''Poekilocerus pictus'', the painted grasshopper, aak grasshopper or ak grasshopper, is a fairly large and brightly coloured species of

grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...

found in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...

and

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...

, especially in drier regions. Both adults and

nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typ ...

are toxic; the nymphs are notorious for being able to squirt a jet of noxious liquid at up to around away when grasped. ''P. pictus'' was long regarded as the only ''

Poekilocerus ''Poekilocerus'' is a genus of grasshoppers in the family Pyrgomorphidae and the monotypic tribe Poekilocerini. Species are found in the northern half of Africa, and in Southwest and South Asia, often in arid or semi-arid areas. Adults are typic ...

'' of the

Indian subcontinent The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...

(other species are found in Southwest Asia and Africa), but in 2016 a new species, the overall yellowish-brown '' P. geniplanus'', was described from

Chhattisgarh Chhattisgarh (, ) is a landlocked state in Central India. It is the ninth largest state by area, and with a population of roughly 30 million, the seventeenth most populous. It borders seven states – Uttar Pradesh to the north, Madhya Prade ...

Description

Adults of ''P. pictus'' typically are long. The nymphs are greenish-yellow with fine black markings and small crimson spots. The mature grasshopper has canary yellow and turquoise or blue stripes on its body, green

tegmina A tegmen (plural: ''tegmina'') designates the modified leathery front wing on an insect particularly in the orders Dermaptera (earwigs), Orthoptera (grasshoppers, crickets and similar families), Mantodea (praying mantis), Phasmatodea (stick an ...

with yellow spots, and pale red hind wings.

Feeding and toxicity

Both adults and nymphs of ''P. pictus'' feed extensively on poisonous ''

Calotropis ''Calotropis'' is a genus of flowering plants in the family Apocynaceae, first described as a genus in 1810. It is native to southern Asia and North Africa. They are commonly known as milkweeds because of the latex they produce. ''Calotropis'' ...

'' milkweeds, notably '' C. gigantea'' and '' C. procera'', gaining their own toxins from the plants. When given the choice, both adults and nymphs tend to prefer ''C. procera'' over ''C. gigantea''. However, both adults and nymphs of ''P. pictus'' may also feed on a wide range of other plants, including several that are important agricultural crops, and for this reason they are sometimes regarded as a serious pest. When nymphs mainly feed on other plants than ''Calotropis'' milkweeds, their development is not as fast, but the first couple of

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

s tend to still prefer various weeds over ''Calotropis'' if given the choice. The common name aak grasshopper or ak grasshopper is based on the local name of the main food plants, ''Calotropis gigantea'' and ''C. procera''. If starving,

cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, b ...

is a regular occurrence. Upon slight pinching of the head or

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

, the nymphs ejects liquid in a sharp and sudden jet, with a range of up to around or more, from a

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

opening between the first and second abdominal segments. The discharge is directed towards the pinched area and may be repeated several times. The liquid is pale and milky, slightly

viscous The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inter ...

with an unpleasant smell and taste, containing

cardiac glycoside Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for co ...

s that the insect obtains from the plant it feeds upon. In the adults, the discharge occurs under the tegmina and collects as viscous bubbly heap along the sides of the body, lacking the squirting effect seen in nymphs.

Research

''P. pictus'' females produce a

sex pheromone Sex pheromones are pheromones released by an organism to attract an individual of the same species, encourage them to mate with them, or perform some other function closely related with sexual reproduction. Sex pheromones specifically focus on ind ...

that is secreted from a thin sac-like gland in the metathoracic segment. ''P. pictus'' has an inducible

chromosomal A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

repair mechanism that acts in

meiotic Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately res ...

cells.Mahmood R, Vasudev V. Inducible protective processes in animal systems. III. Adaptive response of meiotic cells of the grasshopper, Poecilocerus pictus, to a low dose of ethyl methanesulfonate. Mutat Res. 1992 Dec;283(4):243-7. doi: 10.1016/0165-7992(92)90055-m. PMID: 1383796

References

{{Taxonbar, from=Q7207335 Pyrgomorphidae Insects described in 1775 Taxa named by Johan Christian Fabricius