Here on Earth, we have a number of primary producers:
- Plants and other photosynthetic organisms, which convert sunlight into chemical energy.
- Chemotrophs, which get energy (via a few intermediate steps) from geothermal activity.
What are the primary producers of Arrakis? The planet receives a lot of sunlight, and is geologically active, but I do not know of any organisms in the Dune canon that use either of these energy sources.