Effects of lufenuron treatments on the growth and development of Spodoptera frugiperda (Lepidoptera: Noctuidae)

Lufenuron is an effective benzoylurea insecticide that inhibits the synthesis of chitin and regulates the growth of insects. However, little is known about the effects of lufenuron treatment on the development of Spodoptera frugiperda (J. E. Smith). In this study, we assessed the toxicity of lufenuron on S. frugiperda and evaluated the effects of lufenuron treatment on the growth and development of S. frugiperda. The results showed that lufenuron exhibits high insecticidal activity against S. frugiperda, with the LC50 value of 0.99 mg L−1. Lufenuron treatments can significantly prolong the larval developmental duration and reduce the rates of pupation and emergence. To further explore the underlying mechanism of this observation, the expression profiles of the chitin synthase gene (SfCHS) and chitinase gene (SfCHT), two key enzyme genes involved in the molting of S. frugiperda, were determined after exposure to lufenuron for 96 h. The results of qRT-PCR demonstrated that lufenuron treatments can significantly reduce the expression of SfCHT, while the expression of SfCHS remained relatively stable. Furthermore, we found that lufenuron strongly interacted with chitinase (SfCHT) (−10.8 kcal/mol) and chitin synthase (SfCHS) (R1: −9.7 kcal/mol; R2: −10.2 kcal/mol). Our results indicated that lufenuron has significant effects on the development of S. frugiperda that might be attributed to the differential expression of SfCHT and SfCHS.