Longidorus africanus

Taxonomy, Common Name, Disease

Scientific name - Longidorus africanus

Common name - needle nematode

Historical

First recognized as a problem in the Imperial Valley of California when growers initiated the practice of precision seeding of lettuce at discrete intervals to minimize need for thinning.

Hosts

Broad host range; best - sorghum, snap bean, lima bean, sugarbeet; good - barley, bermudagrass, corn, wheat, cotton, okra, lettuce, cucumber, eggplant, tomato, grape; fair-poor - oat, sunflower, alfalfa, pea, carrot, cantaloupe, crookneck squash, zucchini, watrmelon, pepper, spinach, spearmint, onion, broccoli, raddish, cabbage, cauliflower.

Distribution

Zimbabwe, Israel, South Africa, California. Occurs in desert regions of southern California (Palo Verde, Coachella, and Imperial Valleys).

Life Cycle

Migratory ectoparasite (all stages found outside of roots in soil). Feeds at root tips. Males are rare and reproduction is probably by parthenogenesis. First stage juvenile hatches from the egg. Adult to adult 7 to 9 weeks at 28 C. Egg to adult 4 weeks at 25 C. Can survive in fallow soil at least 3 months at 25 C.

Symptoms-Pathogenicity

Galls are formed at root tips. Devastating to seedling root systems.

Management

Preplant nematicides. Timing of planting of fall crops to avoid temperature conditions favorable to the nematode; plant when soil temperatures are below about 22 C.

Importance

Important pests of vegetables in southern California.

Characteristics

Longidorus - Very long, 2-11 mm, slender nematodes with a very long, 44-180 um, needle-like mouth spear (odonstyle) plus a rather weak basal extension (odontophore). Anterior esophagus narrow, cylindrical, posterior part a shorter but much wider, muscular, cylinder that abuts the intestine. Amphids large, pouch-like, but with minute apertures opening at the base of the lip region. A prominent single guide ring located around the anterior half of the odontostyle. Vulva about mid body with short, paired, opposed gonads with reflexed ovaries. Tails vary from short bluntly rounded to conoid. Male has massive, banana-shaped spicules without a gubernaculum but with small lateral accessory pieces; prominent copulatory muscles in the posterior region cause the tail end to curl ventrally when killed by heat; prominent ventral, supplementary papillae also present in the posterior region. Juveniles with two odontostyles, the second replacement one just behind and in line with the functional one.

References

  1. Jacobs, P.J.F. and J. Heyns. 1987. Eight new and two known species of Longidorus from South Africa (Nematoda: Longidoridae). Phytophylactica 19:15-33.
  2. Kolodge, C.M., J.D. Radewald, and F. Shibuya. 1979. A revision of the host range of Longidorus africanus from the Imperial Valley in southern California. Journal of Nematology 11:305.
  3. Radewald, J.D., J.W. Osgood, K.S. Mayberry, A.O. Paulus, and F. Shibuya. 1969. Longidorus africanus a pathogen of head lettuce in the Imperial Valley of southern California. Plant Disease Reporter 53:381-384.
  4. Evans, K., D.L. Trudgill, and J.M. Webster. 1993. Chapter 1. Extraction, Identification and Control of Plant Parasitic Nematodes. in Plant Parasitic Nematodes in Temperate Agriculture. CAB International, UK. 648 pages.