New research shows just how much plants and crops depend on a host of dark-dwelling creeping creepers.
When you think of pollination, you probably picture a beautiful butterfly or
bee flitting between flowers. But while these are indeed important pollinators, the natural world and food supply depend on a host of other creatures, some of which are far less attractive.
Most of the world's 350,000 species of flowering plants reproduce with the help of animal pollinators.
In recent years, pollinators and their importance to ecosystems have increasingly come under the spotlight due to dramatic declines in their numbers. Affected are
birds,
bats, bees, bumblebees and butterflies, with some populations declining by 80% or more. Causes include habitat loss, pesticides and
climate change.
Recent studies have also shown that pollinator diversity is as important to ecosystems and cultivated plants as pollinator numbers, and found that this diversity is declining for the same reasons.
Scientists estimate that 3-5% of fruit, vegetable and nut crops worldwide are lost due to inadequate pollination, which affects the availability of healthy food and threatens human health.
From cockroaches and beetles to tiny "sea bees," here are some of the most unexpected and sometimes frightening pollinators the world continues to rely on, even if people don't always notice them.
Cockroaches
Cockroaches are, in the words of one scientist, "one of the most despised creatures on Earth." But recent research shows that they play a useful and long-neglected role as plant pollinators - especially in darker parts of the forest that are often avoided by the more human-favorite bees and butterflies.
"Traditionally, pollination has been associated with bees, flies, moths and butterflies," said Kenji Suetsugu, a professor of biology at Kobe University in Japan. "But new research suggests that unexpected guests such as cockroaches may play an important role under certain conditions."
These "
alternative pollinators," he adds, are often especially important in environments where common pollinators are scarce, such as "
in dense, shaded undergrowth where light is limited and typical pollinators are rare." As soon as the first flowers bloomed from their buds at the beginning of
the chalky period, pollinators began to visit them. But it wasn't bees or butterflies that first landed on their petals.
Photo: bbc.com
In fact, a growing body of research suggests that cockroaches act as pollinators in a rich and diverse range of ecosystems, a role that has previously gone largely unnoticed because these creatures are nocturnal and less obvious in their interactions with plants than bees.
In recent years, there has been evidence of cockroach pollination of plant species such as Clusia blattophila of the genus Clusia, an evergreen shrub growing on rocky outcrops in French Guiana, and the rare endangered Hainan's Lastowen (Vincetoxicum hainanense) in China (a perennial liana), as well as others.
Suetsugu studied the role of cockroaches in the pollination of dense evergreen forests on Yakushima Island, a lush subtropical island off the coast of Japan. In particular, he was interested in cockroach pollination of the parasitic fungus-like plant Balanophora tobiracola of the genus Balanophora.
Because cockroaches are elusive and nocturnal, he used several tricks to better understand their interaction with this plant. For example, he placed a waterproof digital camera in front of one flowering plant that photographed it at 50-second intervals from dusk to dawn for about three weeks.
The resulting photographs - more than 34,000 images - showed that the cockroaches visit the flower at night. Suetsugu also photographed the cockroaches after they visited the plant to identify and count the number of pollen grains on their bodies.
To find out how a single cockroach visit affects the probability of the plant bearing fruit, he closed five flowers of the plant with fine netting and opened it for only one visit by the cockroach Margattea satsumana (the most frequent visitor to the plant) and then closed it again. He compared this with other treatments of the plant, such as closing the flowers with netting for the entire flowering period to exclude all pollinators.
The study, published in 2025, represents the "first direct evidence of effective pollination by cockroaches" of this plant species, says Suetsugu. "In the case of a single cockroach visit, nearly 40% of the flowers developed pollen tubes, which is a strong indicator of successful pollination."
Bugs
As soon as the first flowers bloomed from buds in the Early Cretaceous, they were visited by pollinators. The first to land on the petals were the pollination pioneers, which are thought to have had six legs and a tough, shiny shell. They were beetles.
The beetles remain important pollinators to this day, often visiting flowers with the most seemingly unpromising appeal - little nectar, greenish flowers, a pungent, possibly putrid odor - a set of signs known as "pollinator beetle syndrome."
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Despite millions of years of
evolution, beetles remain among the most frequent pollinators of primitive flowers dating back to the time of the dinosaurs, such as magnolias. And unlike better-known modern pollinators, many beetles like to work at night, flying or crawling to the warmth and delightful scent exuded by some beetle-specialized flowers, such as orchids from the Lowiaceae family in Borneo, which smell strongly of feces, a favorite treat of dung beetles.
Moths
Hovering above the flowers of wild tobacco, revellers (or hawk moths) unfurl their 8-centimeter-long proboscis to drink nectar, one of their favorite foods. In doing so, pollen grains magically penetrate air gaps of a few millimeters or even centimeters. There is a scientific explanation for this
During flight, moths build up so much static electricity that pollen is attracted to them through the air.
The fact that moths don't need to touch flowers to pollinate them makes them very good pollinators. Most pollination research has focused on daytime insects, but now researchers are studying what happens at night.
In 2023, scientists from the University of Sussex, UK, have discovered that moths may be even more effective pollinators than bees. The team studied day and night visits by pollinators to bramble plants, a species widespread in Europe that is important to pollinators for its pollen and nectar.
The study found that 83% of all visits were made during the day and only 17% under the cover of darkness (almost exclusively by moths), yet the moths were able to pollinate the flowers faster than their daytime counterparts.
Photo: bbc.com
The authors say nocturnal pollination is poorly understood. They say that because moths carry pollen from a wide variety of plant species, further research is needed to fully appreciate the role they and other nocturnal insects play in pollination.
