Life Cycle

The life cycle of this root-knot nematode is around 30 days, depending on the temperature and suitability of the host plant.  Females can lay 300-500 eggs in masses protected by a gelatinous matrix.  These egg masses can be found inside the root or protruding from the plant tissue, depending on the size of the galls.  Small galls will normally result in external egg masses.  The embryos develop in the eggs for 7-10 days until a first-stage juvenile is formed. 

This first juvenile (J1) remains in the egg and continues to develop into a second-stage juvenile.  The second-stage juvenile (J2) hatches from the egg and moves to find a new infection site in the root.  Once a new infection is initiated, the subsequent juveniles will be sedentary or non-mobile.  The nematode induces the formation of a permanent feeding site termed a giant cell (GC), which is created by cell division without formation of cell walls between daughter cells, resulting in a large cell with multiple nuclei. 

The nematode infection also elicits abnormal root tissue growth around these feeding sites, or galls.  Galls are what give root-knots nematodes their common name because they appear as knots in the roots that are diagnostic.  Third (J3) and fourth (J4) juvenile stages continue to feed and develop in the root, and eventually differentiate into adult females or males. 

Males are large and vermiform, and they emerge from the root once they molt, living the rest of their lives without feeding.  Females are large and round, but remain in the root.  They continue to feed and grow, diverging resources from the plant toward its nutrition.  The reduction in yield results from this feeding and the energy that is invested in gall formation and from the impaired function of the roots.  Infected roots are less effective in water and nutrient uptake. 

Once fully developed, females start laying eggs in the gelatinous matrix that protects them from desiccation and infection by microorganisms.  Females do not require fertilization by the males to produce offspring. Adult females can only be found by sampling roots. Like with all root-knot nematodes, when only soil samples are taken, the stages that can be detected are eggs, second-stage juveniles and males.

Meloidogyne enterolobii has been observed to develop faster than M. incognita and M. javanica on tomato, which could explain why this nematode has the potential to be more damaging (Collett et al. 2019; english summary by J. Desaeger).