TABLE CONTENTS

SESSION FIFTY – RENIFORM, LESION AND FALSE ROOT-KNOT
NEMATODES
CONVENORS: AN MACGUIDWIN & MARCELO DOUCET
Nacobbus aberrans Thorne, 1935) Thorne & Allen, 1944 in Argentina
Doucet, M.E. & P. Lax
Centro de Zoología Aplicada, Universidad Nacional de Córdoba, C.C. 122, 5000, Córdoba, Argentina
In Argentina, the false root-knot nematode is represented by populations with origin in
cultivated and uncultivated areas. The sites where the species is found are located in very
diverse geographical areas that are subjected to highly different conditions and climates.
There seems to be some correlation between each one of these populations and their
geographical origin as well as the host on which they multiply. Clear differences among
populations have been observed so far through comparisons that considered diverse
parameters. Thus, for example, based on morphometrical characters, grouping of populations
raised on the same host have been detected. Furthermore, a genetic structure analysis showed
that populations tended to group together according to their original host, revealing a certain
degree of similarity among populations originated in the same host. When considering the
evaluation of the reproductive capacity of populations multiplied on different plants under
controlled conditions, different behaviours were observed. Such differences were recorded
both among populations for a single host and among plants for a single population. These
studies confirm the existence of biological entities of different agricultural importance within
the species that would show preferences for certain hosts. The great variability that N.
aberrans shows in relation to its host/s indicates the need for detecting an accurate
differential host test that will be useful to establish suitable management strategies and to
gain knowledge on associations between populations.
Basic Biology of Rotylenchulus reniformis on Cotton
Lawrence, K.S., G.W. Lawrence, S.R. Moore, J.D. Castillo, N. Sekora & J. Thompson
Auburn University, Alabama, USA
Basic biological questions of Rotylenchulus reniformis currently being evaluated at Auburn
University include: 1) the potential vertical, horizontal and temporal movement of this
nematode under irrigated and non-irrigated field conditions; 2) the effect of enhanced
seedling plant vigor on nematode numbers; 3) the identification of nemaphagous fungi
pathogenic to R. reniformis; and 4) the evaluation of FAME analysis for identification of R.
reniformis. Vertical movement of both R. reniformis was observed to migrate from the initial
2.5 cm depth placement to a depth of 91cm in irrigated and non-irrigated tests. Movement of
R. reniformis males was affected by irrigation, with males in the irrigated test migrating twice
the distance of males in the non-irrigated test. Populations of vermiform females and
juveniles were higher in the inoculated row while higher populations of males were found
dispersed in adjacent rows. Nitrogen and Nitrogen plus Phosphorus starter fertilizer
applications applied to cotton at planting produced fewer R. reniformis per gram of root in
greenhouse evaluations as compared to the control. Fungi found associated with vermiform
R. reniformis life stages and eggs across the state include: Arthrobotrys dactyloides,
Paecilomyces lilacinus, Fusarium oxysporum and Dactylaria brachophaga. Pathogenicity
5 th International Congress of Nematology, 2008 182