Miller Magazine Issue: 115 July 2019

78 ARTICLE MILLER / JULY 2019 improve sealing, before starting the actual application itself. This can be done through pressure tests that may reveal a leaky structure on which the application of nitrogen is useless. Second, in a chamber the tem- perature level can be easily controlled, as elevated temperatures greatly improve the insecticidal effect of nitrogen. Conversely, in the case of a silo with 1,500 t of grain, the temperature level cannot be controlled and any application should be carried out at the con- ditions prevailing. This consists a complicated pro- cedure, as the algorithms on which the application of nitrogen should be applied may change with the temporal change of temperature, providing different required exposure intervals each time. Third, a silo is very likely to have areas with “oxygen nests”, where the application is practically ineffective. Although the oxygen nest risk cannot be completely eliminated, sealing is the solution in this case as well. The pres- ence of area with oxygen that is high- er than 1 and often 3 %, can result in insect survival, that, despite stress, can lay eggs before death, causing additional quantitative losses. Real world applications Surprisingly, and despite the fact that the application of low oxygen has wide industrial applications in different types of food production facilities, the published data are dis- proportionally few, in comparison with other methods, such as heat, ozone or carbon dioxide. Relatively recently, in nitrogen chambers, Athanassiou et al. (2016) found that currants can be successfully treated with applications that are extremely short (less than one week), while the use of nitrogen resulted in the decrease of the pres- ence of molds. When the same technique was ap- plied or grains, it was found that there same efficacy levels could be obtained with a considerably higher exposure interval, that often exceeded three weeks (Navarro et al. 2012). In such an application, it is gen- erally considered that some internal feeders, such as the lesser grain borer, Rhyzopertha dominica (F. ) (Coleoptera: Bostrychidae) or the rice weevil, Sitophi- lus oryzae (L.) (Coleoptera: Curculionidae) are less susceptible than external feeders, such as the saw- toothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae). This is due to the fact that immature development of external feeders occurs outside of the kernel, resulting in increased suscep- tibility. Eggs and pupae have been found to be less susceptible than adults and larvae for both stored product beetles and moths (Athanassiou et al. 2016, Athanassiou and Arthur 2018). Continuous monitoring and early detection of possible failures con- sist the basis for the establishment of an effective and reliable low ox- ygen application strategy in silos. In chambers a few sensors may do the work accurately, but when it comes to large bulks in silos the number of sensors should be dras- tically increased to minimize the chances of having oxygen nests in the treated area. Apart from moni- toring of the percentage of oxygen Treating products in controlled atmosphere chambers (agrospecom.com) Monitoring nitrogen treatments through an online platform (centaur.ag )