Relative importance of diurnal and nocturnal pollinators for reproduction in the early spring flowering shrub Stachyurus praecox (Stachyuraceae)

Abstract

Generalized pollination systems may be favored in early spring flowering plants, as during this period pollinator activity is unpredictable. Many previous studies have concentrated on the importance of diurnal visitors in pollination, and consequently, information on the contribution of nocturnal visitors to pollination in early spring is limited. This study was conducted to evaluate the relative importance of diurnal and nocturnal pollinators in the early spring flowering dioecious shrub Stachyurus praecox (Stachyuraceae), in two temperate forests in central Japan. Visitors to the female and male flowers were observed during day and night, and their relative contributions to seed set were compared. The pollinator observations revealed that the diurnal and nocturnal insects visited both male and female flowers, and that the main flower visitors were diurnal small bees and flies as well as nocturnal settling moths. The diurnal and nocturnal flower visitors also acted as pollinators, as the pollen grains of S. praecox were attached to the insects collected from the female flowers. Pollination experiments demonstrated that the contributions of diurnal pollinators to the seed set were higher than those of the nocturnal pollinators. The results of this study indicate that S. praecox has a generalized pollination system, comprising both diurnal insects and nocturnal settling moths. Although the roles of diurnal insects are more important in the pollination of S. praecox, nocturnal settling moths may have a complementary role in early spring.

Phenology of Zamia boliviana (Zamiaceae), a threatened species from a seasonally dry biodiversity hotspot in South America

“…Phenology is an integrative environmental science studying the timing of recurrent biological events related to climate and its effects on different species of plants and animals (Morellato et al, 2016). Studies examining the phenology of dioecious species, with different pollination modes and from diverse phylogenetic lineages, are relevant for understanding the influence of sexual selection on the evolution and maintenance of sexual dimorphism and sex allocation in plants (Escobedo‐Sarti & Mondragón, 2016; Morellato, 2004; Munguia‐Rosas et al, 2011) because overlapping between sexes is essential for reproductive success (Funamoto & Sugiura, 2021; Lazcano‐Lara & Ackerman, 2018; Morellato, 2004; Obeso, 2002; Octavio‐Aguilar, Iglesias‐Andreu, et al, 2017; Segalla, Pinheiro, & Morellato, 2021).…”

Night and day: Contributions of diurnal and nocturnal visitors to pollen dispersal, paternity diversity, and fruit set in an early‐blooming shrub, Daphne jezoensis

“…Yearly variation in fruit set was larger in night‐open flowers than in day‐open flowers, suggesting that the pollinator activity was more unstable during nighttime in early spring, due to cool temperature. Several studies have reported that settling moths were inefficient or less important as pollinators in early‐blooming plants (Alonso, 2004; Jürgens et al, 2014; Funamoto and Sugiura, 2020). However, in the present study, both diurnal and nocturnal pollinators were effective in D. jezoensis .…”

“…This is because a generalized pollination system increases the opportunity for pollen transfer via a wide range of insect groups (Rathcke, 2003;Darling and Barrett, 2011). These reproductive characteristics have been reported frequently in early-blooming and alpine plants, whose flowering season is characterized by low temperatures and unstable weather conditions (Schemske et al, 1978;Alonso, 2004;Rosati et al, 2019;Funamoto and Sugiura, 2020).…”

“…Nevertheless, hawkmoths are not common in forests, especially in early spring. Alternatively, small settling moths may be important pollinators in early spring, as they are active even under cool conditions (Sayama et al, 2012; Funamoto and Sugiura, 2020) and visit flowers of various species (Singh et al, 2022). However, their actual contribution as pollinators, especially their pollen dispersal ability, remains mostly unknown.…”

Flowering, floral visitors and climatic drivers of reproductive phenology of two endangered magnolias from neotropical Andean forests

“…Generalized pollination is typical of high mountain species where pollinator availability is unpredictable (Funamoto & Sugiura, 2020). Notwithstanding, these two Magnolia species that cohabit in remnant Andean cloud forests do not share their floral visitors, underscoring their highly specialized insect relationships.…”