Pachyrhynchus

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Pachyrhynchus
Pachyrhynchus tobafolius 21491380.jpg
Pachyrhynchus tobafolius
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Infraorder: Cucujiformia
Family: Curculionidae
Subfamily: Entiminae
Tribe: Pachyrhynchini
Genus: Pachyrhynchus
Billberg, 1820

Pachyrhynchus is a genus of weevils in the family Curculionidae. Most species are found on Southeast Asian islands. [1]

Contents

Description

Pachyrhynchus have aposematic coloration. They are flightless, with completely fused elytra. The eggs are inserted into plant tissues. The larvae will then develop and feed inside the stems of the host plants. [2]

The pattern of diversification in this genus suggests stepping-stone dispersal. It is hypothesized that these flightless insects disperse from one island to another by rafting on their host plants. This could be facilitated by the wood-boring life-style of the eggs and larvae, as well as the air cavity under the fused elytra that help adults to float. [1] However, experiments with Pachyrhynchus jitanasaius suggest that survival of adults in water—fresh, brackish, or marine—is low (most died within 12 hours, and no individual survived longer than 40 hours). On the other hand, the larvae living in Barringtonia asiatica fruit is higher, with a fraction of larvae surviving six days of sea water exposure and successfully emerging as adults. This suggests that the eggs and larvae are the primary dispersive stages in Pachyrhynchus. [1] [3] The coloration of the scales in multiple species is produced structurally, by means of photonic crystals (more strictly known as photonic band-gap materials within the biophysics literature); this has been the focus of multiple studies. [4] [5] [6]

Other research has shown that the eggs can survive digestion in certain birds, such as Hypsipetes leucocephalus and Turdus chrysolaus , which may be another explanation for the genus' successful dispersal. [7]

Species

Species include:

References

  1. 1 2 3 Yeh, Hui-Ying; Tseng, Hui-Yun; Lin, Chung-Ping; Liao, Chen-Pan; Hsu, Jung-Ya & Huang, Wen-San (2018). "Rafting on floating fruit is effective for oceanic dispersal of flightless weevils". Journal of Experimental Biology: jeb.190488. doi: 10.1242/jeb.190488 . PMID   30352828.
  2. Tseng, Hui-Yun; Huang, Wen-San; Jeng, Ming-Luen; Villanueva, Reagan Joseph T.; Nuñeza, Olga M. & Lin, Chung-Ping (2018) [2017]. "Complex inter-island colonization and peripatric founder speciation promote diversification of flightless Pachyrhynchus weevils in the Taiwan-Luzon volcanic belt". Journal of Biogeography. 45 (1): 89–100. doi:10.1111/jbi.13110.
  3. "How flightless beetles wander the Pacific". The Economist. 2018-11-01. Retrieved 28 November 2018.
  4. Parker, Andrew R.; Welch, Victoria L.; Driver, Dominique; Martini, Natalia (2003). "Opal Analogue Discovered in a Weevil". Nature. 426: 786–787.
  5. Welch, V. L. (2005). "2- Photonic Crystals in Biology". In Kinoshita & Yoshioka (ed.). Structural Colours in Biological Systems- Principles and Applications. Osaka University Press. ISBN   4-87259-195-X.
  6. Welch, V. L.; Lousse, V.; Deparis, O.; Parker, A.; Vigneron, J.- P. (2007). "Orange reflection from a three-dimensional photonic crystal in the scales of the weevil Pachyrrhynchus congestus pavonius (Curculionidae)". Physical Review E. 75 (4): 041919–041928.
  7. Lin, Si‐Min; Li, Tsui‐Wen; Liou, Chia‐Hsin; Amarga, Ace Kevin S.; Cabras, Analyn; Tseng, Hui‐Yun (2021-05-03). "Eggs survive through avian guts—A possible mechanism for transoceanic dispersal of flightless weevils". Ecology and Evolution. 11 (12). Wiley: 7132–7137. doi:10.1002/ece3.7630. ISSN   2045-7758. PMC   8216937 .