Potential pollinators of Fragaria ananassa (Rosales: Rosaceae) in the Perico valleys of Jujuy (Argentina)

The aims of this study were to identify and estimate the potential pollinators of Fragaria ananassa Duch. “strawberry”, through the analysis of pollen carried out on their bodies. The study was carried out on a commercial farm in Las Pampitas, located in the Perico valleys, Jujuy province (Argentina). Floral visitors and other arthropods were sampled and identified, and their diversity was analyzed. The samples of insects selected to obtain the pollen carried were processed following the acetolysis technique. The potential pollinators of the strawberry crop were estimated by calculating the pollination probability index. The floral visitors corresponded to representatives of Hymenoptera, Diptera, Hemiptera, Lepidoptera, Coleoptera and even Araneae. Apis mellifera L. was the most frequent floral visitor and presented more strawberry pollen than other selected insects. The pollination probability index estimated that this species had a high probability of being a pollinator. Other pollinators such as Allograpta exotica Wiedemann, Halictidae, Meliponini and even Thripidae could complement the action of the honeybee. This is the first contribution to the knowledge of the pollination of F. ananassa in the agroecosystems of Jujuy.

Diversity of Insect Flower Visitors of Xylopia aromatica (Magnoliales, Annonaceae) in a Brazilian Savanna

Small beetles are important pollinators of Annonaceae whose flower chambers are small and have diurnal and/or nocturnal anthesis. The pollinators of these flowers belong to the families Nitidulidae, Staphylinidae, Chrysomelidae, and Curculionidae. In this study, the first conducted in the Cerrado of Chapada dos Guimarães, Mato Grosso, Brazil, the behavior of the insect flower visitors of Xylopia aromatica was observed, in both the field and the laboratory. The chambers of 253 flowers were collected from 11 plants, and the biological aspects of their visitors were analyzed quantitatively and qualitatively. The most abundant visitors were thrips and beetles. Coleoptera was represented by four morphospecies occurring frequently in the floral chambers (>70% of individuals). Among beetles, one species belonged to Nitidulidae (Cillaeinae, Conotelus sp. 1) and two belonged to Staphylinidae (Aleocharinae sp. 1 and Aleocharinae sp. 2). These three morphospecies of small elongate beetles have setae where pollen may adhere. In addition, they were present on both male and female phases of the flowers, indicating potential cross-pollination. In the study area, X. aromatica possesses mixed pollination promoted by Thysanoptera and small Nitidulidae and Staphylinidae beetles. This study brings the first record of Lamprosomatinae (Chrysomelidae) and, especially, of Conotelus (Nitidulidae) in the flower chambers of X. aromatica, with new information on behavior of floral visitors coupled with their morphological traits that may promote cross-pollination in this plant species.

Trade-offs among plant reproductive traits determine interactions with floral visitors

Plant life-history strategies are constrained by cost-benefit trade-offs that determine plant form and function. However, despite recent advances in the understanding of trade-offs for vegetative and physiological traits, little is known about plant reproductive economics and how they constrain plant life-history strategies and shape interactions with floral visitors. Here, we investigate plant reproductive trade-offs and how these drive interactions with floral visitors using a dataset of 17 reproductive traits for 1,506 plant species from 28 plant-pollinator studies across 18 countries. We tested whether a plant's reproductive strategy predicts its interactions with floral visitors and if the different reproductive traits predict the plant's role within the pollination network. We found that over half of all plant reproductive trait variation was explained by two independent axes that encompassed plant form and function. Specifically, the first axis indicated the presence of a trade-off between flower number and flower size, while the second axis indicated a pollinator dependency trade-off. Plant reproductive trade-offs helped explain partly the presence or absence of interactions with floral visitors, but not differences in visitation rate. However, we did find important differences in the interaction level among floral visitor guilds on the different axes of trait variation. Finally, we found that plant size and floral rewards were the most important traits in the understanding of the plant species network role. Our results highlight the importance of plant reproductive trade-offs in determining plant life-history strategies and plant-pollinator interactions in a global context.

