Submitted to: Biotechnology and Bioengineering
Publication Type: Proceedings
Publication Acceptance Date: 9/16/2003
Publication Date: 2/12/2004
Citation: Fife, J.P., Derksen, R.C., Ozkan, H.E., Grewal, P.S., Chalmers, J.J., Krause, C.R. 2004. Evaluation of a Contraction Flow Field on Hydrodynamic Damage to Emtopathogenic Nematodes - A Biological Pest Control Agent. Biotechnology and Bioengineering. 86(1):96-107.
Technical Abstract: Delivering living organisms, such as entomopathogenic nematodes (EPNs), through a mechanical system involves risk of loss of viability due cause by forces and stresses produced within various components of the application device. The goal of this study was to evaluate the effect that flow through a contraction had on EPNs. The models developed assumed that EPNs followed streamlines with their bodies aligned with the flow. Experimental flow fields through representative nozzles were described using a computational fluid dynamics program. Bench-top investigations were carried out to evaluate the relative viability of different EPN species following delivery through relatively small agricultural nozzles. The type of damage observed varied between EPN species. The model results suggest that the fast-transient stress field generated at the entrance to the contraction caused tensile loading and then relaxation which, along the length of different EPN species, caused different forms of damage. The models were used to calculate energy dissipation rates. H. bacteriophora were damaged at lower average energy rates compared to H. megidis. It was also observed that significant damage was observed at lower energy dissipation rates S glaseri compared to S. carpocapsae. The relative elasticity of the EPN structural membrane may explain differences in relative viability observed between species. The relationship discovered between average energy dissipation and EPN damage shows how selection of delivery components could be evaluated to determine to estimate risk of damage to biological pest control agents and to aid in selection of components that will result in greater numbers of viability organisms.