Male Cricket Fights

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I was doing some research on crickets today, specifically agonistic behaviour, so I dug out Tachon et al. (1999) to read up on them. It turns out fights in male crickets all follow the same pattern, starting off with gentle antennal touching. If a fight is decided on, the two crickets battle it out with their antennae (kind of like a thumbfight), eventually escalating into grappling with the mandibles. When this happens, they grab each other and headbutt, the stronger headbutter being the winner.

The last stage, the most violent one, doesn’t occur for mating; it’s only for defending territories, as Jang et al. (2008) show that non-territorial species don’t grapple, while territorial ones do. In fact, sexual competition is overall very low in crickets, according to a talk I heard a year or so ago. Being the biggest and most aggressive male cricket doesn’t grant you higher reproductive success, neither does having a high social status.

Also, in case you didn’t know, many crickets (and most other Ensifera, i.e. cricket relatives such as bushcrickets, mole crickets, wetas, etc.) can hear with their tibia (the last leg segment). Unrelated to the stuff above, but it’s a discussion on that ability that led to my sudden interest in their behaviour – it was an argument about whether this tibial organ is autapomorphic for the Ensifera, or whether it evolved multiple times convergently. Given how easy it is to build such a system (Boyan, 1993) and to lose it (Michel, 1980), I thought it best to look for evidence outside of morphology. (I say it’s apomorphic, but there is no conclusive evidence supporting either hypothesis, it can go both ways.)

My quest was a dead end. But at least I now know how male crickets fight (and so do you).

References:

Boyan GS. 1993. Another look at insect audition: The tympanic receptors as an evolutionary specialization of the chordotonal system. Journal of Insect Physiology 39, 187-200.

Jang Y, Gerhardt HC & Choe JC. 2008. A comparative study of aggressiveness in eastern North American field cricket species (genus Gryllus). Behavioral Ecology and Sociobiology 62, 1397-1407.

Michel K. 1980. Die Scolopalorgane in den atympanalen Tibien von Gryllus bimaculatus DE GEER und Phaeophilacris spectrum SAUSSURE (Gryllidae, Insecta). Zoologische Jahrbücher 103, 122-132.

Tachon G, Murray A-M, Gray DA & Cade WH. 1999. Agonistic Displays and the Benefits of Fighting in the Field Cricket, Gryllus bimaculatus. Journal of Insect Behavior 12, 533-543.