How generalist insect herbivores respond to alien plants? The case of Aphis fabae-Myzus persicae-Rhododendron ponticum.

Background: The enemy release hypothesis (ERH) predicts that alien plant species are unsuitable hosts for native phytophagous insects. However, the biotic resistance hypothesis (BRH) predicts that generalist herbivores may prefer an alien plant over their common host plant. In this study, we have tested these two hypotheses by comparing the potential colonization of the invasive Pontic rhododendron (Rhododendron ponticum L.) versus the common rearing host plants by two generalist aphid species (Aphis fabae and Myzus persicae). We assessed (i) the probing behavior using the electrical penetration graph (EPG) technique and (ii) survival and fecundity in Petri dishes.

Results: The results showed the inability of A. fabae and Myzus persicae to immediately colonize R. ponticum. Despite their ability to feed on this invasive plant, the two aphid species hardly survived and poorly reproduced.

Conclusion: Our results are consistent with the ERH, since R. ponticum appeared as an unsuitable host for native phytophagous insects. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.