Towards more intimacy: moderate elevation of temperature drives increases in foraging and mutualistic interactions between Lasius niger and Aphis fabae

Abstract

1. Climate change will likely affect the association between species interacting at different trophic levels. However, studies focusing on the impact of an elevation of temperature on ant-hemipteran mutualism remain scarce. 2. In the present study we investigated, in laboratory conditions, the foraging behaviour of the ant Lasius niger and its mutualistic interaction with the aphid Aphis fabae under three conditions of temperatures (i.e. 20 ∘ C, 23 ∘ C, and 26 ∘ C), as predicted by climatic scenarios. 3. Aphids were more mobile but as likely to release honeydew droplets at higher temperatures. As regards the ants, a moderate 3 ∘ C increase of temperature positively impacted their mutualistic interaction with aphids. Such reinforcement was achieved through an increase in the walking speed of ant foragers, in the number of mobilised ants as well as in the total amount of honeydew harvested by the colony. 4. A further elevation of temperature to 26 ∘ C reduced the benefits gained by the aphid-tending ants, in terms of lower amount of collected honeydew. 5. Based on our results, we hypothesise that, in temperate regions, a moderate increase of ambient atmospheric temperature by 3 ∘ C will benefit to the L. niger-A. fabae mutualistic interaction. A more marked elevation of 6 ∘ C may represent a threshold thermal value above which a switch of partners or a disruption of the interaction may occur under the temperatures predicted for the end of the century. These results demonstrate the fragility of mutualistic interactions, and more particularly their sensitivity to temperature increases predicted by realistic forecast models.

Becoming nose‐blind—Climate change impacts on chemical communication

“…Climate change will also beneficially impact the semiochemistry of aphid‐ant mutualism (Blanchard et al, 2019; Verheggen et al, 2012). Under elevated temperatures, ants walked more actively through an aphid colony, providing increased care and defence to their partners while receiving more honeydew in exchange (Blanchard et al, 2021). These studies illustrate the complex effects of increased temperature and CO 2 concentrations on multitrophic interactions and demonstrate the idiosyncratic characteristics of natural enemy responses (Boullis et al, 2015, 2016).…”

Invasive ant establishment, spread, and management with changing climate

“…Honeydew producers may benefit from intermittent drought due to increased nitrogen availability in phloem [48], which may reduce honeydew excreted per individual [49]. Elevated carbon dioxide and/or temperature affect population growth, behaviour, honeydew production, and chemical communication of sap-sucking insects sometimes to the benefit of the ants or their trophobionts, but often dependent on host plants, seasonal timing, ant attendance, or natural enemies [7, [50][51][52][53][54]. Phenological and spatial mismatches characteristic of lagged responses to warming are more likely between species that share an evolutionary history [5], but more work is required to understand its importance for mymrecophilous bugs and their host plants.…”

Heat shock protein 70 and Cathepsin B genes are involved in the thermal tolerance of Aphis gossypii

“…The global temperature is predicted to increase by 2-4 °C, and even up to 6 °C as the worst case scenario by the end of the 21st century. 1,2 As poikilotherms, such climate change poses a considerable environmental challenge for insects due to their limited ability to modulate body temperature. 3 Temperatures outside of their developmental thresholds can accelerate the developmental time, shorten longevity, and decrease fecundity of insects.…”

“…The global temperature is predicted to increase by 2–4 °C, and even up to 6 °C as the worst case scenario by the end of the 21st century 1,2 . As poikilotherms , such climate change poses a considerable environmental challenge for insects due to their limited ability to modulate body temperature 3 .…”