Herança da resistência de Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae) ao inseticida teflubenzuron
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Data
2021-02-25
Autores
Thiesen, Leonardo Vinicius
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A lagarta falsa medideira, Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae), é considerada praga chave da soja e potencial desfolhadora do algodão. Grande parte do manejo dessa espécie tem sido realizada por pulverizações de inseticidas químicos nos campos de produção. Os inseticidas químicos do grupo das benzoilureias são muito utilizados para o controle de lepidópteros e, dentro desse grupo, o ingrediente ativo teflubenzuron é amplamente utilizado para o controle dessa espécie. Porém, o uso intenso e contínuo desse inseticida tem elevado a pressão de seleção no campo e favorecido a seleção de populações resistentes a esse ingrediente ativo. Para contornar esse problema, as estratégias de Manejo da Resistência de Insetos devem ser empregadas para retardar a evolução da resistência. Dessa forma, estudos para compreender o padrão de herança da resistência são necessários principalmente para aprimorar o monitoramento das populações resistentes, permitindo acompanhar a evolução da resistência e definir qual a melhor estratégia para reestabelecer a suscetibilidade. O presente trabalho foi conduzido para caracterizar a herança da resistência de C. includens ao teflubenzuron em indivíduos expostos ao inseticida em campo. Para isso, pressões de seleção com o inseticida foram realizadas sobre as populações de campo a fim de selecionar em laboratório indivíduos resistentes homozigotos. Os estudos para observar a herança da resistência foram realizados a partir de cruzamentos recíprocos e retrocruzamentos entre uma população sabidamente suscetível e a população resistente de laboratório. A população resistente selecionada apresentou uma razão de resistência superior a 10.613 vezes, enquanto a razão de resistência para os cruzamentos recíprocos não ultrapassou 10 vezes. Porém, quando analisada em concentrações elevadas do inseticida, a mortalidade dos heterozigotos descendentes de machos resistentes não obteve incremento. A hipótese da herança ser monogênica foi rejeitada. Testes demonstraram que, em altas concentrações do inseticida, herança da resistência é completamente recessiva. Nossos resultados sugerem que a herança da resistência de C. includens ao teflubenzuron é ligada ao sexo, poligênica e recessiva.
The soybean looper, Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae), is among the main pests of soybean and a potential pest in cotton farms. In most cases, soybean looper management has been made by spraying insecticides in fields. Benzoylureas represent an important class of insecticides used for the management of lepidopteran species and the active ingredient teflubenzuron is widely adopted for the management of soybean looper. However, the intense and continuous use of this active ingredient is increasing the selection pressure in field and favored the selection of teflubenzuron resistant populations. To overcome this problem, Insect Resistance Management strategies must be employed to delay the evolution of resistance. Thus, studies to understand the pattern of inheritance of resistance are required to improve the scouting of resistant populations, allowing to track the evolution of resistance and to define the best strategy to reestablish susceptibility. The present work was conducted to investigate the inheritance of resistance to teflubenzuron in a laboratory-selected population of C. includens. For this, a population of C. includens resistant to teflubenzuron was selected in laboratory using field-collected insects. Inheritance pattern of resistance was observed using reciprocal crosses between a teflubenzuron-susceptible and a teflubenzuron-resistant population. The teflubenzuron-resistant population presented a resistance ratio greater than 10,613-fold, but the resistance ratio for the offspring of the reciprocal crosses was never bigger than 10-fold. In high insecticide concentrations, the offspring obtained from crosses of male from the resistant population and susceptible females, no increase in mortality was observed. The hypothesis of monogenic inheritance was rejected, and the inheritance was completely recessive. Results suggest that inheritance to teflubenzuron is sex-linked, polygenic and recessive in C. includens.
The soybean looper, Chrysodeixis includens (Walker, 1858) (Lepidoptera: Noctuidae), is among the main pests of soybean and a potential pest in cotton farms. In most cases, soybean looper management has been made by spraying insecticides in fields. Benzoylureas represent an important class of insecticides used for the management of lepidopteran species and the active ingredient teflubenzuron is widely adopted for the management of soybean looper. However, the intense and continuous use of this active ingredient is increasing the selection pressure in field and favored the selection of teflubenzuron resistant populations. To overcome this problem, Insect Resistance Management strategies must be employed to delay the evolution of resistance. Thus, studies to understand the pattern of inheritance of resistance are required to improve the scouting of resistant populations, allowing to track the evolution of resistance and to define the best strategy to reestablish susceptibility. The present work was conducted to investigate the inheritance of resistance to teflubenzuron in a laboratory-selected population of C. includens. For this, a population of C. includens resistant to teflubenzuron was selected in laboratory using field-collected insects. Inheritance pattern of resistance was observed using reciprocal crosses between a teflubenzuron-susceptible and a teflubenzuron-resistant population. The teflubenzuron-resistant population presented a resistance ratio greater than 10,613-fold, but the resistance ratio for the offspring of the reciprocal crosses was never bigger than 10-fold. In high insecticide concentrations, the offspring obtained from crosses of male from the resistant population and susceptible females, no increase in mortality was observed. The hypothesis of monogenic inheritance was rejected, and the inheritance was completely recessive. Results suggest that inheritance to teflubenzuron is sex-linked, polygenic and recessive in C. includens.
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Palavras-chave
Benzoilureias, Falsa medideira, Manejo da resistência de insetos, Herança ligada ao sexo