THE HIERARCHICAL ENVIRONMENT FOR RESEARCH MODELING OF ECOLOGICAL SYSTEMS: OBJECT-ORIENTED SIMULATION MODELING FOR THE ENTOMOLOGIST

Authors: LEGASPI, BENJAMIN - TEXAS AGRIC. EXPT. STN.; Carruthers, Raymond; LARKIN, TIMOTHY - ARS, ITHACA, NY

Submitted to: American Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: This paper has two objectives: First, we want to show entomologists what computer models are and how they may be used. Second, we present HERMES, a tool for building models that can be used even by people who are not very familiar with mathematics or computer languages. Computer models are representations of complex biological systems. These models can have many uses, such as predicting the effects of different management strategies in a farming system. Many entomologists can benefit from the use of models in their research, but are reluctant to learn the mathematics and computer languages necessary to build them. One solution to this problem is HERMES which stands for the Hierarchical Environment for Research Modeling of Ecological Systems. An entomologist can build a model using HERMES simply by linking together icons which represent different components in a biological system and supplying the necessary data. To illustrate the versatility of HERMES, we demonstrate an example of an alfalfa cropping system. The alfalfa system consisted of the crop, a pest, an insect that parasitized the pest, and a disease of the pest. Farmers may cut their alfalfa several times during a season. We used the model to predict the effects of cutting the alfalfa two times versus three times and showed how the different management strategies can have significant effects on the numbers of pests. Computer models such as the one we built can be used to investigate questions such as this which would be too difficult or expensive to do in reality. The models also work together with actual experiments in order to guide research and gain a truer understanding of the biological system.

Technical Abstract: In this paper we define simulation models and their relevance to the research performed by entomologists. However, many entomologists are reluctant to pursue the use of models because of the need for mathematics and programming skills. To address this need, we present HERMES: The Hierarchical Environment for Research Modeling of Ecological Systems. HERMES takes advantage of recent developments in object-oriented programming, including a graphical user interface that allows a user to construct detailed models through the intuitive manipulation of graphical icons. These icons are pre-designed computational components specifically tailored to suit the needs of modeling entomological systems. Among these components is a 1-dimensional time varying distributed delay (TVDD) component which simulates insect development as affected by temperature. Although insect models are easily constructed using TVDDs, HERMES is extremely flexible in allowing a variety of modeling techniques to be used We illustrate the ease and flexibility of HERMES by creating an alfalfa model which consists of the crop, a leafhopper pest, an egg parasitoid of the leafhopper, and a disease of the leafhopper. The components were modeled using different techniques. The parasitoid was modeled using TVDDs, while the disease used 2-dimensional TVDDs (allowing for simultaneous processes of disease incubation and host maturation). The alfalfa and leafhopper components were modeled using functions. In order to illustrate the effects of a management strategy on the system, we simulated the effects of a 2-cut versus a 3-cut system on the dynamics of the plant, the pest and the associated natural enemies.