Data from: Multiple factors, including arena size, influence the functional responses of ladybird beetles

1. Functional response studies are often used to determine the suitability of predators as biocontrol agents. Ladybird beetles (Coleoptera: Coccinellidae) often are used for the control of crop pests such as aphids. However, most functional response studies on coccinellids compare a limited number of species at different life stages, temperatures, or sexes. A large-scale comparison of ladybird beetle functional responses is needed to evaluate the utility of these species as potential biocontrol predators and to understand the traits that influence the interaction strength between ladybird beetles and their prey. 2. We compiled 158 ladybird beetle functional responses from 30 studies and tested for effects of taxa, traits, temperature, and arena size on functional response parameters using linear mixed-effects models. 3. Our results show that functional response parameters (handling time and space clearance rate) are affected by predator stage, predator mass, prey type, temperature, and arena size. Although complicated by interaction terms, space clearance rate generally increased with predator size, temperature, and predator stage, while handling time decreased with predator size, temperature, and predator stage. Coleopteran prey induced the highest handling times. 4. Our results also show that experimental arena size has a large, consistent effect on space clearance rate. Arena size is more important in determining foraging rates at low prey densities than any other factor considered here, including predator mass and temperature. Efforts to use laboratory-based functional response experiments to evaluate the efficacy of biocontrol predators are therefore confounded by the choice of arena size. 5. Synthesis and applications. In addition to confirming known body mass and temperature effects, our study reveals previously unclear age-related effects and the importance of prey types, which can be used to optimize biocontrol programs. The arena size effect is unexpected and problematic because failure to account for arena size precludes accurate comparison of biocontrol predator effectiveness. We suggest managers and biocontrol practitioners re-evaluate the efficacy of candidate biocontrol predators, perhaps by statistically controlling for arena size to minimize the influence of this widely unconsidered factor on functional response estimates.

1. 功能反应（functional response）试验常被用于评估捕食者作为生防天敌（biocontrol agent）的适配性。瓢虫（鞘翅目Coleoptera: 瓢虫科Coccinellidae）常被用于防治蚜虫等作物害虫。然而，当前针对瓢虫科昆虫的功能反应研究，大多仅在不同龄期、温度或性别条件下，对比有限的物种。目前亟需开展大规模的瓢虫功能反应对比研究，以评估这些物种作为潜在生防捕食者的应用价值，并解析影响瓢虫与猎物间互作强度的关键性状。
2. 我们从30项已有研究中整合得到158组瓢虫功能反应数据，并采用线性混合效应模型（linear mixed-effects models），检验了类群、性状、温度及试验容器尺寸对功能反应参数的影响。
3. 研究结果显示，功能反应参数（包括处理时间（handling time）与空间清除率（space clearance rate））受捕食者龄期、捕食者体重、猎物类型、温度及试验容器尺寸的显著影响。尽管交互项使得分析结果更为复杂，但空间清除率总体上随捕食者体型、温度及捕食者龄期的升高而增大，而处理时间则随捕食者体型、温度及捕食者龄期的升高而缩短。当猎物为鞘翅目昆虫时，捕食者的处理时间最长。
4. 研究结果同时表明，试验容器尺寸对空间清除率具有显著且一致的影响。在猎物密度较低的条件下，试验容器尺寸对觅食速率（foraging rate）的决定作用强于本研究中考虑的其他所有因素，包括捕食者体重与温度。因此，若采用基于实验室的功能反应试验评估生防捕食者的防控效能，试验容器尺寸的选择会对试验结果产生干扰。
5. 综合与应用。本研究除验证了已知的体重与温度效应外，还揭示了此前尚不明确的龄期相关效应，以及猎物类型的重要性，这些发现可用于优化生防防控方案。试验容器尺寸的影响效应既出乎意料又颇具问题：若未考虑试验容器尺寸的作用，将无法准确对比不同生防捕食者的防控效能。我们建议管理者与生防从业者重新评估候选生防捕食者的防控效能，可通过统计学方法控制试验容器尺寸的影响，以最大限度降低这一广泛未被纳入考量的因素对功能反应评估结果的干扰。