Relative susceptibilities of cyclops species from Rajasthan State to guinea worm (Dracunculus medinensis) larvae.

The role of eight different species of cyclops as intermediate hosts of Dracunculus medinensis has been studied by investigating their relative preferences for the ingestion of free-living larvae, the time required for larval penetration into the haemocoel, the number of larvae lethal to the copepods, and the threshold of tolerance for successful development of the larvae within the cyclops. On the basis of larval development up to the infective stage, four species of cyclops-Paracyclops fimbriatus, Thermocyclops oithonoides, Mesocyclops leuckarti sensu lato and Microcyclops varicans-were ranked as suitable hosts. Eucyclops serrulatus was partially refractory, and Tropocyclops prasinus and Ectocyclops rubescens were completely refractory. Guinea worm larvae were pathogenic to Macrocyclops distinctus.