A temperate pollinator with high thermal tolerance is still susceptible to heat events predicted under future climate change. (2nd May 2018)

• Record Type: Journal Article
• Authors: Sutton, Timothy L.; DeGabriel, Jane L.; Riegler, Markus; Cook, James M.
• Is Part Of: Ecological entomology. Volume 43:Number 4(2018)
• Page Start: 506
• Page End: 512
• Publication Date: 2018-05-02
• Subjects: Climate change -- extreme heat -- Ficus rubiginosa -- fig wasp -- humidity -- mutualism -- pollinator; Insects -- Ecology -- Periodicals; Entomology -- Periodicals; 595.7
• DOI: 10.1111/een.12528
• Languages: English
• ISSNs: 0307-6946

Abstract

Abstract : 1. Mutualisms may be particularly vulnerable to climate change as interacting species are likely to respond differently, which could destabilise interactions. 2. Temperate zone insects typically experience mean temperatures below their thermal optima, making them less vulnerable than tropical insects to small increases in mean temperature. However, they are likely to experience a higher frequency of extreme heat events, putting mutualism persistence in jeopardy. 3. This study investigated the potential impacts of climate change on Pleistodontes imperialis, a temperate Australian fig wasp that pollinates Port Jackson figs ( Ficus rubiginosa ). Wasp emergence and longevity were measured at temperatures ranging from those commonly experienced in nature (25 °C) to high values (> 40 °C) that are currently infrequent, but which are becoming more common with climate change. 4. Wasp emergence was unaffected by temperatures up to 39 °C, but it declined drastically above 39 °C. Adult longevity was unaffected by temperatures up to 30 °C, but decreased at 35 °C and above. Low humidity reduced wasp longevity across all temperatures. 5. Fitness reductions were observed at temperatures ∼5 °C above the summer daily mean maximum, suggesting that P. imperialis has a high thermal tolerance, but is vulnerable to extreme heat. Figs located in the shade may provide protected microhabitats under hot conditions. 6. Tropical pollinators may be threatened by small increases in mean temperature. In contrast, it is shown here that temperate pollinators may face a different primary threat from climate change – the increasing frequency of extreme heat events – despite their higher thermal tolerances. Abstract : At temperatures well above local summer mean maxima, females of a temperate fig wasp species were less likely to emerge from figs and died sooner. They also died sooner under low humidity at both high and low temperatures. Figs located in shaded positions had cooler core temperatures than those in direct sunlight, and may provide protected microhabitats during extreme heat conditions. With climate change, temperate fig wasps may be more vulnerable to increasing frequencies of extreme temperature and humidity variation than to small increases in mean temperature.