Examining the Role of Buzzing Time and Acoustics on Pollen Extraction of Solanum elaeagnifolium

Buzz pollination is a specialized pollination syndrome that requires vibrational energy to extract concealed pollen grains from poricidal anthers. Although a large body of work has examined the ecology of buzz pollination, whether acoustic properties of buzz pollinators affect pollen extraction is less understood, especially in weeds and invasive species. We examined the pollination biology of Silverleaf nightshade (Solanum elaeagnifolium), a worldwide invasive weed, in its native range in the Lower Rio Grande Valley (LRGV) in south Texas. Over two years, we documented the floral visitors on S. elaeagnifolium, their acoustic parameters (buzzing amplitude, frequency, and duration of buzzing) and estimated the effects of the latter two factors on pollen extraction. We found five major bee genera: Exomalopsis, Halictus, Megachile, Bombus, and Xylocopa, as the most common floral visitors on S. elaeagnifolium in the LRGV. Bee genera varied in their duration of total buzzing time, duration of each visit, and mass. While we did not find any significant differences in buzzing frequency among different genera, an artificial pollen collection experiment using an electric toothbrush showed that the amount of pollen extracted is significantly affected by the duration of buzzing. We conclude that regardless of buzzing frequency, buzzing duration is the most critical factor in pollen removal in this species.

The light intensity mediates the pollination efficacy of a Caatinga morning glory Ipomoea bahiensis (Convolvulaceae)

Pollination is an ecological process that relies on the matching traits of flower visitors and flowers. Morphology, behavior, and temporal patterns play essential roles in mediating the interactions between plants and floral visitors. This study analyzed the temporal aspects of visitors and flowers interaction and the possible adjustment between both organisms. We used Ipomoea bahiensis and its flower visitors as a model system. We evaluated the visitor frequency on the flowers throughout the day, flower opening and closing times, pollen availability and stigma receptivity. We also evaluated the highest fruit production time during the flower longevity was analyzed, and the time of highest pollinator activity, related to climatic factors. Among the floral visitors, bees, especially Melitoma spp., Apis mellifera, and Pseudaugochlora pandora were the most frequent visitors, presenting regular visits synchronized with the flower opening and closing times, which were also regular. This system was influenced mainly by light intensity. Besides, these bees were very active during the times of the highest fruit production. These data indicate the presence of temporal patterns for both the bees and the visited plants, and synchronization between them, being the light intensity as a modulator of the rhythms of bees and plant, confirming the importance of the temporal adjustments for pollination efficiency.

A Continuum of Conspicuousness, Floral Signals, and Pollination Systems in Rhynchospora (Cyperaceae): Evidence of Ambophily and Entomophily in a Mostly Anemophilous Family

Floral colors and odors are evolutionary strategies used by plants to attract pollinating animals and may be absent in mostly anemophilous groups, such as Cyperaceae. However, considering that insects are floral visitors of some Rhynchospora Vahl species, the objective of this study was to characterize the floral traits and pollination systems within this genus. We analyzed 16 Rhynchospora species with regard to flower morphology, colors of floral structures, floral scents, pollen vectors, and pollination systems. We verified factors that can favor abiotic or biotic pollination in a continuum of floral traits in Rhynchospora. The flower morphology of R. dissitispicula T. Koyama, with inconspicuous brown spikelets in open panicles, is interpreted as a complete adaptation to anemophily. Conspicuous floral traits in Rhynchospora were distinguished from the background by bees. Some species also emit floral volatiles, and we made the first record of floral scent chemistry within the genus. Most of the compounds emitted by these species are known as attractants to many floral-visiting insects. Bees, beetles, and flies visited species with conspicuous floral traits and contributed to fruit set. The investigated floral traits form a continuum across the different pollination systems in Rhynchospora, from anemophilous to ambophilous and then to entomophilous representatives.