A simple method to identify sex at pre-pupal stages of Spodoptera frugiperda (Lepidoptera: Noctuidae)

The sex of Lepidoptera species can typically be identified at the pupal or adult stage by their morphological characteristics. However, for most species, no obvious sex-specific traits can be used at the larval or embryonic stage. The growing interest in studying sex determination and differentiation, along with the potential application of research findings in genetic regulation techniques, is promoting the advancement of new sexing methods at early developmental stages. In this study, the sex of individual eggs and larvae was successfully identified by means of W chromosome molecular markers, which were identified through analysing the previously published W chromosome sequence data of Spodoptera frugiperda (Lepidoptera: Noctuidae). Additionally, we present methods to extract DNA and RNA from individual eggs and larval hemolymph. These techniques provide a simple and dependable method to identify sex at pre-pupal stages. This approach could potentially be extended to other Lepidoptera species of which the W chromosome information is available.