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Research article - Peer-reviewed, 2023

The role of chemical cue similarity in interactions between ants and native versus non-native lady beetles in North America

Uenlue, Ayse Guel; Obrycki, John J.; Menzel, Florian; Bucher, Roman


While native species' interactions underlie coevolution, non-native species might benefit from their novel cues and a lack of recognition, resulting in potential competition advantages in interactions. In predator-predator interactions for example, non-native predators bearing novel cues might experience reduced interference. However, non-native predators might experience similar interference if their cues are similar to those of native predators, such as in congeneric species. Here, we studied aggressive re-sponses by ants towards several native and non-native lady beetles, and in turn compared the responses of these lady beetle species to ants. We expected strongest ant aggression towards coevolved native North American lady beetles, intermediate aggression towards non-native, congeneric lady beetles (due to potential cue similarities) and least aggression towards the non-native Harmonia axyridis. A similar ranking was expected for the lady beetle responses to ants. Furthermore, we analysed cuticular hydro-carbons (CHCs) of all lady beetle species and tested for similarities of CHCs between congeneric native and non-native species in the genera Coccinella and Hippodamia. Overall, similar ant aggression towards different lady beetle species could not be attributed only to cue similarities between them, suggesting that ants might additionally respond to different defensive traits of lady beetles. Surprisingly, we found CHC similarities not only between congeneric native and non-native lady beetles, but also between non-native H. axyridis and both Hippodamia species. Despite similar ant aggression, reaction behaviour of the native Coleomegilla maculata was relatively strong compared to that of non-native lady beetles, sug-gesting a low tolerance towards ant attacks. In particular, during times of food scarcity, non-native lady beetle species that are tolerated by ants might have an advantage over less-tolerated native lady beetles. Future field studies on ant-lady beetle-aphid interactions are required to shed light on ant tolerance and competitive advantages of non-native lady beetle species.& COPY; 2023 The Authors. Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY license ( by/4.0/).


ant aggression; chemical cue; Coccinellidae; intraguild interference; invasion

Published in

Animal Behaviour
2023, Volume: 203, pages: 21-28

      SLU Authors

    • Ünlü, Ayse Gül

    UKÄ Subject classification

    Behavioral Sciences Biology

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