Nacobbus aberrans (Thorne, 1935)
Thorne & Allen, 1944
Sugarbeet False Root-knot Nematode
Nacobbus serendipiticus bolivianus
N. aberrans is considered synonymous
with N. batatiformis (Gerald Thorne called
Sher a fool in correspondence
over the taxonomy). However, there is considerable disagreement regarding
the taxonomy of N. aberrans (Sher, 1970; Baldwin & Cap, 1992) and
some consider N. aberrans sensu lato to include
N. serendipiticus and N. aberrans sensu stricto.
and host range studies suggest that N. aberrans
is a species complex with at least three
groupings. A North/South American group includes populations from
Mexico, Argentina and Ecuador; and two South American groups that include
one from Argentina and another from Bolivia and Peru. The latter has
been characterised as the original N. serendipiticus bolivianus
of Lordello, Zamith and Boock, 1961 now elevated
to species status as N. bolivianus.
saccate (0.8 to 1.4 mm long and 0.2 to 0.45 mm wide);
(Photographs by IgnacioCid del PradoVera)
Vermiform and of the same body length as females.
Spicules and gubernaculum.
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Nebraska, Wyoming, Utah, Colorado, Montana, South Dakota, Kansas in
Also occurs in England, the Netherlands, South America, and Mexico.
Distribution of Nacobbus aberrans in Mexico, 2005
(Cid del Prado et al., 2005)
in California Nematode Pest Rating System.
Nacobbus aberrans is economically important in temperate
and subtropical latitudes of North and South America. The host range,which
includes at least 84 plant species. Many common weeds are good hosts.
Populations can be separated into bean, potato and sugarbeet groups. The
populations of each group have distinct host preferences..Reported yield
losses reported average 65% for potato in the Andean region of Latin America,
55% and 36% for tomato and bean in Mexico, respectively, and 10-20% for
sugarbeet in the United States (Nebraska).
Ref. Manzanilla-Lopez et al. (2002).
Mature females penetrate roots, become swollen and sedentary, cause
formation of root galls and enlarged cells.
The feeding site is a multinucleate syncytium
formed by cell wall breakdown.
Nacobbus aberrans populations, which parasitize sugarbeet in the
western US do not parasitize potato. Similarly, populations in Mexico do
not parasitize potato. However, many South American populations infect
both potato and sugarbeet.
Potatoes, sugarbeets, beans, peppers, crucifers, Solanaceae, e.g., tomato,
but not Poaceae (grasses).
Nacobbus aberrans has a wide host range; important commercial crops
affected in South America and the United States are potato and sugarbeet,
Bean, pepper, and tomato are among the most important hosts of this nematode in South America
Infests plants of the families
is found on important food crops, such as cabbage, carrot, cucumber, lettuce,
mustard, pea, potato, sugarbeet and tomato (Canto, 1992).
The known host
range of N. aberrans includes: Austrian winter pea (Pisum sativum
var. arvense), sweetpotato (Ipomoea batatas), beet (Beta vulgaris),
broccoli, Brussel sprouts, cabbage, collard and kohlrabi (Brassica oleracea),
carrot (Daucus carota), cucumber (Cucumis sativus), egg plant (Solanum
melogena), grain amaranth (Amaranthus sp.), (Brassica oleracea),
lettuce (Lactuca sativa), mashua (Tropaeolum tuberosum),
ornamental gourd (Cucurbita pepo), pepper (Capsicum annuum
and C. baccatum), potato (Solanum tuberosum), prickly pear (Opuntia
sp.), pumpkin (Cucurbita maxima), spinach (Spinacia oleracea),
sugarbeet (Beta vulgaris), tobacco (Nicotiana tabacum), tomato (Solanum lycopersicum), turnip (Brassica rapa).
Other hosts may
be common weeds, including black mustard (Brassica nigra), chickweed (Stellaria
media), corn spurry (Spergula arvensis), fat hen (Chenopodium
album), fireweed (Datura ferox), ground cherry (Physalis),
London rocket (Sysimbrium irio), kochia (Kochia scoparia),
lambsquarter (Chenopodium album), nightshade (Solanum nigrum),
oregano (Origanum vulgare), puncture vine (Tribulus terrestris),
purslane (Portulaca oleracea), quinoa (Chenopodium quinoa),
saltwort (Salsola kali), and shadescale (Atriplex confertifolia) (Brodie,
et al., 1993; CAB International, 2001; Canto, 1992; Society of Nematologists).
Eggs are deposited in a gelatinous matrix;
some may be retained in the posterior part of the body. This is different
from N. dorsalis in which the eggs are
retained in the body.
first molt occurs within the egg; the J2 stage is infective and penetrates host
roots. Subsequent molts occur in either roots or soil. The immature
female moves to the root cortex and gall formation occurs as the nematode feeds.
The posterior of the female extends towards the outside of the root and eggs are
deposited in a matrix. Males may be entangled in the matrix suggesting
that copulation occurs after the feeding site is established and females have
started to swell. Reproduction in N. aberrans is probably sexual, although there
are some suggestions that parthenogenesis may occur (Manzanilla-Lopez et al.
Life cycle is approximately 48 days at 25 C.
In tomato crops in Mexico there are 3 generations: the first is completed
between 0 and 60 days after transplanting (d.a.t.),
the second at 60 to 100 d.a.t. and the third at >100 d.a.t.. (Cristobal,
Most favorable conditions for N. aberrans development include sand to
sandy-loam soils, temperature range between 15 and 23C and 5 and 19% soil
moisture (Cruz et al., 1987).
N. aberrans J3 and J4 survive under field conditions without a host for one year.
The J3 and J4 stages, possibly in an anhydrobiotic state, are the primary inoculum
infecting susceptible hosts the next year. Survival of J3 and J4 increases
if they are in root fragments. Eggs and J2 do not survive without a host or
under adverse conditions
(Cid del Prado et al, 2005; Stone and Burrows, 1985).
The degree of yield losses caused by this nematode depends primarily on soil
In western Nebraska, complete destruction of sugarbeet seedlings has been
observed in heavily infested fields.
[Ref: Inserra, et al. (1985).]
Ignacio Cid del Prado Vera)
Photographs by Ignacio Cid del Prado Vera
Exclusion: The ability of South American populations to adapt to many
hosts and to diverse conditions increases the risk of their establishment in new
locations. Exclusion efforts on a national and regional basis are
Telone II) are most effective.
such as Aldicarb,
oxamyl, and phenamiphos also look promising.
Host Plant Resistance
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
Baldwin, J.H. and Cap, G.B. 1992. Systematics of Nacobbus, the false
root-knot nematode. In: Gommers, F.J. and Maas, P.W.Th. (Eds).
Nematology from molecule to ecosystem. Europeann Soc. Nematologists.
Manzanilla-Lopez, R. H., M. A. Costilla, M. Doucet, J. Franco, R. N. Inserra,
P. S. Lehman, I. Cid del Prado-Vera, R. M. Souza, and K. Evans. 2002. The genus
NacobbusThorne & Allen, 1944 (Nematoda:Pratylenchidae):Systematics,
distribution, biology and management. Nematropica 32:149-227.
Manzanilla-López R.H. 2010. Speciation within Nacobbus:
consilience or controversy? Nematology 12:321-334.
Stone, A.R. and P.R. Burrows. 1985. Nacobbus aberrans. CIH 119.
Back to Top