Many growers are interested in the use of biological
control of pest mites. They are interested for a variety of reasons including
· the desire to reduce the use of pesticides,
· increase worker safety,
· increase plant quality, and, occasionally,
· to reduce pesticide application costs.
Many sites are not well situated for chemical control and may have restrictions
imposed by their sites. Examples of such are
· hospitals, etc.
In these sites, biological control may be an option. By its nature, biological
control generally requires low levels of the pest present in order to
sustain the natural enemy population. These low levels would not be desirable
for plants, which are to be sold or transported. A production nursery
might use a biological control program to suppress bamboo mites below
a damaging threshold, later to clean up their plants before sale with
There has been work to study and develop biological
control programs for bamboo mites. Zhang and colleagues looked at the
potential of Amblyseius cucumeris as a biocontrol agent against
S. nanjingensis (Zhang et al, 2000). A. cucumeris is most
readily known for its augmentative use against thrips. In their research,
the number of prey consumed by predators increased with density. This
numerical response is generally a good trait in predators helping to increase
the suppression of pest mites as the pest population increases. A.
cucumeris was not able to invade intact webs however, but was able
to stay and lay eggs in broken nests, which were common. Typhlodromus
bambusae Ehara is considered a specific predatory mite of the S.
celarius mites in Japan, but is not present in the United States (Saito,
1990b). Pratt and Croft, as well as this author, have looked at the management
of S. longus with an endemic predatory mite, Neoseiulus fallacis
(Garman) that is commercially available. N. fallacis was able to feed,
reproduce and develop on S. longus and significantly reduced the infestation
levels of S. longus (Pratt and Croft, 1999). It readily entered
nests of bamboo mite through natural openings or creating new holes.
This author has worked with Neoseiulus fallacis
in a number of nurseries on a variety of different plant types. It has
been successfully used to suppress
· two-spotted mites,
· citrus red mite,
· spruce spider mite, and
· bamboo mites in commercial operations.
The key to the successful use of biological control in these situations
is good scouting and releasing the mite at the proper threshold. We use
a very conservative threshold of one pest mite per every five leaves.
These low levels of pests are not usually noticed without a rigorous scouting
program. This particular predator mite requires 80% humidity easily found
in the canopy of bamboo grown in the Northwest.
There are a number of other predatory mites, which
might suppress bamboo mites and may deserve further investigation.
· Galendromis occidentalis, the western predatory mite,
may do better in hot, arid climates.
· Phytoseiulis persimilis is often used in greenhouses and
field releases for two-spotted mite. It tends to work very well at higher
densities of prey than controlled by N. fallacis but is not as
adapted to colder temperatures.
· N. californicus has been successful in many crops in California.
Research investigating inundative releases designed to eliminate the bamboo
mite might be useful.
Another consideration with the use of predator
mites, is the use of compatible pesticides if pest problems arise. There
is some data on chemical available for N. fallacis and other predator
mites. Suppliers of the predators may be the best source for this information
for particular predators.
Suppliers of Biological Control Agents:
of Beneficial Organisms in North America
Natural Biocontrol Producers