needs or products or services intended for
the same functional use’ (ANSI/ASQC,
1987). In other words, a standard is the level
of quality at which a specification is written.
A specification for a natural enemy can be
written at a required standard of quality
based on biological, production and market
options. The natural enemy is typically
characterized according to its species
description (identity and purity), life his-
tory and behaviour. For example, a particu-
lar species of parasitoid may oviposit a
maximum of 500 eggs per female but we
specify that females from our colony must
produce an average (SD) of 25025 eggs.
This specification becomes the standard by
which we measure our success in producing
the natural enemy. If this standard is too
difficult or expensive to achieve in practice,
it can be lowered to 20050 eggs.
Standards are relative to requirements or
expectations, which should be realistic
(Boller and Chambers, 1977).
What are Production, Process and
Product Control?
The functions of production, process and
product control are performed within the
production and quality control subdivi-
sions of the production system for natural
enemies (Fig. 2.1). Since they are applied
and interpreted differently in various
industrial manufacturing fields (Besterfield,
1986), they must be defined specifically for
use in mass-rearing arthropods. Production
is responsible for most inputs and therefore
performs production control. Process and
product control are performed by the qual-
ity control subdivision as functions that
support production. It is important to dis-
tinguish between the functions of the pro-
duction and quality control subdivisions
because, rather than inputs, the quality
control subdivision generally monitors out-
puts. The quality of processes and products
is determined by sampling insects, measur-
ing key characteristics and comparing the
results to established specifications and
standards, usually by means of process-
control charts.
Production control is the monitoring and
maintenance of all rearing inputs in terms
of personnel, materials, equipment, sched-
ules, environments, SOPs and so forth.
Most production failures can be traced to
deficiencies in production control and are
due to errors caused by workers, unpre-
dictable changes in materials or loss of envi-
ronmental control. Consequently, problems
are prevented and troubleshooting initiated
by first focusing on the performance of pro-
duction SOPs, abnormal appearance of the
materials and arthropod stages and envi-
ronmental deviations.
Process control is the evaluation of key
components of the manufacturing processes
as they are employed along the production
line (Feigenbaum, 1983). In rearing systems,
process control is accomplished by determin-
ing the constancy of immature arthropod
stages as a means of predicting quality and
identifying sources of increased efficiency. It
is particularly important when unforeseen,
detrimental changes occur or inputs are mod-
ified intentionally. The process-control infor-
mation is used by the production subdivision
to make any necessary adjustments. A com-
mon example is the addition of more females
to an oviposition cage as the number of fertile
eggs per female declines, before determining
and correcting the cause of the decline.
Product control is the same in arthropod
rearing as it is in other industrial processes:the control of products at the source of
production and through field service, so that
departures from the quality specification can be
corrected before defective or non-conforming
products are manufactured and the proper
service can be maintained in the field.
(Feigenbaum, 1983)Thus, the performance of natural enemies is
measured and evaluated at the production
facility and critical points during their trans-
portation, application and impact on the tar-
get pest. Feedback is provided to optimize
production, field performance and customer
satisfaction.22 N.C. Leppla