Computer simulation of the population dynamics of the yellow stem borer Scirpophaga incertulas (Walker)
1988
Jingyuan Xia
Output of the model was subjectively compared with the observed population data obtained during the 1987 wet and 1988 dry seasons in farmers' fields, Calauan, Laguna, Philippines. There was an acceptable agreement between the simulated and observed trends of the insect's population fluctuations for both seasons. The model satisfactorily simulated, over a period of 105 days, the timing of population density peaks of the different developmental stages and substages in each of the two seasons. However, the sizes of most of peak densities were slightly overestimated for the 1987 wet season and underestimated for the 1988 dry season. Sensitivity analysis showed that no single key mortality factor was present. Insect's population fluctuations in a given cropping season were determined by the interaction of numerous factors. The most important factors in the system were: (1) rate of development dependent on temperature; (2) rate of mortality due to egg predation, egg parasitism, and plant age; (3) rate of immigration and emigration; and (4) rate of oviposition. Of minor importance were: (1) egg mortality due to temperature and relative humidity, (2) larval mortality due to parasitism, and (3) pupal mortality due to parasitism. There are many applications of SIPODYSB. It may be used to investigate the ecological processes affecting the insect's population fluctuations in the field, to identify the key mortality factors of the insect's population dynamics, and/or to establish the priorities for future research. Farmers may utilize its short term predictive capacity in making pest management decisions.
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