Rush hours in flower visitors over a day–night cycle

Abstract

Most research on pollination has focussed on a subset of insect taxa within a narrow time window during daylight hours. As a consequence, we have a limited understanding of the diversity and activity of flower visitors during the night or belonging to taxa other than bees or syrphid flies. Here, we quantified the abundance and species richness of flower visitors in ruderal meadows over repeated 24‐h cycles (i.e. day and night), and identified abiotic factors influencing these patterns. From the plant perspective, we investigated the likelihood of being visited by an insect across a 24‐h cycle. Activity of flower‐visiting insects never dropped to zero over 24‐h. During the day, non‐syrphid Diptera and Hymenoptera were the most abundant, and species‐rich groups of flower visitors, Lepidoptera and Coleoptera during night. While two of the seven most frequently visited plant species were most likely to be visited during the day, five also had a high likelihood to be visited during the night. The abundance and species richness of flower visitors was positively related to temperature during both the day and the night, whereas there was only a positive relationship with brightness during the day. We conclude that non‐syrphid Diptera and nocturnal flower visitors are currently underappreciated. As the latter seem to respond differently to abiotic factors compared to diurnal species, they may potentially increase response diversity and resilience of plant‐pollinator communities. There is an urgent need to improve our understanding of their ecological role and potential decline due to global change.

Complex long‐term dynamics of pollinator abundance in undisturbed Mediterranean montane habitats over two decades

“…As found elsewhere (Fijen and Kleijn , Knop et al. ), prior studies in the study area have shown that abundance and diversity of insect pollinators declined considerably in the afternoon (Herrera , ; personal observations ), and there was no evidence of crepuscular or nocturnal pollination for any of the plant species studied here. In addition, flowers of about one‐third of the species studied are not available to pollinators in the afternoon, since their corollas whither (e.g., Asphodelus , Hypericum , Urginea ), close (e.g., Campanula , Catananche , Chondrilla ), or fall (e.g., Cistus , Helianthemum , Linum ) shortly after noon.…”

Nocturnal pollination: an overlooked ecosystem service vulnerable to environmental change

“…bees, may visit other sympatric flowering plants over the course of their lifetime [5]) [6]. Additionally, recent work suggests that many generalist flowers are visited nocturnally as well as during the day [7]. Despite these facts, nocturnal pollinators have been less frequently studied (Table 1), and may therefore be undervalued.…”

The floriphilic katydid, Phaneroptera brevis, is a frequent flower visitor of non-native, flowering forbs

“…To obtain the total number and species of flower-visiting insects within each sampling point, data from both methods were pooled together. Only active flower-visiting insects, defined as any insect that intentionally moved in or on an inflorescence thereby touching the reproductive organs of the flower (Knop et al 2018), were included. The total number of P. brevis adults and immatures inside the hoop was counted and we took note of whether the katydid was on a flower or on the leaves.…”

“…material 1 for the details and explanation of each proposed model). Each model contained a different combination of the following predictors: 1) abundance of all flower-visiting insects, 2) abundance of ambush predator crab spiders, 3) abundance of main competitors (bees, see Lindström et al 2016), 4) presence or absence of ants, 5) time period of sampling (see Knop et al 2018), 6) total flower abundance, and 7) plant species richness. We ensured that all models were biologically meaningful and not overfitted.…”