Soldiers with large weapons behave aggressively against predators: correlated morphological and behavioral defensive traits in a eusocial aphid

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• 作者：M. Hattori ; O. Kishida ; T. Itino
• 关键词：Ceratovacuna japonica ; Prey–predator interaction ; Sociality ; Trait correlation
• 刊名：Insectes Sociaux
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：64
• 期：1
• 页码：39-44
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Entomology;
• 出版者：Springer International Publishing
• ISSN：1420-9098
• 卷排序：64

文摘

In social insects, intracaste variation suggests the existence of adaptive mechanisms such as polymorphism and polyphenism (i.e., subcastes) for maintaining the sophisticated social system. Here, we investigated intracaste variation patterns of a behavior (i.e., aggressiveness) and of morphology in the soldier caste of a eusocial aphid, Ceratovacuna japonica (Homoptera, Hormaphidinae). This species produces sterile individuals (soldiers), which have larger horns and forelegs than non-soldier reproductive individuals and which specialize in colony defense against predators. We previously showed that in midsummer, when predators are abundant, mother aphids produce soldiers with larger horns and forelegs than they do in early summer, when predators are few. However, the aggressiveness of C. japonica soldiers, another functional trait for colony defense, has not yet been quantified, and the relationship between the expression of this behavioral trait with that of the morphological traits has not yet been examined. Here, we experimentally showed that in midsummer soldiers behave more aggressively in response to artificial stimuli mimicking contact with a predator than they do in early summer. Furthermore, this variation correlated with the phenological variation of defensive morphology in soldier aphids. These results suggest that C. japonica defend their colony with not only strengthening soldier’s morphological weapon but also strengthening soldier’s aggressiveness when predator risk is high.