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In the present study, the distribution of phosphine gas in a cylindrical silo was modeled and compared with available sensor data. The cylindrical silo was filled with wheat and a recirculation system was used to enhance the diffusion of phosphine throughout the grain volume. A Computational Fluid Dynamics (CFD) model was developed with OpenFoam software, which accounted for gas transport in porous media and sorption effects of phosphine into the grain. A time-dependent source was used to model the phosphine release from Aluminum Phosphide bags. Furthermore, simulation results were obtained for insect mortality as a function of their exposure to phosphine gas. The phosphine concentration measurements were available from calibrated wireless sensors provided by Centaur Analytics, placed near the silo walls at various heights. As the agreement of phosphine measured data with the simulation results was satisfying, it led to considering that the proposed CFD model (equations, boundary conditions, grain properties, recirculation system approach, etc.) was accurate. Utilizing the capabilities of fumigation modeling, the phosphine concentration could then be determined for every location inside the storage volume and at any given time, thus a prediction method for fumigation duration and success could be enabled. Additionally, as the CFD model correlates phosphine exposure with insect mortality, a methodology for planning precision fumigations can now be established.

Simple Summary: This study explores the prevalence of phosphine resistance in stored-grain insects. The research, conducted in Greece, examined 53 key insect species and used two assessment protocols, namely, dose–response and CORESTA, to estimate phosphine resistance. The results showed that 13.3% of field populations were resistant, and mortality rates increased with higher phosphine concentrations. According to the dose–response protocol, 37.7% of field populations were found to be resistant, while all populations were susceptible according to the CORESTA protocol. The observed resistance patterns differ from those reported in other regions. The study emphasizes the importance of tailored fumigation strategies considering insect species' susceptibility to phosphine and recommends best management practices and rotational strategies to develop effective resistance management plans. The results offer valuable insights into the dynamic landscape of phosphine resistance in stored-product insects and suggest potential avenues for further research and control measures. Post-harvest losses due to insect infestation and spoilage by bacteria and molds pose significant challenges to global cereal production. This study investigates the prevalence of resistance to phosphine, a commonly used grain protection agent, in stored-grain insects. The research, conducted in various storage facilities across Greece, examined 53 populations of key stored-product insect species. Two assessment protocols, namely, dose–response (at 50–1000 ppm for 3 days exposure) and CORESTA (at 300 ppm for 6 days), were used herein to estimate phosphine resistance. The results showed that 13.3% of field populations were resistant, and mortality rates increased with higher phosphine concentrations. Specifically, according to the dose–response protocol, among the 53 field populations, 37.7% were found to be resistant to phosphine, namely, two populations of O. surinamensis, one of S. oryzae, seven of T. confusum, one of C. ferrugineus, one of T. castaneum, and all populations of R. dominica, whereas, according to the CORESTA protocol, all populations were found to be susceptible to phosphine. The observed resistance patterns differ from those reported in other regions of the world. The study highlights the importance of tailored fumigation strategies, considering insect species varying susceptibility to phosphine. It recommends the use of best management practices and rotational strategies, such as combining phosphine with other methods, to develop effective resistance management plans. The results provide valuable insights into the dynamic landscape of phosphine resistance in stored-product insects and suggest potential avenues for further research and control measures. [ABSTRACT FROM AUTHOR]

This study investigates air pollution dispersion in urban areas by means of Computational Fluid Dynamics (CFD). The commercial CFD software FLUENT was used to implement two different turbulence simulation methods (RANS and LES), in domains similar to complex urban environments. Particularly, different combinations of roof shapes were studied and simulation results of pollutant (ethane) concentrations were compared against experimental data. The building height (H) to the neighbour building distance (B) ratio was also taken into consideration. Previous studies showed that both RANS and LES models are accurate enough to predict pollutant concentrations fields inB/H = 1. In the present study the incapability of RANS models to predict accurately pollutant concentration inB/H = 0.5 for all roof shapes configurations is revealed. [ABSTRACT FROM PUBLISHER]