Proposta de modelo para a dinâmica populacional do ácaro Tetranychus urticae (Koch), seu predador Neoseiulus californicus (McGregor) e sua interação

Abstract

Tetranychus urticae (Koch), known as the two spotted spider mite, is a pest which causes damage to many economically important crops in Brazil and worldwide. This species is becoming resistant to chemicals, which complicates management. An alternative is the biological control in which predatory mites are released in infested plantations in order to reduce or even extinguish the pest population. One of the species efficient in this control is the Neoseiulus californicus (McGregor) predatory mite, which is considered an excellent agent in controlling spider mites. In biology, specifically population dynamics, mathematical modeling and statistical and computational tools are being increasingly used to study the behavior of biological systems, complementing experimentation when predictive purposes are involved. Forecasting models are of great interest in Integrated Pest Management (IPM) programs, providing grants in order to establish practices for preventing and controlling pests and diseases. In this work, we conducted a study in order to describe biological and behavioral characteristics of the T. urticae mite and the N. californicus predatory mite, as well as the interaction dynamics between both species, via computer simulation based on experimental data reported in literature. The population dynamics were, first, treated separately, and then interacting with each other. The results indicate that the proposed model was able to reproduce important characteristics in both T. urticae and N. californicus populations, such as reduced longevity and the populations increased intrinsic growth rate in high temperatures. At all temperatures we verified the populations relevant frequency using time series analysis. Inserting predation into the model, we found that, in all simulations, the prey population became extinct, with extinction time tending to stabilize. In all simulations, at higher temperatures, extinction time was lower.