In a group of plants known for trapping their pollinators in death traps, one species offers its flowers as nurseries in return. The Kobe University discovery blurs the line between mutualism and parasitism and sheds light on the evolution of complex plant-insect interactions.

Many plants rely on animals for pollination and most offer rewards for service. However, some plants cheat on their pollinators, and a famous example is the genus Arisema. “It is famous as the only plant that achieves pollination at the cost of the pollinator’s life,” says Kenji SUETSUGU, a biologist at Kobe University. The plant uses a musky odor to attract fungus gnats, which usually lay their eggs on the mushroom in its cup-shaped flowers. Insects can escape from male flowers, but only after temptations that result in them being covered in pollen. However, there is no escape from female flowers. Once they enter them, the unwanted pollen carriers struggle to get out, which ensures that they will pollinate the flower, but they cannot cling to the waxy interior and perish. become

Suetsugu’s group has a “long-standing interest in race. Arisema, but we are also dedicated to challenging conventional ideas in pollination biology. It prompted us to look beyond apparent antagonisms and design experiments that could mask a more sophisticated interaction.” They collected male and female flowers of a particular species. Arisema Species A. thunbergiiand looked closely at both what types of insects were trapped and what happened to the flowers after pollination.

The surprising results have now been published in the journal Plants, People, Planet. The Kobe University team found that the main pollinator, a fungus called the mosquito Leah Ishitani, lays its eggs in the flowers and the larvae feed on the decaying flowers, which develop into adult fungus gnats that emerge after a few weeks. Additionally, they sometimes found mosquitoes emerging from flowers without the bodies of members of the species. This suggests that at least some insects are actually able to escape the trap. Suetsugu explains, “This discovery adds a new dimension to our knowledge of plant-insect interactions, but the most exciting aspect is that even in well-studied fields, there is still much to be learned. Nature is full of surprises!”

Suetsugu further explains, “The interaction between a plant and an insect is probably still different from other common examples of nursery mutualisms.” Fungus gnats are not exclusively dependent A. thunbergii As a nursery and thus those that become permanently trapped in the flower miss out on further opportunities to lay eggs elsewhere. Thus, interaction probably still comes at a cost to insects, but there is an aspect of mutualism that is not exemplified in other members. Arisema “We suggest that this interaction probably represents an intermediate stage in the evolution of nursery pollination mutualism,” says Janis Koby, a biologist at the University.

Such, A. thunbergii From cheating to mutualism may be an example of an unusual evolutionary process. However, the research team hypothesized that by looking more closely at other members Arisema Genus, similar interactions can still be found. Suetsugu says that his team’s result therefore “highlights the need to improve existing models of pollination biology beyond traditional mutualistic or illusory paradigms, thereby understanding more about the dynamics of plant pollination.” Helps in clear understanding.”

This study was financially supported by the Japan Science and Technology Agency PRESTO Program (JPMJPR21D6) and the Japan Society for the Promotion of Science Grants in Aid for Scientific Research (19H03292). This was done in collaboration with researchers from Showa University, the National Museum of Nature and Science Tsukuba, and the Forest Research and Management Organization.