Placement of Siberian silkworm individuals within the outbreak of mass reproduction

Abstract

Regularities of micro and macro-spatial distribution of individuals of Siberian silkworm populations during an outbreak of mass reproduction are considered. When studying the spatial distribution of the Siberian silkworm, a model of the distribution of individuals of the Siberian silkworm among fodder trees on sample plots was considered and the shape of areas damaged by the Siberian silkworm was studied. Additionally, a model of long-term spatial dynamics of insect pest’s population centers is considered. To assess the micro-spatial distribution of individuals on the territory, the spatial dynamics of the distribution of Siberian silkworm caterpillars on trees at different stages of the pest population gradation are considered. To describe the distribution of insects over trees on test plots, a model is proposed – an analogue of the model of phase transitions of the second kind in physical systems. To describe the “movement” of the boundaries of the center of mass reproduction of insect pests, the model of “viscous fingers” is considered and the fractal characteristics of the boundaries of the centers are calculated. By assessing the fractal dimension of the outbreak boundary, it is possible to calculate the ratio of the population density and the time of development of the forage object, and from the fractal dimension of the boundary between the outbreak and the undamaged forest, it is possible to estimate the nature of the further development of the outbreak. Also, based on a single measurement of the structure of the focus boundaries, one can try to estimate the fractal dimension of the focus and the risk of its further development. The considered models were verified according to the observations of various authors. When constructing and verifying the models, we used the data of the counts of the Siberian silkworm population and the population of trees in the foci of its mass reproduction, and remote data on the areas and shape of the foci. Using the proposed models, it is possible to estimate the critical characteristics of the population density and the shape of the foci of mass reproduction of pests at different phases of population gradation based on the data of counts and remote observations.

Keywords

• insects
• mass reproduction
• fractal dimension
• second-order phase transition model