When South American scarab beetles want a hot date they head for a bizarre flower that offers a steamy nightclub atmosphere, according to a new study.

The chamber is complete with heady perfume, sex-hungry mates, ample food and a quiet place to sleep it off the next day.

A team led by Professor Roger Seymour, of the University of Adelaide in South Australia, describes this floral nightclub today in the journal Nature.

The flower is a type of philodendron from French Guiana and has a lily-like flower that heats up. The warmth rewards visiting beetles by letting them conserve their own energy for eating and lovemaking instead of keeping themselves warm.

"The thing that makes this interesting is that it was always thought by botanists that flowers produce heat to make the scents they produce more pungent," Seymour told ABC Science Online.

Now textbooks will have to be revised, he said, because the research has shown that heat alone can be a powerful reward, as nectar and pollen can be. The payback for the flower is that the beetles spread its pollen to other flowers, promoting its own reproductive success.

Seymour said the team's initial interest in the flower, a species named Philodendron solimoesense, was to study its unusual capacity to regulate its own heat, as mammals and birds do. Some flowers generate heat by burning starch or fat as an unregulated by-product of high metabolic activity.

But the researchers discovered that the philodendron self-heated whenever the beetles were in its chamber. The beetles needed to use between two and five times less energy to remain active inside the flower as they did outside it.

Generating their own body heat comes at a significant energy cost to the beetles: "Partly because insects are small, the required increase in metabolic rate can be enormous: for example, it increases 16-fold in terrestrially active beetles," the report said. "A warming floral environment may therefore be a significant energy reward, enabling the insect to reduce the energy cost of its activity."

The team has now pieced together the strange relationship between the
philodendron and two species of scarab beetles.

The flower has a fleshy white stalk surrounded by a green shroud. The stalk consists of hundreds of much smaller parts known as florets. Those at the top are pollen-producing fertile male florets, while those at the base are fertile female florets. In between are sterile male florets that generate heat and provide tasty food rewards for the beetles.

To avoid pollinating itself, the flower times it so that female florets mature first.

As night falls, the flower heats up and its scent attracts many beetles. They quickly head into the shrouded chamber and spend the night energetically mating and feeding. The temperature inside the chamber can be several degrees Celsius warmer than the night air. As they move around, the pollen they carry on their bodies from another flower fertilises the female florets.

The beetles then sleep it off in the chamber the next day while the male florets rapidly mature and produce their pollen.

Just before dusk the flower contracts its shroud tightly, forcing the
beetles out to avoid being crushed. As the partygoers leave, their bodies are dusted with its own pollen, which they then carry to the next receptive flower to repeat the cycle there.

Seymour said self-heating flowers are widespread in tropical forests, with scarab beetles pollinating at least 900 species. He believes that heat rewards may have been even more important during the early evolution of flowering plants.

The source of the given news and copyrights belong to the ABC Online News

Back