Dudová Pavla, Boukal David S, Klecka Jan
Czech Academy of Sciences, Biology Centre, Institute of Entomology, České Budějovice, Czech Republic.
Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.
PeerJ. 2019 Nov 5;7:e7881. doi: 10.7717/peerj.7881. eCollection 2019.
Despite a long tradition of research, our understanding of mechanisms driving prey selectivity in predatory insects is limited. According to optimal foraging theory, predators should prefer prey which provides the highest amount of energy per unit time. However, prey selectivity may also depend on previous diet and specific nutritional demands of the predator. From the long-term perspective, diet composition affects predator fitness. An open question is whether short-term selectivity of predators provides a diet which is optimal in the long-term. To shed more light on these issues, we conducted laboratory experiments on prey selectivity and its long-term consequences in larvae of the dragonfly . We conditioned the larvae to one of two prey types, the cladoceran and larvae of a non-biting midge sp., and then exposed them to various combinations of the two prey types. We found that dragonfly larvae conditioned to larvae consumed the same amount of , but significantly less larvae compared to dragonfly larvae conditioned to . However, there was no effect of previous diet on their success of capture and handling time, suggesting a limited role of learning in their ability to process prey. We then tested the long-term effects of diets with different proportions of both prey for survival and growth of the dragonfly larvae. Individuals fed -only diet had higher mortality and slower growth than dragonflies fed , while larvae fed a mixed diet had the highest survival and growth rate. In conclusion, we show that dragonfly larvae fed by larvae performed poorly and compensated by preferring when both prey types were available. The superiority of the mixed diet suggests that a diverse diet may be needed to satisfy nutritional demands in larvae. We demonstrate that merging short-term predation experiments with relevant data on predator fitness may provide better understanding of predator-prey interactions and conclude that detailed information on the (mis)matches between prey composition and predator nutritional demands is needed for further progress.
尽管有悠久的研究传统，但我们对捕食性昆虫猎物选择机制的理解仍然有限。根据最优觅食理论，捕食者应偏好每单位时间能提供最高能量的猎物。然而，猎物选择也可能取决于捕食者先前的饮食和特定的营养需求。从长期来看，饮食组成会影响捕食者的适应性。一个悬而未决的问题是，捕食者的短期选择是否能提供从长期来看最优的饮食。为了更清楚地了解这些问题，我们针对蜻蜓幼虫的猎物选择及其长期影响进行了实验室实验。我们将幼虫用两种猎物类型之一进行驯化，即枝角类动物和一种非叮咬蠓科（Chironomidae）幼虫，然后让它们接触这两种猎物类型的各种组合。我们发现，用枝角类动物幼虫驯化的蜻蜓幼虫消耗的枝角类动物数量相同，但与用非叮咬蠓科幼虫驯化的蜻蜓幼虫相比，消耗的非叮咬蠓科幼虫显著更少。然而，先前的饮食对它们的捕获成功率和处理时间没有影响，这表明学习在它们处理猎物的能力中作用有限。然后，我们测试了含有不同比例两种猎物的饮食对蜻蜓幼虫生存和生长的长期影响。只喂食枝角类动物的个体死亡率更高，生长速度比喂食非叮咬蠓科幼虫的蜻蜓慢，而喂食混合饮食的幼虫存活率和生长率最高。总之，我们表明，当两种猎物都存在时，以枝角类动物幼虫为食的蜻蜓幼虫表现不佳，并通过偏好非叮咬蠓科幼虫来进行补偿。混合饮食的优越性表明，可能需要多样化的饮食来满足蜻蜓幼虫的营养需求。我们证明，将短期捕食实验与捕食者适应性的相关数据相结合，可能有助于更好地理解捕食者与猎物之间的相互作用，并得出结论，为了取得进一步进展，需要有关猎物组成与捕食者营养需求之间（不）匹配的详细信息。
