In the present study we investigated the potential relative effects of bisphenol A (BPA) and RH-5992 (tebufenozide) on the development and metamorphosis of the corn stalk borer, Sesamia nonagrioides (Lepidoptera: Noctuidae). A number of morphological and molecular factors were examined in order to identify the toxic and the endocrine-relative action of these two chemicals. We observed that BPA, RH-5992 and the combination of BPA/RH-5992 caused a developmental delay by extending the transition period between larval and pupal instars. These chemicals also reduced adult emergence and caused molting malformations during development and metamorphosis. In the corn stalk borer, BPA exhibits ecdysteroid activities in a fashion similar to that of the ecdysone agonist RH-5992. These results suggest that exposure to environmentally relevant concentrations of BPA during the early stages of the corn borer's life cycle can result in various disorders that may be a consequence of endocrine disruption. The molecular mechanism by which BPA interferes with the physiological processes was also investigated. A significant induction was observed in the expression levels of the ecdysone-induced genes SnEcR and SnUSP, after injection of BPA and RH-5992. Additionally, we found that BPA acts as a very weak agonist of ecdysteroids in Bombyx mori derived Bm5 cell lines. From these cellular and molecular assays, our results brought evidence that BPA, like RH-5992, interferes with the ecdysteroidal pathways of the lepidopteran insect species.

In this study we examined the physiological impact of Bisphenol A on the developmental and reproductive processes of Sesamia nonagrioides (Lepidoptera: Noctuidae) under 16L:8D (long day, LD) and 10L:14D (short day, SD) photoperiods. Larvae were continuously exposed to different concentrations of BPA (1, 10 and 100 μg/L) applied in their artificial diets, under LD and SD conditions. During LD photoperiod increased pupal weights were observed in insects grown in culture media with the higher dose of 100 μg/L BPA. The morphological effects of BPA on the reproductive system of S. nonagrioides were also evaluated. Testis size was significantly decreased, while ovaries' size was increased in BPA-treated animals. The sex ratio shifted in favor of females when the larvae were exposed to BPA. During SD photoperiod the BPA exposure significantly decreased larval weight. Additionally, semi-quantitative RT-PCR analyses were used to identify the effects of BPA in the transcriptional regulation of heat shock protein genes SnoHsp20.8, SnoHsc70 and SnoHsp83 during SD conditions. During diapause Downloaded by [University of Otago] at 13:19 15 July 2015 A c c e p t e d M a n u s c r i p t 2 conditions, the expression levels of SnoHsp20.8 and SnoHsp83 were not affected by BPA, while SnoHsc70 mRNA levels were decreased.Here we observed a differential impact of BPA during non-diapausing and diapausing conditions. Our results revealed the physiological impact of environmentally relevant concentrations of BPA in S. nonagrioides.