scholarly journals Divergent thermal specialisation of two South African entomopathogenic nematodes

2015 ◽  
Author(s):  
Matthew P Hill ◽  
Antoinette P Malan ◽  
John S Terblanche
Keyword(s):  
South African ◽  
Entomopathogenic Nematodes ◽  
Field Performance ◽  
Thermal Conditions ◽  
Nematode Species ◽  
Temperature Tolerance ◽  
Phenotypic Flexibility ◽  
Positive Effects ◽  
Thermal Limits ◽  
Low Temperature Tolerance

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.

scholarly journals Divergent thermal specialisation of two South African entomopathogenic nematodes

2015 ◽  
Author(s):  
Matthew P Hill ◽  
Antoinette P Malan ◽  
John S Terblanche
Keyword(s):  
South African ◽  
Entomopathogenic Nematodes ◽  
Field Performance ◽  
Thermal Conditions ◽  
Nematode Species ◽  
Temperature Tolerance ◽  
Phenotypic Flexibility ◽  
Positive Effects ◽  
Thermal Limits ◽  
Low Temperature Tolerance

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.

Diversity of entomopathogenic nematodes and their symbiotic bacteria in south African plantations and indigenous forests

Nematology ◽  
2018 ◽  
Vol 20 (4) ◽  
pp. 355-371 ◽  
Author(s):  
Birhan A. Abate ◽  
Bernard Slippers ◽  
Michael J. Wingfield ◽  
Antoinette P. Malan ◽  
Brett P. Hurley
Keyword(s):  
South Africa ◽  
South African ◽  
Dna Sequences ◽  
Entomopathogenic Nematodes ◽  
Nematode Species ◽  
Symbiotic Bacteria ◽  
Photorhabdus Luminescens ◽  
Time Analysis ◽  
Forestry Plantations ◽  
First Time

Summary The occurrence and diversity of entomopathogenic nematodes (EPN) and their symbiotic bacteria was evaluated in commercial forestry plantations (Eucalyptus spp., Pinus spp. and Acacia mearnsii) and indigenous forests in South Africa. EPN were most prevalent in A. mearnsii plantations, accounting for 60.7% of the isolates, while indigenous forests, plantations of Pinus spp. and Eucalyptus spp. accounted for 35.7, 3.6 and 0% of the isolates, respectively. DNA sequences of the internal transcribed spacer (ITS) and D2-D3 28S rDNA regions were used to identify the nematode species. Four Steinernema spp. were identified, including S. citrae, S. sacchari, two undescribed species, as well as Heterorhabditis bacteriophora and H. baujardi. Heterorhabditis baujardi is reported from South Africa for the first time. Analysis of 16S rRNA of the bacteria confirmed the presence of at least three Xenorhabdus species from Steinernema isolates and two subspecies of Photorhabdus luminescens from Heterorhabditis species.

scholarly journals The role of nitric oxide in priming-induced low-temperature tolerance in two genotypes of tomato

2013 ◽  
Vol 23 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Rayhaneh Amooaghaie ◽  
Khorshid Nikzad
Keyword(s):  
Nitric Oxide ◽  
Seed Germination ◽  
Low Temperature ◽  
Seedling Growth ◽  
Sugar Content ◽  
Temperature Tolerance ◽  
Seedling Vigour ◽  
Positive Effects ◽  
Low Temperature Tolerance ◽  
Root And Shoot Length

AbstractThe present study was conducted to evaluate the contribution of nitric oxide (NO) to the priming effects on seed germination, seedling vigour and low-temperature tolerance of two tomato cultivars (Solanum lycopersicum, cv. Cherry and Falcato) under four different constant temperatures (10, 15, 20 and 25°C). Treatments included priming in a polyethylene glycol 6000 (PEG 6000) solution (osmopriming) or presoaking in sodium nitroprusside (SNP) solution, a donor of NO, for 24 h at 25°C. Suboptimal temperatures reduced seed germination and subsequent seedling growth, as well as amylase activity, in both cultivars, but Falcato was more sensitive to low temperature than Cherry. Both osmopriming and SNP treatments enhanced germination capacity, germination index, seedling root and shoot length, α- and β-amylase activities and sugar content under suboptimal temperatures, especially in Falcato. We observed similarities between the modes of action of the two priming treatments. Both treatments increased seed NO content, whereas their positive effects on germination and subsequent seedling growth under low-temperature stress was reversed by the addition of methylene blue (MB), a scavenger of NO. This is the first report that suggests that positive effects of priming are most likely mediated through NO signalling.

