Abstract: As a result of climate change, temperate regions are facing the simultaneous increase in water and heat stress. These changes may affect the interactions between plants and pollinators, which will have an impact on entomophilous crop yields. Here, we investigated the consequences of high temperatures and water stress on plant growth, floral biology, flower-reward production, and insect visitation of five varieties of common buckwheat (Fagopyrum esculentum), an entomophilous crop of growing interest for sustainable agriculture. The plants were grown under two temperature regimes (21 °C/19 °C and 28 °C/26 °C, day/night) and two watering regimes (well-watered and water-stressed). Our results showed that the reproductive growth was more affected by drought and high temperatures than was the vegetative growth, and that combined stress had more detrimental effects. However, the impact of drought and high temperatures was variety-dependent. Drought and/or high temperatures reduced the number of open flowers per plant, as well as the floral resources (nectar and pollen), resulting in a decrease in pollinator visits, mainly under combined stress. Although the proportion of Hymenoptera visiting the flowers decreased with high temperatures, the proportion of Diptera remained stable. The insect visiting behavior was not strongly affected by drought and high temperatures. In conclusion, the modification of floral display and floral resources induced by abiotic stresses related to climate change alters plant–pollinator interactions in common buckwheat.

Abstract: Synopsis Plant–pollinator interactions are frequently affected by microbes that grow on flowers. Bacteria and yeast commonly grow within floral nectar, which is a sugar-rich floral reward often sought out by pollinators. Nectar is also commonly contaminated with protein-rich pollen. Microbes can induce this pollen to germinate or burst within the nectar, which potentially results in pollen nutrients being made available to nectar foraging pollinators. Yet whether pollen–microbe interactions in nectar impact pollinator behavior remains unknown. We therefore investigated how a common nectar yeast (Metschnikowia reukaufii) and bacteria (Acinetobacter nectaris) affected pollen germination and bursting within artificial nectar and effects on bumble bee (Bombus impatiens) foraging behavior. We found that both bacteria and yeast reduced the proportion of intact pollen in nectar, with bacteria inducing the most germination and bursting. Although microbes may thus potentially increase the quality of the nectar reward via increased access to pollen nutrients, we did not observe effects on bee flower preference. Similarly, bees did not show increased constancy (i.e., fidelity to one flower type across flower visits) to nectar contaminated with pollen and microbes. In contrast, bees were much more likely to reject flowers with nectar contaminated with pollen and yeast alone or together, relative to flowers that offered uncontaminated nectar. Altogether, our work suggests pollen–microbe interactions within nectar may have relatively minor influences on pollinator foraging behavior. We discuss possible explanations and implications of these results for plant and pollinator ecology.

Abstract: During plant fertilization, excess male gametes compete for a limited number of female gametes. The dormant male gametophyte, encapsulated in the pollen grain, consists of two sperm cells enclosed in a vegetative cell. After reaching the stigma of a compatible flower, quick and efficient germination of the vegetative cell to a tip-growing pollen tube is crucial to ensure fertilization success. Rho of Plants (ROP) signaling and their activating ROP Guanine Nucleotide Exchange Factors (ROPGEFs) are essential for initiating polar growth processes in multiple cell types. However, which ROPGEFs activate pollen germination is unknown. We investigated the role of ROPGEFs in initiating pollen germination and the required cell polarity establishment. Of the five pollen-expressed ROPGEFs, we found that GEF8, GEF9, and GEF12 are required for pollen germination and male fertilization success, as gef8;gef9;gef12 triple mutants showed almost complete loss of pollen germination in vitro and had a reduced allele transmission rate. Live-cell imaging and spatiotemporal analysis of subcellular protein distribution showed that GEF8, GEF9, and GEF11, but not GEF12, displayed transient polar protein accumulations at the future site of pollen germination minutes before pollen germination, demonstrating specific roles for GEF8 and GEF9 during the initiation of pollen germination. Furthermore, this novel GEF accumulation appears in a biphasic temporal manner and can shift its location laterally. We showed that the C-terminal domain of GEF8 and GEF9 confers their protein accumulation and demonstrated that GEFs locally activate ROPs and alter Ca 2+ levels, which is required for pollen tube germination. We demonstrated that not all GEFs act redundantly during pollen germination, and we described for the first time a polar domain with spatiotemporal flexibility, which is crucial for the de novo establishment of a polar growth domain within a cell and, thus, for pollen function and fertilization success.

