Dorsal esophageal gland opens into lumen of esophagus in metacorpus,
just anterior to the pump chamber.
Subventral esophageal glands open into lumen of esophagus in metacorpus,
posterior to the pump chamber.
Franklin and Siddiqi, 1972
The nematode has a slender stylet with small, distinct knobs.
Females: 0.66-0.75 mm long and slender.
Males: are as numerous as females.
provided a key to the four important
species related to A. fragariae. The key is useful
in that it provides characteristics to separate the four closely related
species (Allen, 1952).
Sanwal (1961) listed 33 species and provided a key.
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Aphelenchoides besseyi is widely distributed and occurs in most
rice growing areas (Ou, 1985). The known distribution of A. besseyi on rice
includes; Australia, Ceylon, Comoro Islands, Cuba, El Salvador, Hungary, India,
Indonesia, Italy, Japan, Madagascar, Mexico, Pakistan, Philippines, Taiwan,
Thailand, former USSR, and in most countries of central and West Africa (Ou,
1972; Franklin and Siddiqi, 1972). Aphelenchoides besseyi
has also been reported as the causal agent of false angular leafspot of
beans in Costa Rica (Barrantes et al., 2006; Salas and Vargas, 1984).
Aphelenchoides besseyi was first found in Japan in 1915.
In the USA the disease was first noticed in the southern United States in 1935
but was attributed to a nutrient deficiency (Ou, 1972).
Aphelenchoides besseyi has been reported in many Southern U.S.
states that produce rice.
White tip disease caused by Aphelenchoides besseyi, is an economic
problem in many countries. Recent detections of this nematode in
California have sparked the concern of California's rice industry.
From 1959 to 1996, A. besseyi was detected only twice in California
by CDFA Nematologists: once in 1959, in a quarantine strawberry sample
originating in Oregon, and the second time in 1963 in a fungal culture collected
in Butte county. Attempts to find the nematode again from the same field
were unsuccessful. A survey of the state by CDFA for the presence or
absence of A. besseyi in California paddy rice was initiated in
1997. It was intended that this survey would provide a sound basis for
certifying California paddy rice free of A. besseyi, and
thereby, eliminate the requirement by the government of Turkey for methyl
bromide treatments of export shipments. Sampling was designed to detect the presence of the nematode at
the county or rice growing region level and 170 samples were collected.
During the 1997 survey, one confirmed and three suspected findings of A. besseyi
resulted in four samples collected from two counties. These samples tested
negative when examined a second time. However, the government of Turkey
required that batches of rice intended for shipment to that country should be
sampled and certified to be free of the nematode. Between 1998 and 2001, A. besseyi has
been found in three such export loads. Those shipments were rejected,
resulting in millions of dollars in losses.
in California Nematode Pest Rating System.
At the state level there are no formal quarantine regulations implemented
against A. besseyi. There are no prohibitions for the import of
rice seed into California from other states within the US. At the federal
level, federal regulations have prohibited the import of seed and paddy rice
into the US since November 23, 1933. Milled rice can enter California.
Paddy rice exported to Turkey requires certification for freedom from A.
besseyi according to the Turkish Government pest control requirements.
In compliance with the Turkish government, certification is given on a per
shipment basis; each shipment has to be sampled and found free of A. besseyi
before it can be certified and shipped to Turkey.
False angular leafspot of beans is considered an important emergent disease
of beans in Costa Rica. In many areas of Costa Rica beans are grown in
rotation with rice (Barrantes et al., 2006).
Although A. besseyi is widely distributed in Brazil, economic
losses have rarely been reported. However, the frequent association of
A. besseyi with forage grass seeds in Brazil represents a phytosanitary
barrier for export to many countries. In addition, other morphologically
similar but non-pathogenic Aphelenchoides species are also
associated with forage grass seeds, leading to difficulty in attaining a
robust diagnosis (de Jesus et al., 2016).
Mainly ectoparasitic on buds.
Feeds at leaf tips and growing points in rice.
May feed endoparasitically in leaf mesophyll.
Rice is the most important host world wide.
On strawberry A. besseyi is the causal agent of 'summer dwarf'
or 'crimp' in the United States and Australia.
