Acanthoplus discoidalis

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Armoured katydid
Greenarmorednamib.JPG
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Orthoptera
Suborder: Ensifera
Family: Tettigoniidae
Genus: Acanthoplus
Species:
A. discoidalis
Binomial name
Acanthoplus discoidalis
(Walker, 1869)
Synonyms

Hetrodes discoidalisWalker, 1869

Acanthoplus discoidalis Namibgreencricket.JPG
Acanthoplus discoidalis
Koringkriek in Fish River Canyon Namibian Koringkriek (Armoured Ground Cricket).jpg
Koringkriek in Fish River Canyon

Acanthoplus discoidalis is a species in the Hetrodinae, a subfamily of the katydid family (Tettigoniidae). Like its closest relatives, Acanthoplus discoidalis variously bears common names such as armoured katydid, armoured ground cricket, armoured bush cricket, corn cricket, setotojane and koringkriek. The species is native to parts of Angola, Namibia, Botswana, Zimbabwe and South Africa. [2]

Contents

Note that the common names are characteristically misleading; the species is not closely related to true crickets and "katydids" which originally belonged to the unrelated subfamily Pseudophyllinae.

Description

Acanthoplus discoidalis is a wide-bodied, flightless species that typically grows to a body length of about 5 cm/1.95 inches. The pronotum bears several sharp, conical spines. The mandibles, or main biting jaws, are powerful; they can inflict a painful nip and they permit the insect to feed on material such as tough herbage or carrion. Another defense against predators is reflex bleeding (also called "autohaemorrhaging") in which the insects squirt haemolymph from pores in their exoskeleton, achieving a range of a few centimetres. [3]

Diet

Acanthoplus discoidalis is omnivorous and feeds opportunistically on many different foods. One source documented attacks on red-billed quelea nestlings and suggested that the insects might be able to detect the nests by auditory clues. [4]

Especially when their diet is deficient in protein and salt, members of the species commonly become cannibalistic, so much so that when their populations peak in autumn and some of them stray across roads and are crushed by traffic, cannibalistic conspecifics congregate around the casualties and feed until they are killed in turn. During that season their remains may form large patches on roads. [5]

Defense

Acanthoplus discoidalis has several defensive mechanisms apart from the armoured exoskeleton. Their defence takes various forms, depending on the gender of the individual and the method of attack.

When attacked from the side, both males and females will attempt to bite the attacker and males will stridulate (females have no functional stridulatory mechanism). In about half the attacks from the side, either gender may autohaemorrhage, squirting between 5 mg and 80 mg of possibly toxic haemolymph at the attacker at ranges of up to 3 cm.

When attacked from above, and therefore not in a good position to bite the attacker, either gender will autohaemorrhage more than when attacked from the side.

Experiments have shown that the haemolymph is distasteful to at least two reptile species, but the repellent components have not been determined. It has been hypothesised that they may be phytotoxins found in plants that the insects eat and that they then sequester those substances to use as defensive compounds themselves.

After autohaemorrhaging the insects clean themselves meticulously. This is thought to reduce the probability that other members of the species will attack them cannibalistically. Research on the species suggests that autohaemorrhage is a precisely regulated defence response rather than an accidental consequence of being attacked. [5] Another defensive response is to regurgitate their stomach contents when attacked, which happens most often when the insect has already been attacked repeatedly. [5]

Reproduction

In Acanthoplus discoidalis, courtship and mating is a relatively slow process; it starts at sunset and usually is completed by sunrise. [6] First the stridulation of the males attracts females. [5] The male produces a large spermatophore that includes a sperm pouch and an attached spermatophylax, a portion of food that serves as a nuptial gift to the female. Having mated, a male cannot mate again before he has had time to grow a new spermatophore.

A female must mate before laying her first clutch of eggs. Thereafter she may mate and lay eggs again in any arbitrary order, as she can store sperm. Accordingly, it is advantageous for males to mate with virgins, as a higher proportion of the offspring of a virgin female will be their own. Virgins are lighter than non-virgins, which offers males a basis for distinguishing them when copulating. Males accordingly complete more matings with virgins than non-virgins and they transfer their spermatophore more quickly. [6]

Control

Acanthoplus discoidalis is a pest of sorghum and millet in Southern Africa. In bad years, they may cause crop losses of up to 40%. Insecticides can control infestations, but as Acanthoplus discoidalis are flightless they can be controlled fairly easily by constructing a 50 cm deep trench around the field. If it seems worth while, poisoned baits in the trenches can increase the intensity of control. It has been suggested that the insects could be collected and used as a high protein chicken feed. [7]

Related Research Articles

<span class="mw-page-title-main">Tettigoniidae</span> Family of insects

Insects in the family Tettigoniidae are commonly called katydids or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000 species are known. Part of the suborder Ensifera, the Tettigoniidae are the only extant (living) family in the superfamily Tettigonioidea.

