Predator plants may cut back on flies if they can access key nutrients elsewhere, according to research.
Scientists studying carnivorous sundew plants in Swedish bogs found that nitrogen deposition from rain reduced how many insects the plants trapped.
Pollution from transport and industry causes nitrogen-rich rain, meaning more reaches the ground in some areas.
“If there’s plenty of nitrogen available to their roots, they don’t eat as much” says Dr Jonathan Millett.
Dr Millett from Loughborough University led the study, which was funded by the Natural Environment Research Council (NERC) and is being published in the New Phytologist journal.
The findings are based on tests on the round-leaved sundew plant, drosera rotundifolia. By measuring the amount of nitrogen of insect origin and comparing it to the amount taken up by the plant’s roots, scientists could examine the proportions of each taken by plants in different locations.
They found that plants living in lightly polluted areas got 57% of their nitrogen from their prey. In more heavily polluted areas that figure dropped to between 20% and 30%.
But the species as a whole is not thought to be benefitting from this alternative source of nutrition. In fact, the discovery could prove to be bad news for the sundew in the longer term.
“Basically, it’s like adding more fertiliser,” said Dr Millett.
“For an individual sundew it looks like its better. They’re bigger and they’ll probably be fitter and do better, but the problem is that they have to divert resources into being carnivorous.”
Carnivorous plants actually benefit from nutrient-poor environments, because they have less competition from other plants.
Their animal-digesting abilities seem to have evolved as a way to survive in these habitats, and the plants need a great deal of energy to “run” the complicated traps they use to capture and digest their prey. …