Another recent study from the University of Sheffield (UK) found that moths account for a third of all pollination in cities. But the lack of native plant species and diversity of plant life in cities, combined with the stifling smell of air pollution, means that moths are still struggling to find food. Experts are now warning of an "alarming" global decline in moth numbers and diversity.
However, there are ways to help: plant white flowers, leave shrubs, coarse grass and rushes to grow, and turn off lights at night. It turns out that nocturnal pollinators like moths need protection as much as bees.
Bats
Bats are another often overlooked furry nocturnal pollinator. Although most bats feed primarily on insects, at least 500 plant species in the tropics and subtropics are pollinated primarily by nectar-eating bats.
Scientists say bat pollination (chiropterophilia) has advantages: their large size allows them to carry a lot of pollen at one time, and they fly longer distances than many other pollinators.
However, the large size of bats can also make their pollination energetically costly for plants.
Photo: bbc.com
One example is the endangered big-eared leafhopper found in the southwestern United States and Mexico. This bat feeds mainly on pollen and nectar from agave (from which mezcal and tequila are made) and various cacti, hovering over plants like a hummingbird. Along with the little long-nosed bat, it is the main pollinator of agave.
Like
agave, the pale flowers that leafhoppers feed on are often long and bell-shaped, and many bats have devised ways to get to the nectar found in their undersides.
An extreme example is the pipistrelle nectar bat, which lives in the cloud forests of Ecuador. About the size of an ordinary mouse, it has a tongue that is more than one and a half times the length of its body - the longest tongue-to-body ratio of any mammal - and is the only pollinator of plants with bells of this size. When tongue use is not necessary, the animal hides it in its rib cage.
In dispersed tropical habitats, nectar bats play an important role in maintaining populations of some plants as well as pollinating crops for farmers. However, researchers caution that the bats' status as a long-overlooked pollinator means there is a lack of knowledge about how much crop yields and crop quality depend on bats.
For example, a 2020 study found that bats are the primary pollinators of pitaya (pitahaya), a major crop in central Mexico, and that when bats were removed from pollinating the crop, yields dropped by 35%. Experts also warn that declining bat populations could lead to a decline in agave populations.
Bats also play an important ecological role for wild plants and crops around the world, being both seed dispersers and insect-eaters. Bat pest control has been found to help many crops around the world - from coffee in Costa Rica and cacao in Indonesia to rice in Thailand and cotton in the United States - and sometimes generates billions of dollars.
Like many other pollinators, bats are being affected by environmental changes around the world, and researchers warn that these changes are jeopardizing the pollination "services" provided by some bat species.
Sea bees
Despite their tiny, inconspicuous flowers, seagrasses are able to reproduce without the help of animals. For example, Thalassia testudinum, which grows in shallow waters in the Caribbean Sea, has tiny pollen-producing male flowers and female flowers that do not produce pollen. In coordinated cycles, the female flowers open, followed by the male flowers, which release pollen into the tide after sunset.
A decade ago, it was thought that this was the only way seagrasses pollinated, and that pollinating animals only visited flowers that bloomed outdoors. But in an experiment conducted at an aquarium in Mexico in 2016, ecologist Brigitta van Tussenbroek from the National Autonomous University of Mexico and her colleagues showed that marine crustaceans do in fact play a role.
Mostly marine crustacean creatures depend on ocean currents, but when the waters are calm, they are able to swim with purpose, for which they have been nicknamed "sea bees."
"With nightfall, many small organisms that had been hiding from predators during the day began swimming," she says. Most were barely visible crustacean larvae that swam up to male flowers to feast on the energy-rich pollen contained in the "slimy and sticky substance."
Photo: bbc.com
"Part of this substance and pollen adheres to their body parts as they swim around, and is also tossed up and down by the movement of the water," says van Tussenbroek. Female flowers have "tentacle-like snouts that capture small pollen-carrying organisms" and thus settle pollen grains. "These invertebrates are mostly dependent on the whims of ocean currents, but when the waters are calm, they can swim purposefully," she adds.
"This was a complete surprise," says van Tussenbroek, "And it also changed the general view that small free-ranging fauna play no role in sea grass pollination."
But perhaps even more surprising was the discovery in 2022 that tiny Baltic isopods help carry pollen-like "sperm" produced by red algae. Is this considered pollination if there is no pollen?
The researchers call it "animal-mediated fertilization" and wonder what it means for understanding pollination, which is thought to have originated about 130 million years ago when flowering plants first appeared on land.
The discovery suggests the possibility that such symbiotic interactions may have evolved quite separately on land and in water - and that animal-mediated fertilization may have occurred in the sea long before plants came ashore.
Do slugs and snails pollinate?
Suetsugu's study of Japan's forgotten pollinators may also help solve a 100-year-old mystery in the study of pollination: do slugs and snails pollinate plants?
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The idea that slugs and snails can pollinate plants is often mentioned in textbooks, but "there is surprisingly little reliable evidence," says Suetsugu. This type of pollination, known as malacophilia, sounds plausible: slugs and
snails glide over flowers, collect pollen, and carry it away.
However, given that snails and slugs eat flowers, it is unclear whether such visits ultimately help reproduction - or whether they devour flowers before they bear fruit.
A 2019 study by Suetsugu found that one slug species, the Valencia slug, the three-striped garden slug (Ambigolimax valentianus), carries pollen by means of thin strands of viscous mucus after visiting the flowers of the Rohdea japonica plant, but this does not result in fruiting.