Meloidogyne hapla

Meloidogyne hapla	Contents	Rev 10/07/2008
	Classification	Hosts
	Morphology and Anatomy	Life Cycle
Return to Meloidogyne Menu	Economic Importance	Damage
	Distribution	Management
Return to Heteroderidae Menu	Feeding	References
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Classification:

Tylenchida
       Tylenchina
        Tylenchoidea
         Heteroderidae
          Meloidogyninae
           Meloidogyne hapla

Northern root-knot nematode

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.

Distribution:

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

Feeding:

Sedentary endoparasite.

Feeding site establishment and development typical of genus.

Hosts:

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

Life Cycle:

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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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.

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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).

There are few recorded sources of host-plant resistance.