Limits...
Divergent thermal specialisation of two South African entomopathogenic nematodes.

Hill MP, Malan AP, Terblanche JS - PeerJ (2015)

Bottom Line: Acclimation had both negative and positive effects on temperature stress survival of both species, although the overall variation meant that many of these effects were non-significant.There was no indication of a consistent loss of plasticity with improved basal thermal tolerance for either species at upper lethal temperatures.At lower temperatures measured for H. zealandica, the 5 °C acclimation lowered survival until below -12.5 °C, where after it increased survival.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre of Excellence for Invasion Biology, Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University , South Africa.

ABSTRACT
Thermal physiology of entomopathogenic nematodes (EPN) is a critical aspect of field performance and fitness. Thermal limits for survival and activity, and the ability of these limits to adjust (i.e., show phenotypic flexibility) depending on recent thermal history, are generally poorly established, especially for non-model nematode species. Here we report the acute thermal limits for survival, and the thermal acclimation-related plasticity thereof for two key endemic South African EPN species, Steinernema yirgalemense and Heterorhabditis zealandica. Results including LT50 indicate S. yirgalemense (LT50 = 40.8 ± 0.3 °C) has greater high temperature tolerance than H. zealandica (LT50 = 36.7 ± 0.2 °C), but S. yirgalemense (LT50 = -2.4 ± 0 °C) has poorer low temperature tolerance in comparison to H. zealandica (LT50 = -9.7 ± 0.3 °C), suggesting these two EPN species occupy divergent thermal niches to one another. Acclimation had both negative and positive effects on temperature stress survival of both species, although the overall variation meant that many of these effects were non-significant. There was no indication of a consistent loss of plasticity with improved basal thermal tolerance for either species at upper lethal temperatures. At lower temperatures measured for H. zealandica, the 5 °C acclimation lowered survival until below -12.5 °C, where after it increased survival. Such results indicate that the thermal niche breadth of EPN species can differ significantly depending on recent thermal conditions, and should be characterized across a broad range of species to understand the evolution of thermal limits to performance and survival in this group.

No MeSH data available.


Related in: MedlinePlus

Acclimation and lethal thermal tolerances for two species of entomopathogenic nematodes, Heterorhabditis zealandica and Steinernema yirgalemense.Data represents both batches of experiments pooled together. Error bars reflect ±1 standard error, Survival measured between 0 (complete mortality) and 1 (complete survival). (A) Upper lethal temperatures and acclimation for Heterorhabditis zealandica. (B) Upper lethal temperatures and acclimation for Steinernema yirgalemense (C) Lower lethal temperatures and acclimation for Heterorhabditis zealandica. (D) Lower lethal temperatures and acclimation for Steinernema yirgalemense.
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fig-2: Acclimation and lethal thermal tolerances for two species of entomopathogenic nematodes, Heterorhabditis zealandica and Steinernema yirgalemense.Data represents both batches of experiments pooled together. Error bars reflect ±1 standard error, Survival measured between 0 (complete mortality) and 1 (complete survival). (A) Upper lethal temperatures and acclimation for Heterorhabditis zealandica. (B) Upper lethal temperatures and acclimation for Steinernema yirgalemense (C) Lower lethal temperatures and acclimation for Heterorhabditis zealandica. (D) Lower lethal temperatures and acclimation for Steinernema yirgalemense.

Mentions: For both species, acclimation of thermal limits in both species resulted in both negative and positive responses to experimental temperatures as seen in both lower and higher survival limits at different temperatures (Fig. 2). There was considerable variation between acclimation treatments, and the overall effect of acclimation and the interaction with temperature was non-significant (Table 3). For H. zealandica, ULT performance was increased by the 30 °C acclimation treatment, especially at the 39 °C test temperature, although this was not significant. There was no increase in survival at 41 °C test temperatures from any of the acclimation treatments. For S. yirgalemense, the 30 °C acclimation increased survival at 41 °C and even slightly at 43 °C, although this again was not significant.


