Nutrient enrichment is associated with altered nectar and pollen chemical composition in Succisa pratensis Moench and increased larval mortality of its pollinator Bombus terrestris L.

Abstract

Pollinators are declining worldwide and possible underlying causes include disease, invasive pest species and large scale land use changes resulting in habitat loss and degradation. One particular cause of habitat degradation is the increased inflow of nutrients due to anthropogenic combustion processes and large scale application of agricultural fertilizers. This nutrient pollution has been shown to affect pollinators through the loss of nectar and pollen-providing plant species. However, it may also affect pollinators through altering the nectar and pollen chemical composition of plant species, hence influencing pollinator food quality. Here, we experimentally investigated the effect of nutrient enrichment on amino acid and sugar composition of nectar and pollen in the grassland plant Sucissa pratensis, and the subsequent colony size and larval mortality of the pollinating bumblebee Bombus terrestris. We found less of the essential amino acids glycine and arginine in the pollen of fertilized plants, and more arginine, ornithine and threonine in the pollen of control plants. Nectar glucose and pollen fructose levels were lower in fertilized plants as compared to control plants. Furthermore, bumblebee colonies visiting fertilized plants showed more dead larvae than colonies visiting control plants. Our results suggest that the fitness of bumblebees can be negatively affected by changes in their food quality following nutrient pollution. If similar patterns hold for other plant and pollinator species, this may have far reaching implications for the maintenance of pollination ecosystem services, as nutrient pollution continues to rise worldwide.

Atmospheric nitrogen deposition in terrestrial ecosystems: Its impact on plant communities and consequences across trophic levels

“…Ceulemans, Hulsmans, Van den Ende, et al. () also found increased asparagine in the pollen of Succisa pratensis , an N‐sensitive species. Interestingly, Gardener and Gillman () observed that soil enrichment increased production of glutamine and proline and decreased production of GABA (Gamma‐aminobutyric acid) in the nectar of Agrostemma githago .…”

“…In contrast, increased soil N was found to reduce the overall nectar‐sugar reward to pollinators in a lepidoptera‐pollinated orchid, Gymnadenia conopsea (Gijbels, Van den Ende, & Honnay, ). Even if the total sugar reward of nectar or pollen is unaffected, the composition of sugars can be altered by N addition (Ceulemans, Hulsmans, Van den Ende, & Honnay, ; Hoover et al., ). However, this is also species‐specific, with other plant species not showing a change in sugar composition (Gijbels, Ceulemans, Van den Ende, & Honnay, ).…”

“…Soil nutrient enrichment has been shown to alter the concentration and composition of amino acids in nectar. Studies have shown fertilisation consistently increases glutamine (Ceulemans, Hulsmans, Van den Ende, et al., ; Gardener & Gillman, ; Gijbels et al., ), and often increase asparagine (Ceulemans, Hulsmans, Van den Ende, et al., ; Gijbels et al., ). Ceulemans, Hulsmans, Van den Ende, et al.…”

“…Studies have shown fertilisation consistently increases glutamine (Ceulemans, Hulsmans, Van den Ende, et al, 2017;Gardener & Gillman, 2001;Gijbels et al, 2014), and often increase asparagine…”

From plant fungi to bee parasites: mycorrhizae and soil nutrients shape floral chemistry and bee pathogens

“…For example, excessive soil nutrients can decrease amino acid concentrations in pollen, with consequences for bumble bee larval survival (Ceulemans et al 2017). For example, excessive soil nutrients can decrease amino acid concentrations in pollen, with consequences for bumble bee larval survival (Ceulemans et al 2017).…”