Anguina tritici
Taxonomy, Common Name, Disease
Historical
Hosts
Distribution
Life Cycle (Text) (Diagram)
Symptoms-Pathogenicity (Text) (Photos)
Management
Importance
Characteristics
References
Taxonomy, Common Name, Disease
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Scientific name - Anguina tritici
Common Name - Seed and leaf gall nematode
Historical
Anguina contains the first 3 recorded plant parasites: A. tritici in 1743 by Needham, A. agrostis from seed galls of bentgrass by Steinbuch in1799, and A. graminis from galls on grass leaves by Hardy in 1850. GO BACK
Hosts
Wheat, and rye. Oats and barley have been recorded as hosts but little or no reproduction occurs on them. Oats may be attacked and severely deformed at seedling stage. GO BACK
Distribution
Major wheat growing regions of five continents. GO BACK
Life Cycle (Diagram)
Sedentary endoparasites, diploid and amphimictic. Each female lays up to 2,000 eggs within galls. The life cycle follows the standard pattern with 4 molts. The final molt in both sexes occurs only after galls have formed. The adults die soon after oviposition; the eggs hatch quickly and first stage juveniles molt to second stage. By harvest galls contain only second stage juveniles which are very resistant to dessication and have been revived after 28 years storage. If galls are sown with seed, second stage juveniles emerge in moist soil, invade host seedlings and feed ectoparasitically on the tissues of young leaves near the growing point. The galls are shed from the ears more readily than the grains so many fall out during harvest and infest the soil. Each gall contains at first up to 40 or more adults of each sex which produce up to 30,000 or more eggs and/or juveniles. GO BACK
Symptoms-Pathogenicity (Photos)
Infested seedlings are more or less severely stunted and show characteristic rolling, twisting and crinkling of the leaves with consequent growth distortion. Infested ears are generally undersized, shorter and thicker than healthy ones. Some or all of the grains are replaced by galls. GO BACK
Management
The most effective control is by modern mechanical seed cleaning which eliminates the galls. Formerly they were separated from grain by flotation in brine or even in plain water. Wheat and rye should not be sown in infested fields. In moist conditions absence of host plants for one year is sufficient to free the soil from A. tritici, but under conditions of prolonged drought the galls can remain viable for many years. GO BACK
Importance
Formerly caused heavy losses but, due to modern seed cleaning methods that separate galls from healthy grains, has become extinct or rare in most areas. GO BACK
Characteristics
Anguina - Obese, 1.5 to 5 mm long, coiled ventrally when killed by heat. Vulva in posterior fifth of body with single, anterior, reproductive tract, reflexed twice or more anteriorly, where the oocytes are in multiple rows, a short post-vulval sac present. Tail short, conoid. Male somewhat shorter and much thinner than female, slightly curved when killed by heat, tail about two anal body widths long and a bursa and prominent arcuate spicules; testis filling most of the body and reflexed anteriorly. Lip region of all stages low and flattened, head skeleton weak, stylet weak about 10 um long in adults with small basal knobs. Body annules indistinct on adults. Esophagus with median bulb with refractive thickenings; basal bulb of adults enlarged and irregular in shape in mature adults. Adults found only in plant stem or inflorescence galls. GO BACK
References
