0851996884.pdf

trol agents based upon fungi and bac-
uloviruses (BV) depend on the successful com-
pletion of a complex infection process by the
pathogen. Monitoring the quality of microbial
control agents, therefore, can be more complex
than with chemical insecticides. A biocontrol
product that has an infectious agent as the
active ingredient is the result of a complex
biotic process, whether manufactured using in
vitroor in vivotechnology. The quality-assess-
ment procedure of the final product needs,
therefore, to extend back to all levels of the
production process, including any insects or
cell lines used to multiply the agent.
Given the crucial role of quality control in
fungal and viral production, it is a matter of
concern that standardized protocols for the
quality control of these products are not yet
widely agreed or accepted, a situation similar
to that in the production of natural enemies
(Chapters 1, 2 and 19). Even where regulatory
procedures for registration of fungal and viral
control agents are enforced, no standardized
guidelines for quality control procedures are
available. Manufacturers of these microbial
control products are therefore required to
develop their own quality control procedures,
which has resulted in a disparity in standards
between manufacturers of similar products.
Further, in those countries where registration
of microbial control products is not enforced,
manufacturers are not obliged to develop or
conduct any quality control procedures.
There are reports that a number of fungal
and viral products are failing to meet accept-
able standards (Grzywacz, 1995; Kern and
Vaagt, 1996). Unless this matter is addressed
effectively, there is a serious danger in these
countries that poor-quality products, with
their inevitable failures, will erode farmer
confidence in microbial control products and
significantly retard the promotion of this
promising technology.

Production and Quality Control of

Fungal Pathogens and Antagonists

Production technology

Fungal products used in biological control
cover a wide range of fungal genera and

applications, including use as fungal antago-

nists, plant-growth enhancers and weed- and

insect-control agents. Most of these fungi are

produced in vitro. The scale of production

ranges from small-scale agar-based produc-

tion, such as is used for Phlebiopsis gigantea, a

product registered in the UK for application

to conifer stumps to protect them against

Fomes annosus(J.E. Pratt, Midlothian, UK,

1999, personal communication), through to

industrial-scale units, such as that built by

Mycotech Corp., which is capable of produc-

ing tonnes of Beauveria bassiana product

annually (Stephens, 1997).

Methods of production vary consider-

ably. Many are solid-substrate fermenta-

tions based on cereal grains, such as rice

(Alves and Pereira, 1989; Jenkins et al.,

1998), or, occasionally, non-nutritive sub-

strates, such as clay granules (Guillon,

1997). Some encourage the production of

conidia on the surface of static liquid cul-

ture (Kybal and Vlcek, 1976; Ferron, 1981),

while others use deep-tank liquid fermenta-

tion to produce mycelial products, blas-

tospores or submerged conidia (McCabe

and Soper, 1985; Jackson and Bothast, 1990;

Reinecke et al., 1990; Jenkins and Prior,

1993). Arbuscular mycorrhizal fungi are

produced on the roots of plants cultivated

in glasshouses or growth chambers (J. Parat,

Paris, France, 2000, personal communica-

tion). Whichever system is used and at

whatever scale it is employed, there is a

need for strict and standardized quality

control procedures to ensure that the prod-

uct is safe, viable and effective.

Culture maintenance

Once selected for development as microbial

control agents (if not before), fungal isolates

should be lodged with a recognized culture

collection and formally identified by a recog-

nized fungal taxonomist. Taxonomic proce-

dures are becoming more and more complex

and it is now generally accepted that some

kind of molecular identification is needed in

addition to the traditional morphological

characteristics formally used to classify fun-

gal species (Bridge and Arora, 1998).

248 N.E. Jenkins and D. Grzywacz