Comparative assessment of heat tolerance in weevils associated with a fire-prone ecosystem

Javal Marion, Terblanche John S., Smit Chantelle, Haran Julien. 2023. Comparative assessment of heat tolerance in weevils associated with a fire-prone ecosystem. In : ECE 2023 - Books of abstracts. Heraklion : Hellenic Entomogical Society, Résumé, 87. European Congress of Entomology. XII, Heraklion, Grèce, 16 Septembre 2023/20 Septembre 2023.

Résumé : Fire is an important cause of disturbance that directly shapes many ecosystems worldwide, the frequency and intensity of which are expected to increase with climate change. While the effect of fire on floristic dynamics has been widely documented, little is known about how phytophagous insects respond when facing these disturbances. We explored the survival strategies of a set of sixteen weevil species with divergent lifestyles and geographic distribution in fire-prone ecosystems of the Cape Floristic Region (South Africa). More specifically, we investigated how the lifestyle of species correlated with heat tolerance. For instance, wingless species were hypothesized to show higher heat tolerance as they have a limited ability to escape fire and usually remain hidden in the soil. The thermal tolerance of the insects was first measured using a standard heat knockdown set-up. Thermo-limit respirometry was then performed on the most resistant species using a thermal ramping protocol. Our results show that weevils exhibit high variation in thermal tolerance across taxonomic groups. Species ecology better explains thermal tolerance than flight ability or the fire-proneness of ecosystems. Furthermore, some non-flying weevil species were found to be highly heat tolerant with CTmax values reaching up to 51.9°C. This study highlights the diversity of strategies developed by arthropods to escape extreme heat in fireprone ecosystems. Further work is necessary to examine the generality of these patterns across other fire-prone ecosystems to better understand behavioural compensation and evolutionary responses.

Mots-clés libres : Bogert effect, Fynbos, Heat knockdow, Thermolimit respirometry, Coleoptera

Auteurs et affiliations

• Javal Marion, Université de Montpellier (FRA)
• Terblanche John S., Stellenbosch University (ZAF)
• Smit Chantelle, Stellenbosch University (ZAF)
• Haran Julien, CIRAD-BIOS-UMR CBGP (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/606978/)

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