Peanut plant response to lepidopterous pests defoliation and determination of the economic injury level

• Ano de defesa: 2022
• Autor(a) principal: Pinto, José Ricardo Lima [UNESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Pest control; Amendoim; Spodoptera; Floração; Flowering; Controle de pragas
• Link de acesso: http://hdl.handle.net/11449/234387

World agriculture has been undergoing several changes, driven mainly by the integration of new technologies, with the objective of guaranteeing food security and sustainable production systems. However, for some crops, such as peanuts, there is a lack of knowledge to provide the correct adoption of innovative pest management practices. Therefore, due to the lack of studies regarding peanut plants response to defoliation caused by lepidopterous pests and the absence of tools that help producers to determine the ideal moment for control decision-making of these insects, the present work aimed to establish the basis for control decision-making to the main lepidopterous pests that occur in Brazilian peanut crops. Thus, in Chapter II we characterized, over two peanut crop seasons, the abundance of species associated with peanuts and their population fluctuations. We observed that Stegasta bosqueella (Chambers, 1875) (Lepidoptera: Gelechiidae) and the genus Spodoptera are more abundant, with greater occurrence during the bloom/pegging stage (41 ± 70 Days After Planting (DAP)) and pod/setting stage (71 ± 100 DAP). Once we identified the most abundant species, in Chapter III, we evaluated the biological aspects and feeding behavior of the species, S. bosqueella and Spodoptera cosmioides (Walker, 1858) (Lepidoptera, Noctuidae) under two of the main peanut genotypes currently adopted in Brazil, the IAC 503 and the IAC OL3. We concluded that the foliage consumption of S. cosmioides was 31.5 and 27.8 times greater than that observed for S. bosqueella, in the IAC 503 and IAC OL3 genotypes, respectively. Furthermore, the development of S. bosqueella was superior under IAC 503, while, for S. cosmioides, IAC OL3 provided better resources for larval development. After quantifying the foliar consumption potential of the most abundant species in Brazilian peanuts, we characterized in Chapter IV, through gas exchange parameters and hyperspectral remote sensing, how peanut plants respond to herbivory by S. bosqueella and S. cosmioides. Finally, in chapter V we determined the economic injury level (EIL) for S. bosqueella and S. cosmioides in peanuts at different stages of crop development. Thus, we verified that the economic injury level for S. bosqueella is 14.65, 77.96 and 36.30 larvae per plant in the early vegetative, bloom/pegging and pod/setting stages, respectively. For S. cosmioides the economic injury level is 0.74, 2.48 and 1.16 larvae per plant in the early vegetative, bloom/pegging and pod/setting stages, respectively. The generated results will allow extension personnel, producers, and consultants to make more assertive management decisions when dealing with peanut defoliation.