Unraveling the Significance of Draglines: Female Sexual Signalization in the Nursery-Web Spider, Pisaura mirabilis.

Chemical signals used by animals to attract the opposite sex are well known in insects, but heavily understudied in spiders. We investigated the role of chemical signals in female draglines in a gift-giving spider, Pisaura mirabilis, using combined data from behavioral tests and high-performance liquid chromatography (HPLC). We also investigated whether the quality of sexual signalization is influenced by crucial factors, such as female spider ontogeny, nutritional status, and mating status. We found that draglines of adult (versus subadult) and hungry (versus fed) females stimulated male motivation to produce nuptial gift, and highly sexually excited males invested more silk in gift production than less sexually excited males. Unexpectedly, chemical signals of eggsac-carrying females were similarly sexually attractive to draglines of adult females not carrying eggsac. HPLC identified significant chemical differences in female draglines, but these differences did not always correspond to male behavior. The integration of behavioral and chemical approaches is required to better understand animal behavior in future research.

Flower angle favors pollen export efficiency in the snowdrop Galanthus nivalis (Linnaeus, 1753) but not in the lesser celandine Ficaria verna (Huds, 1762).

Flower angle is crucially important for accurate pollination and flower protection against abiotic factors. Evolutionary factors shaping floral traits are particularly strong for bilaterally symmetric flowers because these flowers require more pollination accuracy than radially symmetrical flowers. We experimentally investigated the flower angle in the snowdrop's (Galanthus nivalis) radially symmetrical, early-blooming downward flowers. Bumblebees were able to gather significantly more pollen grains from downward flowers than from upward flowers, but female traits (fertility in the field) seem unaffected by flower angle. Similar experiments with radially symmetrical, later flowering Lesser celandine (Ficaria verna) upward flowers showed no differences in bees' abilities to gather pollen in upward vs downward-facing flowers. The downward angle of snowdrop flowers is an adaptation that increases the ability of insects to collect more pollen grains under unfavorable early spring weather conditions when pollinators are scarce.

Co-occurrence of airborne biological and anthropogenic pollutants in the central European urban ecosystem.

The interactions between organic and inorganic air pollutants, enhanced by the impact of weather parameters, may worsen the respiratory allergy symptoms in allergy sufferers. Pollen grains and fungal spores belong to some of the most crucial aeroallergens. Other allergenic bioparticles in the atmospheric microbiome can include microalgae, fern spores and mites. In this study, we evaluated if and to what extent air pollutants and weather parameters drive the daily variation in airborne concentrations of broad spectrum of bioparticles (pollen grains, fungal spores, microalgae, fern spores and invertebrates) in the air of Bratislava over 3 years, 2019-2021. Air samples were collected using a Hirst-type volumetric sampler. Based on the results of Spearman's correlation analysis, air temperature seems to be the most influential meteorological factor, positively associated with the concentration of all types of bioparticles at assemblage level, even though the association with microalgae was negative. Wind speed, known to have a diluting effect on most airborne particles, appears to be the most influential for microalgae, as their concentration in the air increases along with rising wind speed. Considering air pollutants, correlation analysis revealed that as the daily concentrations of ozone, PM10, CO and/or NO2 increased, so did the levels of most types of analysed bioaerosols at the assemblage level. Regarding that bioparticles may act as carriers for inorganic particles and amplify their allergenic impact, a concomitant increment in the airborne concentration of both organic and inorganic pollutants poses a threat to allergy sufferers in the study area. The concentration of microalgae, on the other hand, decreases with rising levels of CO, NO2 and PM10; thereby, their synergistic effect on allergy sufferers is negligible. Based on our findings, we suggest that the response of pollen and fungal spore concentration to environmental conditions should be investigated at the taxon, not the assemblage level, as each pollen/spore taxon has a different pattern in response to meteorological parameters and air pollutants.

Changes in Diversity and Structure of Thrips (Thysanoptera) Assemblages in the Spruce Forest Stands of High Tatra Mts. after a Windthrow Calamity.

Strong winds, fire, and subsequent forest management impact arthropod communities. We monitored the diversity and changes in the community structure of forest thrips assemblages in the context of secondary succession and anthropogenic impact. There were eight study plots that were affected to varying degrees by the mentioned disturbances that were selected in the Central European spruce (Picea abies (L.) Karst.) forests in Slovakia. The soil photoeclectors were used to obtain thrips in the study plots during two vegetation seasons. The thrips assemblages and their attributes were analyzed by non-metric multidimensional scaling (NMDS). The significant changes in community structure, composition, stratification, species richness, and diversity of thrips assemblages that were caused by natural- (wind) and human-induced disturbance (forestry and fire) were observed in our research. Our analyses revealed a clear relationship between different thrips assemblages and impacted environment. Moreover, our results indicate that silvicolous thrips species may be useful for indicating changes and disturbances in forest ecological systems.

Functional significance of flower orientation and green marks on tepals in the snowdrop Galanthus nivalis (Linnaeus, 1753).

Flower shapes, colors, sizes and fragrances are shaped mostly for pollinator attraction. Flower phenotypes are, however, subjected to conflicting selection directed by both pollinators and non-pollinating agents. We investigated flower attractiveness to a model pollinator in the snowdrop (Galanthus nivalis L.) under laboratory conditions. Naïve bumblebees (Bombus terrestris L.) showed strong, innate preferences for experimentally altered upward positioned flowers, suggesting that the natural, downward orientation did not evolve to attract pollinators. Experimentally treated green marks on inner tepals decreased pollinator attraction compared with flowers expressing intact marks, suggesting that green marks serve to guide/attract pollinators. Attractiveness of green marks was significantly compromised by flower orientation; green marks were attractive only for untreated downward-oriented flowers, but they did not improve the attractiveness of upward-oriented flowers. Our results suggest that downward flowers in snowdrop evolved under conflicting selection directed by biotic and abiotic factors, and that green marks on inner tepals could evolve later to enhance flower attractiveness.