Nematodes--Everything You Need to Know to Identify These Pests
By Hank Becker
March 21, 2001
New information about the anatomy of
microscopic worms called stunt nematodes could help scientists identify one or
more of the 111 known species in this class of destructive pests.
Stunt nematodes (Tylenchorhynchus spp.) are among the most costly
plant parasites. Overall, plant parasitic nematodes in the United States cause
annual economic losses estimated at nearly $10 billion from decreased food,
fiber and ornamental production.
Stunt nematodes damage the roots of field and vegetable crops. Once damaged,
plants become exposed to many destructive soilborne microorganisms and
pathogens. A major problem with determining the damage these nematodes cause is
inadequate knowledge of their distinguishing characteristics, numbers,
relationships and geographic distribution.
After several years of studying specimens and pertinent literature of all
described stunt nematode species, Agricultural Research Service
microbiologist Zafar A. Handoo--an expert on identifying nematodes at the
Laboratory, Beltsville, Md.-- recently completed an identification key.
This is the first accurate, all-inclusive guide to diagnose and identify all
known stunt nematode species. The research has been published in the Journal
Handoo examined and evaluated all the information on these species contained
in the USDA Nematode
Collection, one of the world's largest and most valuable archives of these
worms. It contains information on thousands of nematode species important to
agriculture. His compendium details the most important diagnostic
characteristics of each stunt nematode species.
Handoos key is based on the overall morphology--the external
features--of females, since males are not known in several species. In some
cases, he used the differences in male reproductive organs. In his key, he
identified the main characteristics useful in distinguishing species, such as
the shape of the lip region and shape of the tail. Further studies are needed
of the worms morphology, including scanning electron microscopy to
magnify male and female nematodes from a broader range of habitats.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.
Scientific contact: Zafar A. Handoo, ARS Nematology Laboratory,
Beltsville, Md., phone (301) 504-6666, fax (301) 504-5589,