The effect of different growing substrates on the development and quality ofPhasmarhabditis hermaphrodita(Nematoda: Rhabditidae)

Abstract

The effect of different growing substrates on the development of the slug parasite Phasmarhabditis hermaphrodita has been studied in a series of laboratory experiments. Wild, laboratory and Nemaslug strains of P. hermaphrodita and their monoxenic counterparts with Moraxella osloensis (CCM 5605T) were reared on homogenised pig kidney, Deroceras reticulatum, Arion lusitanicus, and Galleria mellonella, the faeces of D. reticulatum and A. lusitanicus, or leaf compost. Development time, yield, lipid reserves and the body length of nematodes were assessed. All P. hermaphrodita strains were able to grow and reproduce on all tested substrates; however, yields were markedly higher on invertebrate media. Lipid content and body size varied across the substrates and strains. A uniform response of all nematode strains and the most dramatic differences among substrates were recorded in yields, which could indicate that the quality of the substrate is expressed mainly in yield. Monoxenized strains had higher yield, length, lipid content and shorter development time. In general, the strain differences between the observed parameters were most likely due to different bacterial associates. The dramatic differences in yields on invertebrate substrates, in comparison to the others, illustrate the evolutionary advantage of the association of nematodes with invertebrates.

Novelties in Pest Control by Entomopathogenic and Mollusc- Parasitic Nematodes

“…Parasitic nematodes react very strongly to all of them, not only to alive host. Of course it is not surprising statement, we know that P. hermaphrodita or other MPNs are able to complete their life cycles on slug faeces and other organic matter [41][42][43]. This type of behaviour provides the nematode also other advantage.…”

“…Unlike EPNs, some MPNs are able to complete their life cycles in different organic matter in the soil. Naturally, the quality of the growing substrate affects nematode development, however, unlike in EPNs, the quality of the growing substrate is mostly expressed in the yield of dauer juveniles and not in the quality of progeny [42]. On the other hand, in EPNs, the substrate quality influences both yield and quality of IJs [44,45].…”

“…As was mentioned in the previous subchapter, the only commercial product based on MPNs (P. hermaphrodita) is Nemaslug © (BASF). Experiments with other nematodes species as bioagents, for example, A. appendiculatum [42,79] and some other rhabditids [80] were already done, but the results and the potential of these nematodes for the use in bio-control are still questionable and too far from practical impact.…”

“…Negative effect on the earthworms Lumbricus terrestris and Eisenia foetida and others has never been found [134,135], and no effect was found also against insects Pterostichus melanarius, Zophobas morio or Galleria mellonella [136,137]. P. hermaphrodita is freely associated with many soil-dwelling bacteria [55,138], and some of them, for example, Stenotrophomonas maltophilia [42] can be occasionally dangerous for human, especially those with a weakened immunity system.…”

Phylogenetic evidence for the invasion of a commercialized European Phasmarhabditis hermaphrodita lineage into North America and New Zealand

“…A study by Rae et al showed that P. hermaphrodita, when grown on rotting slugs or emerging after parasitising slugs (D. reticulatum), had no evidence of M. osloensis being present [22]. Similarly, Nermut' et al found that P. hermaphrodita strain (DMG0001) lost M. osloensis after repeated culturing [51]. Therefore, it is perhaps not too surprising that wild isolated P. hermaphrodita from the US do not retain M. osloensis as there is little evidence to show this bacterium is vertically transmitted.…”