2 Aspects of Total Quality Control for the Production of Natural Enemies
N. C. Leppla
Department of Entomology and Nematology, University of Florida, Natural Area Drive, PO Box 110630, Gainesville, FL 32611-0603, USA
Introduction: Why Practise Quality Control in the Production and Use of
Natural Enemies?
Quality control is practised in the production of natural enemies, at least intuitively, at some level as a measure of the success or failure of the production system. Adequate yields indicate that rearing operations have been performed efficiently. In a small, hands- on organization, there can be a sense about whether each step in the rearing process has been accomplished adequately. However, what happens when yields decline and the cause is not evident? How are yields main- tained while decreasing inputs and thereby
improving efficiency? How are complaints resolved about the postproduction perfor- mance of natural enemies? How are deci- sions made to correct apparent problems or improve the production system?
Information is required to determine the status of each rearing operation in the system and the quality of the final insect product (Leppla and Ashley, 1989). The cost of obtaining this information should be recovered in reduced incidence of problems and increased efficiencies. It is not an added expense but an integral function in natural- enemy production (Leppla and King, 1996).
Typically, data are derived from a rep- resentative sample of rearing units, i.e.
© CAB International 2003. Quality Control and Production of Biological Control Agents:
Theory and Testing Procedures (ed. J.C. van Lenteren) 19
Abstract
In this chapter the following questions are addressed: (i) what happens when yields of natural enemies decline and the cause is not evident? (ii) how are yields maintained while decreasing inputs and thereby improving efficiency? (iii) how are complaints resolved about the postproduction performance of natural enemies? and (iv) how are decisions made to correct apparent problems or improve the production system? A system of total quality control (TQC) is described, because it is an uncomplicated structure for organizing and addressing the major steps in producing, using and improving natural enemies. TQC can assist in carefully evaluating trade-offs in the system and judiciously investing resources, critical functions for commercial biological control. ‘Of all concepts in the quality function, none is so far- reaching or vital as “fitness for use”’ (Juranet al.,1974). To be marketable, products and services must meet the expectations of users in terms of price, reliability and performance. In this sense, ‘fitness for use’
is the definition of quality for producers of natural enemies and their customers.
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
What is the Relationship Between Specifications and Standards?
There has been some confusion about the differences between specifications and stan- dards as they apply to insect rearing. They are closely related terms and both can be
measures of quality. However, specification is defined as: ‘The document that prescribes the requirements with which the product or service has to conform’ (ANSI/ASQC, 1987). Standard equals grade, ‘An indicator of category or rank related to features or characteristics that cover different sets of Total Quality Control for Biocontrol Agents 21
Fig. 2.2. Total quality-control system emphasizing the control functions (boxes) within generic subdivisions of the production system for natural enemies. The feedback loop provides a means of optimizing the production and use of the natural enemies.
Fig. 2.1. Production system for natural enemies composed of generic subdivisions and associated functions.
Management
Methods Development Production Utilization Quality Control
Material Research Personnel
Policy Planning Administration Design Control
Facilities Equipment Operations Production Control
Treatment Handling Distribution Utilization Control
Process Control Product Control
Information Evaluation Strain Development
Process Capability Pilot Testing Methods Control
Purchasing Specifications
Standards Responsibility
Verification Storage Material Control
Colonization Production
Utilization Quality Control
Selection Training Motivation Health and Safety
Design Control
Production Control
Process Control
Product Control
Utilization Control
Production Quality Control Utilization
Treatment Distribution
Information Evaluation Research/Methods
Development Material/Personnel
Management
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
What is the Management Subdivision of Total Quality Control?
TQC provides a very powerful and flexible system for producing natural enemies because it encompasses all of the necessary elements that must be considered (Fig. 2.2).
The manager’s role is to establish policies, plan the production effort, provide adminis- tration and exercise design control. A produc- tion system is designed by applying TQC to determine priorities and assign resources.
This framework helps the manager avoid common errors of omission, such as adequate storage of materials or the health and safety of employees. Moreover, it indicates subdivi- sions that can be combined or split. Examples of amalgamation include research and meth- ods development, production and material, and management and personnel. Utilization and quality control are often stand-alone activities. In addition to visualizing and defining the entire system, the design-control function of TQC enables the manager to make informed decisions. The feedback loop from planning to evaluation also provides for the involvement and education of the cus- tomer (Penn et al., 1998). TQC can assist in carefully evaluating trade-offs in the system and judiciously investing resources, critical functions for commercial biological control.
A typical example of decision making by the managers of an arthropod production system is whether or not to change a colo- nized strain, formerly based on time, intu- ition or weight of opinion. This question is central to the production of natural enemies but has probably been deliberated in the greatest detail during nearly 50 years of mass-rearing the screw-worm fly, Cochliomyia hominivorax (Coquerel). Initially, a strain from Texas was used to conduct tests of the sterile- insect technique on the Caribbean island of Curaçao and in Florida. Eradication was achieved on Curaçao with the Texas strain in 1954 but, for Florida, a new strain was estab- lished by collecting from 12 locations in Florida and one in Georgia. This Florida strain was used to eradicate the screw-worm from both the south-east and the south-west
by 1966. Between 1966 and 1975, five strains from Texas and Mexico were mass-reared in succession at the Mission, Texas, facility (Meyer, 1987). It became apparent during these years that strains differed greatly in their ability to adapt to production and that their establishment and maintenance depended on the quality of the rearing sys- tem. Screw-worm production was moved to a new facility at Tuxtla Gutierrez, Mexico, in 1976 and seven Mexican strains were reared during the next 8 years (Marroquin, 1985).
Unpredictably, some strains performed well in the rearing facility and field while others failed, so a strain-development programme was initiated to collect, rear and test new strains in advance of their use for eradication.
Managers obtained feedback on the produc- tion and field performance of the current strain to compare with rearing and field-test- ing data on potential replacement strains.
Generally, as strain development and mass- rearing capabilities improved, strains were retained and remained effective in the field for longer periods of time. Annual strain replacement is no longer automatic.
Conclusion
TQC for the production of natural enemies accounts for the major variables in planning, implementing, managing and improving the system. It helps to increase production effi- ciency and cost-effectiveness, rapidly identify and correct the causes of rearing problems, ensure the effectiveness of natural enemies in the field and have the information necessary to optimize their use in pest management.
SOPs are established with reasonable specifi- cations (what result is expected) and stan- dards (what quality is expected) for arthropod products. These standards can be achieved by carefully controlling production (SOPs, facilities and equipment), processes (indicated by insect stages) and products (stage that is delivered and used). TQC is a means of planning, organizing and managing the subdivisions and functions of natural- enemy production systems.
Total Quality Control for Biocontrol Agents 23
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