Modeling the distribution of phosphine and insect mortality in cylindrical grain silos with Computational Fluid Dynamics: Validation with field trials

Abstract In the present work, the distribution of phosphine gas in six metal silos with wheat was modelled and compared with available distribution data from phosphine sensors. During the fumigation, a recirculation system was used to improve the diffusion of phosphine. Three different Scenarios of the recirculation system were used: (a) Scenario 1: the recirculation system was used for only 24 h in the beginning of the fumigation, (b) Scenario 2: the recirculation system was used for four consecutive days from the beginning of the fumigation and (c) Scenario 3: the recirculation system was used from the beggining of the fumigation for approximately 50 hours, the concentration reached over 300ppm and all sensors had gas equilibrium. In each silo, sensors were placed to monitor the concentration of phosphine, along with vials with phosphine-susceptible and -resistant insect populations. The insect species that were used were Rhyzopertha dominica and Oryzaephilus surinamensis. A Computational Fluid Dynamics (CFD) method was used for precision fumigation by using phosphine sensors with the OpenFoam software. Gas transport and sorption effects of phosphine into the grain was accounted through the CFD model. Simulation results were obtained for insect mortality as a function of their exposure to phosphine gas. CFD-based modelling was accurate in simulating and forecasting fumigation results and provided good predictions on each location inside the fumigated areas. Moreover, the fumigation applications resulted in complete control in all populations tested. The recirculation system improved the distribution of phosphine in the fumigated area. The most appropriate Scenario was Scenario 3, showing the least uneven distribution in the treated silo in contrast with the other two. These results indicated that CFD correlates well phosphine concentration with insect mortality and thus, a methodology for precision fumigation can be further established.

[1]  Reed,et al.  Loss of phosphine from unsealed bins of wheat at six combinations of grain temperature and grain moisture content. , 2000, Journal of stored products research.

[2]  Predicted gas loss of sulfuryl fluoride and methyl bromide during structural fumigation , 2008 .

[3]  Ashok K. Singh,et al.  A SOLUTION PROCEDURE FOR THE EQUATIONS THAT GOVERN THREE-DIMENSIONAL FREE CONVECTION IN BULK STORED GRAINS , 1993 .

[4]  J. Campbell,et al.  From immobilization to recovery: Towards the development of a rapid diagnostic indicator for phosphine resistance , 2019, Journal of Stored Products Research.

[5]  T. Phillips,et al.  United States Department of Agriculture-Agricultural Research Service stored-grain areawide integrated pest management program. , 2003, Pest management science.

[6]  Noel D.G. White,et al.  Investigation of 3D geometry of bulk wheat and pea pores using X-ray computed tomography images , 2008 .

[7]  T. Phillips,et al.  Managing resistance to chemical treatments in stored products pests , 2015 .

[8]  P. Agrafioti,et al.  Detection of phosphine resistance in major stored-product insects in Greece and evaluation of a field resistance test kit , 2019, Journal of Stored Products Research.

[9]  Akhlaq Ahmad,et al.  Monitoring of Resistance Against Phosphine in Stored Grain Insect Pests in Sindh , 2013 .

[10]  C. Athanassiou,et al.  Insecticidal efficacy of phosphine fumigation at low pressure against major stored-product insect species in a commercial dried fig processing facility , 2016 .

[11]  R. Kaur,et al.  Developing effective fumigation protocols to manage strongly phosphine-resistant Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae). , 2015, Pest management science.

[12]  P. Collins,et al.  Response of mixed-age cultures of phosphine-resistant and susceptible strains of lesser grain borer, Rhyzopertha dominica, to phosphine at a range of concentrations and exposure periods , 2005 .

[13]  Hervoika Pavic,et al.  Effect of phosphine dose on sorption in wheat. , 2008, Pest management science.

[14]  J. Darby,et al.  Modelling the kinetics of ethyl formate sorption by wheat using batch experiments. , 2009, Pest management science.

[15]  P. Ebert,et al.  Phosphine resistance in India is characterised by a dihydrolipoamide dehydrogenase variant that is otherwise unobserved in eukaryotes , 2015, Heredity.

[16]  P. Collins,et al.  Resistance to phosphine in Sitophilus oryzae in Australia: A national analysis of trends and frequencies over time and geographical spread , 2016 .

