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Male Crickets With Bigger Heads Are Better Fighters, Study Reveals, Echoing Ancient Chinese Text

Date:
January 7, 2009
Source:
Public Library of Science
Summary:
Biologists show that male crickets with larger heads and mouthparts are more successful in fights with smaller-headed rivals.
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A male cricket showing the: a) dorsal view of the head capsule and pronotum, b) ventral view of the head capsule and pronotum (head has been tilted dorsally to expose ventral mouthparts), c) ventral view of the right and left maxillae, d) ventral view of the right and left mandibles, and e) left hind leg.
Credit: Drawings by Janice J. Ting. doi:10.1371/journal.pone.0003980.g001

Observing and betting on cricket fights has been part of Chinese cultural tradition since at least the Sung Dynasty (A.D. 960-1278). This ancient practice has resulted in quite a detailed list of characteristics that Chinese practitioners think make for champion fighters. "Because money was involved, there was a strong incentive for the practitioners of this sport to observe their cricket fighters closely," says Kevin Judge, a biology postdoctoral researcher at University of Toronto Mississauga.

Interestingly, an 800-year-old Chinese text mentions that the best cricket fighters have the largest heads. In nature, male field crickets fight one another over territories and access to potential mates by using their pointed and pincer-like mouthparts as weapons. Judge and co-author Vanessa Bonanno have shown that, indeed, males with larger heads and mouthparts are more successful in fights with smaller-headed rivals. They also show that male field crickets have larger heads and mouthparts than females, which, "makes sense given that female crickets don't fight over mates," says Judge.

Field crickets, a diverse group of insects distributed around the globe, have been important subjects for researchers interested in studying the evolution of animal aggression and the settlement of contests between individuals. For all that study, the influence of heads and mouthparts as weaponry has been largely overlooked in field crickets, unlike their close allies, the New Zealand weta, says Judge.

The study by Judge and Bonanno, "tested theories of contest settlement and sexual selection, and how body shape has evolved to help males in competition with other males," says Judge.

The researchers conducted two experiments to test the hypothesis that relatively larger weaponry conveys an advantage to males in aggressive contests. Pairs of males were selected for differences in head size and consequently were different in the size of maxillae and mandibles. In the first experiment, males were closely matched for body size (pronotum length), and in the second, they were matched for body mass. Males with proportionately larger weaponry won more fights and increasing differences in weaponry size between males increased the fighting success of the male with the larger weaponry.

By examining weaponry, this NSERC-funded study provides a new avenue by which researchers can understand aggression in field crickets.


Story Source:

The above post is reprinted from materials provided by Public Library of Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. Judge et al. Male Weaponry in a Fighting Cricket. PLoS ONE, 2008; 3 (12): e3980 DOI: 10.1371/journal.pone.0003980

Cite This Page:

Public Library of Science. "Male Crickets With Bigger Heads Are Better Fighters, Study Reveals, Echoing Ancient Chinese Text." ScienceDaily. ScienceDaily, 7 January 2009. <www.sciencedaily.com/releases/2009/01/090107092718.htm>.
Public Library of Science. (2009, January 7). Male Crickets With Bigger Heads Are Better Fighters, Study Reveals, Echoing Ancient Chinese Text. ScienceDaily. Retrieved August 2, 2015 from www.sciencedaily.com/releases/2009/01/090107092718.htm
Public Library of Science. "Male Crickets With Bigger Heads Are Better Fighters, Study Reveals, Echoing Ancient Chinese Text." ScienceDaily. www.sciencedaily.com/releases/2009/01/090107092718.htm (accessed August 2, 2015).

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