Screening test of Diatomaceous Earth as an alternative control method for Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) eggs

The sugarcane borer Diatraea saccharalis is a pest that causes damage to sugarcane fields. The female lays imbricated egg masses on the leave. They cause the greatest damage as larvae, and thus, control before egg hatching is desired to prevent the development of this pest and avoid damage to the plant. Diatomaceous Earth, or diatomite, is inert dust with insecticidal properties. In this work, we aimed to test the activity of Diatomaceous Earth on viable eggs of D. saccharalis as a potential alternative control method for sugarcane borer. D. saccharalis eggs 1 day after oviposition were immersed in a Diatomaceous Earth solution (10% - w/v) for 5, 10, or 15 min and observed every 24 h for 216 h of analysis. During the first 72 h, there were no changes observed in egg morphology, which maintained an oval shape, pale yellow in color. After 96 h, chorion striations were observed in the treatments with 10 and 15 min of exposure and were not present in the chorion controls eggs. Differences between embryo's number it was observed after 96h in the 15 min treatment when compared with the untreated eggs control. Besides that, control larvae completely hatched in 192 h and the treatment with 10 min and 15 min not shown completely hatching suggesting a delay in the embryonic development of the D. saccharalis larvae. Overall, our study is the first report of the application of D. saccharalis eggs, and we believe that Diatomaceous Earth could be a potential tool for the control of Diatraea eggs, however, thorough investigations are required to elucidate the action of this powder on Diatraea and would be an alternative method to interrupt the biological cycle of the pest.