Search results for "Pollen"
showing 10 items of 302 documents
Northern Hemisphere forests at temperate and boreal latitudes are substantial pollen contributors to atmospheric bioaerosols
2017
Abstract Forest pollen is a heavy contributor to atmospheric bioaerosols during spring months. This is important because bioaerosols make up 25% of the atmospheric aerosols shaping cloud formation, precipitation and ultimately climate. To test this premise, we drew from available literature, a meta-analysis of 25 forest pollen reports and a comparative analysis of Zea mays versus Pinus taeda pollen. Using available literature, we showed forest pollen grains are not too large or too few in the atmosphere and that some types are prone to bursting into subpollen particles (SPP). High forest pollen concentrations were consistent in the meta-analysis of 25 forest pollen reports from 1937 to 2014…
<p class="Body"><strong>Biological parameters of <em>Neoseiulus longilaterus</em> (Athias-Henriot) (Parasitiformes, Phytoseii…
2019
Tetranychus urticae is the most important pest on different crops worldwide. Search for endemic phytoseiid mites co-occurring with the above pest, which might be good candidates as biocontrol agents, represents the policy followed by most scientists in recent years. The aim of the present work was to assess the various biological and demographic parameters of Neoseiulus longilaterus, associated with T. urticae on weeds, in laboratory conditions using the latter tetranychid and pollen of Oxalis pes-caprae as food. The results showed a better performance of the predator on the prey as regards the postembryonic development (7.63 and 8.18 days for prey and pollen respectively) and the demograph…
Salvia apiana — A carpenter bee flower?
2016
Abstract Salvia apiana has unique mask flowers restricting access to nectar by a bulged lower lip. Stamens and style protrude the flower tube. Most interesting, the staminal lever mechanism usually characterizing bee flowers in Salvia L. is lacking. In the present study, we aim to understand the peculiar pollination mechanism and to identify the pollinators and breeding system of the species. Field experiments were conducted at three natural localities in Southern California and the Rancho Santa Ana Botanical Garden, Claremont. Pollinator behavior was documented on video and interpreted considering frequency, handling time, percentage of successfully touching pollen and stigma, pollen depos…
Inflorescence scents of Calendula maritima, C. suffruticosa subsp. fulgida, and their hybrid
2018
Premise of research. Hybridization is an important driver of plant evolutionary processes. By attracting the same pollinators to different species, floral scents may be involved in the formation of hybrids and breakdown of species boundaries. In contrast, by attracting a different suite of pollinators to hybrids and their parents, floral scents are believed to contribute to speciation processes initiated by hybridization events. Scents may or may not differ between the hybrids and their parents, but little is known about the scent chemistry of parental species and their hybrids. Methodology. We studied the inflorescence scents of parental Calendula maritima and C. suffruticosa subsp. fulgid…
Resource profitability, but not caffeine, affects individual and collective foraging in the stingless beePlebeia droryana
2019
ABSTRACT Plants and pollinators form beneficial relationships, with plants offering resources in return for pollination services. Some plants, however, add compounds to nectar to manipulate pollinators. Caffeine is a secondary plant metabolite found in some nectars that affects foraging in pollinators. In honeybees, caffeine increases foraging and recruitment to mediocre food sources, which might benefit the plant, but potentially harms the colonies. For the largest group of social bees, the stingless bees, the effect of caffeine on foraging behaviour has not been tested yet, despite their importance for tropical ecosystems. More generally, recruitment and foraging dynamics are not well und…
Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily
2007
International audience; In order to empirically assess the effect of actual seed sampling strategy on genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have analysed the genetic composition of two seedling lots (nursery stock and plantation) and their known natural seed origin stand by means of six nuclear microsatellite loci. Significant reduction in genetic diversity and significant difference in genetic composition of the seedling lots compared to the seed origin stand were detected. The female and the total effective number of parents were quantified by means of maternity assignment of seedlings and temporal changes in allele frequencies. Extremely low effective ma…
Introduction of genotypic effects into Genesys-Rape : the example of height and male sterility
2005
Abstract The aim of this study was to introduce effects of rape genotypes on gene flow between rape populations into the existing GeneSys - Rape model and to simulate the influence of existing rapeseed cultivars on gene flow between rapeseed populations in time and in space. The GeneSys - Rape input variables are the regional field pattern, crop successions, cultivation techniques and genotype of cropped cultivars. The main output variables are, for each year and plot, the number of individuals per square meter and the genotype proportions in the harvest. Results comprised: (1) sensitivity analyses of the model to cultivar characteristics, which showed the importance of pollen emission on g…
Effect of temperature on pollen germination for several Rosaceae species: influence of freezing conservation time on germination patterns
2019
[EN] Between February 2018 and April 2018, flowers were collected from eight Rosaceae species. Flowers were kept in a freezer at -20 degrees C for three freezing times (Treatment 1, two months; Treatment 2, four months; Treatment 3, six months). After extracting pollen, in vitro germination was induced in a culture medium and incubated at six different temperatures for 72 h. The percentage of pollen germination, average pollen tube length and maximum pollen tube length were measured. Pollen germination was maximum for all species between 15 degrees C and 30 degrees C. Cydonia oblonga, Malus sylvestris, Prunus avium, Prunus domestica, Prunus dulcis, Prunus persica and Pyrus communis obtained…
Consequences of gene flow between transgenic, insect-resistant crops and their wild relatives
2015
Concerns have been raised about the possibility of the negative impact of transgenic crops on the environment. If wild plants accidentally pick up transgenes through pollen exchange with genetically modified crops, they could gain new environmental advantages or conversely suffer genetic homogenization and loss of biodiversity. This could cause weeds that might create new problems in farmers' fields and wild habitats and change biological equilibriums. Examples of gene flow are given for several cases of crop/ancestor pairs and two cases of more distantly related species. The main concern is that introgression between transgenic, insect-resistant crops and their wild relatives could lead to…
Polymorphism for interspecific hybridisation within a population of wild radish (Raphanus raphanistrum) pollinated by oilseed rape (Brassica napus)
2001
The within-population polymorphism of wild radish (Raphanus raphanistrum) for interspecific hybridisation with two cultivars of oilseed rape (Brassica napus) was investigated by hand crossing experiments and fluorescence microscopy. Wide variability among plants was observed in the ability of oilseed rape pollen to germinate on the wild radish stigma; the frequency of pistils showing pollen tubes ranged from 0 to 1, depending on the female plant. The ratio of fertilised ovules to the total number of ovules in ovaries where pollen tubes arrived ranged from 0.02 to 0.51. Overall, the results provide evidence for the presence of different phenotypes. In 40% of the plants, pistils had no or ver…