Rev 11/11/2022
Tylenchina Tylenchoidea Pratylenchidae Nacobbinae
Nacobbus aberrans (Thorne, 1935) Thorne & Allen, 1944
Sugarbeet False Root-knot Nematode
Synonyms:
Pratylenchus aberrans
Nacobbus batatiformis
Nacobbus serendipiticus
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. batatiformis, N. serendipiticus and N. aberrans sensu stricto.
Molecular, morphological 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.
Caudal alae peloderan.
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 USA.
Also occurs in England, the Netherlands, South America, and Mexico.
Distribution of Nacobbus aberrans in Mexico, 2005
(Cid del Prado et al., 2005)
A-rated pest 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, respectively.
Bean, pepper, and tomato are among the most important hosts of this nematode in South America and Mexico.
Infests plants of the families Apiaceae, Brassicaceae, Cactaceae, Chenopodiaceae, Cucurbitaceae, Fabaceae, Solanaceae and Zygophyllaceae. It 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).
Ecophysiological Parameters:
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.
The 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. 2002)
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, 2001).
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).
In Mexico, 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 population densities.
In western Nebraska, complete destruction of sugarbeet seedlings has been observed in heavily infested fields.
[Ref: Inserra, et al. (1985).]
(photograph by Ignacio Cid del Prado Vera)
Nacobbus aberrans
Greenhouse-grown
tomato (cv El Cid)
Texcoco, Mexico
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 important.
Nematicides
Fumigants (e.g., Telone II) are most effective.
Non-fumigants, such as Aldicarb, oxamyl, and phenamiphos also look promising.
Host Plant Resistance
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. Dundee.
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.
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