Effect of different chemical properties of cereal grains on the foraging and microbiome of the rice weevil (Sitophilus oryzae L.)

Due to global warming, the rice weevil is an increasing threat. Various species of weevils coexist with endosymbiotic Sodalis pierantonius. This study aimed to check whether different chemical properties of different cultivars of common wheat and barley grain cause disturbances in insect feeding and rearrangements of the rice weevil microbiome. It has been observed that foraging increases in the case of cultivars with low protein content, high steric acid content, and low antioxidant activity. Cultivars with higher antioxidant activity, a tendency was observed to increase the number of adult insects and the intensity of feeding. However, the correlation of number of offspring generations and antioxidants was different depending on species of cereals (R2=0.9 for barley, R2<0.1 for wheat). Changes of dominance classes of selected Enterobacteriaceae partially shifted the microbiomes of insects feeding on different barley varieties. In contrast, in some wheat cultivars, displacement of the dominant genus Sodalis by genera Staphylococcus or Mammaliicoccus was observed, severely reducing the rice weevil's foraging ability. Nevertheless, Sodalis sp. almost always dominated (from 16.7 to 90.07% for wheat and from 63.4 to 90.9% for barley), and no correlation was observed between species and variety factors of cereals and their abundance.