<span class="mw-page-title-main">Orthoptera</span> Order of insects including grasshoppers, crickets, weta and locusts

Orthoptera is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and weta. The order is subdivided into two suborders: Caelifera – grasshoppers, locusts, and close relatives; and Ensifera – crickets and close relatives.

<span class="mw-page-title-main">Hump-winged grig</span> Genus of cricket-like animals

Hump-winged grigs are insects belonging to the genus Cyphoderris, in the family Prophalangopsidae, and superfamily Grylloidea (crickets). In modern times they are known only in northwestern North America and central Asia, but the fossil record indicates a wider distribution in the past.

<span class="mw-page-title-main">Spermatophore</span> Packet containing sperm in invertebrate reproduction

A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores may additionally contain nourishment for the female, in which case it is called a nuptial gift, as in the instance of bush crickets. In the case of the toxic moth Utetheisa ornatrix, the spermatophore includes sperm, nutrients, and pyrrolizidine alkaloids which prevent predation because it is poisonous to most organisms. However, in some species such as the Edith's checkerspot butterfly, the "gift" provides little nutrient value. The weight of the spermatophore transferred at mating has little effect on female reproductive output.

<span class="mw-page-title-main">Mormon cricket</span> Species of cricket-like animal

The Mormon cricket is a large insect native to western North America in rangelands dominated by sagebrush and forbs. Anabrus is a genus in the shield-backed katydid subfamily in the Tettigoniidae family, commonly called katydids, bush crickets, and previously "long-horned grasshoppers". Its common name, "Mormon cricket", is a misnomer: true crickets are of the family Gryllidae.

<span class="mw-page-title-main">Red-billed quelea</span> Small, migratory weaver bird native to Sub-Saharan Africa

The red-billed quelea, also known as the red-billed weaver or red-billed dioch, is a small—approximately 12 cm (4.7 in) long and weighing 15–26 g (0.53–0.92 oz)—migratory, sparrow-like bird of the weaver family, Ploceidae, native to Sub-Saharan Africa.

<span class="mw-page-title-main">Ensifera</span> Suborder of cricket-like animals

Ensifera is a suborder of insects that includes the various types of crickets and their allies including: true crickets, camel crickets, bush crickets or katydids, grigs, weta and Cooloola monsters. This and the suborder Caelifera make up the order Orthoptera. Ensifera is believed to be a more ancient group than Caelifera, with its origins in the Carboniferous period, the split having occurred at the end of the Permian period. Unlike the Caelifera, the Ensifera contain numerous members that are partially carnivorous, feeding on other insects, as well as plants.

<span class="mw-page-title-main">Cricket (insect)</span> Small insects of the family Gryllidae

Crickets are orthopteran insects which are related to bush crickets, and, more distantly, to grasshoppers. In older literature, such as Imms, "crickets" were placed at the family level, but contemporary authorities including Otte now place them in the superfamily Grylloidea. The word has been used in combination to describe more distantly related taxa in the suborder Ensifera, such as king crickets and mole crickets.

<span class="mw-page-title-main">Autohaemorrhaging</span> Action of animals deliberately ejecting blood from their bodies

Autohaemorrhaging, or reflex bleeding, is the action of animals deliberately ejecting blood from their bodies. Autohaemorrhaging has been observed as occurring in two variations. In the first form, blood is squirted toward a predator. The blood of these animals usually contains toxic compounds, making the behaviour an effective chemical defence mechanism. In the second form, blood is not squirted, but is slowly emitted from the animal's body. This form appears to serve a deterrent effect, and is used by animals whose blood does not seem to be toxic. Most animals that autohaemorrhage are insects, but some reptiles also display this behaviour.

<i>Acanthoplus</i> Genus of cricket-like animals

Acanthoplus is a genus of African bush crickets in the subfamily Hetrodinae and tribe Acanthoplini.

Acanthoproctus diadematus is an armoured katydid, bush-cricket, or ground cricket endemic to the Namib Desert of southern Africa, where it lives in the tall sand dunes along the Kuiseb River in Namib-Naukluft National Park. The katydid feeds on the !nara melon endemic to the area.

<i>Phaneroptera nana</i> Species of cricket-like animal

Phaneroptera nana, common name southern sickle bush-cricket, is a species in the family Tettigoniidae and subfamily Phaneropterinae. It has become an invasive species in California where it may be called the Mediterranean katydid.

