Does saprophagy play a significant role in nutrition of Opatrum sabulosum (Coleoptera, Tenebrionidae)?

Significance of the saprophagous diet for Opatrum sabulosum (Linnaeus, 1761), which is a pest of cultivated crops such as sunflower and maize, is under consideration. Imagoes of that darkling beetle were kept in plastic containers on substrates of different types of soils and litters of natural ecosystems and agricultural lands with no access to plant food for 15 days. The control group were kept in cases with no substrate. Every day 720 specimens of the beetles were weighed. If there is no food the almost linear decrease in imago body weight was detected (the 15th day – up to 73.9% of the initial weight). Significant differences in the dynamics of weight loss of the beetles kept on the ordinary chernozem of different types and in cases without any substrate (control) were not found. By the 15th day of the experiment the significant changes of weight of O. sabulosum (L.) imago kept on soils taken from the fields sown with Helianthus annuus (L.), Zea mays (L.), Triticum durum (Dest.) and Brassica napus (L.) were also not registered. Keeping imagoes within 15 days on soils sown with Fagopyrum esculentum (Gilib.) and Beta vulgaris (L.) reduced the beetles’ body weight by 5.86% and 8.02% respectively, as compared to the control (probably due to pesticidal treatment of the crops). In the experiments with the litter of artificial forest plantations, the steppe litter (kaldan) and dead plant debris from the thalweg’s meadow the significant changes in the body weight were not registered. The beetles kept in containers with the litter (fragments of pine needles, grass and leaves of the black poplar) from the sandy alluvial soil significantly reduced the body weight by 6.28%, as compared to the control group. Thus, the body weight gain of O. sabulosum (L.) kept in containers with the plant remains from the studied four ecosystems is not registered. The research results showed that the detritophagy is not typical for that darkling beetle (or at least its role in their feeding is greatly exaggerated).