Sublethal effects by deltamethrin and spinosad on the grain weevils Sitophilus zeamais and S. granarius

• Ano de defesa: 2018
• Autor(a) principal: Vélez Ruiz, Mayra Carolina
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Inseticidas; Plantas - Efeitos dos inseticidas; Grãos - Armazenamento - Doenças e danos; Sitophilus zeamais; Sitophilus granarius; Deltametrina; Espinosade; Entomologia Agrícola
• Link de acesso: https://locus.ufv.br//handle/123456789/27266

Insecticides are compounds widely used to prevent and control of pests, allowing the rapidly reduction of their population growth as well as their damage. However, insecticides not necessarily cause pest mortality, this may stimulate sublethal effects which may lead to harmful or even beneficial responses that may affect (or not) the behavior and sexual fitness of the exposed insects. One ongoing concern with pesticides use is the impact on non-target organisms, particularly natural enemies and pollinators. Little is known about such effects on grain weevils. In this context, we evaluated the sublethal effects by deltamethrin and spinosad on two species of grain weevils (Sitophilus zeamais e S. granarius). In the first experiment, we evaluated the insecticide effect of deltamethrin and spinosad on survival, walking activity, irritability and different feeding and drinking responses of S. zeamais and S. granarius. In the second experiment, we evaluated the sublethal effects of deltamethrin and spinosad on mating and reproductive output of S. zeamais. Deltamethrin and spinosad were able to control (100%) both species of grain weevils. Walking activity pattern changes, feeding and drinking responses of both species exposed to insecticides were also detected, but, deltamethrin exhibited a higher impact than spinosad. Couples of S. zeamais sublethally exposed to deltamethrin and spinosad exhibited altered reproductive behavior. A higher grain consumption and increased progeny emergence were observed in deltamethrin- exposed insects. These results suggest that deltamethrin elicit hormetic effects in S. zeamais that may compromise control efficacy by this compound. Although spinosad exhibited less impact on the evaluated behavior this also benefited weevil progeny emergence; this suggests caution using this and others compounds, particularly deltamethrin for controlling the weevil S. zeamais.