<i>Tettigonia cantans</i> Species of cricket-like animal

Tettigonia cantans is a species of bush crickets belonging to the family Tettigoniidae subfamily Tettigoniinae.

Panoploscelis is a genus of very large insects belonging to the true katydid tribe Eucocconotini, which is a subfamily of the Tettigoniidae. Like the other members of the suborder Ensifera, Panoploscelis are part of the insect order Orthoptera, which also contains crickets, grasshoppers and locusts. Members of this genus are among the largest katydids of the Neotropics.

A nuptial gift is a nutritional gift given by one partner in some animals' sexual reproduction practices.

<span class="mw-page-title-main">Hetrodinae</span> Subfamily of cricket-like animals

The Hetrodinae are a subfamily of robust bush crickets, also known as armoured katydids, corn crickets, etc. currently including five tribes.

<i>Thoracistus</i> Genus of cricket-like animals

Thoracistus is a genus of decticine or shield-backed katydids in the family Tettigoniidae. The mostly carnivorous genus is endemic to South Africa.

<i>Chlorobalius</i> Species of cricket-like animal

Chlorobalius is a genus in the bush cricket or katydid family containing a single species, Chlorobalius leucoviridis, commonly known as the spotted predatory katydid. C. leucoviridis is a predator and is an acoustic aggressive mimic of cicadas; by imitating the sounds and movements made by female cicadas, it lures male cicadas to within its reach and then eats them.

<i>Caedicia simplex</i> Species of insect

Caedicia simplex is a species of bush cricket or katydid, native to New Zealand and Australia. A common name is the "common garden katydid".

<i>Siliquofera</i> Subfamily of cricket-like animals

Siliquofera is a genus of bush cricket in the subfamily Phyllophorinae that includes only one species, Siliquofera grandis, which is fairly common and widespread in rainforest canopies of New Guinea and nearby smaller islands, and seemingly rare in Australia where only found in the remote Iron Range region. This very well-camouflaged, green and leaf-like bush cricket is one of the world's largest Orthoptera, with adults typically having a length of 10.7–13 cm (4.2–5.1 in) and a wingspan of 25–27 cm (9.8–10.6 in); it can weigh more than 30 g (1.1 oz).

References

  1. Bazelet, C.; Naskrecki, P. (2014). "Acanthoplus discoidalis". IUCN Red List of Threatened Species . 2014: e.T20636721A43266507. doi: 10.2305/IUCN.UK.2014-1.RLTS.T20636721A43266507.en . Retrieved 19 November 2021.
  2. "Archived copy" (PDF). Archived from the original (PDF) on 2015-01-15. Retrieved 2012-11-24.{{cite web}}: CS1 maint: archived copy as title (link) Developing Integrated Pest Management Strategies for Control of the Armoured Bush Cricket, Acanthoplus Discoidalis (Orthoptera: Tettigoniidae). Poster 120 Mosupi, P. O. P., J. van den Berg, M. A. McGeoch & S. V. Green
  3. Walker, Matt (28 July 2009). "Insect defence all blood and guts". BBC Earth News. Archived from the original on 29 July 2009. Retrieved August 7, 2009.
  4. Cheke, Robert; Jones, Peter; Dallimer, Martin; Green, Stuart (2003). "Armoured Bush Cricket attacks on nestling Red-billed Quelea (Quelea quelea)" (PDF). Ostrich. 74 (1 and 2). NISC Pty Ltd.: 135. doi:10.2989/00306520309485382. ISSN   0030-6525. S2CID   86643532. Archived from the original (PDF) on September 2, 2009. Retrieved August 7, 2009.
  5. 1 2 3 4 Bateman, Philip; Fleming, P. A. (28 Apr 2009). "There will be blood: autohaemorrhage behaviour as part of the defence repertoire of an insect". Journal of Zoology . 278 (4): 342–348. doi:10.1111/j.1469-7998.2009.00582.x. ISSN   1469-7998. Archived from the original on 16 October 2012. Retrieved August 7, 2009.
  6. 1 2 Bateman, Philip; Ferguson, J. W. H. (2004). "Male mate choice in the Botswana armoured ground cricket Acanthoplus discoidalis (Orthoptera: Tettigoniidae; Hetrodinae). Can, and how, do males judge female mating history?". Journal of Zoology . 262 (3): 305–309. doi:10.1017/S0952836903004679.
  7. Green, Stuart; Holt, John; Mazhani, L; Mitchell, Jannette; Mosopi, Pharoah; Mviha, Patrick; Scholtz, Clark; Van der Berg, Johny; Wadhams, L. "Trench warfare to combat crickets in southern Africa Control of Armoured Bush Cricket in southern Africa". Archived from the original on August 20, 2009. Retrieved August 7, 2009.