Divergent thermal specialisation of two South African entomopathogenic nematodes.

Hill MP, Malan AP, Terblanche JS - PeerJ (2015)

Acclimation and lethal thermal tolerances for two species of entomopathogenic nematodes, Heterorhabditis zealandica and Steinernema yirgalemense.Data represents both batches of experiments pooled together. Error bars reflect ±1 standard error, Survival measured between 0 (complete mortality) and 1 (complete survival). (A) Upper lethal temperatures and acclimation for Heterorhabditis zealandica. (B) Upper lethal temperatures and acclimation for Steinernema yirgalemense (C) Lower lethal temperatures and acclimation for Heterorhabditis zealandica. (D) Lower lethal temperatures and acclimation for Steinernema yirgalemense.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493674&req=5

fig-2: Acclimation and lethal thermal tolerances for two species of entomopathogenic nematodes, Heterorhabditis zealandica and Steinernema yirgalemense.Data represents both batches of experiments pooled together. Error bars reflect ±1 standard error, Survival measured between 0 (complete mortality) and 1 (complete survival). (A) Upper lethal temperatures and acclimation for Heterorhabditis zealandica. (B) Upper lethal temperatures and acclimation for Steinernema yirgalemense (C) Lower lethal temperatures and acclimation for Heterorhabditis zealandica. (D) Lower lethal temperatures and acclimation for Steinernema yirgalemense.
Mentions: For both species, acclimation of thermal limits in both species resulted in both negative and positive responses to experimental temperatures as seen in both lower and higher survival limits at different temperatures (Fig. 2). There was considerable variation between acclimation treatments, and the overall effect of acclimation and the interaction with temperature was non-significant (Table 3). For H. zealandica, ULT performance was increased by the 30 °C acclimation treatment, especially at the 39 °C test temperature, although this was not significant. There was no increase in survival at 41 °C test temperatures from any of the acclimation treatments. For S. yirgalemense, the 30 °C acclimation increased survival at 41 °C and even slightly at 43 °C, although this again was not significant.

Bottom Line: Acclimation had both negative and positive effects on temperature stress survival of both species, although the overall variation meant that many of these effects were non-significant.There was no indication of a consistent loss of plasticity with improved basal thermal tolerance for either species at upper lethal temperatures.At lower temperatures measured for H. zealandica, the 5 °C acclimation lowered survival until below -12.5 °C, where after it increased survival.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre of Excellence for Invasion Biology, Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University , South Africa.

ABSTRACT
Thermal physiology of entomopathogenic nematodes (EPN) is a critical aspect of field performance and fitness. Thermal limits for survival and activity, and the ability of these limits to adjust (i.e., show phenotypic flexibility) depending on recent thermal history, are generally poorly established, especially for non-model nematode species. Here we report the acute thermal limits for survival, and the thermal acclimation-related plasticity thereof for two key endemic South African EPN species, Steinernema yirgalemense and Heterorhabditis zealandica. Results including LT50 indicate S. yirgalemense (LT50 = 40.8 ± 0.3 °C) has greater high temperature tolerance than H. zealandica (LT50 = 36.7 ± 0.2 °C), but S. yirgalemense (LT50 = -2.4 ± 0 °C) has poorer low temperature tolerance in comparison to H. zealandica (LT50 = -9.7 ± 0.3 °C), suggesting these two EPN species occupy divergent thermal niches to one another. Acclimation had both negative and positive effects on temperature stress survival of both species, although the overall variation meant that many of these effects were non-significant. There was no indication of a consistent loss of plasticity with improved basal thermal tolerance for either species at upper lethal temperatures. At lower temperatures measured for H. zealandica, the 5 °C acclimation lowered survival until below -12.5 °C, where after it increased survival. Such results indicate that the thermal niche breadth of EPN species can differ significantly depending on recent thermal conditions, and should be characterized across a broad range of species to understand the evolution of thermal limits to performance and survival in this group.

No MeSH data available.


Related in: MedlinePlus