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A tiny nematode, Steinernema glaseri, is a golfers' best friend in the
battle against the destructive larvae of the Japanese beetle, Popillia
japonica. Commonly called "white grub," Japanese beetle larvae feast
on the roots of turf found on golf courses, cemeteries and homeowner's
lawns. The adults are serious pests of flowers, ornamentals, fruit and
fruit trees. The nematode kills the grub by entering its body through its
mouth parts. It then releases a bacteria, Xenorhabdus poinarii,
into the grub's bloodstream. The bacteria kills the grub within 24 hours.
The use of nematodes to control white grubs has been relatively successful
in field trials where S. glaseri killed up to 50 percent of the
white grubs in a 10-square-foot area. Scientists are currently perfecting
the delivery system for S. glaseri and hope to have it ready to
market to the public in the next two years.
Application Technology Laboratory, Wooster, OH
Michael Klein, (216) 263-3896
Natural strains of bacteria discovered by scientists could give dairy
producers new alternatives to insecticides that protect calves from stable
flies and houseflies. Flies infest the animals' sawdust bedding,
biting them and feeding on blood. This causes stress and slows the
calves' growth. In the bedding, however, ARS and Cornell University
researchers discovered 49 strains of Bacillus thuringiensis (Bt)
bacteria. At least two of the strains are previously unknown. In
preliminary tests, scientists fed the flies' immature offspring, or
larvae, a lab diet laced with Bt. The pests soon stopped eating and died,
because the bacterium makes a toxin that punches holes in their stomach
cells. The toxin is harmless to humans, animals and beneficial insects.
Once scientists identify the top candidate Bt's for commercialization, the
bacteria could be mixed in fly baits or sprays for calf pens and
bedding.
Insect Biocontrol
Laboratory, Beltsville, MD
Phyllis Martin, (301) 504-6331
Computers and a genetically engineered, glow-in-the-dark bacterium are
helping pave the way to a chemical-free, natural control for underground
fungi that attack plant seeds and roots. Eventually, ARS researchers
want farmers to be able to use seed coated with such natural strains of
bacteria as Enterobacter cloacae. The bacterium suppresses "damping-off"
diseases caused by the harmful fungus Pythium ultimum. However,
scientists need to pinpoint where, when and how the helpful--but
invisible--bacterium colonizes roots and persists in soil. The
scientists' approach began with inserting genes from a bioluminescent
bacteria species into E. cloacae. These genes allow the modified
bacterium to glow in the dark. This lets scientists do something
virtually impossible under field conditions. They can photograph the
bacterium's exact whereabouts in a laboratory "root box" used to study
root development. Next, they convert the photos into computerized images.
These are later color-coded to better distinguish seed, roots, soil and
bacteria. The scientists can then analyze the images to determine
bacteria's extent and location relative to plant roots.
Biocontrol of Plant
Diseases Laboratory, Beltsville, MD
Daniel P. Roberts, (301) 504-5680
The sex life of a tropical fungus may provide some insight into how
fungal genes control biological processes. Hypocrea
poronioidea, rediscovered during a biological survey of the rainforest
in Puerto Rico, is the seldom-seen sexual state of a genus of important
beneficial fungi, Trichoderma. Strains of Trichoderma are
used to produce enzymes that degrade fibers, or as biological controls of
plant diseases caused by other fungi. ARS scientists identified H.
poronioidea and grew it in the laboratory for the first time. They
recognized it as a species of Trichoderma, even though most
trichodermas are not known to have any sexual phase. Because the new
fungus goes through the whole life cycle, it offers the possibility of
studying how Trichoderma works as a biofungicide. Scientists may
also be able to improve Trichoderma species by sexual reproduction
to better fight crop diseases and may be better able to exploit the
commercial potential of Trichoderma species to produce enzymes that
degrade cellulose and lignin, key components in cotton and wood
fibers.
Systematic Botany and Mycology
Laboratory, Beltsville, MD
Gary J. Samuels, (301) 504-5364
Last updated: October 28, 1996
Return to: Quarterly Report
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