Nematology (2010) 12, 711-720

John Mukuka, Olaf Strauch and Ralf-Udo Ehlers (2010)
Variability in desiccation tolerance among different strains of the entomopathogenic nematode Heterorhabditis bacteriophora
Nematology 12 (5), 711-720
Abstract: The shelf life of biological control products based on the entomopathogenic nematode Heterorhabditis bacteriophora is rather short. In order to prolong shelf life, the metabolism of nematodes during storage must be reduced. This can be achieved by means of desiccation of the infective third-stage dauer juveniles (DJ). The tolerance can be increased by an adaptation to moderate desiccation conditions. Previous investigations indicate that the heritability of the desiccation tolerance is high, justifying a genetic selection for enhanced tolerance. This investigation screened the desiccation tolerance of 43 strains of Heterorhabditis spp. and 18 hybrid/inbred strains of H. bacteriophora. Dehydrating conditions measured as water activity (aw values) were produced by treating DJ with different concentrations of the non-ionic polymer poly(ethylene glycol) 600. Significant inter-specific variation was recorded between nematode strains and species. The mean tolerated aw value (MW₅₀) ranged from 0.90 to 0.95 for non-adapted and 0.67 to 0.99 for adapted nematode populations. For selective breeding, only the 10% most tolerant individuals would be used. The lowest aw value tolerated by 10% of a population (MW₁₀) ranged from of 0.845 to 0.932 for non-adapted nematode populations and 0.603 to 0.950 for adapted nematode populations. Adaptation significantly increased the desiccation tolerance and a weak correlation was recorded for tolerance with and without adaptations. The most tolerant nematode strains will form the basis for the foundation of a parental stock produced by cross-breeding and following genetic selection for enhanced tolerance. Thus, this investigation is another milestone on the road to domestication of H. bacteriophora for commercial use in sustainable pest management.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Ralf-Udo Ehlers

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
formulation/storage of bioagents

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Heterorhabditis bacteriophora/Photorhabdus (entomopathogen)