Insecticide selectivity to the predator Podisus nigrispinus (Heteroptera: Pentatomidae) used in eucalyptus culture

• Ano de defesa: 2021
• Autor(a) principal: Silva, Wiane Meloni
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Lagartas - Controle biológico; Pesticidas; Organismos não-alvos; Entomologia Agrícola
• Link de acesso: https://locus.ufv.br//handle/123456789/28954; https://doi.org/10.47328/ufvbbt.2021.147

The control of defoliating caterpillars in forestry includes chemical and biological insect management. The predatory stink bug Podisus nigrispinus Dallas (Heteroptera: Pentatomidae) is a biological control agent, but some insecticides can affect this natural enemy, which needs risk assessment. Therefore, the selectivity of insecticides for use with non-target organisms in agricultural and forestry areas is essential for integrated pest management. The present work aimed to fill gaps about the effects of insecticides when used together with the predator P. nigrispinus. In chapter 1, the objective was to evaluate the side effects on survival, respiration, behavioral response, preference and consumption in third instar nymphs of P. nigrispinus when exposed to Bacillus thuringiensis (Bt), permethrin, tebufenozide and thiamethoxam in the laboratory. The insecticides permethrin and thiamethoxam were the most toxic to P. nigrispinus nymphs. The survival of nymphs of this predator was 93.3%, 66.7%, 56.6%, 0% and 0% in the control, treatments with tebufenozide, Bt, permethrin and thiamethoxam, respectively. Bt and the insecticides tebufenozide, permethrin and thiamethoxam reduced the respiratory rate of P. nigrispinus. Permethrin, tebufenozide and thiamethoxam affected the locomotion of this insect's nymphs. Prey treated with Bt, permethrin and thiamethoxam were less preferred by P. nigrispinus. Furthermore, the reduction in the consumption of prey, treated with neurotoxic insecticides, reduced the predatory potential of this natural enemy. Bt and tefubenozide had low toxicity for P. nigrispinus, but neurotoxic products had low compatibility with this natural enemy and, therefore, they are not recommended, with this predator, in the management of forest pests. In chapter 2 we investigated the survival, preference and consumption of prey and the histopathology of the midgut of adults of P. nigrispinus fed on prey treated with the lethal concentration (LC 50 ) of Bacillus thuringiensis (Bt), permethrin, tebufenozide and thiamethoxam. The insecticides Bt, permethrin and thiamethoxam reduced survival and prey consumption in P. nigrispinus fed on prey contaminated with these insecticides.However, the four insecticides tested, including tebufenozide, caused histological changes, such as irregular epithelial architecture, cytoplasmic vacuolization and release of cell fragments in the lumen of the midgut of P. nigrispinus. The sublethal effects of Bt, permethrin, tebufenozide and thiamethoxam on the natural enemy suggest that they should be better evaluated to be used in conjunction with P. nigrispinus for integrated pest management in forestry. Keywords: Biological control. Compatibility. Non target organism. Pesticides.