Nematology (2016) 18, 367-376

Temesgen Addis, Nevena Mijuskovic, Olaf Strauch and Ralf-Udo Ehlers (2016)
Life history traits, liquid culture production and storage temperatures of Steinernema yirgalemense
Nematology 18 (3), 367-376
Abstract: Using the hanging drop technique with nematode growth gelrite medium, life history traits of Steinernema yirgalemense (strain Sy 157-C) were investigated at a bacterial density of 10 × 10⁹ cells ml^-1 of Xenorhabdus indica at 25°C. With the same technique, the exit of dauer juveniles (DJ) from the arrested stage (recovery) was assessed at 5 × 10⁹, 10 × 10⁹ and 20 × 10⁹ cells ml^-1 of X. indica. Additionally, S. yirgalemense was incubated in nematode liquid medium at 25, 27 and 30°C. At each culture temperature, DJ recovery, sex ratio at 3 days post DJ inoculation and DJ yield and DJ as a percentage of non-DJ stages at 15 days post DJ inoculation were assessed. DJ survival in Ringer's solution stored at 4, 15 and 25°C was assessed for 66 days. Steinernema yirgalemense has a total fertility rate and net reproductive rate of 487 and 314 offspring per female, respectively. The intrinsic rate of natural increase r m was 0.98 day^-1, population doubling time PDT = 0.71 days and mean generation time T = 5 . 72 days. The average lifespan of S. yirgalemense females starting from first-stage juveniles was 6.55 days. In liquid culture, DJ recovery ranged from 63-75% at 72 h post DJ inoculation and was not significantly different between the incubation temperatures. Parental male to female ratio was not influenced by incubation temperature and usually was at a ratio of 1:2. The percentage of females that entered into endotokia matricida at 72 h post DJ inoculation was 61% at 25°C, whereas at 27 and 30°C it was 24% and 0.5%, respectively. The highest DJ yield was recorded at 25°C (284 114 DJ ml^-1) followed by 27°C (176 932 DJ ml^-1) and the lowest at 30°C with 26 298 DJ ml^-1. At a storage temperature of 4°C, DJ survival did not exceed 42 days, whereas at 15 and 25°C more than 95% of the DJ survived 66 days. Although S. yirgalemense DJ survived for long periods at both 15 and 25°C in liquid storage, their survival in formulated product and virulence after storage needs further investigation.
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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:
rearing/culturing/mass production
formulation/storage of bioagents

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
Steinernema yirgalemense (entomopathogen)