To answer the "plants producing antibodies" part:
in 1989 scientists developed a technique to genetically alter a
tobacco plant so it would produce monoclonal antibodies
Researchers had to adjust the West Nile virus antibody to adapt it for production in Nicotiana benthamiana, a relative of tobacco:
"We altered the genetic coding of ...
Biotic fruit fly pathogens / predators.
You don't need every single one for a basic project. Here are 2 types.
Parasitoid wasps lay eggs in larva.
Drosophila in the wild suffers massive mortality from the attacks of
parasitoid wasps. As many as 80% of Drosophila larvae in natural
environments may be killed by wasps that lay eggs in them. ...
Drosophila melanogaster. (fruit-fly, pomice-fly)
Image, public domain, via Wikipedia 2022.
Development time is under ideal conditions 8.5 days (at 25 Celsius, 77 Fahrenheit), the females produce perhaps 500 eggs per generation which can hatch in 12-15 hours - from the point of view of turnover, you should be able to observe many generations in a short-ish ...