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Computational modeling to describe the dynamics of fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Bt crop areas

Garcia, Adriano Gomes

Biblioteca Digital de Teses e Dissertações da USP; Universidade de São Paulo; Escola Superior de Agricultura Luiz de Queiroz 2017-10-27

Acesso online. A biblioteca também possui exemplares impressos.

  • Título:
    Computational modeling to describe the dynamics of fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Bt crop areas
  • Autor: Garcia, Adriano Gomes
  • Orientador: Godoy, Wesley Augusto Conde
  • Assuntos: Cultivos Transgênicos; Ferramentas De Decisão; Insetos Pragas; Programas Computacionais; Computational Programs; Decision Tools; Insect Pest; Transgenic Crops
  • Notas: Tese (Doutorado)
  • Descrição: Spodoptera frugiperda is one of the main insect pests of the New World, and causes extensive damage to economically important crops such as cotton and corn. One of the most common control strategies is the use of Bt plants; however, their intense and indiscriminate use has led to the evolution of resistance in some populations. The establishment of a refuge can be a viable option to delay this process. Refuges consist of areas where non-Bt crops are planted, in order to provide susceptible insects to the population. In this study, I initially developed a model to describe the evolution of resistance of fall armyworm populations in different refuge configurations (seed mixture, blocks, and strips) and sizes (20% - 50%), considering the larval movement. I demonstrated that with a seed mixture, in most cases, the higher the rate of larval movement, the higher the proportion of resistant insects in the population, regardless of the type of resistance tested; meanwhile, strip configurations showed the opposite trend. In the second part of this study, I obtained data to validate the proposed model. The development of the fall armyworm on corn leaves was determined at five constant temperatures ranging from 14°C to 30°C. These data were also used to estimate the number of generations of fall armyworms at 42 locations in the state of Florida, from 2006 to 2016, which were interpolated and represented on maps, using GIS (Geographic Information System). I observed that counties farther south had the highest numbers of generations, and that fall armyworms should be able to overwinter as far north as ~29°N. Using the data obtained in the experiment, a new model was proposed, covering a wider range of conditions and allowing the user to define the crop area, the thermal requirements of the population studied, the viability and oviposition functions, the migration rate, the rate of larval movement and the frequency of alleles for resistance. The model was verified with monitoring data collected in a crop area in Florida from 2012 - 2015, only 70 km from the area that provided the population for the experiment. I also used the model to estimate the number of adults for 2016 and for two hypothetical situations that considered possible scenarios involving global warming (mean temperatures in 2016 + 1°C and + 2°C). The model succeeded in fitting the monitoring data, and indicated that the simulated increases in mean temperature could produce outbreaks nearly twice as large as the levels of fall armyworm estimated for 2016. The model can be used to estimate the population dynamics of S. frugiperda in a particular area, according to the crop composition and disposal, to investigate the effects of temperature changes on the levels of fall armyworm populations, to define appropriate refuge areas in order to manage the evolution of insect resistance, and to define the best periods for plantation and harvesting during the year to reduce pest populations, among others.
  • DOI: 10.11606/T.11.2018.tde-20032018-135036
  • Editor: Biblioteca Digital de Teses e Dissertações da USP; Universidade de São Paulo; Escola Superior de Agricultura Luiz de Queiroz
  • Data de criação/publicação: 2017-10-27
  • Formato: Adobe PDF
  • Idioma: Inglês
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