The lesser grain borer (Rhyzopertha dominica F.) and the rice weevil (Sitophilus oryzae L.) are stored grain pests that cause significant economic losses in grain storage. This study aimed to analyze the impact of the chemical composition of wheat and barley grain (e.g., protein, fatty acids and total antioxidant capacity) on the development of two species of storage pests and to determine the relationship between the analyzed variables. The study involved the evaluation of 10 wheat cultivars and 10 barley cultivars under laboratory conditions. The observations included assessing the beetles’ progeny abundance, dust mass produced after feeding, and grain mass loss. The chemical composition of the tested wheat and barley cultivars was also determined, and the influence of different chemical compositions on insect development was investigated. The results of the experiment revealed diversity of resistance among cultivars to pest feeding. Larger populations of the lesser grain borer were observed on barley grains, while rice weevil populations were higher on wheat. Cultivars with higher protein and fat content were more susceptible to pest attacks. A connection between the amount of dust, grain mass loss, and the type of pest was also identified, indicating differences in feeding mechanisms and selective food preferences of these insects. The grain chemistry of wheat cultivars, including the content of fatty acids and antioxidants, significantly influenced the progeny abundance of S. oryzae, suggesting the potential of these components as natural barriers against storage pests. This study provides valuable insights for developing breeding strategies to enhance the natural resistance of new grain cultivars to these pests, contributing to the reduction of pesticide use. Statistical analyses confirmed the significance of differences in grain composition in varied resistance to the studied pests. The conclusions drawn from this work may help establish new storage and breeding practices, promoting sustainable agriculture and protecting natural resources.

The aim of this study conducted in 2018–2020 was to determine the effect of biostimulants and herbicide Avatar 293 ZC on the occurrence of external and internal defects and small tubers in the potato yield. The edible cultivars evaluated were Oberon and Malaga and the biostimulants used were: PlonoStart containing prolactic acid bacteria, actinomycetes (N-16.4%, K2O-0.75%, CaO-0.07%, MgO-0.02%, S-941 mg · kg−1), Aminoplant containing free amino acids-11.57%, organic matter-87.7% (N_total-9.48%, N_organic-9.2%, N-NH4- 0.88%, C_organic-25.0%), and Agro-Sorb Folium including total amino acids-13.11%, free amino acids-10.66% (N-2.2%, B-0.02%, Mn-0.05%, Zn-0.09%) with herbicides (clomazone and metribuzin): objects 3,4 and 5 and a single herbicide (object 2), as well as a control object (1). Before harvesting, tubers were collected from 10 randomly selected plants from each plot. The yield structure was determined in these samples - the weight share of tubers below 35 mm, 36–50, 51–60 and above 60 mm. Tubers with a diameter of less than 35 mm were classified as small, non-commercial tubers. Tubers with a diameter above 35 mm constituted the commercial fraction, in which external and internal defects were determined. The sum of tubers with defects and small tubers constituted side yield. The use of all biostimulants with herbicide significantly reduced: the share of tubers with defects, the share of small tubers in the yield and the total weight of small tubers and tubers with defects compared to the control plant. The best effects in reducing the occurrence of tubers with external and internal defects and small tubers were obtained by using the Agro-Sorb Folium and herbicide. Among the cultivars, Malaga cv. turned out to be more resistant to defects and the production of small tubers than the Oberon cv. In the literature, especially foreign, there are sporadic studies on the effect of biostimulants on the occurrence of defects in potato tubers.