Interactions with animals
It is well known that Ceropegia spp. are pollinated by small to very small flies from several families, so it is not really a surprise to find predatory invertebrates like spiders at the flowers or near the flowers.
One such example can be found on page 14 in P. G. Archer’s ‘Kenya Ceropegia Scrapbook’ from 1992, where a crab spider is photographed sitting very prominently close to a flower of a Ceropegia abyssinica Decne. ready for action.
When Prof. J. Ollerton, who investigates pollinators and pollinator-plant-interactions in great detail, dissected flowers of ca. 50 years old herbarium specimens of Ceropegia nilotica Kotschy, he did not only found dried flies on occasion but discovered in one of the flowers two (unidentified) ants – caught in the act; one of them still had a part of a fly wing in its mouth parts, meaning it has been collected and preserved in the act of eating one of the probable pollinators!
Well, this is obviously still the only known case of ants eating flies inside a Ceropegia flower so far, I personally do not know of any other one.
But of course it leads to several questions:
Does that occur more often?
Does that occur all over Ceropegia’s range?
Which ant species are involved?
… and so on ….
BTW: According to a very recent study, Ceropegia nilotica mostly attracts flies from the genus Desmometopa, so-called freeloader flies (family Milichiidae), and from the genus Forcipomyia, biting midges (family Ceratopogonidae). 
… more of that is coming soon ….
 Jeff Ollerton: Fly trapping in Ceropegia flowers – evidence of ant-predation on pollinators. Asklepios 77: 31-32. 1999
 Annemarie Heiduk; Irina Brake; Michael v. Tschirnhaus; Jean-Paul Haenni; Raymond Miller; John Hash; Samuel Prieto-Benítez; Andreas Jürgens; Steven D. Johnson; Stephan Schulz; Sigrid Liede-Schumann; Ulrich Meve; Stefan Dötterl: Floral scent and pollinators of Ceropegia trap flowers. Flora; puplished online: 1-Feb-2017