SOIL NEMATODE COMMUNITY STRUCTURE IN 2 TROPICAL PASTURES

Pastures in the semi-arid tropics of Honduras and the humid subtropics of Florida, U.S.A., were sampled ill 1991-92 to compare composition o f the nematode communities at the trophic group and genus levels under varying climatic conditions. Community structure varied (P less than or equal to 0.10) with location in both the dry and rainy seasons in 1 991. Seasonal fluctuations affected (P less than or equal to 0.05) com position of nematode communities at both locations. Composition of som e trophic groups within each community differed with location, while c omposition of other trophic groups were some what similar in Honduras and Florida. Cephalobus and Eucephalobus were the most abundant bacter ivores in Honduras, but Rhabditis sensu latu and Cervidellus predomina ted in Florida. Tylenchorhynchus sensu latu was the most abundant plan t parasite during the initial dry season in Honduras, but its percenta ge declined over time as Helicotylenchus and Criconemella increased; t he latter two genera were the most common plant parasites in Florida. Tylenchus sensu latu and Aphelenchoides were the most common fungivore genera at both locations. Predators and omnivores together comprised a very low percentage (less than or equal to 2.6%) of the soil nematod e community at both sites. In general, despite the geographic differen ces between Honduras and Florida, nematode community structure seemed to vary more with season than location.