Meloidogyne hapla		Contents		Rev 07/02/2024
Northern Root-knot Nematode		Classification		Hosts
		Morphology and Anatomy		Life Cycle
Return to Meloidogyne Menu		Economic Importance		Damage
		Distribution		Management
Return to Meloidogynidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

 Tylenchida
       Tylenchina
        Tylenchoidea
          Meloidogynidae
           Meloidogyninae

           Meloidogyne hapla Chitwood, 1949

Northern root-knot nematode

Review general characteristics of the genus Meloidogyne.

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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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Distribution:

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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Feeding:

Sedentary endoparasite.

Feeding site establishment and development typical of genus.

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Hosts:

Type Host: Potato (Solanum tuberosum).

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

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Life Cycle:

Ecophysiological Parameters:

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

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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Damage:

Small spherical galls, often with root proliferation at gall.  

Some recorded yield losses include: 

• 36% on alfalfa in midwest (U.S.)
• 70% on peanuts in southeast (U.S.)
•  50% on carrots in northeast (U.S.)
•  20% on sugarbeets in Poland
•  46% on potatoes in Canada
•  64% on onions in Canada

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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Management:

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:

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References:

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: July 02, 2024.