Abstract: In this study, we applied the EMEP MSC-W chemical transport model, extended to include birch pollen emissions and dispersion, over Central Europe. Simulations were run for five consecutive birch pollen seasons (2015-2019), covering various concentration regimes (high, low or moderate seasons). Model predictions were compared to observational data from 12 stations located across Poland. The model consistently predicted earlier start and end dates for the pollen season compared to observations, and generally underestimated pollen concentrations and seasonal pollen integrals (SPIn), especially during high-concentration seasons. A sensitivity analysis was conducted for two selected years (2018 and 2019), adjusting key parameters such as total pollen amount, season length in degree-days, and the heat-sum threshold for season onset. Results showed that modifying the total pollen amount proportionally increased concentrations, while extending the season length tended to decrease early season concentrations, and increase late season concentrations, simultaneously delaying the end of the season. Adjusting the heat-sum threshold for the season start delayed the season, impacting its overall characteristics. Modifying these parameters improved model accuracy, particularly in predicting season onset, which was critical for accurately simulating the temporal dynamics of the pollen season.

Abstract: This study analyzes the behavior of airborne pollen in relation to meteorological parameters. It may be helpful to understand the consequences of this interaction on the health of the population of Madrid in the form of respiratory allergic pathologies. To this end, a multivariate analysis was carried out using Spearman’s linear correlation coefficient between the concentrations in the Madrid atmosphere of six types of tree pollen (Cupressaceae, Olea, Platanus, Pinus, Ulmus and Populus) and each of the six meteorological variables: relative humidity, precipitation, temperature, wind, radiation and insolation. The meteorological parameters most correlated with pollen types, with monthly values, are temperature and insolation, followed by radiation and relative humidity. In addition, there are more significant correlations of meteorological variables with Cupressaceae, Olea, Pinus and Platanus pollen types. Radiation is the meteorological parameter with the highest ρ values, especially with Olea, with ρ > 0.8. Wind is the only variable with significant correlations, all of them positive, with pollen types. The number of statistically significant results obtained from daily values is lower compared to monthly values, and only with Populus, Cupressaceae and Olea. The inter-relationship of meteorological variables with pollen grains can lead to an increase in the number of cases of pollinosis, when there are significant positive correlations.

Abstract: ABSTRACT Accurate pollen collection is essential for understanding bumble bee foraging dynamics, assessing environmental risks and monitoring colony health. Effective monitoring systems provide critical insights into pesticide exposure, floral resource availability and pollinator health. This study compares the efficiency of two pollen trap designs, the newly developed JKI trap and the USDA 3D‐printed trap, in collecting pollen from Bombus terrestris colonies. Field tests using traps with two entrance diameters (6.5 and 7.2 mm) showed that the JKI trap collected significantly more pollen than the USDA trap, with the statistical model predicting approximately 24 times higher yields ( p < 0.001); no significant effect of entrance diameter on pollen yield was observed. The JKI trap's effective performance, coupled with its design flexibility and potential for adaptation across different Bombus species and pollinators, makes it a valuable tool for long‐term ecological monitoring, floral resource assessments, and pesticide risk studies.

Abstract: Abstract Background Pollination strategies to supplement or replace insect pollinators are needed to produce marketable strawberry fruits in indoor vertical farms. To ensure the self-pollination of strawberry flowers, anther dehiscence, and pollen attachment were investigated under different vapor pressure deficit (VPD) conditions and external mechanical wave vibrations. Results The proportion of dehisced anthers was examined under VPDs of 2.06, 1.58, and 0.33 kPa, and the projected area of pollen clumps was assessed under VPDs of 2.06 and 0.33 kPa. After exposing flowers to a VPD of 2.06 kPa, vibrations with various frequency (Hz) and root mean square acceleration (m s −2 ) combinations were used to evaluate pollination effectiveness. The anthers underwent complete dehiscence at VPDs of 2.06, 1.58, and 0.33 kPa. The pollen clump ejection index was highest at a VPD of 2.06 kPa. Pollen clump detachment was effective at 800 Hz with 40 m s −2 , while pollen attachment to the stigma was most effective at 100 Hz with 30 and 40 m s −2 . Conclusions These findings demonstrate that high VPD promotes anther dehiscence timing and facilitates pollen clump formation, while specific vibration frequencies with high acceleration optimize pollen detachment and stigma attachment, offering an effective strategy for controlled strawberry pollination in vertical farming.

Abstract: Although understanding the relationship between the reproductive mode and mass-dispersal potential of plants is crucial for studying invasion phenomena, the morphological features of invasive species’ pollen are not well understood. This study examined the pollen morphology and variability of three Reynoutria (knotweed) taxa ( R. japonica , R. sachalinensis , R. × bohemica) invasive in Europe, and their reaction to different habitat conditions within seven distinguished habitat types. The pollen was sourced from 95 sites from the taxa’s invasive range in Central Europe. In total, 2850 pollen grains were measured and analysed for 11 quantitative and qualitative features. The pollen of R. sachalinensis was distinguished from that of the other two taxa (reticulate perforate) based on its rugulate and fossulate perforate exine ornamentation. The pollen’s response to various habitat conditions, which was most marked in R. × bohemica, was reflected by pollen size and exine thickness. Our research indicates that pollen availability is not a limiting factor for the sexual reproduction of knotweeds in Central Europe, including Reynoutria japonica , long considered male sterile. The observed presence of male-fertile specimens of R. japonica may enhance the efficiency of generative reproduction in this species throughout its invaded ranges. This finding should be considered when planning actions to control the population of these transformer plant species.

