Meloidogyne hapla




Rev 11/10/2022

Northern Root-knot Nematode Classification Hosts
Morphology and Anatomy Life Cycle
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           Meloidogyne hapla Chitwood, 1949

Northern root-knot nematode

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Morphology and Anatomy:


Meloidogyne hapla is identified by the cuticular markings in the perineal area of the mature female. The low upper arch; the lower arch often extended into lateral wings on one or both sides; and the punctations in the tail region are typical.


Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

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Temperate regions or at higher altitudes in warmer areas worldwide;  also occurs on alfalfa in southern California.


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Economic Importance:

C-rated pests in Californian Nematode Pest Rating System.


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Sedentary endoparasite.

Feeding site establishment and development typical of genus.

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Type Host: Potato (Solanum tuberosum).

Over 550 hosts listed by 1965; these include vegetables, clover, alfalfa, and ornamentals.

For an extensive host range list for this species, click


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Life Cycle:

Ecophysiological Parameters:

For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters


Minimum, optimum, and maximum temperatures (C) recorded for M. hapla:

Activity or Process Minimum Optimum Maximum
Hatch - 25 -
Mobility - 20 -
Invasion 5 15-20 35
Growth 15 20-25 30
Reproduction 20 25 -
Survival +/- 0 - -

Reproduction in M.hapla is usually parthenogenic but can also be sexual.  However, when sexual crosses were made between diploid and polyploid isolates of a population, some of the offspring were hermaphroditic (Triantaphyllou, 1993).  This is the only known case of hermaphroditism in the Tylenchida, although it is known in the Rhabditida and Mononchida.  It is considered an abberation in that hermaphrodites were morphological females in which the gonad initially produced eggs and then converted to sperm production.  By the time sperm were produced, eggs had a hardened shell and could not be fertilized.  That differs from Caenorhabditis elegans in which the gonad produces about 300 sperm late in the 4th juvenile stage.  Those sperm are stored in the spermatheca and fertilize eggs that are produced later.

Since M. hapla hermaphrodites produced only a few eggs before converting to sperm production, understanding the underlying mechanism could result in manipulation of the lifecycle to reduce population growth (Triantaphyllou, 1993).

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Small spherical galls, often with root proliferation at gall.  

Some recorded yield losses include: 

Meloidogyne hapla is also associated with other pathogens in disease complexes.

Meloidogyne hapla damage to carrots in Huamantla, Tlaxcala State, Mexico.
Root branching initiated by nematode damage at root tips.

Photograph by Ignacio Cid del Prado Vera


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Clean planting material by using hot water treatment (60 min. at 45.5 °C);  

Dips in DBCP were used on ornamentals when that nematicide was available. 

Crop rotation useful (grasses and cereals are often non-hosts). 

Host Plant Resistance, Non-hosts and Crop Rotation alternatives:

For plants reported to have some level of resistance to this species, click


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CIH Descriptions of Plant-parasitic Nematodes, Set 3, No. 31 (1974)

Triantaphyllou, A.C. 1993.  Hermaphroditism in Meloidogyne hapla.  Journal of Nematology 25:15-26.

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Copyright © 1999 by Howard Ferris.
Revised: November 10, 2022.