Flower-visiting and pollen-carrying arthropods of Leucojum aestivum L. (Amaryllidaceae) in wild, reintroduced and ex situ populations

Abstract

Leucojum aestivum L. is a wetland-dependent perennial geophyte occurring in Europe and western Asia. It is self-incompatible, with high level of fruit-set and seed-set. Yet, its pollinators are poorly known. Here, we present the most recent research on potential pollinators of L. aestivum. We collected data on flower-visiting and pollen-carrying arthropods in three populations of the species in the River Po plain (N-Italy), where L. aestivum occurs mainly in forests with Alnus glutinosa and Fraxinus sp. pl. close to rivers. We studied a wild population, a new reintroduced population and an ex situ population located at the Botanical Garden of the University of Pavia. Our study identified 18 arthropod taxa carrying L. aestivum pollen; the soft-winged flower beetle Dasytes plumbeus (Coleoptera: Melyridae) and the sac-spider Clubiona sp. pl. (Araneae: Clubionidae) were the most frequent visitors. Hymenoptera only occasionally visited L. aestivum flowers (e.g. the sweat bee Lasioglossum punctatissimum). D. plumbeus, the long-horned beetle Grammoptera ruficornis (Coleoptera: Cerambycidae), Clubiona sp. pl. and L. punctatissimum resulted in the taxa with the highest average abundance of pollen grains on their body suggesting a potential role in L. aestivum pollination. Differences in flower-visiting and pollen-carrying arthropods were observed between the three populations, with a decreasing taxonomic diversity of visiting species from the wild population to the ex situ population. Our results, based on direct observation in the field, are partially in contrast with a previous study on L. aestivum pollinators that suggested diurnal and nocturnal Lepidoptera and occasionally bees as main pollinators for the species.

Autumn Leucojum autumnale L. and spring L. trichophyllum Schousb.: the same flower type for different seasons with a different pollination scenario

“…Other spring species of Leucojum probably show a similar facilitated pollination strategy in their communities, as observed by Maggi et al (2021), who found another Dasytidae Coleoptera, Dasytes plumbeus, in the owers of L. aestivum in Italy, and discovered differences in beetle activity in different observation sites and on different dates.…”

“…In L. trichophyllum, pollen grains amounted to an estimated 120000 grains per ower, which is greater than that recorded in the species of Cistaceae mentioned (e.g., H. halimifolium: 55000 grains per ower; H. calycinum: 13000 grains per ower; C. libanotis: 55000 grains per ower; and C. salviifolius: 106000 grains per ower; Herrera 1987Herrera , 1988. However, its grains are much smaller (Valdés et al 1987) so the net mass of pollen is small and, therefore, it could be considered a poor pollen producer, as occurs with L. aestivum (Abeli et al 2016;Maggi et al 2021), about which Percival (1955) stated that it would appear to be di cult to hold the pollinators.…”

“…However, in L. aestivum, which is widespread in the Mediterranean and central Europe and owers in spring, Percival (1955) and Wisdom et al (2019) observed that honeybee pollination activity in its owers was rare. Maggi et al (2021) explained that the difference in the honeybee pollination of this species compared to L. vernum was the lack of nectar as reward (Parolo et al 2011), absence of scent (Abeli et al 2016), as well as poor pollen production (Percival 1955). Abeli et al (2016) hypothesized that L. aestivum could be a food-deceptive plant, whereas Knuth (1909) and Parolo et al (2011) described it as a self-incompatible species with no apomixis, and with high levels of fruit and seed set.…”

“…For L. aestivum, Parolo et al (2011) included as potential pollinators long-tongued nocturnal Lepidoptera, diurnal Lepidoptera and Hymenoptera (e.g., bees and bumblebees), and observed that owers functioned as shelters for several species of beetles and spiders. But a recent study based on eld observations by Maggi et al (2021) identi ed 18 arthropod taxa carrying L. aestivum pollen, of which the most frequent was the pollen-feeding beetle Dasytes plumbeus (Müller 1776); the taxon with the highest average abundance of pollen grains on its body was the Lasioglossum punctatissimum bee (Schenck 1853), but it visited the owers only occasionally. This present study examined different aspects of the reproductive biology of the autumn-owering L. autumnale and spring-owering L. trichophyllum that share a distribution area in the southwest of the Iberian Peninsula.…”

Research trend analysis of Leucojum aestivum based on Citespace visualization software

“…Plants and the assessment of pollinating insect capabilities. [43][44][45][46] Studies have shown that alkaloid synthesis is dominated by the plant genotype, the activity of biosynthetic activities. [47][48][49][50][51][52] At present, there are three methods to produce galanthamine on a large scale vizcomplete chemical synthesis and extraction from field plants (e.g., Narcissus tazetta L. var.…”