The stages of development through which a plant or animal passes during its life. For mosquitoes these stages are: egg, larva, pupa, adult. Normally, development of nematodes included four moults and five successive stages as follows: Adult eggs • (fourth moult) ¯ • Fourth-stage larva First-stage larva • (third moult) (first moult) • Third-stage larva ¬ Second-stage larva (second moult) Generally, there are two types of life cycle for nematodes: direct and indirect types. 1. Direct Life Cycle: requires no intermediate host, after hatching from the eggs the larvae develop in the open from free-living to infective stages and gain access to the definitive host by mouth or penetration through skin. 2. Indirect Life Cycle: requires one or two intermediate hosts for development to infective stage.
Article Categories:Dictionary of Tropical Medicine