Effects of NaCl stress on the biochemical substances in Bt cotton as well as on the growth and development and adult oviposition selectivity of Helicoverpa armigera

Background Recently, due to the development of food security strategies, cotton has been planted in inland saline-alkali dry soils or in coastal some saline-alkali soils in China. Under the condition, to comprehensively prevent and control Helicoverpa armigera in cotton fields with saline-alkali soils, it is important to study the larval growth and development of H. armigera and to study adult oviposition selectivity in H. armigera adults that feed on NaCl-stressed cotton plants. Results In this study, Bt cotton GK19 was used for the experimental group and its nontransgenic parent Simian 3 was used for the control to study the effects of biochemical substances in cotton as well as larval growth and development and adult oviposition selectivity of H. armigera. The experiments were performed by growing cotton indoors under NaCl stress at concentrations of 0 mmol·L− 1, 75 mmol·L− 1 and 150 mmol·L− 1, respectively. The results showed that the expression of Bt protein was significantly inhibited for NaCl-stressed Bt cotton. The content of soluble protein and K+ in the leaves of cotton were decreased, while the content of gossypol and Na+ were increased. In addition, the 5th instar H. armigera larvae exhibited shorten the life span in a 13-day trial period. Under enclosure treatments and at different female densities, the adult oviposition of H. armigera decreased on high NaCl-stressed nontransgenic cotton, while the oviposition on Bt cotton tended to first increase but then decrease under low, moderate and high NaCl stress treatments. Conclusions Under certain content ranges of NaCl stress treatments, larval of H. armigera growth and development, and adult oviposition were no significant difference in the change for a certain period. However, under high NaCl stress, larval growth, development and adult oviposition were affected, which may provide insights for the prevention and control of H. armigera for Bt cotton in saline-alkali soils.