In this study, we evaluated wireless phosphine sensors to quantify and depict spatio-temporal dynamics and distribution of this gas within different types of facilities and commodities. The use of wireless sensors has certain advantages over the use of traditional monitoring techniques (e.g. tubes etc.), as any measurements with these traditional techniques correspond to the specific time and location of monitoring and are not transferable to additional intervals and locations, which leads fumigators to either overestimate or underestimate the concentrations and outcomes of a given fumigation. In fact, in light of our findings, the distribution of phosphine in large warehouses was not usually adequate for a satisfactory level of insect control, and gas concentrations varied remarkably through time and space. In contrast, commercial treatments at containers were sufficient to control the insects tested, even on stored-product insects which were found to be resistant to phosphine. Furthermore, in the case of silos and ship holds, our work indicated that the use of forced recirculation systems for phosphine is essential to increase concentration and, as a result, insect mortality. Overall, our tests clearly suggested that the sensors were very effective in measuring phosphine and are generally expected to play important role in the near future in IPM-based programs at the post-harvest stages of agricultural commodities. At the same time, real-time monitoring can be used with success for the prediction of insect mortality in the treated facilities.
