Spatial and Temporal Variations in Richness, Diversity and Abundance of Floral Visitors of Curry Plants (Bergera koenigii L.): Insights on Plant-Pollinator Interactions

The reproductive success of flowering plants relates to flower-visitor communities and plant-pollinator interactions. These traits are species- and region-specific and vary across regions, pollinator groups, and plant species. However, little literature exists on the spatiotemporal variation in visitor activity, especially in India. Here, we aimed to depict the spatial and temporal variation in visitor activity on the curry plants (Bergera koenigii). Data were collected at different daytime slots from three vegetation zones (confirmed by field surveys and normalized difference vegetation index values in remote sensing)-dense, medium-density, and low-density vegetation in West Bengal, India. The visitors' richness, diversity, and abundance were higher in the area with dense vegetation. Considering daytime patterns, higher values for these parameters were obtained during 10.00-14.00 h. For most visitors, the flower handling time was shorter, and the visitation rate was higher in dense vegetation areas (at 10.00-14.00 h) than in medium- and low-density vegetation areas. The proportions of different foraging categories varied over time. Vital pollinators were Apis cerana, Apis dorsata, Appias libythea, Halictus acrocephalus, Nomia iridescens, and Tetragonula iridipennis. However, the effectiveness of pollinators remained region-specific. Therefore, it can be concluded that floral visitors' richness, diversity, abundance, and plant-visitor interactions varied spatially with their surrounding vegetation types and also changed daytime-wise.

Effect of temporal changes in stamen position on reproductive success in flowers with many stamens: Manipulations of stamen position

PREMISE

Male and female reproductive success is enhanced (increased outcrossing and seed production, respectively) by stamen movement in species that have few stamens per flower. Does such enhancement also occur in species that have many stamens per flower?

METHODS

We examined the effects of stamen movement on male and female reproductive success in Anemone flaccida, which has many stamens per flower. We measured stamen movement, including temporal changes in anther-stigma and anther-anther distances. We experimentally fixed stamens in their pre- or post-movement positions.

RESULTS

The anthers moved horizontally away from the stigmas with increasing flower age, thus reducing female-male interference. The dehisced anthers tended to move farther from the stigmas, while the undehisced or dehiscing anthers remained closer to them. The number of anthers touched per flower visit was higher in flowers whose stamens were fixed in the pre-movement position than in flowers whose stamens were fixed in the post-movement position or in flowers that were not manipulated. Thus, this position may promote male reproductive success. Seed production was lower for the untreated flowers than for those with stamens fixed in the post-movement position, suggesting that the post-movement stamen position is advantageous and stamen movement is suboptimal for female reproductive success.

CONCLUSIONS

Stamen movement promotes male reproductive success in the early flowering stage and female reproductive success in the late flowering stage. In species having many stamens per flower, female-male interference can be reduced, but not eliminated, by stamen movement due to the conflict between female and male reproductive successes.

Updating the list of flower-visiting bees, hoverflies and wasps in the central atolls of Maldives, with notes on land-use effects

Maldives islands host a unique biodiversity, but their integrity is threatened by climate change and impacting land-uses (e.g. cemented or agricultural areas). As pollinators provide key services for the ecosystems and for the inhabitants, it is crucial to know which pollinators occur in the islands, to characterise their genetic identity and to understand which plants they visit and the size of the human impact. Given that no significant faunistic surveys of Hymenoptera have been published for the country in more than 100 years and that Syrphidae were only partly investigated, we sampled islands in the central part of the Maldives country (Faafu and Daahlu atolls) and hand-netted flower-visiting bees, wasps and hoverflies (Hymenoptera: Anthophila, Crabronidae, Sphecidae, Vespidae, Scoliidae and Diptera: Syrphidae). Overall, we found 21 species; 76.4% of the collected specimens were Anthophila (bees), 12.7% belonged to several families of wasps and 10.8% of individuals were Syrphidae. It seems that one third of species are new for the Maldives, based on the published literature. Human land-uses seem to shape the local pollinator fauna since the assemblages of bees, wasps and hoverflies from urbanised and agricultural islands differed from those in resort and natural ones. These pollinators visited 30 plant species in total, although some invasive plants hosted the highest number of flower visitor species. Biogeographically, this pollinating fauna is mostly shared with Sri Lanka and India. Genetically, the used marker hinted for a unique fauna in relation to the rest of the distribution ranges in most cases, although generally within the level of intraspecific genetic variation. This study significantly contributes to increasing the knowledge on the pollinator diversity and genetic identity in Maldives islands also considering the important implications for the islands' land-use and the role of invasive plants. This study will be pivotal for future pollination studies and biodiversity conservation efforts in the region.

Ultramorphological Comparison of Proboscis and Associated Sensilla of Scotogramma trifolii and Protoschinia scutosa (Lepidoptera: Noctuidae)

Simple Summary

The clover cutworm, Scotogramma trifolii Rottemberg, and the spotted clover moth, Protoschinia scutosa (Denis & Schiffermuller), are worldwide polyphagous pests, and the larvae feed mainly on the leaf backs of many agricultural crops. However, the food sources and feeding habits of the adults are still poorly known. We investigated the ultramorphology of the proboscis and associated sensilla of S. trifolii and P. scutosa using scanning electron microscopy. The results show that the proboscises of S. trifolii and P. scutosa are structurally similar, both including three sensillum types and three zones (Zone 1–3). The sensillum chaeticum is non-porous hair-like, the sensillum basiconicum is a short smooth cone with a sensory pore on the blunt tip, and each sensillum styloconicum is composed of a uniporous sensory cone inserted into a ribbed stylus. In addition, the movement and fluid uptake mechanisms of the proboscis and the possible function of sensilla are briefly discussed.

