Morphological characterisation of five Indian populations of root-knot nematode, Meloidogyne javanica (Treub, 1885) Chitwood, 1949

Five populations of root-knot nematodes, Meloidogyne javanica collected from Delhi, Haryana, Rajasthan, Tamil Nadu and Gujarat, were identified and characterised morphologically. In general, the body sue of the females and larvae was maximum in Rajasthan-population and minimum in Delhi-population. But, the neck size was minimum in the former and maximum in the latter. The females with longer necks tend to have bigger median bulb and its valve and its more posterior location from the head. Like wise in juveniles, the sue and location of median bulb, tail length and anal body width exhibited direct correlation with the body length. Inter-population differences were also evident in morphometrics of perineal patterns, stylet and oesophagous of females and second stage juveniles and tail of second stage juveniles. Among the various taxonomic characters, the perineal pattern, head and stylet morphology of mature females were the most reliable for precise identification of this species. Evaluation of morphometric characters indicated that stylet length, distance from head to stylet base, length and width of median valve, position of dorsal oesophageal gland orifice of females, length, width and ratio a of eggs were the least variable characters; length and width of median bulb and ratio a of females were moderately variable; while length and width of female body and its neck, distance from head to median bulb and ratio a of neck were highly variable characters. In second stage juveniles (J₂), body length, width, stylet length, width of median bulb, distance from head to stylet base, median bulb, median valve, excretory pore and oesophageo-intestinal junction, tail length, anal body width, ratios a, b, c' and b₁ were stable characters; distance from head to oesophageal gland base, length of median bulb and b' were moderately variable while position of dorsal gland orifice, 0%, hyaline part of tail and ratio were highy variable characters. Most of these characters were in conformity with the type description of M. javanica except for some variations, which have been discussed.