush crickets found in western South America, ...
'' is now placed in the tribe Acridoxenini of the Mecopodinae (previously its own subfamily, Acridoxeninae).


Extinct taxa

The ''Orthoptera species file'' lists: *† Pseudotettigoniinae (North America, Europe) *† Rammeinae (Europe) *† Tettigoidinae (Australia) ;Genera ''
incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...
'' * †'' Locustites'' Heer, 1849: 3 spp. * †'' Locustophanes'' Handlirsch, 1939: †''L. rhipidophorus'' Handlirsch, 1939 * †'' Prophasgonura'' Piton, 1940: †''P. lineatocollis'' Piton, 1940 * †'' Protempusa'' Piton, 1940: †''P. incerta'' Piton, 1940 * †'' Prototettix'' Giebel, 1856: †''P. lithanthraca'' (Goldenberg, 1854) The genus †'' Triassophyllum'' is extinct and may be placed here or in the
Archaeorthoptera The Cohort (taxonomy), cohort Polyneoptera is one of the major groups of winged insects, comprising the Orthoptera (grasshoppers, crickets, etc.) and all other neopteran insects believed to be more closely related to Orthoptera than to any other ...
.


Ecology

The diet of most tettigoniids includes
leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...
,
flowers Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...
,
bark Bark may refer to: Common meanings * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...
, and
seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
s, but many species are exclusively
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 ...
y, feeding on other
insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s,
snail A snail is a shelled gastropod. The name is most often applied to land snails, terrestrial molluscs, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gas ...
s, or even small
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
s such as
snake Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have s ...
s and
lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...
s. Some are also considered pests by commercial crop growers and are sprayed to limit growth, but population densities are usually low, so a large economic impact is rare. Tettigoniids are serious insect pests of
karuka The karuka (''Pandanus julianettii'', also called karuka nut and ''Pandanus'' nut) is a species of tree in the screwpine family (Pandanaceae) and an important regional food crop in New Guinea. The nuts are more nutritious than coconuts, and ar ...
(''Pandanus julianettii''). The species '' Segestes gracilis'' and '' Segestidea montana'' eat the leaves and can sometimes kill trees. Growers will stuff leaves and grass in between the leaves of the crown to keep insects out. By observing the head and mouthparts, where differences can be seen in relation to function, it is possible to determine what type of food the tettigoniids consume. Large tettigoniids can inflict a painful bite or pinch if handled, but seldom break the skin. Some species of bush crickets are consumed by people, such as the ''
nsenene Nsenene is the Luganda name for ''Ruspolia differens'': a bush cricket (a.k.a. katydids or misnamed "long-horned grasshoppers") in the tribe Copiphorini of the 'cone-head' subfamily. It is often confused with the closely related '' Ruspolia nit ...
'' (''Ruspolia differens'') in
Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...
and neighbouring areas.


Communication

The males of tettigoniids have sound-producing
organs In a multicellular organism, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to a ...
located on the hind angles of their front wings. In some species, females are also capable of stridulation. Females chirp in response to the shrill of the males. The males use this sound for courtship, which occurs late in the summer. The sound is produced by rubbing two parts of their bodies together, called
stridulation Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...
. In many cases this is done with the wings, but not exclusively. One body part bears a file or comb with ridges; the other has the plectrum, which runs over the ridges to produce a vibration. For tettigoniids, the fore
wings A wing is a type of fin that produces both lift and drag while moving through air. Wings are defined by two shape characteristics, an airfoil section and a planform. Wing efficiency is expressed as lift-to-drag ratio, which compares the bene ...
are used to sing. Tettigoniids produce continuous songs known as trills. The size of the insect, the spacing of the ridges, and the width of the scraper all influence what sound is made. Many species stridulate at a tempo which is governed by ambient temperature, so that the number of chirps in a defined period of time can produce a fairly accurate temperature reading. For American katydids, the formula is generally given as the number of chirps in 15 seconds plus 37 to give the temperature in degrees Fahrenheit.


