Interactions of Helicotylenchus dihystera, Pratylenchus pseudopratensis, and Tylenchorhynchus gladiolatus on Two Plants from the Soudano-Sahelian Zone of West Africa

Interactions between Helicotylenchus dihystera, Pratylenchus pseudopratensis, and Tylenchorhynchus gladiolatus were studied on millet (Pennicetum typhoides) and acacia (Acacia holosericea). Interactions between H. dihystera and P pseudopratensis were similar on both plants; reproduction of each was lower when the other nematode species was present. T. gladiolatus reproduction was stimulated in the presence of the other species on millet, whereas it was inhibited on acacia at the lowest inoculum levels (50 and 200 nematodes/plant). Damage to plants was not density dependent. Damage to millet differed with the species composition of the community. Only monospecific populations of T. gladiolatus and P. pseudopratensis significantly reduced the millet biomass, particularly the root system. H. dihystera reduced the pathogenicity of the two other species on this plant. Each nematode assemblage suppressed dry shoot and root weight of acacia; most assemblages reduced the number of Rhizobium