Data from: The metabolic costs of sexual signalling in the chirping katydid Plangia graminea (Serville) (Orthoptera: Tettigoniidae) are context dependent: cumulative costs add up fast

Katydids produce acoustic signals via stridulation which they use to attract conspecific females for mating. However, direct estimates of the metabolic costs of calling to date have produced diverse cost estimates and are limited to only a handful of insect species. In this study, we therefore investigated the metabolic cost of calling in a unstudied sub-Saharan katydid, Plangia graminea. Using wild-caught animals, we measured katydid metabolic rate using standard flow-through respirometry while simultaneously recording the number of calls produced. Overall, the metabolic rate during calling in P. graminea males was 59% higher than the resting metabolic rate (0.443±0.056 vs. 0.279±0.028 CO2 ml g−1 h−1) although highly variable among individuals. While individual call costs were relatively inexpensive (ranging from 0.02–5.4% increase in metabolic rate per call) the individuals with cheaper calls called more often and for longer than those with expensive calls resulting in the former group having significantly greater cumulative costs over a standard amount of time (9.5 h). The metabolic costs of calling are however context dependent since the amount of time spent calling greatly influenced these costs in our trials. A power law function described this relationship between cumulative cost and percentage increase per call (y=130.21x−1.068, R2=0.858); where y=cumulative cost, and x=percentage increase per call. The choice of metric employed for estimating energy costs (i.e. how costs are expressed) also affects the outcome and any interpretation of costs of sexual signalling. For example, the absolute, relative and cumulative metabolic costs of calling yield strongly divergent estimates and any fitness implications depend on the organism's energy budget and the potential trade-offs in allocation of resources that are made as a direct consequence of increased calling effort.

螽斯通过摩擦发音行为产生声学信号，用以吸引同种雌性完成交配。然而，目前针对鸣叫代谢成本的直接估算结果差异较大，且仅覆盖了极少数昆虫类群。因此本研究针对一种此前未被探索的撒哈拉以南螽斯物种*Plangia graminea*，探究其鸣叫行为的代谢成本。本研究采用野外捕获的个体，通过标准流式呼吸测热法测定螽斯的代谢速率，同时同步记录其鸣叫次数。整体而言，*Plangia graminea*雄性在鸣叫期间的代谢速率较静息代谢率提升59%（分别为0.443±0.056与0.279±0.028 mL CO₂·g⁻¹·h⁻¹），但个体间差异显著。尽管单次鸣叫的代谢成本相对较低（单次鸣叫仅使代谢速率提升0.02%~5.4%），但单次鸣叫成本较低的个体，其鸣叫频率更高、持续时长更长，因此在标准时长（9.5小时）内，该类个体的累计代谢成本显著更高。不过，鸣叫的代谢成本具有情境依赖性：本试验中，个体的总鸣叫时长对代谢成本影响显著。累计代谢成本与单次鸣叫代谢提升率之间的关系可通过幂律函数拟合：$y=130.21x^{-1.068}$，决定系数$R^2=0.858$，其中$y$为累计代谢成本，$x$为单次鸣叫代谢提升率。用于估算能量成本的指标选择（即成本的表达形式），同样会影响研究结果及性信号成本的解读。例如，鸣叫的绝对、相对与累计代谢成本的估算结果差异显著，而其适合度相关含义则取决于生物体的能量预算，以及因鸣叫投入增加而直接产生的资源分配潜在权衡。