The forthcoming European Union (EU) Fertilizing Products Regulation 1 proposes a claim-based definition of plant biostimulants, stipulating that “plant biostimulant” means a product stimulating plant nutrition processes independently of the product’s nutrient content, with the aim of improving one or more of the following characteristics of the plant: nutrient use efficiency, tolerance to abiotic stress, crop quality traits or availability of confined nutrients in the soil and rhizosphere. The future regulation also specifies that a plant biostimulant “shall have the effects that are claimed on the label for the plants specified thereon.” This creates an onus for manufacturers to demonstrate to regulators and customers that product claims are justified. Consequently, the justification of the agronomic claim of a given plant biostimulant will be an important element to allow it to be placed on the EU market once this new European regulation is applied. In this article, members of the European Biostimulant Industry Council (EBIC) propose some general guiding principles to follow when justifying plant biostimulant claims, that are outlined in this article. These principles are expected to be incorporated into harmonized European standards that are being developed by the European Committee for Standardization (CEN) to support the implementation of the regulation.

The free-living nematode Panagrellus redivivus is a suitable food source for first feeding fish. In the present report, a new method for the mass production of P. redivivus is presented. The technique involves multiplication of the nematode in monoxenic (single microorganism: Saccharomyces cerevisiae) solid culture (fluid media supported by 1- to 4-cm(3) sponge cubes) in autoclavable plastic bags (size range: 50 x 30 cm to 75 x 67 cm). Two growing media were tested: oat-meal medium (OM), which is an oat-based medium (16.7% oat-meal flour in 0.8% saline solution), and purified ingredient medium (PIM), a semi-synthetic medium (1.64% meat peptone, 0.94% yeast extract, 12.6% corn starch, 0.24% glucose, 1.48% sunflower oil, in 0.8% saline solution). The bags were inoculated with 350 nematodes/g medium. After an average period of 12 days (11-13 days) at 25 degrees C, the average yield (number of nematodes/g medium) was 241 x 10(3) for OM and 333 x 10(3) for PIM in 12-l bags (50 x 30 cm). The production scale has currently reached a bag volume of 50 l (75 x 67 cm); using PIM and the conditions described above, it was possible to harvest more than 1.3 x 10(9) nematodes/bag (291 x 10(3) nematodes/g medium). In PIM, when sun flower oil was replaced with the same amount of fish oil or cod liver oil, yields of 259 x 10(3) and 290 x 10(3) nematodes/g medium, respectively, were attained. The technology for mass production and formulation of P. redivivus should enable fish-hatchery operators to rely on a cheap, standardised, and permanently available live food product for first feeding fish larvae.

The free-living nematode Panagrellus redivivus has been recommended as a suitable food source for first-feeding fish.A new technology for mass production of P. redivivus enables fish hatchery operators to rely on an inexpensive, standardized and permanently available live food for first-feeding fish larvae. The proximate composition, and the fatty acid and amino acid profiles of nematodes mass produced on oat-based and purified ingredient media were determined. The quality of nematodes was significantly influenced by the culture medium used. The lipid content and fatty acid composition of nematodes could be modified by using lipid-enriched media.Mass-produced nematodes were tested on first-feeding common carp (Cyprinus carpio L.) and whitefish (Coregonus lavaretus) larvae. Carp larvae, grown on nematodes cultured on oat medium enriched with sunflower oil, showed a higher survival rate (87.1%) than the control group fed frozen zooplankton (82.9%) at the end of the 1-week feeding experiment. Differences in larval mass between the treatments disappeared after subsequent feeding of a dry diet for 2 weeks. Whitefish larvae can be reared exclusively on a dry diet; here, the initial feeding of nematodes had no effect on final biomass and survival of larvae.

The free‐living nematode Panagrellus redivivus was mass produced on a solid culture medium enriched with sunflower oil or fish oil by means of a new technology. Nematodes with different fatty acid compositions were obtained. A 7‐day experiment was performed in order to compare the lipid enriched nematodes with Artemia as live food for first feeding common carp (Cyprinus carpio L.) larvae. Larvae fed nematodes doubled their body mass and had a mean survival rate higher than 80%. No significant differences could be observed between the two groups fed nematodes. Fish larvae fed with Artemia showed almost no mortality and had a final body mass five times higher than larvae fed nematodes. It is concluded that mass produced nematodes are a promising food source for first feeding common carp larvae. However, further research is needed on the development of improved culture media to increase the nutritional value of P. redivivus.

Summary The use of Panagrellus redivivus as live feed for bighead carp and Asian catfish larvae was tested. In experiment 1, carp larvae were given Artemia nauplii (control) or Panagrellus twice daily for 21 days. A third treatment consisted of unfed larvae. The same three treatments were used in experiment 2 plus another with a commercial entomopathogenic nematode (EPN). Bighead carp larvae given Panagrellus in experiment 1 had much lower growth and survival than those fed Artemia nauplii. This could be due to low nematode density (5–30 mL−1 water) during feeding. The unfed larvae had 100% mortality by days 11–13. In experiment 2, growth and survival of carp larvae given Artemia nauplii (5–10 mL−1) and Panagrellus (50 mL−1) did not differ significantly (P > 0.05). All unfed larvae had died by day 13, while larvae fed EPN were all dead by day 8. Two experiments on Asian catfish were likewise conducted. In experiment 1, the catfish larvae were fed Tubifex (ad libitum), Panagrellus (50–100 mL−1 per feeding) orArtemia (5 nauplii mL−1 per feeding) three times daily for 14 days. In experiment 2, larvae were fed Artemia alone (10 nauplii mL−1 per feeding), Panagrellus alone (100 mL−1 per feeding), or their combination with a 38% protein dry diet twice daily. For both experiments, catfish larvae fed Panagrellus had significantly lower growth and survival than those fed Tubifex or Artemia. The combination of Panagrellus and dry diet created little improvement in the growth and survival of catfish larvae.