''Aphelenchoides besseyi'' is a plant pathogenic nematode. It is sometimes referred to as ''rice white tip'', ''spring dwarf'', ''strawberry bud'', ''flying strawberry nematode'' or ''strawberry crimp disease'' nematode. This foliar nematode is found in

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North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north ...

, Central, and South America,

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, and Pacific islands.Bridge, J., and Jim L. Starr, Plant Nematodes of Agricultural Importance - A Colour Handbook. 2007.McGawley, E.C., M.C. Rush, and J.P. Hollis, Occurrence of Aphelenchoides besseyi in Louisiana Rice Seed and Its Interaction with Sclerotium oryzae in Selected Cultivars. J Nematol, 1984. 16(1): p. 65-8.Hoshino, S. and K. Togashi, Effect of Water-Soaking and Air-Drying on Survival of Aphelenchoides besseyiinOryza sativa Seeds. J Nematol, 2000. 32(3): p. 303-8.

Morphology

''A. besseyi'' has a well-developed and distinct metacorpus. The stylet is small with well-developed knobs. The tail has a mucro with three points. Males have a rose thorn spicule and no bursa.

Life cycle

The nematodes survival stage is to remain anhydrobiotic in seed until planting. As surrounding plants grow the nematodes become active and feed on meristematic tissue. ''A. besseyi'' reproduces

amphimictic Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote that d ...

ly although

parthenogenesis Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...

can take place. As the plant begins to reach reproductive maturity the number of nematodes increases dramatically. The nematodes migrate to feed on reproductive structures eventually settling in the developing rice seed. As the kernel dries the nematode slowly desiccates and can remain viable in the kernel for up to three years. The life cycle of ''A.besseyi'' is generally short consisting of around 8–12 days. This species is

thermophilic A thermophile is an organism—a type of extremophile—that thrives at relatively high temperatures, between . Many thermophiles are archaea, though they can be bacteria or fungi. Thermophilic eubacteria are suggested to have been among the earl ...

. The lower threshold for development is and the optimum temperature varies between . The sum of effective temperatures for the development of one generation is 80 degree-days.AgroAtlas
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Host-parasite relationship

''A. besseyi'' is an

ectoparasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

nematode which means it feeds on the plant tissue externally. This nematode is most often associated with a disease in which the leaves of the rice plant turn white in the

meristem The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells conti ...

atic regions followed by necrosis.Adamo, J.A., C.P. Madamba, and T.A. Chen, Extracting the Rice White-Tip Nematode, Aphelenchoides besseyi, with Match Sticks. J Nematol, 1976. 8(2): p. 178-9. These nematodes can also cause stunting and sterility with yield losses of up to 50% reportedHoshino, S. and K. Togashi, A Simple Method for Determining Aphelenchoides besseyi Infestation Level of Oryza sativa Seeds. J Nematol, 1999. 31(4S): p. 641-3.

Management

The most common management practice for ''A. besseyi'' is to maintain clean seed stocks. Since the nematode survives in the seed it is fairly easy to control. Seed can be chemically treated to kill nematodes or can be cleaned using a method in which the seed is initially soaked in cool water to activate the nematode and then briefly soaked in hot water to kill them. These seeds can then either be directly planted or quickly dried for storage.

References

{{DEFAULTSORT:Aphelenchoides Besseyi Agricultural pest nematodes besseyi Nematodes described in 1942