Critical thermal maxima and body size positively correlate in red imported fire ants,<i>Solenopsis invicta</i>

Wendt, Clara Frasconi; Verble-Pearson, Robin

doi:10.1894/0038-4909-61.1.79

Cited by 25 publications

(15 citation statements)

References 28 publications

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“…We found the mean S. invicta CT max (46.4 ± 0.1˚C) to be similar to that found in other studies: 50.6˚C [22] and 46.5˚C (for large workers [23]). The mean CT min for S. invicta ants in our study (6.8 ± 0.1˚C) was higher than that found in low-elevation ants collected by Bentley et al [22]: 4.1˚C.…”

Section: Plos Onesupporting

confidence: 91%

“…The difference may lie in research methodology. Moreover, we found no appreciable difference in thermal tolerance between the smallest (minors) and largest (majors) polymorphic workers, whereas the relationship between S. invicta size and thermal tolerance are mixed for other studies [22,23]. This suggests that there may be regional differences in how body size of S. invicta affects thermal tolerance, or that differences in research methodologies may affect cross-study comparisons.…”

Section: Plos Onecontrasting

confidence: 58%

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Invasion and high-elevation acclimation of the red imported fire ant, Solenopsis invicta, in the southern Blue Ridge Escarpment region of North America

2020

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The red imported fire ant (Solenopsis invicta) is a non-native invasive species that rapidly spread northward in the United States after its introduction from South America in the 1930s. Researchers predicted that the northward spread of this invasive ant would be limited by cold temperatures with increased latitude and greater elevation in the Blue Ridge Escarpment region of the United States. The presence of S. invicta at relatively high elevations north of their projected limits suggests greater cold tolerance than previously predicted; however, these populations might be ephemeral indications of strong dispersal abilities. In this study, we investigated potential physiological adaptations of S. invicta that would indicate acclimation to high elevation environments. We hypothesized that if S. invicta colonies can persist in colder climates than where they originated, we would find gradients in S. invicta worker cold tolerance along a montane elevational gradient. We also predicted that higher elevation S. invicta ants might incur greater physiological costs to persist in the colder climate, so we measured colony lipid content to assess health status. For comparison, we also collected physiological temperature tolerance data for the co-occurring dominant native woodland ant Aphaenogaster picea. We found that S. invicta occurring at higher elevations exhibited greater physiological tolerance for cold temperatures as compared to lower-elevation conspecifics-a cold tolerance pattern that paralleled of the native A. picea ants along the same gradient. Both S. invicta and A. picea similarly exhibited lower thermal tolerances for colder temperatures when moving up the elevational gradient, with A. picea consistently exhibiting a lower thermal tolerance overall. There was no change in S. invicta colony lipid content with elevation, suggesting that greater metabolic rates were not needed to sustain these ants at high elevations.

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Section: Plos Onesupporting

confidence: 91%

Section: Plos Onecontrasting

confidence: 58%

Invasion and high-elevation acclimation of the red imported fire ant, Solenopsis invicta, in the southern Blue Ridge Escarpment region of North America

2020

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“…In ants, Aphaenogaster iberica workers have been found to be larger at higher latitudes (Shik et al ., 2019). Furthermore, in a number of social insect species, researchers have observed a positive relationship between body size and heat tolerance, where larger workers were more heat resistant than smaller workers [ants (Cerdá & Retana, 1997, Cerdá & Retana, 2000, Clémencet et al ., 2010, Oberg, del Toro, & Pelini, 2012, Baudier et al ., 2015, Baudier & O'Donnell, 2016, 2017, Wendt & Verble‐Pearson, 2016); termites (Janowiecki et al ., 2019)].…”

Section: Morphological Adaptationsmentioning

confidence: 99%

Adaptations to thermal stress in social insects: recent advances and future directions

