Could Bryophagous Beetles (Coleoptera: Byrrhidae) Help Us Understand Bryophyte Taxonomy? Preferences within the Hypnum cupressiforme Hedw. Species Complex.

Intrataxonomic differences in terms of angiosperm suitability for herbivorous insects stem from variables such as plant structure, palatability, and chemistry. It has not yet been elucidated whether these differences also occur in terms of the bryophyte's suitability to bryophages. Hypnum cupressiforme Hedw. is a morphologically variable moss species frequently inhabited or fed by insects. In this investigation, we offered five morphotypes of H. cupressiforme to two bryophagous species of Byrrhidae (Coleoptera) to reveal whether the intrataxonomic variability affects beetles' preferences. The morphotypes were offered with preserved and removed spatial structures. There were no significant differences in morphotype preferences when spatial structures were preserved, although during the daytime, the beetles moved from the flat morphotype to the usual and turgid morphotypes. The beetles preferred the turgid morphotype when the spatial structures were removed. The results suggest that the spatial structure variations in the H. cupressiforme complex are accompanied by different chemical, physiological, or microscopic morphological profiles that are recognized by the bryophagous insects. Phylogenetic and epigenetic analyses can reveal multiple differences within the H. cupressiforme complex. Their interconnection with information about the preferences of bryophagous insects can help us to elucidate which of these differences are ecologically relevant.

Effect of Bacterial and Fungal Microbiota Removal on the Survival and Development of Bryophagous Beetles.

Insect microbiota may play a wide range of roles in host physiology. Among others, microbiota can be involved in diet processing or protection against pathogens, both of which are potentially important in bryophagous (moss-feeding) insects, which survive on extreme diets and live in the stable environment of moss clumps suitable for the growth of fungi and bacteria. We treated Cytilus sericeus (Forster, 1771) (Coleoptera: Byrrhidae) as a model organism with bactericides and fungicides to test the effect of bacterial and fungal removal on egg hatching and larval development. Furthermore, we supplied larvae with adult feces to determine whether feces is a source of beneficial microbiota or pathogens. Bactericides had a positive effect, but fungicides had a negative effect on beetle fitness, both of which manifested during egg hatching. The feces did not play a positive role. Our conclusions indicate the presence of beneficial fungal microbiota associated with eggs but not transmitted through feces. Based on preliminary cultivation and fungicide tests, Fusarium or Penicillium may be important for suppressing pathogens, but their exact role needs to be further studied.