Insecticide use is the prevailing control tactic for the mosquito Aedes aegypti, a vector of several human viruses, which leads to ever-increasing problems of insecticide resistance in populations of this insect pest species. The underlying mechanisms of insecticide resistance may be linked to the metabolism of insecticides by various cells, including oenocytes. Oenocytes are ectodermal cells responsible for lipid metabolism and detoxification. The goal of this study was to evaluate the sublethal effects of deltamethrin on survival, behavior, and oenocyte structure in the immature mosquitoes of insecticide-susceptible and resistant strains of A. aegypti. Fourth instar larvae (L4) of both strains were exposed to different concentrations of deltamethrin (i.e., 0.001, 0.003, 0.005, and 0.007 ppm). After exposure, L4 were subjected to behavioral bioassays. Insecticide effects on cell integrity after deltamethrin exposure (at 0.003 or 0.005 ppm) were assessed by processing pupal oenocytes for transmission electron microscopy or TUNEL reaction. The insecticide resistant L4 survived all the tested concentrations, whereas the 0.007-ppm deltamethrin concentration had lethal effects on susceptible L4. Susceptible L4 were lethargic and exhibited less swimming activity than unexposed larvae, whereas the resistant L4 were hyperexcited following exposure to 0.005 ppm deltamethrin. No sublethal effects and no significant cell death were observed in the oenocytes of either susceptible or resistant insects exposed to deltamethrin. The present study illustrated the different responses of susceptible and resistant strains of A. aegypti following exposure to sublethal concentration of deltamethrin, and demonstrated how the behavior of the immature stage of the two strains varied, as well as oenocyte structure following insecticide exposure.
Considerando as dificuldades que alguns alunos recém-ingressos na Universidade apresentam para compreender conceitos abstratos, este trabalho descreve um Curso de Extensão, na área de Biologia Celular, que foi realizado com o objetivo de contribuir com a aprendizagem efetiva de um grupo de graduandos da Universidade Federal de Viçosa (MG). O trabalho relata também a importância da experiência vivenciada para os pós-graduandos que ministraram o Curso. No Curso foram utilizadas atividades lúdicas diversificadas, escolhidas de acordo com o tema que seria abordado. Os resultados mostraram que o Curso foi muito bem aceito pelos graduandos, ajudando na compreensão dos conteúdos, através de um processo agradável e acessível, que viabilizou a construção dos saberes. Para os discentes da pós-graduação que ministraram o Curso, a experiência foi única e contribuiu para sua formação profissional dos mesmos. Portanto, a experiência foi significativa para todos os envolvidos.
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