Abstract

The proboscis is an important feeding organ for the glossatan moths, mainly adapted to the flower and non-flower visiting habits. The clover cutworm, Scotogramma trifolii Rottemberg, and the spotted clover moth, Protoschinia scutosa (Denis & Schiffermuller), are serious polyphagous pests, attacking numerous vegetables and crops, resulting in huge economic losses. However, the feeding behavior and mechanisms of the adult stage remain unsatisfactorily explored. In this study, the proboscis morphology of S. trifolii and P. scutosa are described in detail using scanning electron microscopy, with the aim of investigating the morphological differences and feeding behavior of these two species. The proboscises of S. trifolii and P. scutosa are similar in morphology and structure and are divided into three zones (Zone 1–3) based on the morphological changes of the dorsal legulae. Three sensillum types are located on the proboscises of both species, sensilla chaetica, sensilla basiconica, and sensilla styloconica. Significant differences were observed in the length of the proboscis and each zone between these two species, as well as in sensilla size and number. Based on the morphology of the proboscis and associated sensilla, S. trifolii and P. scutosa are potential flower visitors, which was also reinforced by the pollen observed at the proboscis tip. These results will strengthen our understanding of the structure of the proboscis related to the feeding behavior of Noctuidae.

Wild bees of Chile: a database on taxonomy, sociality, and ecology

Bees are a diverse group of insects that have tremendous importance as pollinators. In recent decades, there has been a global decline in bee populations because of land-use change, intensive agriculture, and climate change. Unfortunately, our knowledge of native bees' ecology is rather scarce, and such knowledge gaps are also a major threat to its conservation. In this sense, biological collections are a priceless natural history legacy and an information source for new research and decision making. Chile has a remarkable bee diversity, with 464 species currently known from Chile and a high incidence of endemism and a variety of habitats (including the Mediterranean biodiversity hotspot). The largest wild bee collection in Chile is held at the Pontificia Universidad Católica de Valparaíso (comprising a century of data). This collection has been recently included in GBIF. Here we present a database with 36,010 records, including information on sociality and ecology (including information on floral visitation range, the resource collected, and nesting substrates) for 160 out of the 167 bee species included (36% of the Chilean bee diversity, including 49 genera and five families). All records have the taxonomy resolved, and 83% of them have geographic coordinates, covering a latitudinal range between 18° S and 53° S from the continental and insular territories. This data set is released for noncommercial use only. Credits should be given to this paper (i.e., proper citation), and the products generated with this database should be shared under the same license terms (CC BY-NC-SA).

Horizontal orientation of zygomorphic flowers: significance for rain protection and pollen transfer

Floral traits are recognized to have evolved under selection for abiotic and biotic factors. Complex zygomorphic flowers usually face horizontally. It has been proved that a horizontal orientation facilitates pollinator recognition and pollination efficiency, but its significance in adaptation to abiotic factors remains unknown. The floral orientation of Abelia × grandiflora naturally varies around horizontal (with an angle of -30 to +33° between the floral main axis and the horizontal). We examined whether three different floral orientations affected flower thermal conditions, response to rain and pollination. Results showed that floral orientation had no effect on diurnal variations in flower temperature. The anthers of all three flower orientations were wetted by rainfall, but the inclined upward-facing flowers contained significantly more rainwater. The horizontal flowers received significantly higher visitation by hawkmoths and had a higher stigmatic pollen load. In contrast, the upward flower orientation reduced pollination precision, while downward-facing flowers had decreased pollinator attraction. This study indicates that horizontal flowers may have evolved as a trade-off between rain protection and pollination. Zygomorphic flowers that deviate from a horizontal orientation may have lower fitness because of flower flooding by rainwater and decreased pollen transfer.

Flower-visitor communities of an arcto-alpine plant-Global patterns in species richness, phylogenetic diversity and ecological functioning

Pollination is an ecosystem function of global importance. Yet, who visits the flower of specific plants, how the composition of these visitors varies in space and time and how such variation translates into pollination services are hard to establish. The use of DNA barcodes allows us to address ecological patterns involving thousands of taxa that are difficult to identify. To clarify the regional variation in the visitor community of a widespread flower resource, we compared the composition of the arthropod community visiting species in the genus Dryas (mountain avens, family Rosaceae), throughout Arctic and high-alpine areas. At each of 15 sites, we sampled Dryas visitors with 100 sticky flower mimics and identified specimens to Barcode Index Numbers (BINs) using a partial sequence of the mitochondrial COI gene. As a measure of ecosystem functioning, we quantified variation in the seed set of Dryas. To test for an association between phylogenetic and functional diversity, we characterized the structure of local visitor communities with both taxonomic and phylogenetic descriptors. In total, we detected 1,360 different BINs, dominated by Diptera and Hymenoptera. The richness of visitors at each site appeared to be driven by local temperature and precipitation. Phylogeographic structure seemed reflective of geological history and mirrored trans-Arctic patterns detected in plants. Seed set success varied widely among sites, with little variation attributable to pollinator species richness. This pattern suggests idiosyncratic associations, with function dominated by few and potentially different taxa at each site. Taken together, our findings illustrate the role of post-glacial history in the assembly of flower-visitor communities in the Arctic and offer insights for understanding how diversity translates into ecosystem functioning.