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3.3. GYPSEX: A KNOWLEDGE-BASED SYSTEM FOR AERIAL APPLICATION OF PESTICIDES AGAINST GYPSY MOTH

Foster et al.
U.S. Forest Service, Penn State University, Forest Pest Management, USDA Forest Service, 1989

GYPSEX was reported in 1989 (Foster 89) after field verification. This expert system provides knowledge-based decision support for two aspects of aerial application of insecticides against gypsy moth: calibration and characterization. According to the makers of the system, the successful aerial application of pesticides against gypsy moth requires information about gypsy moth population dynamics, insect sampling techniques, potential gypsy moth impact on trees, weather, pesticide effectiveness, and aircraft spraying systems. Problems of particular difficulty are spray system configuration for the desired flow rate (calibration) and for adequate, evenly distributed pesticide deposition (characterization). The system includes so called Desk Calculations and Field Tests for calibration. Desk Calculation supports the user with advice on the configuration of spray systems. The Field Test section provides troubleshooting advice when initial tests on flow rate is not in accord with expectations.

In terms of characterization, the principal purpose is to assure appropriate pesticide deposition. The Characterization module first provides the user with a pairwise juxtaposition of the test spray pattern. Next, the user will select one of the spray patterns suggested. Finally, the system will provide heuristic advice on the spray nozzle numbers and positions.

A third module was ready for field test at the turn of the decade. This has been called Spray Timing. Its purpose is to advise on the optimal date for aerial application of Bacillus thuringiensis against gypsy moth based on weather forecasts and insect and host tree phenology.

At the time of verification, the system was supported by Macintosh SE and IBM PC platforms. It was written in C by means of a frame-based, object-oriented toolkit. Heuristic rules were accommodated in frame structures. The heuristic modules were built to cooperate with both simulation models and calculation-based system components.

3.4. ISPBEX: THE INTEGRATED SOUTHERN PINE BEETLE EXPERT SYSTEM

Flamm et al.
Texas A&M University, USDA Forest Service, Texas Forest Service, 1991

The ISPBEX system is similar to GYPSEX in objective and approach. It was developed at the same time, and it is interesting to note how the builders move toward interconnected systems applying a register of databases, different platforms, and different tools.

The ISPBEX system addresses pest management in forestry (Flamm 91). Its focus is the southern pine beetle, Dendroctonus frontalis, found in the U.S. The effort behind the system was driven by the wish to define the problem of southern pine beetle management and to develop a knowledge-based system to both promote and demonstrate the capabilities of an expert system within the field of pest management in forestry. The pine beetle is a pest insect that infests and kills yellow pines throughout the southern U.S. It can severely disrupt forest management goals, plans, and practices.

Managing damage caused by the southern pine beetle is difficult for two reasons. The first reason centers on the process of decision-making by the forest manager, and the second deals with efficient use of information derived from research.

Before the system research on the southern pine beetle pest was initiated, few immediate results on the forest management practice were experienced. One paramount cause for this was the fact that newly acquired knowledge could not be readily delivered to the forest managers. It was found necessary to find ways to facilitate integration, interpretation, and use of the different types of information needed. Another principal requirement was the need to blend the qualitative knowledge of the manager with the quantitative results derived from the R&D programs.

The ISPBEX initiative was antedated by the SPDSS (Southern Pine Beetle Decision Support System). This was the first concerted effort to use computer technology to accommodate the R&D results generated. The principal task of this system was to present information to the user and not directly solve problems. Since the system never came into practical use, a formal examination was triggered. Investigation of the unsuccessful effort revealed lack of user involvement and user-specific needs. The lack of heuristic knowledge in the system disfavored its use. This gave lead to the ISPBEX system.

The ISPBEX system is built around three functional objectives:

  • To incorporate qualitative domain-specific information into the insect pest management (IPM) process
  • To accommodate problems that do not respond to algorithmic solutions
  • To use meta-level knowledge (knowledge about the problem-solving process itself) to effect more sophisticated control of problem-solving strategies
  • To integrate the different representations of knowledge for IPM problem-solving and decision-making

As a task-oriented system, ISPBEX considers three aspects of IPM: suppression, prevention, and utilization. Suppression deals with actions that enable regulation and modification of the insect population. Prevention deals with actions taken to minimize risks of adverse impacts of the insect on resource management goals. Utilization deals with actions taken to make use of resources damaged by the activities of the insect. The ISPBEX systems has three modules that are built around each of these tasks (see Figure 5). The knowledge bases are built around rules that are very much fact driven. Yet, typically for the second-generation expert system, ISPBEX is much more than an accumulation of rules.

The system accesses several databases on a central mainframe computer. These include bases like the GIS forest stand maps, SPB historical data, and the SPBIS (Southern Beetle Information System). The databases fuel the system with data required to support the various tasks.

In order not to compromise early user-specific lessons, the development team made serious efforts in order to suit the system to the target user group. As an example of this, they structured menus to resemble Forest Service data forms and reports. The number of keystrokes were minimized. In addition, extensive help menus were included.

In addition to the important database connections, the system includes a geographical information system (GIS). Simulation models were also added to the system along with a significant amount of heuristics. Simulation models of both southern pine beetle population dynamics and infestation geometry were included when management decisions affect infestation located in wilderness areas and within close proximity of other special use forest.


FIGURE 5 The task structure of ISPBEX.

Several tools were used to implement the system. The most important being CLIPS, FIFTH, and KERMIT. CLIPS is a forward-chaining expert system shell that was developed by NASA. FIFTH is a programming environment for FORTH that was used to develop the user interface. It compiles menus defined in a textual format into binary code. KERMIT is a widely used communication protocol for transferring files between computers. It was especially popular during the 1980s. ISPBEX is based on hybrid code written in many languages ranging from C and FORTRAN to Assembler.

ISPBEX is run on PCs and interacts with the Forest Service Data General mainframe computer. Version 1.0 of ISPBEX was released for Beta testing in May 1989. It has been subjected to continued development. In the early 1990s, the developers initiated work around the same domain, pursuing the knowledge system environment approach.


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