Rapid disruption of pollination function by the invasive plant Impatiens glandulifera.
Pérez-Barrales R, Taylor LM, Horn G, Ben-Menni Schuler S
Invasive Species
That pretty pink-flowered plant spreading along your local riverbank or woodland edge could be quietly starving native wildflowers of the bee visits they need to set seed — before you'd ever notice fewer bees around.
Researchers found that when Himalayan balsam — a tall, fast-spreading plant with pink flowers — moves into an area, bumblebees start visiting it almost immediately and become covered in its pollen. This means when those bees land on native plants like hedge woundwort, they're delivering the wrong pollen, and the native plant's seeds can't form properly. In an experiment, native flower pollination dropped by more than 80% in under a week of the invader arriving — long before anyone would notice a dramatic change in bee numbers.
Key Findings
Native hedge woundwort (Stachys sylvatica) stigmas in invaded habitats received approximately 3 times less of their own pollen compared to uninvaded sites.
Conspecific pollen deposition on native plants declined by 81.5% within just 4 days of experimentally introducing Himalayan balsam to a previously uninvaded site.
Bumblebees rapidly shifted to carrying pollen loads dominated by Himalayan balsam, disrupting pollen transfer to native flowers even without a large overall drop in pollinator visitation rates.
chevron_right Technical Summary
An invasive plant called Himalayan balsam can devastate the pollination of native wildflowers within just four days of arriving in an area, by hijacking bumblebees away from native plants and flooding their pollen-carrying capacity with its own pollen.
Abstract Preview
Biological invasions can disrupt plant-pollinator interactions by altering pollinator behaviour and pollen transfer dynamics, yet the mechanisms and timing of these effects remain poorly understood...
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Species Mentioned
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Impatiens glandulifera, Himalayan balsam, is a large annual plant native to the Himalayas. Via human introduction it is now present across much of the Northern Hemisphere and is considered an invasive species in many areas. Uprooting or cutting the plants is an effective means of control.