The role of predator-prey naïveté for the invasion success of lady beetles - A comparison of species interactions across two continents
Final Report Abstract
Predator-prey and predator-predator naïveté can contribute to the invasion success of non- native predators. Naïveté should occur if non-native predators have specific cues that are unknown to native interaction partners. To gain a better understanding of the underlying mechanisms of naïveté in insects, we examined the interactions between native and non- native ladybeetle species with aphids as native prey and ants as native predators. Experiments were conducted in Europe and North America to provide an intercontinental comparison of species-interactions. To test for predator-prey naïveté, we compared avoidance behavior of aphids towards chemical cues of native and non-native ladybeetles. Moreover, we quantified aphid consumption of ladybeetles to assess their voracity. Predator-predator naïveté of ants was tested in behavioral assays with native and non-native ladybeetle species by assessing ant aggression and ladybeetle reaction. Furthermore, we tested if chemical cues of ladybeetles play a role in ant aggression and analyzed their composition to see whether chemical cues are species-specific. Our findings showed that aphids avoid chemical cues of most native ladybeetle species. Moreover, aphids avoided chemical cues of the non-native Asian ladybeetle Harmonia axyridis in North America, but not in Europe. On both continents, H. axyridis and Coccinella septempunctata were the largest ladybeetle species and consumed the most aphids. In line with our expectations, we found weaker aggression of the native ant Lasius niger towards H. axyridis compared to most native European ladybeetle species. In North America, however, behavioral assays revealed contrasting patterns of ant aggression and ladybeetle reaction. The removal of chemical cues from ladybeetle elytra reduced ant aggression. We were able to restore natural levels of L. niger aggression by artificially applying ladybeetle cues on washed elytra. Furthermore, we found that cuticular chemical cues of ladybeetles are species-specific, which is a prerequisite for predator-prey naïveté. Lacking cue avoidance in aphids and reduced ant aggression likely contribute to the invasion success of H. axyridis in Europe. We suggest that cross continental differences in aphid and ant interactions with H. axyridis are due to differences in the invasion history of H. axyridis. Aphid avoidance behavior and ant aggression towards the Asian H. axyridis in North America might indicate rapid adaptation of native aphids and ants towards chemical cues of novel non-native ladybeetles. Interactions of aphids and ants with more recently introduced European ladybeetles in North America are comparable to congeneric native species possibly due to cue similarity. Overall, predator-prey and predator-predator naïveté advantages of non- native insect predators exist in early stages of the introduction but might diminish over time due to rapid adaptation or learning. In contrast, a relatively large body size compared to native competitors might continue to benefit non-native predators and contribute to their invasion success in the long term.
Publications
- (2018) Predation and avoidance behavior of the pea aphid Acyrthosiphon pisum towards native and invasive lady beetles in Europe. Book of abstracts, Annual meeting of the Ecological Society of America, New Orleans, USA
Ünlü, A.G., Terlau, J.F., Bucher, R.
- (2018) Predator-predator naivete contributes to the invasion success of the ladybeetle Harmonia axyridis in Europe. Book of abstracts, Annual meeting of the Ecological Society of America, New Orleans, USA
Bucher, R., Japke, L.M., Ünlü, A.G., Menzel, F.
- (2019) Comparison of predator-prey interactions between native and non-native lady beetles: similarities in predation rates but differences in cue recognition between European and North American populations. Book of abstracts, International symposium Ecology of Aphidophaga 14, Montreal, Canada
Ünlü, A.G., Bertleff, D., Diekmann, J., Brand, S., Obrycki, J.J., Bucher, R.
- (2020) Comparison of native and non-native predator consumption rates and prey avoidance behavior in North America and Europe. Ecology and Evolution, 10:13334−13344
Ünlü, A.G., Obrycki, J.J., Bucher, R.
(See online at https://doi.org/10.1002/ece3.6932) - (2020) Predation and avoidance behavior of the pea aphid Acyrthosiphon pisum confronted with native and invasive lady beetles in Europe. Biological Invasions, 22:1647−1656
Ünlü, A.G., Terlau, J.T., Bucher, R.
(See online at https://doi.org/10.1007/s10530-020-02209-5) - (2021) Predation and avoidance behavior in aphid-ladybird interactions of native and invasive ladybirds in Europe. Ecological Entomology, 46:41−47
Bertleff, D., Diekmann, J., Brand, S., Ünlü, A.G., Bucher, R.
(See online at https://doi.org/10.1111/een.12938)
