Conserving diversity in Irish plant–pollinator networks

Abstract

Beneficial insects provide valuable services upon which we rely, including pollination. Pollinator conservation is a global priority, and a significant concern in Ireland, where over half of extant bee species have declined significantly in recent decades. As flower‐visiting insects rely on flowering plants, one way to conserve and promote pollinator populations is to protect high‐quality habitat. We analyzed the structure of insect–flower interactions from multiple habitat categories in a large database of interactions from Ireland. Our primary goals were to compare spatial and temporal variation in Irish network structures, compare Irish networks to published networks from other countries, and provide evidence‐based recommendations for pollinator conservation in Ireland by identifying well‐visited plant species that may promote high pollinator diversity, abundance, and functional complementarity. Habitat types within Ireland differed substantially: seminatural grasslands had the highest pollinator species richness and largest number of unique pollinator species, while intensively managed habitats exhibited negative asymmetry (more plant than pollinator species). This negative asymmetry is notable because most plant–pollinator networks exhibit a positive asymmetry. Within intensively managed habitats, agricultural and urban habitats differed. Urban habitats had the highest number of non‐native plant species while agricultural habitats had the lowest pollinator species richness. We also found Irish networks varied across the growing season, where July had the highest plant and insect species richness. When comparing Irish networks to published networks from other countries, we found Irish networks had a higher ratio of plant species to pollinator species, and that this difference was most evident in agricultural habitats. This ratio means the typical network asymmetry (more pollinator than plant species) was flipped (more plant than pollinator species) in the Irish network. We conclude that conserving seminatural grasslands in Ireland will be an essential component of pollinator conservation and identify thirty‐five plant species important for restoring seminatural habitats.

Pollinator responses to farmland habitat features: one-size does not fit all

“…8). Thirty surveys were completed in this way and while the results were not robust enough for statistical analysis, they did support the findings of Russo et al (2022) in that R. fruticosus agg. was most frequently interacted with (209 interactions).…”

“…In the case of livestock farms, enriching the diversity and quantity of ground flora is pivotal for attracting and supporting solitary bees (Potts et al 2010). Recent work examining the plant-pollinator networks in Ireland found that, unlike in many other contexts, the networks in Irish agricultural landscapes are highly asymmetrical, with more plant species than pollinators (Russo et al 2022). However, the many non-native plant hosts present on agricultural land were shown not to be attractive to pollinators.…”

Fertilizer and herbicide alter nectar and pollen quality with consequences for pollinator floral choices

“…Boraginaceae, and Plantago lanceolata , L. Plantaginaceae). These comprised six native perennial and one non-native annual herbaceous species ( P. tanacetifolia ), selected as pollinator-attractive ( Clifford, 1962 ; Russo et al, 2022 ), and likely to be found on agricultural field edges in Europe. They represent a diverse group of plant families with regard to floral resource quality ( Ruedenauer et al, 2019b ; Vaudo et al, 2020 ; Zu et al, 2021 ).…”