Hello Katrin:

Gonium is a genus of colonial algae, a member of the order Volvocales. Most aquatic insects are opportunistic feeders, ingesting a wide variety of food items available in their environments, including algae. For example many stoneflies, caddisflies, mayflies, and aquatic beetles that inhabit rivers and streams  feed on both algae and organic matter associated with a given microbiota. 

Algae is also an important autotrophic food item, included in the diet of  aquatic insects of different trophic groups, e.g., herbivores, periphyton feeders, and omnivores. However, a diet based exclusively on algae is  only found in caddisflies. Four your lab experiments you can try larvae of different species of caddisflies collected from freshwater streams and rivers.

If you think this answer is useful please recommend it.

Regards,

Luis Miguel

Hi Katrin, have you tried Didinium? A PhD student in the lab got Didinium from a culture collection, and it was meant to eat Paramecium only, but it seems to go after my Chlamy(domonas) strains happily enough, so it might accept your Gonium samples, too? Did you grow your Asplanchnas in EPA? And they didn't like it? Maybe they miss something from their native pond water? I don't know a culture collection that stocks Asplanchna in axenic or reasonably clean samples, but sciento have mixed rotifer cultures that can include Asplanchna depending on the season. and maybe some laboratories that use them routinously keep them in permanent culture? Hope this helps, 

Best, 

Elisa