Geographic Origin and Host Dependent Metabolic Responses Affect Spodoptera frugiperda Susceptibility to Insecticides

Spodoptera frugiperda is one of the most harmful pest threatening crops in tropical regions. It is particularly difficult to control due to its high polyphagia, mobility and the evolution of resistance. One of the main strategies enabling this insect to extend its geographic range, is the expression of a wide repertoire of detoxification enzymes, that neutralizes diverse environmental xenobiotics as well as insecticides. Hence adaptation to particular ecological niches can lead to different enzyme expression which consequently may affect its control. Even though the molecular basis of adaption is well known, there is not much applied studies regarding the effect of the geographic region in S. frugiperda physiology and management. Thus, the objective of this work was to determine the activity of detoxification enzymes, as well as the susceptibility to insecticides of S. frugiperda from distinct geographic origins in local hosts plants. Larvae from Pelotas, a region characterized by crop succession with oats and maize and larvae from Cascavel, which is characterized by highly intensive maize systems thought the year were used in the experiments. Our study showed that only larvae from Pelotas had increased enzyme activity after feeding on oat plants. In most insecticide treatments, mortality increased on population Cascavel after feeding on oats, the same was not observed on larvae from Pelotas. Our results are in accordance with previous studies that pointed distinct geographic conditions could lead to genetic variability and different responses to control. Information on S. frugiperda dynamics is essential to develop local management programs as well to better understand the complex nature of plant-insect interactions.