Five copepod species, Acantocyclops robustus, Macrocyclops albidus, Mesocyclops annulatus, Thermocyclops sp. (all Cyclopoidea) and Argyrodiaptomus bergi (Calanoidea), were evaluated under laboratory conditions as potential predators of preparasites of the mermithid nematode Strelkovimermis spiculatus. Adults of all five copepod species consumed 70-100% of the preparasites within 24 h. Copepodids and adults of M. annulatus predated upon 93 and 100% of the nematode pre-parasites, respectively. An average of 197 pre-parasites was daily predated upon by an adult M. annulatus. Copepod density affected prevalence and intensity of S. spiculatus on mosquito larvae. Prevalence and intensity of S. spiculatus on Aedes aegypti larvae was reduced from 98% and 2.8 nematodes per larva in control containers free of copepods to 61.4% and 1.4 nematodes per larva in containers with 50 M. annulatus females per l.