Survival of Steinernema feltiae in different formulation substrates: Improved longevity in a mixture of gel and vermiculite

• Published in: Biological control 2018-11, Vol.126, p.192-197
• Main Authors: Leite, Luis G., Shapiro-Ilan, David I., Hazir, Selcuk
• Format: Article
• Language: English
• Subjects: Biological control; Entomopathogenic nematode; Infective juveniles; Preservation; Viability
• ISSN: 1049-9644; 1090-2112
• DOI: 10.1016/j.biocontrol.2018.05.013

[Display omitted] •Survival of Steinernema feltiae in different formulations was assessed.•The greatest survival at 35 °C and 25 °C was observed in peat and vermiculite.•At 15 °C the polyacrylamide gel and water treatments were superior.•The gel formulation held higher numbers of nematodes in the substrate.•A mixture of vermiculite + gel provided the best overall preservation. Entomopathogenic nematodes (EPNs) have been commercially produced as biopesticides, but nematode products still face significant barriers related to preservation and formulation. This study assessed the performance of seven different formulation substrates and two combinations involving vermiculite and gel, to preserve Steinernema feltiae at three temperatures: 15 °C, 25 °C and 35 °C. The first two experiments assessed the survival and mobility of S. feltiae infective juveniles (IJs) in mushroom compost (Hobin Wood Landscaping Products), peat (sphagnum peat moss), Potting mix (Metro Mix®), polyacrylamide gel, diatomaceous earth, vermiculite, and water (control). A third experiment assessed the survival of IJs in combinations of the two best substrates selected from the prior tests: vermiculite, polyacrylamide gel (1.33%), double polyacrylamide gel (2.66%), vermiculite + gel (1.33%), vermiculite + double gel (2.66%), and water (control). The greatest IJ fitness at 35 °C and 25 °C was observed in peat and vermiculite, respectively, and at 15 °C the gel and water treatments were superior. In general, vermiculite and polyacrylamide gel were the two best substrates considering that they provided the best results at 25 °C and 15 °C. The polyacrylamide gel formulation held higher numbers of nematodes in the substrate compared with the solid substrates. The mixture of vermiculite + double polyacrylamide gel provided the best preservation at 35 °C compared to the substrates tested separately. The combination of vermiculite with polyacrylamide gel preserves S. feltiae IJs with viability higher than 80% for at least 30 days at 35 °C, 233 days at 25 °C, and 241 days at 15 °C.