The 'night shift': Nocturnal pollen-transport networks in a boreal pine forest

Abstract

Diurnal plant-visitor networks are well studied, but the community-level dimension of nocturnal visitation by insects has been largely overlooked.This study focused on the role of moths as pollen vectors in a boreal pine forest in Scotland. Light traps were used to sample moths in 20 plots in two consecutive years. The pollen on moths' bodies was identified and pollen grains counted. This information was used to build a nocturnal pollen-transport network for each year. These are the first networks to characterise a nocturnal plant-visitor community.A total of 4162 moths belonging to 103 species were captured; 25 moth species were found to carry pollen of 12 plant taxa. Adding nocturnal data to diurnal networks increased number of plant taxa, insect species, and unique interactions in the network.Despite differences in species composition, nocturnal networks exhibit similar properties to diurnal networks: significant nestedness, marked asymmetry of interactions, high dependence on a core of generalists, and high inter-annual variation in species abundances and occurrence of interactions.Traditional diurnal plant-visitor networks exclude a significant component of the community, i.e. nocturnal visitors. Exploring links across boundaries between networks (such as between diurnal and nocturnal networks) will provide a more accurate picture of ecosystem structure and function. © 2010 The Authors. Ecological Entomology © 2010 The Royal Entomological Society.