Identification and diversity of the root-knot nematodes affecting yam (Dioscoreaspp.), in Nigeria

Root-knot nematodes, Meloidogyne spp.
represent an important threat to yam (Dioscorea
spp.) production in West Africa. With the aim
to characterize the species affecting yam
plants, for control and resistance screening
purposes, surveys were conducted in the main
yam producing areas. Infected, galled tubers
were collected from farmers and markets in 12
states in Nigeria. To trap Meloidogyne species,
infected yam peels were inoculated in a ring
surrounding the root system of susceptible
tomato cv “Ibadan local” and celosia plants.
Young egg-laying females were extracted from
roots of infected tomato and or celosia plants
and used for enzymatic (Esterase: EST and
Malate dehydrogenase: MDH) analysis with
PhastSystem. Out of 46 populations examined,
results revealed that yam tubers were mostly
64 6th International Congress of Nematology
infested by Meloidogyneincognita (68%), followed
by Meloidogyne javanica (16%), Meloidogyne
enterolobii (2%) and Meloidogyne arenaria (5%).
In most of the samples, tubers were infected by
a single species. However, in 9% of the analysed
samples, mixed populations of M. enterolobii
and M. incognita (7 %) and M. enterolobii, M.
incognita and M. javanica (2 %) were recorded.
The distribution of the Meloidogyne spp. in the
main yam producing areas is discussed. This
constitutes the first report of M. arenaria and M.
enterolobii on yam in West Africa.