Predation

Some tettigoniids have spines on different parts of their bodies that work in different ways. The Listroscelinae have limb spines on the ventral surfaces of their bodies. This works in a way to confine their prey to make a temporary cage above their mouthparts. The spines are articulated and comparatively flexible, but relatively blunt. Due to this, they are used to cage and not penetrate the prey's body. Spines on the tibiae and the femora are usually more sharp and nonarticulated. They are designed more for penetration or help in the defensive mechanism they might have. This usually works with their diurnal roosting posture to maximize defense and prevent predators from going for their head.


Defense mechanisms

When tettigoniids go to rest during the day, they enter a diurnal roosting posture to maximize their cryptic qualities. This position fools predators into thinking the katydid is either dead or just a leaf on the plant. Various tettigoniids have bright coloration and black apical spots on the inner surfaces of the tegmina, and brightly colored hind wings. By flicking their wings open when disturbed, they use the coloration to fool predators into thinking the spots are eyes. This, in combination with their coloration mimicking leaves, allows them to blend in with their surroundings, but also makes predators unsure which side is the front and which side is the back.


Reproductive behavior

The males provide a
nuptial gift Formally, a nuptial gift is a material presentation to a recipient by a donor during or in relation to sexual intercourse that is not simply gametes in order to improve the reproductive fitness of the donor. Often, such a gift will improve the fit ...
for the females in the form of a
spermatophylax A spermatophylax is a gelatinous bolus which some male insects eject during copulation with females through their aedeagi together with spermatophores, and which functions as a nutritive supplement for the female. See also *Nuptial gift Formall ...
, a body attached to the males'
spermatophore A spermatophore, from Ancient Greek σπέρμα (''spérma''), meaning "seed", and -φόρος (''-phóros''), meaning "bearing", or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especiall ...
and consumed by the female, to distract her from eating the male's spermatophore and thereby increase his paternity.


Polygamy

The Tettigoniidae have polygamous relationships. The first male to mate is guaranteed an extremely high confidence of paternity when a second male couples at the termination of female sexual refractoriness. The nutrients that the offspring ultimately receive will increase their fitness. The second male to mate with the female at the termination of her refractory period is usually
cuckolded A cuckold is the husband of an adulterous wife (or partner for unmarried companions); the wife of an adulterous husband is a cuckquean. In biology, a cuckold is a male who unwittingly invests parental effort in juveniles who are not genetica ...
.


Competition

The polygamous relationships of the Tettigoniidae lead to high levels of male-male competition. Male competition is caused by the decreased availability of males able to supply nutritious spermaphylanges to the females. Females produce more eggs on a high-quality diet; thus, the female looks for healthier males with a more nutritious spermatophylax. Females use the sound created by the male to judge his fitness. The louder and more fluent the trill, the higher the fitness of the male.


Stress response

In species which produce larger food gifts, the female often seeks out the males to copulate. This, however, is a cost to females as they risk predation while searching for males. Also, a cost-benefit tradeoff exists in the size of the spermatophore which the male tettigoniids produce. When males possess a large spermatophore, they benefit by being more highly selected for by females, but they are only able to mate one to two times during their lifetimes. Inversely, male Tettigoniidae with smaller spermatophores have the benefit of being able to mate two to three times per night, but have lower chances of being selected by females. Even in times of nutritional stress, male Tettigoniidae continue to invest nutrients within their spermatophores. In some species, the cost of creating the spermatophore is low, but even in those which it is not low, it is still not beneficial to reduce the quality of the spermatophore, as it would lead to lower reproductive selection and success. This low reproductive success is attributed to some Tettigoniidae species in which the spermatophylax that the female receives as a food gift from the male during copulation increases the reproductive output of the reproduction attempt. However, in other cases, the female receives few, if any, benefits. The reproductive behavior of bush crickets has been studied in great depth. Studies found that the tuberous bush cricket ('' Platycleis affinis'') has the largest testes in proportion to body mass of any animal recorded. They account for 14% of the insect's body mass and are thought to enable a fast remating rate.


See also

* List of Orthopteroid genera containing species recorded in Europe


References


External links

*
North American Katydids
with range maps and audio files of katydid songs * {{Authority control Orthoptera families Extant Jurassic first appearances Taxa named by Hermann August Krauss