oviposition cages and containers for
holding parasitized hosts. Measurements
may include the number and condition of
hosts, the sex ratio and fecundity of the
natural enemy, the yield of the final product
and the emergence, condition and longevity
of adult parasitoids (Williams and Leppla,
1992; van Lenteren and Tommasini, 1999).
Predators are monitored similarly, except
that the host may be replaced by artificial
diet. The number of units sampled is
usually small and the data are acquired in a
way that makes them easy to analyse
(Chambers and Ashley, 1984).
Optimization or troubleshooting of the
production system is accomplished by
analysing production units, not batches.
Batches are generally worker shifts, days or
weeks that combine the products of individ-
ual units. For example, a shift may produce
a certain number of parasitized eggs,
regardless of the number of oviposition
cages. This measurement of yield combines
the variability from all of the cages and
obscures the rate of parasitization in indi-
vidual cages. How can we know the num-
ber and identity of cages that are producing
well versus those that are having some diffi-
culty? Cages with problems could be at the
end of the process line, set up by an inexpe-
rienced worker, positioned in an
unfavourable environment or associated
with some other cause. The source of the
problem can be corrected only if the
affected production units can be identified.
Otherwise, we just know that yields have
declined and there is a problem somewhere
in the system. Changes made intentionally
to improve the system must be monitored
similarly by sampling individual produc-
tion units. It can be very costly to attempt to
manage an entire natural-enemy production
system without knowing the condition of its
individual units.
What is Total Quality Control for the
Production of Natural Enemies?
Total quality control (TQC) is an uncompli-
cated structure for organizing and address-
ing the major steps in producing, using and
improving natural enemies (Leppla and
Fisher, 1989; Leppla, 1994). More generi-
cally, it is:
An effective system for integrating the quality-
development, quality-maintenance, and
quality-improvement efforts of the various
groups in an organization so as to enable
marketing, engineering, production, and
service at the most economical levels which
allow for full customer satisfaction.
(Feigenbaum, 1983)
TQC is composed of eight generic sub-
divisions: management, research, methods
development, material, production, utiliza-
tion, personnel and quality control (Fig.
2.1). Although often not individually
identified, all of these elements are present
in pest-management systems based on
mass-reared natural enemies and each has
internal control functions. Coordination
across these interdependent subdivisions
and feedback to management provide a
means of ensuring production of the most
efficacious natural-enemy products and
eliminating unnecessary costs (Fig. 2.2).
These products must be monitored and
evaluated during and after production, and
while being used, to assure that they meet
expectations.
A TQC system begins with the ability to
raise a natural enemy that is effective in con-
trolling populations of a specific pest
(Leppla, 1989). This ability entails methods
to accurately identify and effectively collect,
handle, house, feed, cycle and harvest an
adequate number of natural enemies.
Standard operating procedures (SOPs) are
described for all rearing operations, ranging
from acquisition and storage of supplies to
maintenance and preparation of reports.
Workers who actually perform the opera-
tions should participate in writing or at least
reviewing the SOP steps. In practice, the
details and potential pitfalls of SOPs often
exist only in the experience of senior work-
ers. Detailed procedures must be docu-
mented along with associated standards of
performance. Check sheets may be devel-
oped to keep track of their completion.20 N.C. Leppla