## 1 Introduction  
The family of Curculionidae includes very destructive species for stored cereals. The rice weevil, _Sitophilus oryzae_ (L.), and the granary weevil, _Sitophilus granarius_ ([PERSON]), as well as the maize weevil, _Sitophilus zeamais_ [PERSON], can particularly develop in different commodities, such as wheat, rice, barley, and maize [1, 2, 3]. Earlier works illustrated that there are cases where more than one species of the genus _Sitophilus_ coexist and co-infest the same commodity in different types of facilities and grains [2, 4]. The abundance of different primary and secondary pests, fungus feeders, parasitoids, and predators is a main part of stored product insect ecology in storage and processing facilities [5, 6, 7]. All these species can coexist and co-infest stored products in a dynamic succession of population fluctuations [8, 9]. In this context, the competition of different stored product insect species was studied using different biological characteristics, such as population growth and progeny production [10, 11, 12, 13, 14, 15, 16], in a changing micro-environment that is highly affected by a series of biotic and abiotic conditions, such as temperature, relative humidity, and commodity [2, 4, 16]. According to [PERSON] et al. [16], temperature and relative humidity can increase or decrease the abundance of a population of a given species and the concomitant damage to the commodity. For instance, adults of the large grain borer, _Prospelmus truncatus_ ([PERSON]) (Coleoptera: Bostyrchidae) can damage a higher number of maize kernels than the lesser grain borer, _Rhyzopertia dominica_ (F.) (Coleoptera: Bostyridae) at 25 and 30 \({}^{\circ}\)C and 55 and 75% relative humidity (RH) [16]. Competition is important among grain beetles as they share the same microenvironment for their development [8, 17, 18]. Regarding interspecific competition, there are numerous studies with stored product pests [12, 19, 20, 21, 22, 23, 24]. For example, [PERSON] et al. [23]examined the competition of _P. truncatus_ with _S. oryzae_ and found that _S. oryzae_ produced lower progeny than _P. truncatus_ at 26 and 30 \({}^{\circ}\)C. Moreover, [PERSON] et al. [21] noted that the khapra beetle, _Trogoderma granarium_ ([PERSON]) (Coleoptera: Dermestidae), could successfully compete with _S. oryzae_ and _R. dominica_ when temperatures exceeded 30 \({}^{\circ}\)C.  
Intraspecific competition may be more aggressive than that of species from different families [2; 9]. For instance, [PERSON] and [PERSON] [9] found that the yam beetle, _Dinatorus porcellus_ ([PERSON]) (Coleoptera: Bostrychidae), benefited from the presence of either _R. dominica_ and _P. truncatus_ in the same substrate. Moreover, [PERSON] et al. [2] tested the three _Sitophilus_ species on rice and maize and found that _S. oryzae_ produced higher numbers of emerged adults than the other species. There are studies that demonstrate the importance of the commodity type for the competitive ability of different stored product insects. [PERSON] et al. [2] found that commodity was important when three species of Bostrychidae were together in the same commodity. Furthermore, [PERSON] [25] reported that the competition between _S. oryzae_, the cigarette beetle, _Lasioderma serricorne_ ([PERSON]) (Coleoptera: Anobiidae), the red flour beetle, _Tribolium castaneum_ ([PERSON]) (Coleoptera: Tenebrionidae), and the rusty grain beetle, _Cryptolestes ferringineus_ ([PERSON]) (Coleoptera: Laemophloeidae), for 6 weeks at 30 \({}^{\circ}\)C on wheat and wheatfeed showed different interactions on the progeny production among the different food sources. More recently, [PERSON] and [PERSON] [9] studied the competition among the yam beetle, _Dinoderus porcellus_ ([PERSON]) (Coleoptera: Bostrychidae), _R. dominica_, and _P. truncatus_ and found at 25 and 30 \({}^{\circ}\)C on wheat and maize kernels that progeny production of _R. dominica_ was high on wheat in both temperatures and _P. truncatus_ was recorded with no progeny production on wheat but high on maize.