Scientists discover moths’ nocturnal ‘pollination services’

The team installed 15 time-lapse cameras in the Swiss Alps to monitor pollinator visits to grassland plants.

From June to August 2021, the cameras tracked 36 red clover flowers, an important crop used as livestock forage.

The discovery highlighted previously unknown benefits of moths' night pollination on clover — an increase in seed production.

"This work may help deepen scientists' understanding of the pollination services provided by nocturnal moths," said Daichi Funamoto, a pollination biologist at the University of Tokyo, who was not involved with the new study.

Credit to cameras

Alison credited most of the team's discovery to the cameras.

"You can't feasibly have someone stand there for 24 hours and record consistently what is visiting a flower," Alison said.

"Fortunately, you can do that with cameras."

The researchers took more than 164,000 photos of red clover flowers, 44 of which included insect pollinators. Most of these nectar-seekers, 61 percent, were bumblebees.

However, a sizable proportion — 34 percent — were moths with large yellow underwings called Noctua pronuba, visiting in the early morning hours.

Butterflies, wasps, and other bee species accounted for the remaining five percent of visits.

It's clear "the role of nocturnal moths as pollinators of crops has largely been neglected," Funamoto said.

"I think future studies will reveal many plant species that are thought to be dependent on pollination by diurnal insects are indeed pollinated by nocturnal moths, to some extent."

Alison and his colleagues are now attempting to replicate their findings at different European latitudes to confirm that N. pronuba moths pollinate red clover in other locations.

The researchers also plan to install artificial intelligence AI-driven programs in cameras to recognize and quickly classify the type of pollinator paying a visit.

"The future isn't just cameras," Alison said. "But cameras should be a big part of it."

Study abstract

Recent decades have seen a surge in awareness about insect pollinator declines. Social bees receive the most attention, but most flower-visiting species are lesser known, non-bee insects. Nocturnal flower visitors, e.g. moths, are especially difficult to observe and largely ignored in pollination studies. Clearly, achieving balanced monitoring of all pollinator taxa represents a major scientific challenge. Here, we use time-lapse cameras for season-wide, day-and-night pollinator surveillance of Trifolium pratense (L.; red clover) in an alpine grassland. We reveal the first evidence to suggest that moths, mainly Noctua pronuba (L.; large yellow underwing), pollinate this important wildflower and forage crop, providing 34% of visits (bumblebees: 61%). This is a remarkable finding; moths have received no recognition throughout a century of T. pratense pollinator research. We conclude that despite a non-negligible frequency and duration of nocturnal flower visits, nocturnal pollinators of T. pratense have been systematically overlooked. We further show how the relationship between visitation and seed set may only become clear after accounting for moth visits. As such, population trends in moths, as well as bees, could profoundly affect T. pratense seed yield. Ultimately, camera surveillance gives fair representation to non-bee pollinators and lays a foundation for automated monitoring of species interactions in future.