Divergent thermal specialisation of two South African entomopathogenic nematodes
Date
2015-07-02
Journal Title
Journal ISSN
Volume Title
Publisher
PeerJ
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.
Description
CITATION: Hill, M. P., Malan, A. P. & Terblanche, J. S. 2015. Divergent thermal specialisation of two South African entomopathogenic nematodes. PeerJ, 3:e1023, doi:10.7717/peerj.1023.
The original publication is available at https://peerj.com
The original publication is available at https://peerj.com
Keywords
Entomopathogenic nematodes, Thermal tolerance, Acclimation, Biocontrol, Plasticity, Entomology, Parasitology
Citation
Hill, M. P., Malan, A. P. & Terblanche, J. S. 2015. Divergent thermal specialisation of two South African entomopathogenic nematodes. PeerJ, 3:e1023, doi:10.7717/peerj.1023.