scholarly journals Potential of in vivo- and in vitro-cultured entomopathogenic nematodes to infect Lobesia vanillana (Lepidoptera: Tortricidae) under laboratory conditions

2020 ◽  
Author(s):  
Francois du Preez ◽  
Antoinette Paula Malan ◽  
Pia Addison
Keyword(s):  
Research And Development ◽  
South African ◽  
Entomopathogenic Nematodes ◽  
Nematode Species ◽  
Significant Difference ◽  
Steinernema Yirgalemense ◽  
Laboratory Bioassays ◽  
Better Than

AbstractThe in vivo- and in vitro-cultured South African entomopathogenic nematodes (EPNs), Steinernema yirgalemense and Steinernema jeffreyense (Rhabditida: Steinernematidae), were evaluated against larvae and pupae of Lobesia vanillana in laboratory bioassays. For larvae, high mortality was observed for all treatments: In vitro-cultured S. yirgalemense (98%) performed better than S. jeffreyense (73%), while within in vivo cultures, there was no difference between nematode species (both 83%). No significant difference was detected between in vivo- and in vitro cultures of the same nematode species. The LD50 of the in vitro-cultured S. yirgalemense, the best performing species, was 7.33 nematodes per larva. Mortality by infection was established by dissecting cadavers and confirming the presence of nematodes, which was > 90% for all treatments. Within in vitro cultures, both S. yirgalemense and S. jeffreyense were able to produce a new cohort of infective juveniles from L. vanillana larvae. Pupae, however, were found to be considerably less susceptible to EPN infection. The relative success of local in vivo- and in vitro-cultured EPN species against a tortricid species in laboratory assays is encouraging for further research and development of this technology.

scholarly journals Potential of in vivo- and in vitro-cultured entomopathogenic nematodes to infect Lobesia vanillana (Lepidoptera: Tortricidae) under laboratory conditions

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0242645
Author(s):  
Francois du Preez ◽  
Antoinette Paula Malan ◽  
Pia Addison
Keyword(s):  
South African ◽  
Mass Culture ◽  
Entomopathogenic Nematodes ◽  
Insect Pests ◽  
Nematode Species ◽  
Commercial Application ◽  
Significant Difference ◽  
Steinernema Yirgalemense

Entomopathogenic nematodes (EPNs) have been successfully applied as biological control agents against above ground and soil stages of insect pests. However, for commercial application, it is crucial to mass culture these nematodes using in vitro liquid culture technology, as it is not attainable when using susceptible insects as hosts. Lobesia vanillana (Lepidoptera: Tortricidae) is regarded a sporadic pest of wine grapes in South Africa. The in vivo- and in vitro-cultured South African EPNs, Steinernema yirgalemense and Steinernema jeffreyense (Rhabditida: Steinernematidae), were evaluated against larvae and pupae of L. vanillana in laboratory bioassays. For larvae, high mortality was observed for all treatments: In vitro-cultured S. yirgalemense (98%) performed better than S. jeffreyense (73%), while within in vivo cultures, there was no difference between nematode species (both 83%). No significant difference was detected between in vivo- and in vitro cultures of the same nematode species. The LD50 of the in vitro-cultured S. yirgalemense, was 7.33 nematodes per larva. Mortality by infection was established by dissecting L. vanillana cadavers and confirming the presence of nematodes, which was > 90% for all treatments. Within in vitro cultures, both S. yirgalemense and S. jeffreyense were able to produce a new cohort of infective juveniles from L. vanillana larvae. Pupae, however, were found to be considerably less susceptible to EPN infection. This is the first study on the use of EPNs to control L. vanillana. The relative success of in vitro-cultured EPN species in laboratory assays, without any loss in pathogenicity, is encouraging for further research and development of this technology.

Bioinspired strengthening and toughening carbon nanotube@polyaniline/graphene film using electroactive biomass as glue for high rate, volumetric capacitance and low-temperature tolerance flexible supercapacitor

2021 ◽  
Author(s):  
Dan Wu ◽  
Chuying Yu ◽  
Wenbin Zhong
Keyword(s):  
Carbon Nanotube ◽  
High Performance ◽  
Graphene Film ◽  
Temperature Tolerance ◽  
High Rate ◽  
Flexible Supercapacitor ◽  
Low Temperature Tolerance ◽  
Electrical Devices ◽  
Brick And Mortar ◽  
Volumetric Capacitance

Natural nacre built up with brick-and-mortar architecture, exhibiting extraordinary strength and toughness, provides an inspiration to construct high-performance multifunctional film for flexible energy storage and portable electrical devices. In the...

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