The energetic costs of fighting in the house cricket, Acheta domesticus L

Abstract

The cost of performing an agonistic behavior, or tactic, will have consequences for an individual's rate of cost accrual, the tactic's evolutionary stability if used as an assessment signal, and its pattern of use in the behavioral choreography of a contest. Few studies have attempted to quantify the costs of fighting, particularly with regard to energy expenditure. Flow-through respirometry revealed that house cricket males can expend energy at relatively high rates when fighting (more than eight times resting levels) depending on the particular tactic performed. Acoustic signalling (stridulation) constituted the least costly of seven measured agonistic tactics, while wrestling with an opponent, the most energetically costly tactic, consumed oxygen at a net rate more than 40 times that of stridulation. Low-cost tactics are used by opponents more frequently than more costly tactics, providing evidence for an escalating tactical convention based on energetic costs. The moderate energetic cost of some tactics suggests they may function as reliable signals in the assessment of wrestling ability. Net energy costs per contest increased linearly with contest duration for both contest winners and losers, but winners tended to expend more energy per contest than losers. The likely fitness effects of energy expended while fighting are discussed. The results of this study indicate that energy expenditure is an important cost shaping contest strategies in Acheta domesticus