Abstract: (Uploaded by Plazi from the Biodiversity Heritage Library) No abstract provided.

Abstract: Agricultural management significantly affects insects, especially pollinators, which are crucial for crop pollination and biodiversity. In agricultural landscapes, various factors spanning different spatial scales are known to affect pollinator health, which, in turn, can influence pollination services. However, the importance of these factors in driving the health and performance of different pollinator groups remains unclear. Using a long-term biodiversity research platform, the German Biodiversity Exploratories, we investigated links between local and landscape-level land-use, health and pollination services in common pollinators, the bumblebee Bombus lapidarius and the syrphid fly Episyrphus balteatus, by measuring various traits as proxies for pollinator health and pollination services. Because of their different life histories, we expected the territorial bumblebees to be more vulnerable to land-use intensification at both spatial levels, compared with the migratory syrphid flies. Both land-use and environmental factors (climate) across spatial scales affected pollinator health, mostly via changes in body size: High land-use intensity reduced bumblebee body size, whereas higher ambient air temperature decreased syrphid fly body size. Increasing proportions of intensively managed areas at the landscape level decreased viral infections in both species. Additionally, landscape-level land-use and climate changed the bumblebees cuticular chemical profile, which is essential for communication in these social insects. Increasing land-use intensity at the local level and higher proportions of intensive land-use at the landscape level both had an indirect negative effect on pollination services in bumblebees via local flower cover and body size. Pollination services in both species were linked to body size. Thus, land-use factors affect pollinator health differently: bumblebees are more vulnerable to local and landscape-level land-use intensification, while syrphid flies are more resilient potentially due to their higher mobility. As pollinator health affects pollination services, our results indicate that land-use intensification poses a high risk to crops pollinated by species with small home ranges.

Abstract: Development, reproduction, and life table parameters of the predatory mite Euseius scutalis (Athias-Henriot), fed on cattail pollen (Typha latifolia L.), were studied at constant temperatures ranging from 15 to 40 °C under laboratory conditions. The pre-imaginal developmental time of females decreased from 24.75 days at 15 °C to 4.06 days at 35 °C, then increased to 4.13 days at 40 °C. An average of 91.51 degree-days was required for E. scutalis females to complete development above the lower threshold temperature of 10.72 °C. Juvenile mortality rates were 58%, 2%, 8%, 2%, 18%, and 65% at 15, 20, 25, 30, 35, and 40 °C, respectively. Females of E. scutalis oviposited an average of 0.00, 10.48, 18.31, 16.19, 4.21, and 3.13 eggs at 15, 20, 25, 30, 35, and 40 °C, respectively, and had a mean longevity of 16.60, 18.31, 17.97, 9.18, 8.75, and 4.73 days at the respective temperatures. The intrinsic rate of population increase (r) at different temperatures ranged from 0.058 to 0.274, with the highest value recorded at 30 °C. These data indicate that E. scutalis is well adapted to high temperatures above 30 °C and could be a useful biological control agent for spider mites during the summer when such temperatures prevail in southwestern Iran. The results could also be used to develop a population model for E. scutalis under field conditions.

Abstract: Abstract Background and Aims Pollen:ovule ratios are often lower in species and populations with higher selfing rates. This may be due either to higher pollination efficiency through selfing, or to lower male competition when less allo-pollen is available. Changes in pollination can also impact pollen traits, such as the number of apertures. Viola arvensis has experienced a rapid recent increase in selfing rates, and a rapid floral trait evolution towards the selfing syndrome. This study tests the hypothesis that V. arvensis is also undergoing a rapid evolution in its pollen:ovule ratio and pollen heteromorphism. Methods Using the resurrection ecology methodology, we compared four ancestral populations (from ca. 30 years ago) to their descendants (from 2021). We counted ovules and pollen and measured the three pollen aperture morphs in 50 individuals per population. We also developed a model to better understand the links between the number of apertures and the mating system. Key Results We found no temporal change in pollen or ovule production. However, populations with the lowest pollen:ovule ratios were also the ones with the highest ancestral selfing rates, suggesting that the pollen:ovule ratio could have evolved on a similar time scale to population differentiation. Our model predicts a positive correlation between number of apertures and selfing rates, if pollination parameters remain constant. However, this positive correlation was not found in our results, neither across populations nor through time. Conclusions Unlike floral morphology, pollen and ovule production did have not evolve rapidly with increased selfing rates, suggesting a delayed change of the pollen:ovule ratio compared to other traits of the selfing syndrome. The absence of correlation between pollen heteromorphism and selfing rate can be explained by multiple (non-mutually exclusive) factors: a decrease in allo-pollen deposition correlated with the evolution of the selfing syndrome, pollinator declines, or the absence of selection in this trait.

Abstract: (Uploaded by Plazi from the Biodiversity Heritage Library) No abstract provided.