LAUSR

BACKGROUND Itol A, extracted from the Itoa orientalis Hemsl. (Flacourtiaceae), possesses bioactivity on Spodoptera litura (Lepidoptera: Noctuidae) and Nilaparvata lugens (Stål) (Hemiptera: Delphacidae). Our previous study showed that the effects on Spodoptera frugiperda, a destructive pest found worldwide, were similar to those of fenoxycarb (FC), a juvenile hormone analog (JHA). Thus, we speculate that itol A could have growth-regulating effects. The current work explored juvenile hormone (JH) levels and mRNA levels of crucial JH signaling pathway enzyme genes in S. frugiperda larvae treated with itol A and FC. RESULTS Itol A caused severe growth obstacles in S. frugiperda, extended the larval duration and reduced the mean worm weight and body length rates. 3 and 7 d after exposure to a sublethal concentration of itol A (500 mg/L), the JH level of the larvae significantly decreased by 36.59% and 22.70%, respectively. qPCR inferred that the mRNA expression levels of crucial JH metabolism enzymes (SfJHE and SfJHEH) significantly raised by 6.58-fold and 2.12-fold, respectively, relative to the control group 3 d after treatment. CONCLUSIONS Itol A adversely affects the development of S. frugiperda, We propose that this effect was caused by decreasing JH levels and disrupting the JH signaling pathway via mediating its synthetic and metabolic. This article is protected by copyright. All rights reserved.