[17]  P. Ebert,et al.  Phosphine Resistance in the Rust Red Flour Beetle, Tribolium castaneum (Coleoptera: Tenebrionidae): Inheritance, Gene Interactions and Fitness Costs , 2012, PloS one.

[18]  Alien Arias Barreto,et al.  Analysis of storage conditions of a wheat silo-bag for different weather conditions by computer simulation , 2013 .

[19]  T. Phillips,et al.  Resistance of Lasioderma serricorne (Coleoptera: Anobiidae) to Fumigation with Phosphine , 2015, Journal of economic entomology.

[20]  C. H. Bell.  The tolerance of developmental stages of four stored product moths to phosphine , 1976 .

[21]  R. Winks.  The toxicity of phosphine to adults of Tribolium castaneum (Herbst): Time as a response factor , 1982 .

[22]  L. Faroni,et al.  Spread of phosphine resistance among brazilian populations of three species of stored product insects. , 2010, Neotropical entomology.

[23]  Hongyu Zhang,et al.  Phosphine resistance in Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) from different geographical populations in China , 2011 .

[24]  Hrvoje Jasak,et al.  A tensorial approach to computational continuum mechanics using object-oriented techniques , 1998 .

[25]  P. Collins,et al.  Optimising indoor phosphine fumigation of paddy rice bag-stacks under sheeting for control of resistant insects , 2006 .

[26]  François Garde,et al.  Sky temperature modelisation and applications in building simulation , 1998 .

[27]  Matthew W. Schramm,et al.  Developing and verifying a fumigant loss model for bulk stored grain to predict phosphine concentrations by taking into account fumigant leakage and sorption , 2018, Journal of Stored Products Research.

[28]  Graham R Thorpe,et al.  A solution procedure for three-dimensional free convective flow in peaked bulks of grain , 1993 .

[29]  M. Braby,et al.  Phosphine fumigations of wheat in 2500 m3 steel bins without recirculation facilities , 1996 .

[30]  R. Winks.  The toxicity of phosphine to adults of Tribolium castaneum (Herbst): Phosphine-induced narcosis , 1985 .

[31]  James A Darby.  A kinetic model of fumigant sorption by grain using batch experimental data. , 2008, Pest management science.

[32]  P. Collins,et al.  Strong resistance to phosphine in the rusty grain beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae): its characterisation, a rapid assay for diagnosis and its distribution in Australia. , 2013, Pest management science.

[33]  F. Arthur,et al.  Evaluation of Wireless Phosphine Sensors for Monitoring Fumigation Gas in Wheat Stored in Farm Bins , 2019, Insects.

[34]  D. Maier,et al.  Sensitivity analysis of a fumigant movement and loss model for bulk stored grain to predict effects of environmental conditions and operational variables on fumigation efficacy , 2018, Journal of Stored Products Research.

[35]  T. Phillips,et al.  Geographic Variation in Phosphine Resistance Among North American Populations of the Red Flour Beetle (Coleoptera: Tenebrionidae). , 2017, Journal of economic entomology.

[36]  Nicholas R. Price,et al.  Phosphine resistance in stored-product insects collected from various grain storage facilities in Morocco , 2004 .

[37]  T. Phillips,et al.  Phosphine Resistance in North American Field Populations of the Lesser Grain Borer, Rhyzopertha dominica (Coleoptera: Bostrichidae) , 2017, Journal of Economic Entomology.

[38]  Patrick J. Collins.  Research on stored product protection in Australia: a review of past, present and future directions. , 2010 .

[39]  Zhangxin Chen,et al.  Critical review of the impact of tortuosity on diffusion , 2007 .

[40]  C. H Bell,et al.  Fumigation in the 21st century , 2000 .

[41]  C. Athanassiou,et al.  Susceptibility of Two Strains of the Confused Flour Beetle (Coleoptera: Tenebrionidae) Following Phosphine Structural Mill Fumigation: Effects of Concentration, Temperature, and Flour Deposits , 2015, Journal of economic entomology.

[42]  Neil A. Kelson,et al.  Mathematical modelling and numerical simulation of phosphine flow during grain fumigation in leaky cylindrical silos , 2016, HiPC 2016.