Other host plants include; onion, garlic, sweet corn, sweet potato,
soybean, yan chinese cabbage, sugar cane, horseradish, lettuce, millet, many
grasses, orchids, wishbone, chrysanthemum, marigold, mexican sunflower, african
violets, rubber plant, Hibiscus brachenridgii, and hydrangea
(Franklin and Siddiqi, 1972).
Aphelenchoides besseyi has also been reported as the causal agent of
false angular leafspot of beans in Costa Rica (Barrantes et al., 2006; Salas and
The following are listed as hosts in various literature sources:
Anhydrobiotic in dry tissues, under hulls of rice grains; viable after
This nematode is not thought to survive long periods in soil between
crops (Cralley and French, 1952).
This nematode is mainly ectoparasitic feeding on young tissue. At the
end of the growing season many nematodes are in a state of cryptobiosis under
the hulls of seed (Taylor, 1969).
Seed infected with Aphelenchoides besseyi is planted and the
nematodes become active and are attracted to the meristematic areas.
During early growth, A. besseyi is found in low numbers within the folded
leaf sheath, feeding ectoparasitically around the apical meristem (Todd and
Atkins, 1958). A rapid increase in nematode numbers takes place at late
tillering and is associated with the reproductive phase of the plant.
Nematodes are able to enter the spikelets before anthesis and feed
ectoparasitically on the plants reproductive structures. As grain filling
and maturation proceed, reproduction of the nematode ceases, although the
development of third stage juveniles to adult continues until the hard dough
The population of nematodes is predominately adult female which are normally
amphimictic, although parthenogenetic reproduction has been reported (Sudakova
and Stoyakov, 1967).
These nematodes coil and aggregate in the glume axis.
The optimum temperature for oviposition and hatch is 30C.
At 30C the life cycle is approximately 8-12 days and no development occurs
below 13C (Sudakova, 1968).
Aphelenchoides besseyi slowly desiccate as kernel moisture is
lost. They become anhydrobiotic dormant, and are able to survive in a
quiescent state on infested seed for long periods of time, from 8 months to 3
years (Cralley, 1949; Yoshi and Yamamoto, 1950). Survival is enhanced by
aggregation and a slow rate of drying (Huang and Huang, 1974), but the
infectivity of the nematode is reduced as seed age increases (Cralley and
In the rice seed-bed, emergence of severely infected seedlings is delayed and
germination is low.
The most conspicuous symptoms occur at the tillering stage (Taylor,
Yields of rice may be reduced 50%.
shown that different varieties of rice are affected to different degrees of
infestation. Yields have been reported to be reduced by 17-54% in
susceptible varieties and 24% in resistant (Atkins and Todd, 1959).
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
Hot water treatment of seed can be used to
destroy this nematode infecting the seeds (Atkins and
Todd, 1959). Pinherio et al. (1997), found that thermal
wet treatment was the most effective. Aphelenchoides
besseyi was not recovered from rice seeds which
received hot water treatment at 55-60C for 15 minutes,
but was observed in seed subjected to hot water treatment
at 50C (Gergon and Prot, 1993). Lower temperatures
(52-53C for 15 minutes) for hot water treatment have been
reported (Crawley, 1959; Tenente et al., 1994). At
temperatures reported for controlling A. besseyi,
no effect on seed germination or viability was reported
if seed was planted quickly.
Chemical treatments of seed have also been reported as
being effective in controlling A. besseyi.
Benomyl applied as a seed treatment reduced average
numbers of nematodes (Gergon and Prot, 1993; Templeton et
al., 1971). Thiabendazole has also been reported as an
effective seed treatment (Tenente and Manso, 1994). Carbofuran
(Tenente and Manso, 1994; Todd and Atkins, 1959)
and aluminum phosphate fumigation (Tenente et al., 1994),
are not effective chemical seed treatments for A.
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nematodes related to Aphelenchoides fragariae (Ritzema Bos,
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frijol: una enfermedad que avanza en Costa RicaManejo Integrado de Plagas y
Agroecologia (Costa Rica) No. 78, 2006
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nematodes in subtropical and tropical agriculture. Wallingford, UK: CAB
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(2013). Molecular characterization and functions of fatty acid and retinoid
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