## 4 Discussion
granaries_, and _S. zemnais_ are associated with the presence of fungi in the commodities that they infest, with certain fungal species acting, at least to a certain extent, synergistically for insect development [2; 23; 32]. Commodity played a pivotal role in the competition of closely related stored product species according to a series of previous publications with similar experimental protocols to the one tested here [3; 12; 13; 26; 33]. For instance, [PERSON] et al. [34] tested the population growth of _T. granarium_ and _T. variable_ in wheat and rice and found similar population dynamics in both commodities, with similar fluctuations according to the treatments tested,which is in agreement with the current results for _S. oryzae_ and _S. granarius_. While we have no data for the physicochemical properties of the varieties tested in the current experiments, we saw that both wheat and barley were able to provide a considerable population growth of both species in a relatively short interval. Both wheat and barley are highly preferred in _S. oryzae_ and _S. granarius_, while maize is typically infested via _S. oryzae_ and _S. zeamais_ but not that much via _S. granarius_[35; 36]. We saw that grain damage was higher on wheat or barley, with _S. oryzae_ and _S. granarius_ having been placed alone, respectively, which can be considered as a slight preference trend for the two commodities tested here. Nevertheless, there are cases where the type of commodity is determinative in the outcome of the competition of stored grain insects. For instance, [PERSON] and [PERSON] [9] found that _P. truncatus_ could develop well on maize but not wheat, where it was outcompeted via _R. dominaa_. Apparently, temperature is an extremely critical parameter in the population growth of stored product insects [10; 31]. As noted above, _S. granarius_ seems to perform better at 25 \({}^{\circ}\)C, where the effect of competition via the simultaneous presence of _S. oryzae_ can be drastically reduced. While the increase in temperature is expected to cause an increase in population growth, our results have shown that this may not be the case, as, in most of the combinations tested, there was no considerable increase in progeny production with the increase in temperature for any of the species tested. We hypothesize that the term \"temperature\" is likely to have a different meaning in confined areas with limited food availability, as in the case of the vials tested here, given that the only temperature level that was controlled was that of the incubator chamber and not the temperature inside the grain mass per se. Hence, the temperature level in the grain might have been increased due to the insect activity inside the vial, especially when insect numbers were high. Additional testing is needed to clarify this hypothesis, probably through temperature sensors that can be introduced within the vials. For the combinations tested here, it was clear that there was considerable competition between the two species and that _S. oryzae_ is more likely to be the superior competitor in this competition. We also consider that at longer incubation periods, and due to the turnover due to the overpopulation of the major competitor, _S. granarius_ can still develop well and continue to cause grain damage. Moreover, temperature seems to be critical for the progeny production of both species. At the same time, both species coexisted during the entire 120-day period tested, which underlines that, at least for that interval, both species can effectively utilize the same food source. Conceptualization, M.K.S. and C.G.A. ; methodology, M.K.S. and C.G.A. ; formal analysis, M.K.S. and G.T. ; investigation, M.K.S. and C.G.A. ; writing--original draft preparation, M.K.S. and C.G.A. ; writing--review and editing, M.K.S. and C.G.A. ; supervision, C.G.A. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable. Data Availability Statement: Data will be made available upon request.