Parasitic plant has some unlikely allies for pollination and seed dispersal

The discovery of a unique relationship between insects and plants has solved a longstanding mystery. For over a century, botanists have wondered how the tiny seeds of Balanophora were dispersed, and who the pollinators were – considering their less-than-attractive appearance and yeasty smell.

Researchers at Kobe University have revealed that insect species, such as ants and crickets, can both pollinate and disperse seeds for plants. This highlights the remarkable role that insects play in our ecosystems.

Mystery of Balanophora’s reproduction

Deep within the moist, shaded understories of the subtropical forests of Shimoshima Island in Japan, parasitic plants known as Balanophora thrive.

These plants, which depend on the roots of other plants for sustenance, have puzzled botanists. Among them, Balanophora subcupularis stands out for its dull colors and yeasty smell, contrasting with its bright red relatives that attract birds and mammals for seed dispersal.

Traditionally, researchers suggested that these plants relied on wind to disperse their seeds. However, the windless nature of these forest understories made this hypothesis unlikely.

Moreover, the mechanisms of pollination for B. subcupularis remained unclear, as its unremarkable appearance seemed to dissuade typical pollinators like bees.

Plants relying on insects for pollination

Kobe University botanist Suetsugu Kenji, who specializes in understanding the interactions between parasitic plants and their surrounding ecosystems, took on the challenge of uncovering the secrets of B. subcupularis.

Suetsugu and his team dedicated over 100 hours to observing the plants and capturing tens of thousands of automated nighttime photographs during the flowering and fruiting stages.

These observations were complemented by animal exclusion experiments and seed feeding trials to confirm which animals contributed to pollination and seed dispersal.

The results, published in two consecutive papers in the journal Ecology, revealed a surprising truth: ants and camel crickets are the primary pollinators of B. subcupularis. These insects, drawn by the plant’s pollen and nectar, also consume the fleshy seed-bearing leaves, effectively dispersing its seeds.

“It is well known that many plants rely on insects for pollination, although it’s rare for ants and crickets. Also, many plants use birds and mammals to distribute their fruits, and again it’s very unusual that crickets or other tiny arthropods take over this role,” noted Suetsugu.

“Even more striking, it is very rare for the same animal to perform both functions, and it is unique that the same invertebrates do so.”

Insects’ dual role in plant pollination

Suetsugu believes the dual role of ants and crickets is influenced by ecological factors.

“B. subcupularis blooms late in the year when many typical pollinators, such as bees, are less active. In addition, our study site is a small island at the northern edge of the plant’s distribution, which might contribute to the scarcity of pollinators and seed dispersers,” explained Suetsugu.

The insects’ involvement in both pollination and seed dispersal likely evolved due to these environmental constraints, where traditional agents like birds, mammals, and bees are scarce. This rare adaptation underscores the resilience and ingenuity of nature.

Significance of plant-insect relationships

The findings extend beyond the reproduction of B. subcupularis.

“This underscores the importance of invertebrates in plant reproduction and encourages us to look deeper into how these relationships evolve and what environmental factors drive such unique adaptations. More practically, our findings also contribute to conservation strategies for rare and endangered plants like Balanophora subcupularis,” Suetsugu noted.

“Understanding their reliance on specific invertebrates for both pollination and seed dispersal helps inform habitat preservation efforts and the management of invertebrate populations, which are crucial for these plants’ survival.”

Call to preserve unique ecosystems

This remarkable research on plant and insect interaction illuminates the intricate and often overlooked roles of invertebrates in ecosystems.

The study calls for greater attention to the conservation of such species, which play vital roles in maintaining biodiversity. By protecting the habitats and populations of these tiny but significant creatures, we can ensure the survival of plants like B. subcupularis and the ecosystems they support.

The story of ants and crickets aiding Balanophora subcupularis highlights a rare and remarkable partnership, providing a glimpse into nature’s adaptability and interconnectedness.

As researchers like Suetsugu continue to unveil these secrets, the importance of conserving even the smallest actors in our ecosystems becomes undeniably clear.

The study is published in the journal Ecology.

Image Credit: Hashiwaki Hiromu

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–