The Biodôme presents a number of ecosystems from the Americas, each with its own climate and physical environment. This design, incorporating both living and non-living components, represented an enormous conceptual, biological and technological challenge.
The landscapes in the Biodôme's ecosystems may look real, but the cliffs, cave, rocks and even the giant trees in the Tropical Rainforest are made of concrete, a remarkably versatile material. All the rocks are artificial and hollow, for several reasons:
- Structural: the site would not be able to support the enormous weight of all these rocks if they were real.
- Conceptual: to enable us to create the landscape we wanted.
- Technical: most of the infrastructures required to keep the ecosystems functioning (water, heating, etc.) are concealed within the rocks.
Similarly, the six giant trees in the Tropical Rainforest, as well as contributing to the illusion of a mature forest, serve structural and technical functions:
- They hold up the glass roof over the ecosystem.
- They emit warm air full of “clean vapour,” to help maintain the proper humidity.
- They spray fine water droplets onto the foliage (misting).
Creating a rock, Biodôme style
- Use metal rods to make the frame.
- Cover with concrete and fibreglass moulds taken from real rocks.
- Fill in the cracks with sprayed concrete.
- Then come the artists! Work the concrete with trowels and chisels …
- … and add the finishing touches of colour, working with fine brushes.
Did you know?
The Biodôme's rocks even reproduce the correct rock formations from the natural ecosystems:
- limestone in the Tropical Rainforest;
- gneiss in the Laurentian Maple Forest;
- granite in the Gulf of St. Lawrence;
- schist in the Labrador Coast;
- basalt in the Sub-Antarctic Islands.
The “forests” at the Biodôme are very attractive to insects and other arthropods fond of plants. Several species of spider mites, whiteflies, mealybugs, scale insects, aphids, thrips and borers attack the plants. How best to stop their ravages?
Highly toxic pesticides are out of the question because of the presence of animals in the ecosystems. We can use some low toxicity chemicals such as soap, horticultural oil and growth hormones, but their effectiveness is limited.
Instead, the Biodôme relies on biological control, or the introduction of natural enemies of the pests into the ecosystem. These may be predators, parasitoids or microorganisms such as certain types of fungi.
Watching for harmful insects
The predators used are carnivorous insects or acarids, which feast on various kind of prey during their lifetimes.
- Aphidoletes aphidimyza, a type of fly whose orange-coloured larvae are very effective predators of aphids, is raised in British Columbia for biological control.
- The Haplothrips subtilissimus (thrips) larvae help control spider mites in the Laurentian Maple Forest.
- Parasitoids are insects that lay their eggs on or in other insects. The larva consumes its prey from within, and emerges as an adult.
- Various kinds of parasitoid wasps are used in biological pest control; for instance, Leptomastix dactylopii is effective against citrus mealybug.
Sometimes, plants bring their own protection with them when they arrive. This was the case for the plants imported from Florida for the Biodôme's tropical forest. In just a few months, most of our sap-sucking scale insects that had hitched a ride on the plants were eliminated by their natural enemies that came with them.
In another case a fungus that was present in one of the aphid species in the Biodôme's Tropical Rainforest spread rapidly due to the hot, humid conditions and wiped out that aphid. In the Laurentian Maple Forest, a species of thrips native to Quebec came in from outside and colonized the forest, helping us control the spider mites that attack our birch trees.
Biological control agents are usually easy to come by because companies in Canada, the United States and Europe raise them for sale to agricultural producers.
But the Biodôme's forests are sometimes afflicted by pests that are uncommon or even unknown in an agricultural context. So we often have to test the commercially available predators against these new pests or find other natural enemies, either in the wild or in co-operation with research laboratories.