Final answer:
Anoplocephala spp., Gasterophilus spp., and Onchocerca cervicalis are all parasites transmitted by flies, with life cycles that generally involve the parasitization of horses, rather than transmission to cattle and pigs that usually occurs through the ingestion of contaminated vegetation as seen with Taenia saginata and Taenia solium.
Step-by-step explanation:
The Anoplocephala spp., Gasterophilus spp., and Onchocerca cervicalis are examples of parasites that have a life cycle involving a transmission via flies. These parasites vary in terms of the diseases they cause and their hosts. Anoplocephala spp. are cestodes, which are types of tapeworms generally found in horses and transmitted by orbatid mites.
Gasterophilus spp. are known as botflies; their larvae parasitize the stomach of horses and can cause gastrointestinal issues. Onchocerca cervicalis is a nematode that causes onchocerciasis, also known as 'neck threadworm', which affects horses and is transmitted by biting midges.
It should be noted, however, that cattle and pigs do not get infected by these particular organisms via flies, but rather through ingestion of contaminated vegetation as is the case for Taenia saginata in cattle and Taenia solium in pigs.