Perez

2020

Biological Reviews

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Thermal stress is a major driver of population declines and extinctions. Shifts in thermal regimes create new environmental conditions, leading to trait adaptation, population migration, and/or species extinction. Extensive research has examined thermal adaptations in terrestrial arthropods. However, little is known about social insects, despite their major role in ecosystems. It is only within the last few years that the adaptations of social insects to thermal stress have received attention. Herein, we discuss what is currently known about thermal tolerance and thermal adaptation in social insects – namely ants, termites, social bees, and social wasps. We describe the behavioural, morphological, physiological, and molecular adaptations that social insects have evolved to cope with thermal stress. We examine individual and collective responses to both temporary and persistent changes in thermal conditions and explore the extent to which individuals can exploit genetic variability to acclimatise. Finally, we consider the costs and benefits of sociality in the face of thermal stress, and we propose some future research directions that should advance our knowledge of individual and collective thermal adaptations in social insects.

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“…The Red Imported Fire Ant example, (Solenopsis invicta) with populations in Hong Kong introduced from the USA (Ascunce et al , 2011), is relevant to illustrate this,. The CT max of this species in the USA has been measured using slow ramping rate of 0.12 or 0.2 °Cmin −1 (Bentley, Hahn & Oi, 2016; Roeder, Roeder & Kaspari, 2018) or faster ramping rate 1.0 °Cmin −1 (Bentley, Hahn & Oi, 2016; Wendt & Verble-Pearson, 2016). Coincidently, our field observations on the fire ant activity (N = 1,398) corresponds to the thermal threshold observed for the fast ramping rate in both the USA and in Hong Kong (this study), with a difference of 0.71 °C on average, but not with those retrieved at slow ramping rate which are superior by 4.77 °C on average (FT max > CT max ).…”

Section: Discussionmentioning

confidence: 99%

Critical Thermal maximum measurements and its biological relevance: the case of ants

Leong

Tsang

Guénard

2020

Preprint

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Upper thermal limit (UTL) is a key trait in evaluating ectotherm fitness. Critical Thermal maximum CTmax, often used to characterize the UTL of an organism in laboratory setting, needs to be accurate to characterize this significant and field-relevant threshold. The lack of standardization in CTmax assays has, however, introduce methodological problems in its measurement and incorrect estimation of species upper thermal limit; with potential major implications on the use of CTmax in forecasting community dynamics under climate change. In this study we ask if a satisfactory ramping rate can be identified to produce accurate measures of CTmax for multiple species.We first identified the most commonly used ramping rates (i.e. 0.2, 0.5 and 1.0 °Cmin−1) based on a literature review, and determined the ramping rate effects on CTmax value measurements in 27 ant species (7 arboreal, 16 ground, 4 subterranean species) from eight subfamilies using both dynamic and static assays. In addition, we used field observations on multiple species foraging activity in function of ground temperatures to identify the most biologically relevant CTmax value to ultimately develop a standardized methodological approach.Integrating dynamic and static assays provided a powerful approach to identify a suitable ramping rate for the measurements of CTmax values in ants. Our results also showed that among the values tested the ramping rate of 1 °Cmin−1 is optimal, with convergent evidences from CTmax values measured in laboratory and from foraging thermal maximum measured in the field. Finally, we illustrate how methodological bias in terms of physiological trait measurements can also affect the detection of phylogenetic signal (Pagel’s λ and Bloomberg’s K) in subsequent analyses.Overall, this study presents a methodological framework allowing the identification of suitable and standardized ramping rates for the measurement of ant CTmax, which may be used for other ectotherms. Particular attention should be given to CTmax values retrieved from less suitable ramping rate, and the potential biases that functional trait based research may induce on topics such as global warming, habitat conversion or their impacts on analytical interpretations on phylogenetic conservatism.

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Critical thermal maxima and body size positively correlate in red imported fire ants,Solenopsis invicta

Cited by 25 publications

References 28 publications

Invasion and high-elevation acclimation of the red imported fire ant, Solenopsis invicta, in the southern Blue Ridge Escarpment region of North America

Invasion and high-elevation acclimation of the red imported fire ant, Solenopsis invicta, in the southern Blue Ridge Escarpment region of North America

Adaptations to thermal stress in social insects: recent advances and future directions

Critical Thermal maximum measurements and its biological relevance: the case of ants

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