Poekilocerus pictus

Poekilocerus pictus, the painted grasshopper, aak grasshopper or ak grasshopper, is a fairly large and brightly coloured species of grasshopper found in India, Pakistan and Afghanistan, especially in drier regions.[1][2][3] Both adults and nymphs are toxic; the nymphs are notorious for being able to squirt a jet of noxious liquid at up to around 30 cm (1 ft) away when grasped.[4][5]

Painted Grasshopper
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Orthoptera
Suborder: Caelifera
Family: Pyrgomorphidae
Subfamily: Pyrgomorphinae
Genus: Poekilocerus
Species:
P. pictus
Binomial name
Poekilocerus pictus
(Fabricius, 1775)
Synonyms
  • Poekilocerus sonnerati Serville, 1831
  • Poecilocerus tessellatus Bolívar, 1904

P. pictus was long regarded as the only Poekilocerus of the Indian subcontinent (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.[6]

Description
Nymph
Mating pair

Adults of P. pictus typically are 4.3–6.1 cm (1.7–2.4 in) long.[7] 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 with yellow spots, and pale red hind wings.[4][5]

Feeding and toxicity

Both adults and nymphs of P. pictus feed extensively on poisonous Calotropis milkweeds, notably C. gigantea and C. procera, gaining their own toxins from the plants.[4][5][7] When given the choice, both adults and nymphs tend to prefer C. procera over C. gigantea.[8] 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.[2][4][7][8] When nymphs mainly feed on other plants than Calotropis milkweeds, their development is not as fast,[4] but the first couple of instars tend to still prefer various weeds over Calotropis if given the choice.[3] The common name aak grasshopper or ak grasshopper is based on the local name of the main food plants, Calotropis gigantea and C. procera.[3][5][8] If starving, cannibalism is a regular occurrence.[8]

Upon slight pinching of the head or abdomen, the nymphs ejects liquid in a sharp and sudden jet, with a range of up to around 30 cm (1 ft) or more, from a dorsal opening between the first and second abdominal segments.[4][5] The discharge is directed towards the pinched area and may be repeated several times. The liquid is pale and milky, slightly viscous with an unpleasant smell and taste,[4][5] containing cardiac glycosides that the insect obtains from the plant it feeds upon.[9][10] 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.[5]

Research

P. pictus females produce a sex pheromone that is secreted from a thin sac-like gland in the metathoracic segment.[11]

P. pictus has an inducible chromosomal repair mechanism that acts in meiotic cells.[12]

References
  1. "species Poekilocerus pictus (Fabricius, 1775): Orthoptera Species File". orthoptera.speciesfile.org.
  2. Sultana, R.; et al. (2015). "Studies on the importance of common Calotropis procera (Asclepiadaceae) and close association of Poekilocerus pictus (Fabricus, 1775)". Pak. J. Entomol. 30 (2): 161–164. doi:10.26540/ijgsr.v9.i2.2022.219.
  3. Bhargava, R.N. (1995). "Ecobiology of the ak grasshopper (Poekilocerus pictus Fab.) in Indian desert". Rec. zool. Surv. India. 95 (1–2): 17–21.
  4. Sawant, Madhavi (May–Aug 2010). "Study of juvenile and adult growth, and behavioural characteristics of Poecilocerus pictus (Fabricius) feeding on Calotropis gigantea under laboratory conditions". Journal of the Bombay Natural History Society. 107 (2): 122–129. Archived from the original on 27 July 2014. Retrieved 25 July 2014.
  5. Hingston, M. R. W. G. (2009). "The Liquid-Squirting Habit of Oriental Grasshoppers". Transactions of the Royal Entomological Society of London. 75: 65–68. doi:10.1111/j.1365-2311.1927.tb00060.x.
  6. Gupta, S.K.; Chandra, K. (2016). "A new species of the Aak grasshopper genus Poekilocerus Serville, 1831 (Orthoptera: Pyrgomorphoidea) from India". International Journal of Global Science Research. 3 (6): 371–378.
  7. Husain, A.; Dube, A.K. (2022). "New record of Aak Grasshopper Poekilocerus pictus (Fabricius, 1775) (Orthoptera: Pyrgomorphidae) with a new host plant from Ashoknagar district, Madhya Pradesh (India)". International Journal of Global Science Research. 9 (2): 1892–1901. doi:10.26540/ijgsr.v9.i2.2022.219.
  8. Raziuddin, M.; Singh, S.H.; Sharma, A.; Singh, B.K. (1991). "Feeding habits of Poekilocerus pictus Fabricius (Acridoidea: Pyrgomorphidae)". Environment & Ecology. 9 (1): 100–102.
  9. Mathen, C; Hardikar, B (2010). "Cytotoxic compounds from Poecilocerus pictus feeding on Calotropis gigantea". Journal of Experimental Therapeutics & Oncology. 8 (3): 177–85. PMID 20734917.
  10. Wang, Z. N.; Wang, M. Y.; Mei, W. L.; Han, Z.; Dai, H. F. (2008). "A New Cytotoxic Pregnanone from Calotropis gigantea". Molecules. 13 (12): 3033–9. CiteSeerX 10.1.1.361.9898. doi:10.3390/molecules13123033. PMC 6244834. PMID 19052526.
  11. Gupta BD. Sex pheromone of Poecilocerus pictus (Fabricus) (acridoidea: pyrogomorphidae): I. Experimental identification and external morphology of the female sex pheromone gland. Biochem Exp Biol. 1978;14(2):143-8. PMID: 753373
  12. 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
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